articles+ search results

Ti 6Al–4V alloy, Zirconia, Co–Cr–Mo alloy additive manufacturing, Osteoarthritis, Knee joint, FDM, Internal medicine, RC31-1245, Surgery, and RD1-811

Additive manufacturing (Rapid Prototyping) is a significant innovation in medical field. It allows scientists to create custom-made parts that are often more precise and robust than their standard counterparts. Osteoarthritis (OA) is very common and serious problems in aging people. It is a progressive disease that affects the cartilage, the substance that cushions the bones and joints. Artificial knee joints are being developed as a sort of replacement for the human knee joint. One of the most intricate parts of the human body is the knee joint. This complex joint comprises of a ball-and-socket relationship, which is a very difficult part of the anatomy to design. The joint consists of both the kneecap and the Cartilage, and it has been designed with the intention of having the joint supported by a bone, rather than a cartilage. In this review article the results of a recent study, which was performed by researchers from the various renowned universities of Europe & United States of America over Artificial Knee Joint by Additive Manufacturing Technology.

Digital mental health, Human-centered design, Methodology, Information technology, T58.5-58.64, Psychology, and BF1-990

As digital mental health interventions (DMHIs) proliferate, there is a growing need to understand the complexities of moving these tools from concept and design to service-ready products. We highlight five case studies from a center that specializes in the design and evaluation of digital mental health interventions to illustrate pragmatic approaches to the development of digital mental health interventions, and to make transparent some of the key decision points researchers encounter along the design-to-product pipeline. Case studies cover different key points in the design process and focus on partnership building, understanding the problem or opportunity, prototyping the product or service, and testing the product or service. We illustrate lessons learned and offer a series of questions researchers can use to navigate key decision points in the digital mental health intervention (DMHI) development process.

3d food printing, extrusion, food waste, sustainability, dysphagia, hydrocolloids, Science, Manufactures, and TS1-2301

Food waste utilisation and zero waste approach are among the many ways of building a sustainable economy. Food waste as authentic edible food being accepted by the consumers still has many barriers to overcome. One tool to help in the valorisation of food waste to value-added products is three-dimensional food printing (3DFP). These products can lead to easier and greater acceptance of food waste by consumers, having familiar nature with respect to taste, texture and appearance as other consumables. In the present study, food ink recipes were formulated from spinach stems and kale stalks, the common green leafy vegetable wastes. These spinach and kale inks were then characterised on their rheological properties of shear thinning and yield stress. The inks were subjected to IDDSI tests meant for standardisation of soft foods for dysphagia patients. This paper demonstrates ways of converting vegetable wastes into edible diets that are aesthetically pleasing through 3DFP.

3d printing, additive manufacturing, cooperative robots, mobile robots, teams of robots, cooperative printing, Science, Manufactures, and TS1-2301

Additive manufacturing (AM) is a key enabler and technological pillar of the fourth industrial revolution (Industry 4.0) as it increases productivity and improves resource efficiency. However, current AM systems present some limitations in terms of fabrication time, versatility, and efficiency. The concept of teams of robots represents a novel approach for AM aiming to address these limitations. This review paper discusses the current state-of-the-art of the use of cooperative AM systems based on gantry systems, robotic arms, and mobile robots. The information flow, path planning and slicing strategies are discussed in detail, and several examples of the use of cooperative AM systems are provided. Finally, major research challenges and future perspectives are discussed.

miniaturisation, compliant mechanisms, customization, design automation, design synthesis, Science, Manufactures, and TS1-2301

Micro-additive manufacturing techniques have the potential to meet the demand for miniaturised functional components for minimally invasive surgical instruments. These techniques create monolithic, compliant mechanisms with micro-sized free-form structures that can be tailored to patient-specific surgical procedures. The automated design synthesis of the mechanisms using building blocks results in structures that are shape-programmable. This is achieved through an algorithmic-based computational workflow, which automatically converts user-specified 2D and 3D curves into discrete curve segments. The actuated motion of the mechanisms can be designed to move in a specific way, both forwardly and inversely. The mechanisms are manufactured using micro-laser powder bed fusion and hardenable stainless steel 17-4 PH. By carefully selecting the process parameters, it is possible to 3D-print micro-sized features such as a compliant beam thickness of 80 μm and an actuation hole of 100 μm. Both 2D planar curved mechanisms and 3D spatial curved mechanisms have been implemented and experimentally validated.

laser powder bed fusion, 3d-printing, automation, compliant mechanisms, design synthesis, design freedom, Science, Manufactures, and TS1-2301

Additive manufacturing (AM) facilitates the fabrication of compliant mechanisms through its free-form and design customisation capabilities. Specifically, the properties of kinetic mechanisms such as springs can be extended with regards to their inherent (non-)linear stiffness functions. This allows for the customisation of AM springs according to user preferences. By combining the design synthesis approach of building blocks with the structural optimisation approach for AM, it is possible to define and customise spring stiffness functionalities. The optimisation process employs an automated computational framework based on a genetic algorithm scheme, which has been demonstrated through randomised and reference case studies. This framework enables the attainment of linear, progressive (stiffening), and degressive (softening) stiffness curves. The manufacturability of the springs has been validated through laser powder bed fusion using stainless-steel material 17–4 PH (H900). The springs have resulted in an accuracy error of maximum 6.48% and precision error of maximum 5% through compression testing.

bainitic crossing nose, functionally graded material (fmg), laser directed energy deposition (l-ded), microstructure, wear and rolling contact fatigue (rcf) resistance, Science, Manufactures, and TS1-2301

In this paper, 20Mn2SiCrMo bainitic crossing noses were repaired by depositing 420SS, Stellite 6, 17-4PH and 18Ni300 alloys on the rail surfaces to form functionally graded materials (FGM) using laser directed energy deposition (L-DED) technology. As a result, only 18Ni300 deposit achieves an excellent strength-toughness combination, which possesses a yield strength of ∼1120 MPa together with an impact energy of ∼85.05 J, better than those of substrates (∼1071 MPa, ∼71.34 J). Besides, the wear and rolling contact fatigue (RCF) resistance of 20Mn2SiCrMo/18Ni300 FGM is enhanced to 2.7 and 23.6 times as much as those of substrates. Massive ultrafine nanoprecipitates and a small amount of austenite make 18Ni300 deposit strong enough as well as a certain work-hardenability, ensuring good wear resistance therein; the significant RCF resistance originates from the improved shakedown limit. Therefore, all findings reveal that 18Ni300 is the most promising depositing material for repairing bainitic crossing noses by L-DED.

additive manufacturing, sensor data fusion, thermal imaging, spatter monitoring, shape agnostic monitoring, porosity, Science, Manufactures, and TS1-2301

We developed and applied a novel approach for shape agnostic detection of multiscale flaws in laser powder bed fusion (LPBF) additive manufacturing using heterogenous in-situ sensor data. Flaws in LPBF range from porosity at the micro-scale (< 100 µm), layer related inconsistencies at the meso-scale (100 µm to 1 mm) and geometry-related flaws at the macroscale (> 1 mm). Existing data-driven models are primarily focused on detecting a specific type of LPBF flaw using signals from one type of sensor. Such approaches, which are trained on data from simple cuboid and cylindrical-shaped coupons, have met limited success when used for detecting multiscale flaws in complex LPBF parts. The objective of this work is to develop a heterogenous sensor data fusion approach capable of detecting multiscale flaws across different LPBF part geometries and build conditions. Accordingly, data from an infrared camera, spatter imaging camera, and optical powder bed imaging camera were acquired across separate builds with differing part geometries and orientations (Inconel 718). Spectral graph-based process signatures were extracted from this heterogeneous thermo-optical sensor data and used as inputs to simple machine learning models. The approach detected porosity, layer-level distortion, and geometry-related flaws with statistical fidelity exceeding 93% (F-score).

negative poisson’s ratio, triply periodic minimal surfaces, auxetic structure, bone implant, hip joint, Science, Manufactures, and TS1-2301

Based on the triply periodic minimal surface (TPMS), 3D auxetic structures are successfully implemented using a dual-period function. A series of shape-controllable, dual-period deformation functions are obtained by summarising the characteristics of periodic deformation functions and applying Bezier curve fitting methods. Then, with the geometry originating from the Schwarz primitive (P) of TPMS, the periodic shape transformation of TPMS is achieved using the dual-period deformation functions. The property (negative Poisson’s ratio) of the auxetic structure is investigated based on the control parameters (the TPMS c value, periodic function η, and deformation index γ). The auxetic structures can exhibit excellent 3D negative Poisson’s ratio properties, and the Poisson’s ratio can be effectively adjusted. Moreover, a heterostructure with positive and negative Poisson’s ratio structures is obtained and applied to a stem in the hip joint. The simulation proves that the heterostructure can effectively prevent the failure of the bone implant.

terahertz, metamaterials, 3d printing, mortise and tenon structures, reconfigurable multi-functional, Science, Manufactures, and TS1-2301

The emergence of metamaterial has provided an unprecedented ability to manipulate electromagnetic waves, especially in the terahertz band where there is a lack of natural response materials. However, most metamaterials are fixed single function due to the fixed structure at the beginning of design. The paper reports a reconfigurable multi-functional terahertz metamaterial with variable structures based on mortise and tenon mechanism. And a hybrid 3D printing method based on FDM and E-jet is proposed to fabricate the metamaterials, which simplifies the processing process, improves the speed, and reduces the cost compared to traditional semiconductor processing methods. Through flexible mortise and tenon connections, the metamaterial can achieve: (1) narrowband transmission and broadband absorption; (2) perfect reflection; (3) narrowband reflection and broadband absorption. Relying on ingenious design and processing, the multi-functional metamaterials are expected to be widely used in fields such as electromagnetic shielding, radar stealth, communication and so on.

design workflow, scaffolds, patient-specific, 3d printing, generative design, voronoi, scaffold-guided bone regeneration, Science, Manufactures, and TS1-2301

A streamlined design workflow that facilitates the efficient design and manufacture of patient-specific scaffolds independently applied by the surgical team has been recognised as a key step in a holistic approach towards the envisioned routine clinical translation of scaffold-guided bone regeneration (SGBR). A modular design workflow was developed to semi-automatically fill defect cavities, ensure patient specificity and ideal surgical scaffold insertion for a given surgical approach, add fixation points to secure the scaffolds to the host bone and generate scaffold based on Voronoi, periodic lattice and triply periodic minimal surface pore architectures. The adopted functional representation modelling technique produces models free from 3D printing mesh errors. It was applied to a clinical case of a complicated femoral bone defect. All models were free from mesh errors and the patient-specific fit and unobstructive insertion were validated via digital inspection and physical investigation by way of 3D printed prototypes. The real-time responsiveness of the workflow to user input allows the designer to receive real-time feedback from the surgeon, which is associated with reducing the time to finalise a patient-specific scaffold design. In summary, an efficient workflow was developed that substantially facilitates routine clinical implementation of SGBR through its ability to streamline the design of 3D printed scaffolds.

zirconium alloy, zr-4, additive manufacturing, laser powder bed fusion, annealing, Science, Manufactures, and TS1-2301

Zirconium (Zr) alloys are widely used in nuclear energy because of their excellent mechanical properties and low thermal neutron absorption cross-section. This work investigated the printability, microstructure, and mechanical properties of Zr-4 alloy additively manufactured by laser powder bed fusion (LPBF) for the first time. The effect of annealing temperature on the microstructural and the mechanical property evolution of the printed Zr-4 alloy was studied. The results exhibited that the Zr-4 alloy with a high relative density of 99.77% was obtained using optimised printing parameters. With an increase in the annealing temperature, the formed α phase of the Zr-4 alloy changed from an acicular shape to a coarse-twisted shape, and finally to an equiaxed shape. Such microstructure change endowed the alloy with a high compressive strength of 2130 MPa and compressive strain of 36%. When the annealing temperature exceeded 700°C, Zrx(Fe2Cr) compounds were precipitated, strengthening the alloy by pinning effect. These findings provide valuable guidance for the manufacture of geometrically complex Zr alloy parts for nuclear power applications.

wire and arc additive manufacturing (waam), recursive bead profile, multi-bead overlapping model, axisymmetric drop shape analysis (adsa), surface topography, Science, Manufactures, and TS1-2301

Dimension prediction of robotic wire and arc additive manufacturing (WAAM) part is fundamentally dependent on the modelling accuracy of single-bead profile and its subsequent overlapping ones. Current multi-bead overlapping models are still not capable of describing the flatten valley area of WAAM parts. This paper proposes a new recursive model, based on coordinate transformation and axisymmetric drop shape analysis (ADSA), to predict multi-bead overlapping profiles. First, a single-bead profile model for WAAM is established based on ADSA, followed by detailed description of conventional and proposed modified recursive ADSA profile model. The properties of developed recursive ADSA model are then investigated to reveal the effects of overlapping ratio and single-bead aspect ratio. Finally, multi-bead overlapping deposition experiment is carried out to validate the model feasibility. The results show that the modified recursive ADSA model is more accurate than the conventional one for its better accountability of valley areas. It is also indicated that the modified recursive ADSA model is suitable for the robotic WAAM process. The research outcome is beneficial to improving the forming accuracy of WAAM parts and geometry prediction of other additive manufactured products.

al-sc alloys, heat treatment, laser powder bed fusion (lpbf), strengthening mechanism, Science, Manufactures, and TS1-2301

According to the material nature, aluminium alloys are widely applied in aerospace, construction and automotive applications due to their characteristics, such as lightweight, good formability and good corrosion resistance. Among the aluminium alloys, scalmalloy (Al-4.49Mg-0.71Sc-0.51Mn-0.27Zr-0.07Fe-0.03Si alloy) was developed to overcome the hot crack issue during the laser powder bed fusion (LPBF) process. Hence, the degree of lightweight can be further improved by introducing this high-specific strength material with a structure of the lightweight design. However, the strengthening mechanism of the heat-treated 3D printed scalmalloy has not been sufficiently explored. In this study, the synergistic effect of the strengthening mechanisms is explored through detailed microstructure analysis. The grain size, size and spacing of the precipitate and coherent phase contribute to the strengthening of scalmalloy. Through the observation of the microstructure feature, the theoretical strength of the heat-treated 3D printed scalmalloy can thus be calculated by three strengthening mechanisms and match the experimental results perfectly.

mechanical alloying, selective laser melting, amorphous/crystalline, zn60zr40 alloys, mechanical properties, Science, Manufactures, and TS1-2301

In the present study, mechanical alloying (MA) was employed for synthesising non-equilibrium Zn60Zr40 amorphous powders, and then consolidated into amorphous/crystalline Zn60Zr40 alloys using selective laser melting (SLM). The results showed that the MA process destabilised the atomic periodicity of Zn and Zr powders and induced crystalline-to-amorphous transformation due to atomic size mismatch and negative heat of mixing. Moreover, the amorphisation trend of as-milled powders was intensified with increasing milling time and attained almost fully amorphous structure after 30 h of milling. During SLM, the ultra-high cooling rate restricted the long-range atomic diffusion of the amorphous powders and enabled successful survival of amorphous phase, leading to amorphous/crystalline Zn60Zr40 alloys. The alloys exhibited a maximum compressive yield strength and microhardness of 160.9 ± 9.1 MPa and 3.73 ± 0.8 GPa, respectively. These findings demonstrated that the developed MA-SLM process might be a promising strategy for the preparation of amorphous/crystalline alloys with superior properties.

invar 36 alloy, laser powder bed fusion, high cycle fatigue, microstructures, defects, Science, Manufactures, and TS1-2301

The Invar 36 alloy was additively manufactured by laser powder bed fusion (PBF-LB), and systematical observations and experiments for microstructure, defects, metallography, especially high cycle fatigue behaviour and fractography were conducted. Inadequate laser energy density results in hardly overlapping melting traces, generating numerous defects. Accordingly, the fabricated Invar 36 alloy presents an inferior high cycle fatigue life, as it failures from the rapid aggregation of the defects. In contrast, an adequate laser energy density remarkably enlarges the overlapping between adjacent melting traces. The large molten pools with steady boundaries are beneficially to generate favourable microstructures and low porosity. Consequently, the Invar 36 alloy shows superior high cycle fatigue life, completely generated from small crack propagation, long crack propagation and final fracture stages. Above experimental results and analysis primarily link up the PBF-LB process, microstructures (defects) and high cycle fatigue performance for PBF-LB Invar 36 alloy.

4d printing, additive manufacturing, energy absorption, shape memory materials, recoverability, crashworthiness performance, Science, Manufactures, and TS1-2301

The emergence of 4D printing from additive manufacturing has opened new frontiers in crashworthiness application. Energy-absorbing structures with fixed geometrical shapes and irreversible deformation stages can be programmed such that after mild or extreme deformation, their initial shapes, properties and functionalities can be recovered with time when actuated by external stimuli. This survey delves into the recently-accelerated progress of shape memory/recovery energy-absorbing metamaterials (EAMM) and energy-absorbing smart/intelligent structures (EASS). First, the introduction gives some fundamental concepts of metamaterials and their application to energy-absorbing structures. Next, some common 3D printing technologies that have led to 4D printed EAMM and EASS are succinctly described. Shape memory materials, their functional properties and recovery process, are then discussed. Finally, various recoverable/reversible energy absorbers with their future challenges and perspectives, are presented. With well-tailored 4D printed EAMM and EASS, reusability with minimal maintenance and higher energy absorption capacity can be retained.

laser powder bed fusion, overhang, downskin, high-speed thermal imaging, homography, parameter optimization, Science, Manufactures, and TS1-2301

One of the most revolutionary aspects of Laser Powder Bed Fusion (LPBF) is to be able to lift the design constraints from conventional manufacturing. However, as a rule of thumb, any surfaces lower than 45° with respect to the horizontal plane would still require sacrificial supports in order to complete the printing. Fundamentally, it is unclear whether it is feasible to print a 1st layer 0° overhang nor how the print parameters for the 1st layer can be optimised. This research demonstrates that large 1st layer 0° overhangs can be printed with a coverage above 90%. For the first time, the parameter space of laser power, scan speed and hatch spacing for the 1st layer has been simultaneously explored efficiently. The use of the rate of change of the mushy zone is proposed for the parameter selection instead of the average melt pool temperature. Adaptive Parameter 28 (AP28: 250W_4000 mm/s_50 µm) is the best choice. Several surface morphological phenomena are discussed. The core parameter (285W_960 mm/s_110 µm) causes severe balling and its mechanism is revealed. The average melt pool temperature of the 1st layer by the core parameter is lower than that of the bulk. The ramifications beyond the 1st layer are also illustrated.

hybrid rocket engine, additive manufacturing/three-dimensional printing, breathable blade, composite fuel grain, mechanical and combustion properties, porous structure, Science, Manufactures, and TS1-2301

Hybrid rocket engines suffer from the restricted mechanical properties and low regression rates of current polymeric fuel grains. We propose a three-dimensional printed aluminium (Al) nested composite fuel grain with millimetre-scale lattice pores (referred to as Al-L). In this study, breathable Al blades with micrometer-scale interconnected pores (Al-B) and blades combining millimetre-scale and micrometer-scale pores (Al-B&L) are designed. The formation mechanisms, characteristics, and effects of the breathable blades are analysed in simulations, micro-computed tomography, and cyclic compression tests. The mechanical properties of the composite fuel grains are investigated numerically and in compression tests. Al-B has the highest Young’s modulus at more than 15 times that of a paraffin-based fuel grain and Al-B&L has the highest yield stress at 4 times that of the paraffin-based fuel grain. Referring to combustion properties, the regression rates of the Al-B and Al-B&L grains are respectively 63.3% and 58.2% greater than the regression rate of the paraffin-based fuel grain.

wire arc additive manufacturing, mg-gd-y-zr alloy, heat treatment, microstructure evolution, mechanical properties, Science, Manufactures, and TS1-2301

A detailed and systematic investigation on the effect post heat treatment has on the microstructure evolution and the resultant mechanical properties of the wire arc additive manufacturing processed Mg-5.9Gd-2.8Y-0.7Zr alloy is conducted in this work. The microstructure of the as-built sample is composed mainly of fine equiaxed α-Mg grain and Mg24(Gd, Y)5 phase. The solution heat treatment (400°C × 1 h) has relatively little effect on grain size, but it can effectively reduce the content of the Mg24(Gd, Y)5 phase, which leads to a significantly improved elongation with slightly decreased strength. Further ageing heat treatment at 200°C induces prismatic βʹ precipitates formation and does not influence other phases and grain size. The samples directly following the peak ageing heat treatment process demonstrate the best tensile properties with yield strength of 227 ± 9 MPa, ultimate tensile strength of 350 ± 4 MPa and elongation of 5.5 ± 0.6%.

multi-photon photopolymerisation, laser direct writing, order of absorption, tunable wavelength, group delay dispersion, resolution bridges, Science, Manufactures, and TS1-2301

Multiphoton photopolymerisation (MPP), also known as 3D nanoprinting, was studied using a wavelength-tunable femtosecond laser. The possibility of using any colour of the spectrum from 500 to 1200 nm with a fixed pulse width of 100 fs revealed an interplay of photophysical mechanisms more delicate than just two-photon photopolymerisation. An effective order of absorption, i.e. the X-photon absorption, as well as optimal exposure conditions were assessed for photosensitised and pure SZ2080$^{{\rm TM}}$ pre-polymer. The tunability of wavelength greatly influenced the dynamic fabrication window (DFW), optimised conditions resulting in a 10-fold increase. Furthermore, a non-trivial energy deposition by X-photon absorption was noted with an onset of a strong lateral size increase at longer wavelengths and can be understood as due to reaching epsilon-near-zero conditions. Such a control over the voxel aspect ratio and, consequently, the photopolymerised volume, may boost 3D nanoprinting efficiency. Overall, the results reveal wavelength being an important degree of freedom to tailor the MPP process and, if optimised, benefiting broad applications in areas of micro-optics, nanophotonic devices, metamaterials and tissue engineering.

additive manufacturing, cellular materials, lattice structures, metamaterials, fused filament fabrication, Science, Manufactures, and TS1-2301

One of the areas that have benefited the most from the advent of additive manufacturing is the development of customized cellular materials, scaffolds and lattices. Although these different groups of materials are typically considered separately, they can be categorized as mechanical metamaterials. Among the different additive manufacturing techniques, perhaps the most popular is that of Fused Filament Fabrication. Numerous works have been reported in the literature in which this fabrication technique has been used to produce such materials. Inspired by the increasing volume of work dealing with the subject, we present a review of the manufacturing and characterization of cellular and lattice-based mechanical metamaterials using Fused Filament Fabrication. An overview of the topologies, their effective mechanical properties and intrinsic manufacturing aspects are presented. The methods for failure analysis at different scales are also discussed. Finally, studies comparing the production of mechanical metamaterials using Fused Filament Fabrication and other additive manufacturing techniques are presented, in addition to recommendations and current trends in the production of these structures by Fused Filament Fabrication.

cationic photoinitiators, photopolymerisation, photopolymerisation kinetics, 3d printing, photo-cured composites, photoinitiating systems, Science, Manufactures, and TS1-2301

In this article, the application of 10 new amino-m-terphenyls in 3D-VAT printing was described. New compounds have specially designed D-π-A structure, where the central phenyl ring with nitrile and amino groups is the acceptor and the modifiable amino group is donor. Such design eliminates problem with acid scavenging and guaranteed desire properties and photoactivity as well as it allows further development of such system for 3D-VAT printing. Efficient excitation with intramolecular charge transfer provides excellent absorption and electrochemical properties, which can be tuned by modification of the amino group. The design allows photoinitiation of free radical, hybrid and especially cationic polymerisation even at 455 nm with more than 70% of monomer conversion. Such properties allow to use the developed compounds as efficient visible light photoinitiators for 3D printing of nanocomposite materials. The terphenyls can efficiently cure resins containing CuO and Al2O3 nano additives leading to high-resolution 3D prints.

titanium, β-tricalcium phosphate, direct ink writing, composite porous scaffold, Science, Manufactures, and TS1-2301

A Ti/β-TCP composite porous scaffold with a hierarchical pore structure composed of 3D printed interconnected macroscopic pores and sintered microscopic pores was prepared by direct ink writing (DIW) 3D printing technology. This method can control the extrusion of composite ink at room temperature and produce a 3D scaffold using layer-by-layer deposition. We studied the effects of the β-TCP powder particle size, β-TCP/Ti powder ratio and solid loading on the rheological properties of the ink and optimised the DIW printing process parameters. After sintering, the compressive strength and elastic modulus of the composite scaffold reached 45 MPa and 1 GPa, which is close to the strength of human cancellous bone. The cell culture experiment confirmed that the composite scaffold had better biological properties than the pure titanium scaffold. The composite scaffold has satisfactory mechanical and biological properties, meeting the requirements for orthopaedic implants.

robotic system, grid-stiffened shell structure, continuous fibre-reinforced polymer additive manufacturing, surface conformal toolpath, Science, Manufactures, and TS1-2301

The advents in continuous fibre-reinforced polymer additive manufacturing (CFRP-AM) present unprecedented opportunities for the rapid development of next-generation high-performance composites with selectively and spatially distributed reinforcement. However, the widely adopted 3-degree-of-freedom motion configuration in current CFRP-AM systems hinders the exploration of composite structures with non-planar fibre layouts. This work presents a novel conformal CFRP-AM system to fabricate grid-stiffened shell structures leveraging its multi-DoF motion to pattern spatial features. The system integrates a 6-axis robot with an optimally designed co-extrusion module and operates through a design-to-manufacturing workflow. The proposed workflow includes three steps: system calibration, conformal toolpath generation, and process implementation. The conformal toolpath generation is a surface-mapping-based method that allows a simultaneous exploration of various geometric designs and their toolpaths. Experimental comparisons were made between parts fabricated by different processes, i.e., planar and conformal based, with different toolpaths, i.e., shells filled with zigzag and arc-offset patterns, and with various geometric designs, i.e., stiffener ribs with different crossline angles. The results manifest that the proposed system can significantly improve the compression strength and stiffness of grid-stiffened shell structures. Meanwhile, the additional design freedom on process and structure opens up a new possibility to customise their mechanical performance.

vat photopolymerization (vpp), superamphiphobic interface, rapid moulding, Science, Manufactures, and TS1-2301

Vat photopolymerization (VPP) is one of the convenient methods to create high-precision parts; however, due to the significant adhesion between the cured layer of the photopolymer resin and the release film, the currently prevalent VPP equipment is less productive and thus challenging in achieving production on a large scale. To tackle the issues above, a facile method is utilised to produce a transparent film capable of effectively resisting the photopolymer resin. Such film is achieved by incorporating micron-nanometre layered rough features and low surface energy materials onto the surface of quartz glass. It allows innovative applications in speedy VPP processes, achieving a printing speed of up to 323 mm/h in an LCD (Liquid Crystal Display) 3D printer while maintaining sound accuracy, exceptional durability and fair applicability, thanks to the features of the prepared film. The presented approach provides new perspectives into the production and application of VPP technology.

al–mn–mg–sc–zr alloy, laser powder bed fusion, fabrication rate, layer thickness, high strength, Science, Manufactures, and TS1-2301

The high cost of laser powder bed fusion (LPBF) fabricated high-strength Sc containing aluminium alloy hinders its applications. To reduce the cost, we reported a LPBF fabricated strong and ductile Al–Mn–Mg–Sc–Zr alloy using large layer thicknesses to improve the fabrication efficiency on coarse powder particles. A high relative density exceeding 99.2% was achieved at layer thicknesses up to 120 μm. In post-process heat-treated specimens, the yield strength only had a slight 6% decrease from layer thickness of 30 to 120 μm; such a decrease in strength was attributed to the larger grain size resulted from the adopted larger layer thickness. The fabricated sample at layer thickness of 120 μm still exhibited high tensile yield strength of 472 MPa and fracture strain of ∼10%. This work showed a successful application of improving the LPBF fabrication efficiency of high-strength Al–Mn–Mg–Sc–Zr alloy using large layer thickness in LPBF process.

direct laser writing, photopolymerization, multi-photon polymerisation, femtosecond projection, nanoscale 3d printing, Science, Manufactures, and TS1-2301

Large and deterministic 3D structures with nanoscale features and porosities are valuable for various applications but are challenging to print due to the proximity effects that lead to the merging of adjacently printed features. Here, this challenge has been overcome by minimising the proximity effects in projection two-photon lithography (P-TPL), which is a high-throughput photopolymerization-based 3D printing technique. Through empirical studies and physics-based computational models, it is demonstrated that the proximity effects arise from distinct optical and chemical sources. Processing conditions that individually minimise these sources have been identified. These insights have been leveraged to generate an interspersing P-TPL technique capable of rapidly printing 3D structures with features smaller than 300 nm, pores finer than 700 nm, and at rates greater than 0.5 mm2/s per layer. As interspersing P-TPL is up to 50 times faster than conventional point-scanning TPL, it can enable the scalable printing of nanoporous 3D structures.

laser powder bed fusion, crystal-inspired structure, hybrid lattice structure, mechanical property, structural feature sensitivity, Science, Manufactures, and TS1-2301

Node-strengthened hybrid structures with lower relative density inspired by solid solution strengthening mechanism, namely the edge center interstitial lattice (ECIL) structures and vertex node substitutional lattice (VNSL) structures were designed and fabricated by laser powder bed fusion (LPBF). The geometric feature-dependent defects distribution, the intense microstructure sensitivity as well as the node size effect on the mechanical response were investigated. The microstructure sensitivity induced by geometric feature was found to be related to the different supporting condition and distinctive thermal history. ECIL-1.5 structure possessed the highest plateau stress of 1.79 MPa and the largest crush force efficiency of 59.1%, which increased by 59.8% and 15.2% compared to the initial face centre cubic with z-struts (FCCZ)structure. VNSL-1.5 exhibited the greatest specific energy absorption of 14.6 J/g, demonstrating the highest strengthening efficiency was achieved at the critical sphere diameter to strut thickness (Sph-strut) ratio of 3. This method further improved lightweight efficiency, indicating the inherent strengthening mechanism of crystal materials could guide the design of metamaterials.

gas flow direction, laser powder bed fusion, crystallographic orientation, scan strategy, thermal conductivity, Science, Manufactures, and TS1-2301

This study demonstrated that the gas flow direction in the laser beam powder bed fusion (PBF-LB) significantly affects the crystallographic texture evolved in the products. The effect on texture is attributed to the difference in the melt pool depth, which depends on gas flow direction. The melt pool was shallower when the laser scanning and gas flow directions were parallel than when they were perpendicular. This phenomenon should be of particular concern when applying Scan Strategy_XY wherein the laser was scanned with a 90° rotation in each layer, which is often used in PBF-LB. The asymmetry in the melt pool depth generated by laser scanning in the x- and y-directions can lead to unintended variations in the crystallographic texture. The gas phase would interact with a part being manufactured immediately beneath the gas and affect the crystallographic feature of the product.

tensile test, miniature specimens, additive manufacturing, local mechanical properties, Science, Manufactures, and TS1-2301

The various process-specific differences in techniques compared to traditional techniques can produce significantly different mechanical behaviour in additively manufactured (AM) parts compared to traditional bulk counterparts. Components produced by AM are built layer by layer via localised melting. Therefore, both location- and orientation-dependent properties can be expected. Since many AM parts take advantage of the design and topology freedom provided by AM, properties characterisation with the use of standard specimens is not always possible, requiring the use of small-sized specimen techniques. In the current paper, three AM-produced IN-718, Ti-6Al-4V and H13 parts using electron beam powder bed fusion and laser powder bed fusion are evaluated. Local mechanical properties have been assessed with the use of mini-tensile tests that were developed for cases where limited amounts of material are available. The results obtained demonstrate the ability to measure location- and orientation-dependent properties in AM components using such approaches and highlight that additional work by the AM community remains in order to determine the source(s) of such differences.

vat photopolymerisation, smart materials, laser ablation in liquids, feni, magnetic nanoparticles, millirobots, Science, Manufactures, and TS1-2301

Masked stereolithography printing can be used to produce functionalised magneto-responsive polymer structures. Magnetic filler additivation of the photopolymer enables the production of powerful and fast soft robotics. However, current approaches require high filler concentrations, reducing the mechanical properties and compromising the processability. In this study, FeNi nanoparticles were added to a photopolymer to take advantage of their soft magnetic response and high magnetisation. Field-assisted printing gives rise to magnetic anisotropy by arranging laser-synthesised FeNi nanoparticles into uniaxial magnetic strands of up to 500 μm length. Favoured by the small size and even distribution of the nanoparticles, only 0.02 wt% are needed to detect magnetic responsivity. Thus, the impact on the mechanical property is reduced while facilitating the control over the composite magnetic properties. The practical feasibility of the composites is demonstrated by actuating gripper and impeller structures which offer possibilities in applications like drug delivery and tissue engineering.

laser powder bed fusion, spark plasma sintering, niti alloys, superelasticity, healing crack, Science, Manufactures, and TS1-2301

The pursuit of enhancing NiTi superelasticity through laser powder bed fusion (L-PBF) and [001] texture creation poses a challenge due to increased susceptibility to hot cracking in the resulting microstructure with columnar grains. This limitation restricts NiTi's application and contributes to material waste. To overcome this, we introduce a pioneering approach: utilising spark plasma sintering (SPS) to heal directional cracks in [001] textured L-PBF NiTi shape memory alloy. Diffusion bonding and oxygen utilisation for Ti2NiOx formation was found to successfully heal the cracks. SPS enhances mechanical properties, superelasticity at higher temperatures, and two-way shape memory strain during thermomechanical cycling. This work provides an alternative solution for healing cracks in L-PBF parts, enabling the sustainable reuse of cracked materials. By implementing SPS, this approach effectively addresses hot cracking limitations, expanding the application potential of L-PBF NiTi parts while improving their functional and mechanical properties.

additive manufacturing, laser powder bed fusion, aluminium alloys, fe, strengthening mechanisms, Science, Manufactures, and TS1-2301

Achieving superior mechanical properties of Al alloys with high content of Fe impurities is very challenging. Here, a feasible method was applied to accommodate high Fe content (∼2.2 wt.%) and obtain superior strength in an Al–5Mg2Si–2Mg–2Fe alloy by using additive manufacturing. Heterogeneous distribution of Fe, including a high number density of α-Al12(Fe,Mn)3Si particles distributed at the melting pool boundary and excessive Fe segregated along the cell boundaries that divided by Mg2Si eutectics, was verified as the beneficial factor for the alloy design and strength enhancement. In addition to the heterogeneous grains that contain fine cells, the interactions between dislocations and coherent Mg2Si eutectics and the α-Al12(Fe,Mn)3Si particles played an important role in improving the mechanical properties. This work represents a breakthrough in recycling high-strength Al alloys with extremely high Fe doping for green industrial application through additive manufacturing.

high-entropy alloying, cracking inhibition, laser additive manufacture, d019 precipitates, post-aging treatment, Science, Manufactures, and TS1-2301

Developing high-performance high-entropy alloys (HEAs) fabricated by laser additive manufacturing (LAM) is the pursuit of the metallic community. In the present work, we designed a series of [(Al6-xNbx)-(FeCoNi)12]Cr3 HEA compositions using a high-entropy alloying strategy based on a cluster-plus-glue-atom model. And their thin-wall-sharped bulks were fabricated by LAM and post-aging treatment. The effects of cracking inhibition and microstructure evolution on the tensile properties were researched in detail. The results show that as the Nb substitutes for Al atoms, the cracking behaviour is ameliorated, ascribed to the tiny Laves phase refined the dendrite spacings and back-filled in the inter-dendritic liquid film. Also, introducing Nb atoms improves the strength but deteriorates the ductility. Significantly, the Nb4 HEA possesses the best tensile-property combination (i.e. σs ∼ 419.2 MPa, σb ∼ 787.4 MPa, and δ ∼ 15.5%) with a strain mechanism of dislocation slip mode. After post-aging for 72 h, the microstructure comprises fully recrystallized equiaxed FCC grains and many tiny needle-like D019 precipitates, leading to high strength and sufficient ductility (i.e. σ0.2 ∼ 535.9 MPa, σb ∼820 MPa and δ value of 8.9%). These findings provide a new paradigm for the LAM of crack-free HEAs with excellent mechanical properties.

alsi10mg, laser powder bed fusion (lpbf), thermal stability, deformation-free recrystallisation (dfrx), Science, Manufactures, and TS1-2301

Laser powder bed fused (LPBFed) AlSi10Mg is recognised for its superior mechanical properties. However, its thermal stability has never been justified. Herein, we exposed as-built AlSi10Mg to different temperatures (200–500°C) for only 3 min to evaluate its thermal stability. Results showed that LPBFed AlSi10Mg had relatively low thermal stability. Only 3 min of thermal exposure at 200°C would deteriorate its tensile strength dramatically. Microstructural analysis revealed that with increasing thermal input, as-built AlSi10Mg exhibited a microstructural evolution similar to annealing of cold-worked metals, namely recovery, recrystallisation followed by grain-growth. The excessive energy stored in as-built microstructure due to fast cooling during LPBF was deduced as the driving force for this phenomenon. Therefore, such microstructural change was at the expense of dislocations stored in the as-built material, which in turn caused deterioration in tensile strength. The present findings may provide guidance for the application of LPBFed AlSi10Mg.

laser-directed energy deposition, niti, ni4ti3, martensitic transformation, precipitation behaviour, Science, Manufactures, and TS1-2301

In this study, we report an unconventional precipitation and martensitic transformation behaviour of directly aged Ni-rich NiTi alloys fabricated via laser-directed energy deposition (LDED). Ni4Ti3 particles precipitate uniformly under all ageing conditions and no traditional multiple-step martensitic transformations are observed. We conclude this unique behaviour to the intrinsic characteristics of the LDED technique, which are metastable microstructures and high residual stresses. On the one hand, these features make grain boundaries no longer a fevered location for precipitation and, on the other hand, significantly suppress the martensitic transformation when ageing at low temperatures (300°C/400°C). As the aging temperature increase (500°C), residual stresses release significantly, accompanied by the growth of Ni4Ti3 precipitates from several nanometres to 452 ± 181 nm with increased interparticle spacing. At the same time, reverse martensitic transformations change from two-step (B19′ → R → B2) to single-step (B19′ → B2).

3d printing, bayesian optimisation, convolutional neural network, supercapacitor, Science, Manufactures, and TS1-2301

A convolutional neural network (CNN) guided Bayesian optimisation framework is introduced to strategically maximise the surface to volume ratio of 3D printed lattice supercapacitors. We applied Bayesian optimisation on printing parameters to exploit regions where uniform and narrow lines are printed. A line shape classifying CNN model guided the optimiser’s search space to straight-line printed regions, minimising optimisation time and cost. An automatic scoring method allowed each iteration to be conducted within two minutes with accurate and precise measurements. The optimisation process has been demonstrated with graphene oxide (GO) and poly(3,4-ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS) inks. The results were compared to the parameters that follow the conventional methodologies of direct ink writing (DIW) 3D printing. For each printed line of GO and PEDOT:PSS inks, irregularities decreased by 61.8% and 18.9% and average widths decreased by 39.0% and 28.6%. PEDOT:PSS lattice supercapacitor printed using optimised result showed a 151.0% increase in specific capacitance.

mechanical properties, optimisation, pha, phbh, Science, Manufactures, and TS1-2301

The crystallisation process of polyhydroxyalkanoates (PHA) polymers plays a key role on final properties of manufactured parts due to most PHA are highly sensitive to physical aging which leads to embrittlement. The secondary crystallisation associated with the aging process can be partially controlled by the cooling process during manufacturing or, even, by heat treatments such as annealing. A critical parameter in additive manufacturing is the difficulty to achieve good adhesion of the material to the printing bed. The bed temperature plays a key role on PHBH crystallisation, which leads to shrinkage having a negative effect on polymer-to-bed adhesion. In this work, a study of the effect of different processing parameters such as the printing temperature, the bed temperature, the cooling conditions, as well as raster direction on the final properties of PHBH 3D-printed parts is carried out.

additive manufacturing, preceramic polymer, digital light processing, shape transformation, composites, Science, Manufactures, and TS1-2301

It remains challenging to broaden the application fields of ceramics, largely because the hardness and brittleness of ceramics mean that they cannot undergo shape reconfiguration. In this study, we developed an ultraviolet light-curable preceramic polymer slurry, and this slurry was used for digital light processing printing of flexible green parts in designed shapes. These parts were subsequently transformed into complex structures by an assisted secondary molding strategy that enabled the morphology of their green and pyrolyzed forms to be well controlled. The collapse of bulk pyrolyzed parts was avoided by impregnating their precursors with silicon nitride (Si3N4) particles. The effects of different proportions of Si3N4 on the weight loss, shrinkage, density, porosity, and mechanical properties of the pyrolyzed composites were investigated, and the bending strength and Vickers hardness of the composites with 10 wt.% Si3N4 were found to be 130.61 ± 16.01 MPa and 6.43 ± 0.12 GPa, respectively.

bipolar plate, active screen plasma nitriding, laser powder bed fusion, 316l stainless steel, Science, Manufactures, and TS1-2301

Laser powder bed fusion (LPBF) is capable to process complex flow field structures on 316L stainless steel (316L SS) bipolar plates, which is promising to improve the performance of proton exchange membrane fuel cell (PEMFC). However, insufficient corrosion resistance and relatively high interfacial contact resistance (ICR) hinder the widespread of LPBF-processed 316L SS bipolar plates. In this work, active screen plasma nitriding (ASPN) was used to modify 316L SSs fabricated by the LPBF process and forging, respectively. Results showed that the nitrided layer of LPBF-processed 316L SS (2000 mm/s, 300 W) exhibited the highest surface nitrogen concentration, thickest nitrided layer and highest average hardness. The ICR values decreased significantly after ASPN treatment. The corrosion current of nitrided LPBF-processed 316L SS (2000 mm/s, 300 W) was much lower than that of the nitrided forged 316L SS. By comparing multiscale microstructures between LPBF-processed and forged 316L SS, the ASPN mechanism of LPBF-processed 316L SS was proposed.

functionally graded material, laser directed energy deposition, acoustic emission, optical emission spectroscopy, artificial intelligence, Science, Manufactures, and TS1-2301

Laser directed energy deposition (L-DED) allows the production of multi-materials and functionally graded material (FGM) parts. But for commercialisation, process and quality monitoring of parts is required. For the first time, a novel monitoring method for chemical composition and process regimes of FGMs is proposed using a cost-effective acoustic emission (AE) (microphone) and optical emission spectroscopy (OES) sensors. Four chemical compositions (100%Ti, 58%Ti42%Nb, 37%Ti63%Nb, and 100% Nb) and two process parameters (475 W – 1'400 mm/min and 175 W – 2'000 mm/min) were selected, leading to four regimes/quality (conduction mode, partial, minor, medium, and severe lack of fusion pores). The signals were classified using seven mainstream artificial intelligence algorithms. The main conclusions are twofold. First, microphones are unsuitable candidates for monitoring the laser-material interaction during L-DED. The acoustic waves generated by the laser-material interaction are shielded by high gas flow surrounding it and so are either highly disturbed or does not reach the microphone. Conversely, OES are suitable candidates as the classification accuracies are higher than 90% for most category and machine learning algorithms, even after drastic feature reduction. Considering the wide range of chemical composition and quality, our proposed methods using OES have high industrialised potentials for them during L-DED FGM.

laser printing, laser sintering, conformal printing, silver nanoparticles inks, flexible electronics, Science, Manufactures, and TS1-2301

The laser induced forward transfer and sintering of metal nanoparticle inks has been proven a key enabling technology for flexible electronics. Nevertheless, many challenges concerning the conformal processing of non-planar substrates incorporating thermally sensitive layers are yet to be addressed. In this work, we study the behaviour of conformal laser printing of silver nanoparticle inks on patterned samples comprising sensitive underlying structures, by correlating the laser sintering powers employed to the undesired effects on the adjacent interfaces. The latter include demanding surface topographies with periodic patterns and micro-components exhibiting aspect ratio in the nano to 100-micron scale. We investigate the contribution of crucial processing parameters, such as the per pulse energy, repetition rate and the pulse to pulse spatial and temporal overlap to the overall result. The demonstrated results validate the versatility of laser processing which can offer application specific solutions on different use cases involving multilayered and multimaterial electronics.

additive manufacturing, multi-material, ceramic, laser powder bed fusion, computational fluid dynamics, Science, Manufactures, and TS1-2301

Experiments on Laser powder bed fusion (LPBF) of powdered Ti on Al2O3 substrate were conducted and the interface formation was studied using a multi-material fluid dynamics model. Results show that the melt pool is relatively shallow, with relatively flat interlayer interface under LPBF’s conduction mode. In this condition, a thin sheath of molten Al2O3 forms and acts as a lubricating film for the molten Ti, leading to Rayleigh instability due to high flow inertia. Keyhole formation penetrates the Al2O3 substrate, resulting in a wavy interlayer interface. The recoil pressure from the keyhole and overall melt inertia are suppressed by the highly viscous molten Al2O3, thereby improving single-track melt pool stability. However, the thermal expansion coefficient difference between Ti and Al2O3 led to the formation of transverse cracks. Achieving a defect-free metal-on-ceramic single track remains a challenge, despite this study serving as a guide for melt track and interface control.

meltpool monitoring, laser powder bed fusion, additive manufacturing, scan strategy, hot spots detection, porosity, process monitoring, near-infrared sensors, Science, Manufactures, and TS1-2301

In-situ co-axial meltpool monitoring has become a popular tool for digitising the laser powder bed fusion (L-PBF) process , providing baseline data for certification. Each layer produces an image where the pixel position represents the laser coordinates and the pixel intensity denotes the sensor response. The 3D image stacks represent the infrared emission during the manufacturing of the physical component. However, interpreting monitoring data remains a challenge. To address this issue, this study evaluates the performance of a near-infrared photodiode in detecting typical geometrical features such as porosity and overhanging structures ranging from the micro-to-meso scale. Monitoring data is highly sensitive to heat accumulation around overhanging structures and can quantify dross formation based on hotspots. Cold spots, which represent a lack of fusion porosity at scan track intersections, can indicate a probability of defect formation. However, the sensitivity and predictive value of monitoring data for porosity are low due to the healing of defects in subsequent layers. Local process variables, such as the scan strategy and part orientation, significantly influence dross and hot spot formation. This study shows the potential of NIR photodiodes in deriving metrics for in-line certification of L-PBF components, leading to improved process control and quality assurance.

multi jet fusion, polyamide 12 matrix, polyimide fibres, fibre-reinforced polymer composites, annealing, Science, Manufactures, and TS1-2301

Multi Jet Fusion (MJF) has attracted extensive attention because of its ability to print support-free complex structures. However, the mechanical properties of MJF-printed polymer parts are still unsatisfactory for certain industrial requirements. Herein, by leveraging the fibre reinforcement effect and high specific strength of polyimide (PI) fibres, this work developed PI/polyamide 12 (PA12) composites with largely enhanced mechanical performance via MJF. Specifically, the tensile strength and modulus were increased by 43% and 42%, and the flexural strength and modulus were improved by 39% and 46%, respectively, compared to those of the neat PA12 parts. Furthermore, the incorporation of lightweight PI fibres endowed the composites with high specific tensile strength (67.60 kN·m/kg) and specific flexural strength (93.70 kN·m/kg), which are superior to those of MJF-printed PA12 composites reinforced with other fibres. This work provides new insights into enhancing the mechanical performance of lightweight parts printed by MJF and other powder-based techniques.

elastomer, carbon fibres, mechanical properties, additive manufacturing, Science, Manufactures, and TS1-2301

Mechanical dependence of 3D-printed thermoplastic polyurethane (TPU) reinforced with continuous carbon fibres (CCFs) on the selected printing conditions was investigated. The melt-extrusion-based 3D-printing (ME3DP) method was employed to fabricate specimens, of which the dependence of tensile, flexural and cryo-impact properties on layer thickness, printing speed and layer number was evaluated. Results showed that the printed TPU reinforced with raw CCFs revealed an over five-fold increase in tensile yield stress with the occurrence of necking phenomenon whereas those reinforced with preimpregnated CCFs (PCCFs) displayed brittle fracture which was also confirmed by the impact testing. The flexural strength and modulus of the printed CCFs/TPU were greatly raised over that of TPU and the PCCFs provided a much more enhancement. Both the increased yield stress and flexural strength implied an improved capacity for dynamic load bearing. Finally, the structure–property relationship was established via interface microstructure detection and simulation.

additive manufacturing, acoustics, defect detection, sensor, Science, Manufactures, and TS1-2301

In additive manufacturing of metals, numerous techniques have been employed to sense print defects. Among these, acoustic-based sensing has the advantage of low cost and shows the most potential to identify both external and internal defects as an in-situ monitoring system. Using acoustic signals, researchers have broadly investigated non-machine learning and machine learning-based approaches to identify defects like balling, micro defects, lack of fusion pores, keyhole pores, cracks, and porosity. While most of these works have shown promising results for laser-based AM systems, few have explored how acoustic signals can be used effectively for Wire Arc Additive Manufacturing (WAAM) defect detection. This paper proposes a methodology to construct machine learning (ML)-based models on identifying geometrically defective bead segments using acoustic signals during the WAAM process. Geometrically defective bead segment or geometric defect is a defect that causes voids in the final printed part due to incomplete fusion between two non-uniform overlapping bead segments. Such a defect is currently not explored in the literature. The proposed methodology uses a novel dataset labeling approach to identify good and bad bead segments based on an optimal threshold of the range of mean curvature. Furthermore, the methodology targets defective bead segments based on acoustic feature inputs like Principal Components (PC) or Mel Frequency Cepstral Coefficients (MFCC). To understand the resulting performance of the defect identification models constructed based on the proposed methodology, experiments are performed and tested on a variety of ML models (KNN, SVM, RF, NN, and CNN) based on the Inconel 718 material. The results show that the combinatorics of two acoustic input features and five ML models can be able to identify geometrically defective segments accurately with F1 score that ranges from 80% to 85%.

metal additive manufacturing, additive manufacturing, topology optimisation, aerospace, automotive, medical, Science, Manufactures, and TS1-2301

Metal additive manufacturing is gaining immense research attention. Some of these research efforts are associated with physics, statistical, or artificial intelligence-driven process modelling and optimisation, structure–property characterisation, structural design optimisation, or equipment enhancements for cost reduction and faster throughputs. In this review, the focus is drawn on the utilisation of topology optimisation for structural design in metal additive manufacturing. First, the symbiotic relationship between topology optimisation and metal additive manufacturing in aerospace, medical, automotive, and other industries is investigated. Second, support structure design by topology optimisation for thermal-based powder-bed processes is discussed. Third, the introduction of capabilities to limit manufacturing constraints and generate porous features in topology optimisation is examined. Fourth, emerging efforts to adopt artificial intelligence models are examined. Finally, some open-source and commercial software with capabilities for topology optimisation and metal additive manufacturing are explored. This study considers the challenges faced while providing perceptions on future research directions.

4d printing, high flexibility, anisotropic magnetic property, digital light processing, smart manufacturing, Science, Manufactures, and TS1-2301

Flexible anisotropic soft-magnetic composite (FASMC) presents superior magnetic properties in one or more specified directions, showing great potential in the application of microwave absorption, soft robots, and other smart sensors/actuators. However, the fabrication of FASMC using additive manufacturing is challenging due to a trade-off between magnetic properties of the composites enhanced by iron particles and printability during printing. Here, we developed a 4D printing scheme using flexible soft-magnetic photosensitive resin consisting of flexible long-chin acrylic resin monomer and soft magnetic iron particles. Multiple complex structures with good spatial resolution of ∼170 μm were fabricated using magnetic field-assisted digital light processing (MF-DLP). Directional magnetic field was applied during printing, enabling the fabrication of FASMC with strong anisotropic magnetic properties. FASMC with high CIP (carbonyl iron powder, CIP) concentration of up to 45 wt.% was fabricated with excellent tensile strength and elongation up to 460%. Strong anisotropic magnetic properties were demonstrated through a series of stimuli-response testing such as large deformation, anti-deflection, controlled motion, variable stiffness metamaterial, and array assembly, under external magnetic field. This study demonstrates the feasibility and potential of MF-DLP technique for fabrication of FASMC, shedding light on the design and fabrication of next-generation sensors and actuators.

laser powder bed fusion, bulk metallic glasses, composites, microstructure, mechanical properties, Science, Manufactures, and TS1-2301

In this work, a new design principle, i.e. doping with refractory metal particles with a low diffusion rate to prevent the formation of cracks and to improve the mechanical properties of bulk metallic glass (BMG) composites, was put forward. It was proven that crack-free and dense Mo(p)/Cu47Zr47Al6 BMG composites with enhanced mechanical properties can be produced via LPBF. The dislocations generated in the Mo particles can release thermal stress, thereby inhibiting the formation of thermal-cracks. The fracture patterns of Mo particles show that they can delay rapid of crack expansion, thereby improving the inherent strength and toughness of the material.

additive manufacturing, discrete element method, fiber-reinforced polymer composite, fiber orientation, fiber homogeneity, Science, Manufactures, and TS1-2301

The packing characteristics of fiber/polymer powder in powder bed fusion additive manufacturing exhibit a high correlation with the mechanical behaviours of printed composite parts such as homogeneity and anisotropy. A discrete element model has been developed to investigate the packing characteristics of glass fiber/polyamide 12 (PA12) powder, which include fiber orientations, fiber homogeneity, and packing density. The predicted probability distributions of fiber orientations in the powder bed are comparable with those measured in glass fiber–reinforced PA12 composites printed via multi jet fusion. Three types of fibers with different length distributions are adopted to study the effects of the fiber length distribution on their packing characteristics. The simulation results reveal that a large average fiber length is beneficial to fiber alignment in the powder spreading direction but lowers the fiber homogeneity and packing density of the powder bed. Furthermore, varying the fiber length can provide an effective way to regulate fiber orientations in the powder packing process, which would help achieve satisfactory anisotropic mechanical properties for composite parts.

3d printing, fused deposition modelling, polymer-ceramic composite, polyethylene terephthalate glycol-modified, titanium dioxide, Science, Manufactures, and TS1-2301

3D-printed electronics belong to new approaches to how to build a complex object with multiple desired functions. For that purpose, materials with specific electric properties are needed: conductors, insulators, magnetics, or dielectrics with high permittivity. However, such materials are not commonly available in the form of filament for fused deposition modelling since the development is still ongoing. This paper describes the electrical properties of PETG-ceramic composite filaments. PETG (polyethylene terephthalate glycol-modified) was filled with titanium dioxide (10 and 20 wt.%) to increase the dielectric constant and, simultaneously, to preserve printing simplicity as the material key advantage. Dielectric spectroscopy and measurement of volume resistivity were performed on printed samples. Relative permittivity increased by 50% for a composite filled with 20 wt.% of ceramic particles (ϵr = 2.5÷4.4) against pure PETG. Permittivity and dielectric loss exhibited frequency and temperature independence. The prepared composite can be used for dielectric applications in electronics.

laser powder bed fusion, al-fe-v-si alloy, heterogeneous microstructure, mechanical properties, Science, Manufactures, and TS1-2301

The relationship between processing parameters, microstructure, and mechanical properties of Al-8.3Fe-1.3V-1.8Si alloy processed by laser powder bed fusion is seldom studied. Therefore, fully dense alloys with two parameters were selected to investigate this key issue. The results show that the alloy with low power and scanning speed (S200) shows fan-shell-shaped melt pools and laser tracks while another (S350) shows a deeper and wider melt pool. Both alloys obtain a heterogeneous microstructure without a secondary phase in melt pool (MP) and a nano-sized phase in melt pool boundary (MPB). The difference between solid-solution strengthening and Orowan strengthening in MP and MPB contributes to the difference in compressive yield strength (S200: 380 ± 14 MPa and S350: 705 ± 16 MPa), and heterogeneous nano-hardness results in different crack behaviours and failure strains. This work indicates that adjusting processing parameters is an effective method to control microstructure and mechanical properties of this alloy.

suture structure, polyjet printing, multi-materials, nanoindentation, three-point bending, numerical simulation, Science, Manufactures, and TS1-2301

Among various bio-inspired structures, sutures are a prominent structure which has evolved independently to optimize their functionalities. The diabolical ironclad beetle suture-inspired structure was fabricated using multi-material additive manufacturing (3D printing) system with TangoBlackPlus (TBP) as the soft suture layer and VeroWhitePlus (VWP) as the hard material. The print quality of the specimen was assessed through the optical microscope images, and a nanoindentation test was performed to investigate the interfacial hardness between TBP and VWP. Flexural properties of the suture structure when changing the thickness of the soft layers were then studied. Experiments were continued to identify the effect of combining different sizes of suture modules to develop the suture structure. A numerical simulation model was then generated and validated using the experimental results to proceed with the parametric study. A design of experiment (DoE) was developed to analyse the effect of changing the suture geometry to optimize performance. The research concluded that gradually decreasing the size of the suture allowed the structure to withstand higher loads. It was also evident that the deformability of the structure could be increased by incorporating smaller interlocking angles and larger a:b ratios, while larger interlocking angles and smaller a:b ratios generate stiff structures.

wire arc additive manufacturing (waam), multi-material, overlapping model, gas metal arc welding, stainless steel, creep-resistant steel, Science, Manufactures, and TS1-2301

The single-material overlapping models are incompatible with multi-material wire arc additive manufacturing (WAAM). A newly developed generalised model considers dissimilar adjoining beads in multi-material WAAM. The geometric model of dissimilar overlapping beads coupled with an algorithm identifies the process conditions for the two materials to maintain the same bead heights. The model, implemented for stainless-steel and creep-resistant-steel pair, yields significant scientific and practical findings. Compared to a fixed overlapping distance in single-material, e.g. 0.66 or 0.738 times the bead width, the multi-material overlapping distance is a complex function of individual bead widths. The bi-metallic interface fusion is affected by the molten metal flow, bead dimensions, and heat input. Contrary to the prevailing notion of a flat-top surface in the intermediate layer ideal for multi-layer deposition, a slight hill ensures a defect-free interface. The repeatable and defect-free bi-metallic walls and matrix is expected to have a breakthrough in multi-material WAAM.

powder bed behaviour, discrete element method, powder spreading, real-time curing, binder jetting additive manufacturing, Science, Manufactures, and TS1-2301

Understanding powder bed system behaviour in powder spreading is a fundamental issue in binder jetting additive manufacturing (BJAM). This work established a discrete element model incorporating a parallel bond model to compatibly depict local cross-links between powder particles. BJAM parameters including layer thickness, gap compensation, recoat speed, rotation speed, and layer number were studied quantitatively for their effects on recoated powder's packing density and microscopic pore size and bonded layer's breakage and layer shift. Evolutions and influence mechanisms on both layer shift and bond breakage were further elucidated. Some practical implications include: gap compensation corresponding to an ideal recoated powder structure is ∼75 μm; rotation speed should be controlled at 40–120 rad/s to avoid low-rotation-speed layer shift surge and high-rotation-speed breakage; layer shift occurring at a certain stage is irreversible and must deserve well-maintained. This research can provide theoretical guidance for developing BJAM and even support-free powder bed – based additive manufacturing.

two-photon polymerisation, anti-counterfeiting label, semiconductor quantum dot, fluorescence, Science, Manufactures, and TS1-2301

Microprinting is changing anti-counterfeit technology by producing complex micro-/nano-scale labels to increase the security level. However, the current microprinted anti-counterfeiting labels only contain 2D features, thought of as single coding (e.g. mostly in texts or graphs), unable to satisfy the high-end anti-counterfeiting demands of producing multi-coding, high-storage-density labels. Here, we introduce an approach for fluorescence printing to produce a 3D colourful, sophisticated anti-counterfeiting label. In the method, pre-synthetic QDs are printed with photoresists based on two-photon polymerisation, allowing for accurate regulation of fluorescence in both 2D and 3D. The fabricated photoresists exhibit immediate and postprocessing-free colour emissions under UV light. We demonstrated the ultra-high free design and accurate manufacturing capability of the approach by fabricating multi-colour, multi-layer patterns containing both texts and graphs on a 50μm × 50μm × 30μm portable label. The approach can also be applied to multi-dimensional optical data storage and colourful microdisplays.

material extrusion, cellulose-chitin biopolymers, shrinkage compensation, neural network regression, Science, Manufactures, and TS1-2301

Loss of geometric accuracy due to shrinkage is a challenge in material extrusion of biological composites using water-based inks, such as the cellulose-chitin biopolymers used here. The shape of 3D printed objects often departs from the intended design geometry due to evaporative loss of water during curing. Moreover, such materials' viscoelastic characteristics result in complex volumetric changes that are difficult to predict and compensate for. We developed a prediction-correction scheme by 3D printing and scanning cylindrical and conic surfaces, computing the geometric deviations between designed and cured artefacts, and training a neural network such that given the machine path for a 3D print, the model can predict shrinkage deformations and apply adjustments on the generating machine paths to proactively compensate it. In this article, we present the shrinkage characteristics of the material used and the results of applying the predictor-correction scheme. The approach substantially improves geometric accuracy, enabling nearly seamless assembly of separately 3D printed parts. Addressing such a fundamental problem of quality control as geometric accuracy may enable the broader adoption of biopolymers and potentially displace the generalised use of synthetic plastics.

alloy design, additive manufacturing, 3d printing, ti6al4 v, selective laser melting, Science, Manufactures, and TS1-2301

Alloy design coupled with metal additive manufacturing (AM) opens many opportunities for materials innovation. Investigating the effect of printing parameters for alloy design is essential to achieve good part quality. Among different factors, laser absorptivity, heat diffusivity, and in situ intermetallic phase formations are critical. In this study, the first step employed was a reduction in Al and V contents in Ti6Al4 V to design Ti3Al2 V alloy, and further 10 wt.% tantalum (Ta) and 3 wt.% copper (Cu) were added to Ti3Al2 V. A synergistic effect of Ta and Cu addition in Ti3Al2 V negated their effect with higher porosities in Ti3Al2V-Ta-Cu. Ti3Al2V-Ta composition was more sensitive to the laser power, whereas Ti3Al2V-Ta-Cu to the overall energy density. Understanding the effect of energy density on these alloys’ microstructural evolution and mechanical properties highlights the need for process-property optimisation during alloy design using AM.

polymer-matrix composites, hybrid fillers, crystalline structure, thermal properties, mechanical properties, Science, Manufactures, and TS1-2301

With the development of 5G technology, the miniaturised and highly integrated electronic devices urgently require thermal management materials possessing high thermal conductivity and mechanical properties. In this work, isotactic polypropylene (iPP)/high-density polyethylene (HDPE)-based dielectric composites possessing ideal thermal conductivity and balanced mechanical properties were prepared via Fused Filament Fabrication (FFF). The advanced material properties were achieved by the introduction of hybrid fillers and tailored polymer crystalline structure. The highly oriented h-BN, oriented iPP crystalline and iPP/HDPE epitaxy crystalline were observed. Meanwhile, we studied the effect of the ratio of hybrid fillers on various properties of composites. The thermal conductivity of iPP/HDPE/h-BN/Al2O3 composites reach 1.802 W·m−1·K−1. The impact strength and tensile strength reach 13.23 KJ/m2 and 40 MPa, respectively. In addition, the composites maintain ideal dielectric properties. This work offers a feasible strategy to fabricate dielectric and thermal conductive composites with balanced mechanical properties using semicrystalline polymer through FFF process.

concurrent multiscale topology optimisation, moving morphable components, bio-mimicking, porous infillings, additive manufacturing, Science, Manufactures, and TS1-2301

This paper presents a novel multiscale explicit topology optimisation approach for concurrently optimizing the structure at the macro level and the bio-mimicking porous infillings at the micro level. Solid bar components with cross-section control at the macro level and sphere components at the micro level are constructed as the minimal control units to replace the manipulation of material distribution at each grid. The overlapping, moving and morphing of bar components provide the ability to generate flexible structural shapes at the macro level. Using the inspiration of the turtle shell (carapace), the sphere components are designed to move, overlap, and resize inside the bar to sufficiently mimic both the regular and irregular porous features. Classical beam designs, lattice structure designs and unit cell designs are illustrated as numerical examples to demonstrate the functionalities and correctness of the proposed method. As a result, the stochastic pores distribution and porosity control can be validated. The abilities of optimising lattice structure at truss-level and single unit cell level are demonstrated. Moreover, the samples are fabricated by selective laser melting (SLM) technology and then scanned with the X-ray micro-computed tomography (micro-CT) technique to further examine the manufacturability.

gf, pa1212, selective laser sintering, tensile properties, tribological behaviour, Science, Manufactures, and TS1-2301

Glass fibre (GF) and glass bead (GB)–reinforced polyamide1212 (PA1212) was additively manufactured by selective laser sintering. The effects of laser power and GF content on the tensile and tribological properties of the printed specimens with a base GB weight fraction of 40 wt.% were investigated. The strengthening mechanism of GFs/GBs was illustrated by analyzing the interfacial adhesion between the fillers and the PA1212 matrix. The specimens with 40 wt.% GBs and 10 wt.% GFs fabricated at a laser power of 30 W exhibited a strength of 52 MPa, a friction coefficient of 0.23, and a wear rate of 0.0011 mm3/N·m. The selected optimal laser power and GF addition contributed to the strong interfacial adhesion, which realised flat surface morphology and an adequate encapsulation of fillers in the specimen. The reinforcement of GBs/GFs in PA1212 can serve as a reference for a deeper understanding of the strengthening mechanisms for other additively manufactured engineering plastics.

material extrusion, multi-material manufacturing, hybrid manufacturing, printed electronics, conductive silver films, Science, Manufactures, and TS1-2301

Multi-material manufacturing through the hybridisation of printed electronics and additive manufacturing has gained great interest recently. However, such hybridisation attempts are not trivial due to the need for functional material development and compatible process identification, as well as further performance understanding, comprehensive characterisation and long-term reliability evaluation of multi-material parts. While some multi-material structures from functional materials such as silver inks have been demonstrated via the integration of direct writing systems into stereolithography or material extrusion platforms, the performance assessment and characterisation of parts manufactured using such integrated systems is still required. Therefore, this research presents a comprehensive assessment of multi-material structures manufactured using syringe deposition and material extrusion platforms. Test specimens were subjected to various characterisation activities such as thickness measurement, resistance measurement, roughness tests, wettability measurement, adhesion tests, and morphological analysis. Results and statistical analyses suggested that the dry thickness and conductivity of deposited films were dependent on the substrate material. Adhesion between the conductive film and substrate was affected by both substrate material and ink deposition angle. Also, the interaction of conductive films with polycarbonate substrate was found to be noticeably better among all substrates due to low resistivity and enhanced adhesion at low thicknesses.

negative poisson's ratio, tubular structure, triply periodic minimal surface, compressive properties, finite element modelling, Science, Manufactures, and TS1-2301

A novel type of tubular structure with negative Poisson's ratio based on gyroid-type triply periodic minimal surfaces (TPMSs) is proposed in this study. This work is an attempt to design auxetic tubular structures based on TPMS. A series of auxetic tubular structures were designed and then fabricated using laser power bed fusion. Compressive behaviours of the fabricated auxetic tubular structures were investigated using experimental and numerical methods. To obtain optimal designs of tubular structures with controllable auxetic properties, the influence of several parameters were investigated comprehensively. Subsequently, several graded auxetic tubular structures were designed based on the parametric analysis and studied numerically. The mechanical properties of the tubular structures could be controlled effectively using the proposed approach. The proposed method can be used for guiding the design and optimisation of auxetic tubular structures, showing excellent potential for various applications such as biomedical devices, vehicle crashworthiness, and protective engineering.

large-scale, ceramic matrix composites, material extrusion, additive manufacturing, Science, Manufactures, and TS1-2301

Large-scale short carbon fibre-reinforced silicon carbide (Csf/SiC) ceramic matrix composites (CMCs) have important applications in the field of aerospace engineering. This study proposed the use of material extrusion based additive manufacturing to fabricate large-scale Csf/SiC CMC preforms. In this paper, we determined how the key material extrusion parameters, including solid loading, nozzle diameter and layer height impact the stability of the additively manufactured Csf/SiC CMCs. The solid loading significantly influenced the stability of the Csf/SiC CMCs, and the slurry with 50 vol.% solid loading was better for additive manufacturing. The layer height played a significant role in the void formation in CMCs. It was appropriate for structure retention to set the layer height as 60–75% of the nozzle diameter. The effect of angle from vertical on the stability of out-of-plane structure was also investigated. When the angle was over 40o, the out-of-plane structure additively manufactured without supports tended to collapse. Large-scale Csf/SiC CMC preforms with out-of-plane structures were finally successfully fabricated. This study is believed to provide some fundamental understanding for the fabrication of large-scale fibre-reinforced ceramic matrix composites.

additive manufacturing, melt-based embedded printing, freeform fabrication, overhanging structures, flexible scaffolds, Science, Manufactures, and TS1-2301

We developed a novel melt-based embedded printing strategy to fabricate polycaprolactone (PCL) structures with complex overhanging geometries within a thermally stable supporting matrix. By optimising the concentration of the supporting matrix, process parameters, and inter-filament thickness, continuous PCL filaments can be stably printed with the smallest width of 50.6 ± 4.7 μm. The one-step in situ post-solidification process provides a unique approach to regulate the surface morphology of the printed filaments, and reduce structural anisotropy. Various 3D structures with overhanging geometries, such as truss structures and flexible scaffolds were successfully fabricated by melt-based embedded printing. The effective modulus of the printed flexible PCL scaffolds can be widely tuned in the range of 867.4 ± 21.6 to 9.1 ± 1.2 kPa by adjusting the design parameters. We envision that the presented strategy might provide an innovative tool to fabricate flexible polymeric scaffolds with complex structural organisations for soft tissue engineering.

vat photopolymerisation, digital light processing, microfabrication, additive manufacturing, Science, Manufactures, and TS1-2301

Digital Light Processing (DLP) is an advanced additive manufacturing technology which has garnered substantial recognition and has been extensively applications in various fields. This review focuses on the precision microfabrication process of DLP, providing an overview of the DLP 3D printing system, including the digital light engine, project lenses, motorised stage and resin vat for micro-structure fabrication. Additionally, this review paper comprehensively analyses commercially available DLP printers, covering resolution, cost and a detailed discussion on the importance of photopolymer resins, emphasising the monomer, photo-initiator, photo-absorber, etc. Based on the photopolymerisation theory, the DLP high-precision printing process is analysed, which is critical for producing complex microstructures. It also briefly discusses the application of DLP microfabrication including microfluidic chip printing. Finally, this paper summarises the advanced trends and challenges of DLP printing in high-precision, large-area, multi-material and high-speed printing; and it provides an in-depth understanding of DLP technology, highlighting its potential for various applications and addressing challenges that need to be overcome in future research.

wire-arc directed energy deposition, cryogenic cooling mode, defects, microstructure evolution, strength-ductility synergy, Science, Manufactures, and TS1-2301

Motivated by the effect of cooling rate on microstructure, standard air cooling (AC) and novel cryogenic cooling (CC) were employed in the wire-arc directed energy deposition process of Mg-alloy. The influences of cooling modes on macrostructure, defects, microstructure, mechanical properties and deformation behaviour were systematically investigated. Compared with AC component, CC component exhibits improved performance with yield strength, ultimate tensile strength and elongation increased by 50%, 58% and 174%, respectively. The improved strength-ductility synergy can be attributed to the decreased porosity, profuse nano-precipitates, finer equiaxed grain within inter-layer and the transformation of columnar to equiaxed grain within intra-layer. The enhancement of strain hardening rate by highly coherent nano-precipitates impeding dislocations glide, dynamic Hall-Petch effect of multiple twins and numerous 3D obstacle networks of dislocations should be responsible for the significant elongation improvement. This study thus introduces new insights into defect alleviation, microstructure modification and performance enhancement of additive manufacturing Mg-alloys.

additive manufacturing, structural design, residual stresses, multi-physics, thermomechanical simulation, Science, Manufactures, and TS1-2301

Residual stresses, related distortions and cracks are detrimental in metallic Additive Manufacturing (AM). Previously developed stress-control strategies based on reducing thermal gradients hardly diminish the stress concentrations at the built basement and easily affect other physical phenomena involved in AM. To overcome this, a novel strategy, named as Smart-Substrate, consisting of optimising the inner structure and local stiffness of the substrate is proposed to avert stress accretion and related part deformations. To demonstrate its advantages, a coupled thermomechanical finite element model for AM, experimentally calibrated with in-situ temperature and displacement measurements, is employed to analyse the thermal and mechanical behaviour of three groups of different structures with increasing geometrical complexity (single-wall, rectangular and block parts) fabricated by Directed Energy Deposit (DED) on the standard and smart substrates, respectively. Through using Smart-Substrate, the generation of residual stresses, especially the stress concentrations at the bottom corner of DED-builds being highly sensitive to cracks, and the induced deflections, are fundamentally throttled, and contrariwise for the standard substrate. More importantly, the use of Smart-Substrate is almost without prejudice to the temperature field, metallurgy and resulting mechanical hardness. This provides a possibility for addressing different physical problems individually, enlarging the AM process window.

surface modification, multi jet fusion, polyamide 12, mechanical performance, flame retardancy, Science, Manufactures, and TS1-2301

Multi jet fusion (MJF), a powder-based additive manufacturing technology, is suitable for fabricating fibre-reinforced polymer composites. However, the types of reinforcement fibres applied in MJF are limited due to the incompatibility between the fibres and polymer. Herein, a simple and cost-effective surface modification method for Fe3O4-coated aramid fibres (Fe3O4@AF hybrids) is proposed to fabricate polyamide 12 (PA12) composites by MJF. The optimal fibre content for Fe3O4@AF/PA12 composites is 6 wt%, which resulted in 10.83% and 16.05% higher ultimate tensile strength and Young’s modulus, respectively, compared with AF/PA12. The addition of Fe3O4@AF hybrids also improved the flame retardancy of AF/PA12 by reducing the peak heat release rate (PHRR) and postponing the temperature at PHRR. This practical surface modification method can be potentially applied to other reinforcement fibres for fabricating functional polymer composites by other powder-based manufacturing technologies.

additive manufacturing, deposition error, molten pool, liquid metal flow, error control, melting and solidification, Science, Manufactures, and TS1-2301

Although additive manufacturing (AM) is a net/near-net forming process, significant deviations may occur between the finally manufactured product and the designed object. This study is inspired by the deposition errors in a typical closed-contour structure manufactured via laser-directed energy deposition (DED). A series of experiments were carried out and a multi-physics mechanistic model was developed to reveal the origins and the spatiotemporal variations of the errors in representative processes. The results demonstrate that the irregularity of the deposition can be initiated by the liquid metal flow in the molten pool driven by forces including the recoil pressure and surface tension. The deviations are subsequently aggravated due to the inheritance between layers. Supported by the revealed underlying mechanisms, solution strategies including layer-wise dynamic compensations are thus proposed. The novel scientific findings can be insightful to researches for other metal AM processes and structures considering the universality of the uncovered mechanisms.

binder jetting, 316l stainless steel, hot isostatic pressing, pore features, strength, Science, Manufactures, and TS1-2301

In this work, a hot isostatic pressing (HIP) treatment was used to reduce the pores and improve the mechanical properties of binder jetting (BJ) fabricated 316L stainless steel. The relative density of the HIP treated samples sintered under vacuum, nitrogen, and argon atmospheres increased from 89.20∼90.76% to 94.02∼98.35%. The mean diameter of the internal closed pores decreased from 11.83∼14.70 μm to 0.94∼1.53 μm, and the internal porosity reduced from 5.47∼8.67% to 0.14∼0.35%. A remarkable enhancement of mechanical properties was achieved with the tensile strength by ∼15% and the elongation by ∼100% due to the reduction of porosity. The mechanical properties of the BJ 316L sintered under nitrogen and treated with HIP were even better than those of the direct powder HIP components due to the interstitial solution strengthening. These findings will be a valuable reference for optimising the HIP parameters to produce metal BJ components with superior mechanical properties.

multifunctional metasurface, thermal expansion, em frequency selection, 4d printing, continuous fibre, Science, Manufactures, and TS1-2301

Multifunctional metamaterials with unique electromagnetic and mechanical properties are highly desired in many fields, including space exploration and satellite communication, where broad tunability of the working frequency and controllable mechanical deformation properties are usually necessary. In this study, we propose a metasurface exhibiting simultaneous electromagnetic frequency selection capability and isotropic negative/positive/near-zero thermal expansion. The metasurface is designed based on chiral structures and is fabricated via 4D printing of continuous fibre composites. Both the effective thermal expansion coefficient and electromagnetic transmission band were investigated in different structural parameters based on theoretical calculation, finite element analysis simulations and experiments. The measured results were in good agreement with the theoretical data which reveal the influence law of structural parameters on thermal deformation and electromagnetic frequency control. Thus, the electromagnetic functionality of the metasurface can be thermally controlled and is expected to be useful in extreme situations where the coupling of multiphysical fields is required.

lattice structure, tantalum, additive manufacturing, mechanical property, deformation mechanism, energy absorption, Science, Manufactures, and TS1-2301

Tantalum (Ta) has excellent prospects in the bone-implant field due to its satisfactory biocompatibility. Two novel Ta lattice structures were designed and printed by selective laser melting (SLM), including the imitation saddle surface (ISS) and the imitation arch bridge telescopic (IABT) structures. Quasi-static compression tests and finite element analysis were adopted to investigate the effects of design parameters on the mechanical properties, deformation modes, and energy absorption of lattice structures. Compared with the typical lattice structure body-centred cubic (BCC) structure, the ISS lattice structure had a higher yield-stress-to-elastic-modulus ratio, and the IABT lattice structure had higher energy absorption. The failure mode of the BCC and ISS lattice structures was shear band formation. The IABT lattice structure showed hierarchical deformation during compression and collapsed with vertical strut buckling. The results indicated that the ISS lattice is the most potential candidate for bone implant applications.

dlp, multifunctional metamaterial, microlattice, sound absorption, mechanical property, Science, Manufactures, and TS1-2301

It is of significance, but still remains a key challenge, to attain excellent sound-absorbing and mechanical properties in a material simultaneously. To overcome this challenge, herein, novel multifunctional microlattice metamaterials based on a hollow truss-plate hybrid design are proposed and then realised by digital light processing 3D printing. Quasi-perfect sound absorption ($\alpha$ > 0.999) and broadband half-absorption have been measured. The sound-absorbing capacity is verified to be based on the designed cascaded Helmholtz-like resonators. Physical mechanisms behind the absorptive behaviours are fully revealed by numerical analyses. The present microlattices also display superior modulus and strength to the conventional cellular materials and modified microlattices, which is attributed to their near-membrane stress state of the plate architecture. The mechanically robust behaviour of the present microlattices in turn derives from the hollow struts. This work represents an effective approach for the design and engineering of multifunctional metamaterials through 3D printing.

laser powder bed fusion (lpbf), co-cr-mo alloy, nitrogen doping, strengthening mechanisms, strain induced martensite transformation (simt), Science, Manufactures, and TS1-2301

This study presented a comprehensive investigation into the microstructures, strengthening mechanisms and deformation behaviours of a novel N-doped Co-28Cr-6Mo (CCMN) alloy fabricated by laser powder bed fusion (LPBF). In addition to the well-known cellular structures, lattice defects including dislocations and stacking faults (SFs), the near-spherical shaped Cr2N precipitates with two typical size distributions were detected. Tensile test results revealed that the LPBF fabricated CCMN alloy demonstrated superior yield strength of 845 ± 49 MPa and elongation to fracture of 12.7 ± 1.9%. The grain boundaries (∼277 MPa), high density of dislocations (∼176–193 MPa), Cr2N precipitates (∼243 MPa) and SFs (∼131 MPa) are regarded as the dominate strengthening contributors. On the other hand, HCP phase triggered by strain induced martensite transformation (SIMT) and the Lomer-Cottrell locks (L-C locks) associated with the numerous SFs significantly enhanced the alloy strain hardening rate. More importantly, the formed Cr2N nanoprecipitates effectively suppressed the strain localisation and the premature failure along the HCP/FCC interfaces by deflecting the continuous growth of SFs, further contributing to the high ductility of the LPBF processed CCMN alloy. The present study is expected to shed light on the future development of N-doped high-performance cobalt-based alloy for the LPBF process.

laser powder bed fusion, static magnetic field, thermoelectric magnetic force, alsi7mg, columnar-to-equiaxed transition, Science, Manufactures, and TS1-2301

This work studied the effects of an on-line static magnetic field on the defects, microstructures, and mechanical properties of AlSi7Mg samples fabricated by laser powder bed fusion (LPBF). Process experiments were carried out on a self-developed LPBF equipment with an on-line static magnetic field generating system, where magnetic field intensity was adjustable from 0 to 0.3 T. With the action of static magnetic field, the relative density of samples increased from 96.9% to 98.6%. Furthermore, the solidification front of the columnar grain in the mushy zone was broken. With the increase of magnetic field intensity, the crystallographic orientation changed from strong to , and uniform distribution and the average grain was gradually refined from 8.35 to 7.22 μm. Based on the above optimisation, the ultimate tensile strength increased from (326.67 ± 5.31) MPa to (382.00 ± 2.45) MPa. Simultaneously, the elongation at break increased from 8.48% ± 0.20% to 11.78% ± 0.20%. In general, the reduction of pores, the refinement of grains and the increase of Mg2Si precipitates contributed to the simultaneous enhancement of strength and toughness together. This study could provide a new idea for laser additive manufacturing of excellent performance aluminum alloys.

ultrasound-assisted directed energy deposition, spatters and plume, image processing, auto-encoding, real-time monitoring, Science, Manufactures, and TS1-2301

Ultrasound-assisted directed energy deposition (UADED) is a promising technology for improving the properties of printed parts. However, process monitoring during UADED remains a challenge as ultrasound obscures the physical characteristics of DED. Here, the physical phenomena during UADED are captured using in-situ imaging and an unsupervised learning with auto-encoding is proposed to reconstruct images of the melt pool and analyse the features of spatter and plume to achieve the forming quality monitoring. This method enables effectively identifying the dynamic relationship in melt pool-spatter-plume, and the average recognition accuracy for reconstructed images reaches 94.52% during fully connected auto-encoders. Based on recognition results, the spatters during UADED are more intense, but the plume phenomenon is weakened compared to DED. The reason is that the flow mode was changed into reciprocal flow due to ultrasound. Subsequently, experiments indicated the method possessed high accuracy and robustness. The paper aims to provide a reference source for research studies on intelligent monitoring metal 3D printing.

cracking defects, precipitation-strengthened alloy, laser powder bed fusion, ni-based composite, high-temperature performance, Science, Manufactures, and TS1-2301

Avoiding cracking defects is crucial to ensuring processability in the laser powder bed fusion (LPBF) of metallic materials. In this study, a crack-free Ni-based superalloy with a high volume fraction of the γ′ phase was designed for the LPBF process using the thermodynamic approach. The results indicate that the designed SD01 Ni-based alloy was crack-free and over 21% of the spherical γ′ phase was uniformly distributed in the matrix after heat treatment. In addition, 1 wt.% TiB2 particles were introduced into the SD01 alloy to further enhance high-temperature mechanical performance. It was found that the morphology of the γ′ phase was altered from spherical to cubic structures, and its volume fraction increased from 21% to 40% after the TiB2 addition. The SD01-TiB2 composite exhibited an excellent combination of tensile strength (437.43 MPa) and elongation (7.71%) at 900 °C compared with the SD01 alloy (252.03 MPa, 3.02%). These findings provide a new metallic material design method for the LPBF of crack-free high-performance Ni-based materials.

Collaborative and adaptive cyber Défense strategies, Healthcare networks, Cyber security edge computing, Cyber Défense strategies, Internet of Things, Computer applications to medicine. Medical informatics, and R858-859.7

The Internet of Things (IoT) is a massive network connecting various devices and computer systems. This technology makes prototyping and distributing cutting-edge software and services easier. Through specifically created healthcare networks, the IoT makes it simple to link digital and tangible devices. Disputes continue to arise in the industry due to the absence of uniformity and the rapid growth of products, services, and methods. This study seeks to provide a birds-eye perspective of the technologies and protocols that support the IoT’s foundation. We start by introducing an elaborate process to examine the function of healthcare networks in creating and disseminating IoT-based software and some solutions to the current problems. We then discuss and formulate future challenges and the unanswered concerns surrounding the IoT’s support for healthcare networks. The primary focus of this research is to dissect the IoT, or horizontal network, into its constituent parts. These elements are essential for creating secure and robust mobile applications.

weather derivatives, parametric (index) insurance, pricing, willingness to pay, hedge effectiveness, integrative literature review, Finance, HG1-9999, Economic theory. Demography, and HB1-3840

AbstractThe agriculture sector observed the penetration of parametric weather risk financial products, including weather index insurance and weather derivatives, between the late 1990s and the early 2000s. However, the adoption of such products remains low. While the reasons for low adoption are mentioned in the extant literature, there is a lack of a theoretical framework that captures the moderators accelerating and inhibiting pricing structure and willingness to pay for parametric weather risk mitigants in agriculture. Also, the extant literature does not adequately explain the relationships or interdependencies between pricing structure and willingness to pay for parametric weather risk mitigants. This study bridges this gap by performing an integrative literature review. The review integrates the bibliometric analysis and systematic literature review and categorizes the extant literature into five focal areas: (1) weather analytics capability; (2) design, pricing, and testing; (3) users’ criteria for adoption; (4) prototyping; and (5) product efficacy of weather risk mitigation. A conceptual framework evolved from the review classifies the moderators into accelerants and inhibitors of pricing and willingness to pay. The framework hypothesizes that product design, contract specifications such as tick size and strike levels, hedge effectiveness, and instrument adoption have a recursive interaction with the willingness to pay and pricing structure. Future research directions guided by the proposed framework can motivate scholars and practitioners to explore the scope of bundling parametric (index) insurance and weather derivatives as a standalone product to enhance adoption.

Kinetic architecture, Shading device, Kinetic design, Environmental control, Architecture, and NA1-9428

This paper presents a design framework of a shading device applied on a building envelope, with a scheduled automatic activation logic, based on a sun path diagram. This proposal aims to balance the direct sun indoor exposure by evaluating the envelope area exposed to direct sun rays and the hourly activation rate of shading devices. These procedures are over the parametric modeling and simulation platform using raytracing, structural finite element analysis, and Computer Numerical Control (CNC) prototyping. The design process of building envelopes equipped with kinetic devices can use all these design resources. The kinetic device's activation logic relies on the feed-forward paradigm, scheduling the activation from the parametric modeling and the sun path diagram, using an angle threshold between the device post and the sun vector as a parameter. The design framework showed the preliminary path to develop shading devices considering the building envelope shape with a feed-forward activation logic based on local sun path characteristics.

Chemistry and QD1-999

haptic displays, soft electronics, tactile sensation, temporary tattoo substrates, thermo‐mechanical actuation, Electric apparatus and materials. Electric circuits. Electric networks, TK452-454.4, Physics, and QC1-999

Abstract Conformable electronics has emerged in recent years as an innovative research field and the ability of conformable devices to monitor human physiological signals has been extensively explored. Therefore, in this study, the possibility of using conformable electronics as active devices capable of providing stimuli to the human body is investigated. In particular, a new approach is proposed to elicit tactile sensations on human skin using an operating principle based on the generation of localized heat in correspondence with a closed volume of air. This latter consequently expands causing the deformation of a thin membrane. The use of fast prototyping fabrication techniques, i.e., inkjet printing, and commercially available materials, i.e., transfer tattoo paper, allow the device to be produced quickly and easily transferred on the target substrate. Despite the ultrathin thickness (few micrometers), it is possible to observe forces and displacements thanks to localized heating at very low working powers (

Food environments, cocreation, health promotion, frameworks, practical guidance, continuous quality improvement, Public aspects of medicine, and RA1-1270

Introduction: Food environments are a key determinant of food intake and diet-related health. This paper describes the development of an iterative, adaptive, context-specific framework for health-enabling food environments embedded in cocreation theory. Methods: A 3-stage multimethod framework for the coproduction and prototyping of public health interventions was followed in an iterative manner during the development of the framework. These 3 stages were (1) evidence review, including systematic review, consultation with experts, and observation of current work; (2) codesign of the framework prototype with multiple stakeholders; and (3) coproduction through refinement of the prototype through stakeholder workshops and expert reviews with incorporation of researcher notes and workshop evaluation. We use the term prototype during the development phase and the term framework to report on the final product. Results: COACH (CO-creation and evaluation of food environments to Advance Community Health) is a process framework that describes what best practice application of cocreation in health-enabling food retail environments should involve. COACH consists of 10 interdependent factors within a 4-phase continuous quality improvement cycle. The 4 phases of the cycle are engagement and governance establishment, communication and policy alignment, codesign and implementation, and monitoring and evaluation. Conclusions: Utilizing cocreation theory represents an innovative step in research and practice to improve the healthiness of food retail environments. COACH provides a specific, unique, and comprehensive guide to the utilization of cocreation to improve the healthiness of food environments in practice.

Phonon anisotropy, Heating effects, Temperature definition, Graphene, Monte Carlo method, Boltzmann equations, Engineering (General). Civil engineering (General), and TA1-2040

The effect of inclusion of the planar phonon anisotropy on thermo-electrical behavior of graphene is analyzed. Charge transport is simulated by means of Direct Simulation Monte Carlo technique coupled with numerical solution of the phonon Boltzmann equations based on deterministic methods.The definition of the crystal lattice local equilibrium temperature is investigated as well and the results furnish possible alternative approaches to identify it starting from measurements of electric current density, with relevant experimental advantages, which could help to overcome the present difficulties regarding thermal investigation of graphene.Positive implications are expected for many applications, as the field of electronic devices, which needs a coherent tool for simulation of charge and hot phonon transport; the correct definition of the local equilibrium temperature is in turn fundamental for the study, design and prototyping of cooling mechanisms for graphene-based devices.

analysis-ready data, Amazon Web Services, KOMPSAT-3/3A, multi-cloud, open data cube, OpenStack, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, and QD1-999

This study introduces a multi-cloud model that combines private and public cloud services for processing and managing satellite images. The multi-cloud service is established by incorporating private clouds within organizations and integrating them with external public cloud services to utilize the data. Private clouds can maintain data security within an organization or between organizations, while public clouds offer easy processing options for general users with access accounts. The model for the private cloud service utilizes open-source OpenStack software to create virtual machines, allowing users to manage analysis ready data (ARD) of the Korea Multi-Purpose Satellite (KOMPSAT)-3/3A images simultaneously. The public cloud service through Amazon Web Services (AWS) offers four services and uses the Open Data Cube (ODC) to manage data and provide web-based time-series visualization and processing. The model utilizes OpenStack to create virtual machines, and the public cloud service through AWS offers various services using ODC to manage data. A system that handles large amounts of satellite imagery in a multi-cloud environment has benefits such as improved availability, cost savings through open-source, and enhanced scalability. We present a prototyped utilization model that can be used with the ODC user interface (UI) that applies the proposed multi-cloud model. The multi-cloud model of this study can be applied to constructing a country-scale data cube system, that deals with large-scale satellite image data. It can also be applied to systems that need to be built with data that is tailored to a specific user’s needs at any institution.

3d printing, image processing, outer ear, reconstruction, biomaterials, and Medicine

Manufacturing replicas for replacing missing or defective body parts also incorporates 3D technology, including scanning, image processing and printing. In the case of the ears, both aesthetics and functionality play a significant role. Based on these techniques, outer ear replicas were produced using 3D scans of human skulls in a rapid prototyping procedure for actual patients. Hand-held scanners delivered accurate images for post-processing of the mesh and for printing in a cost- and time efficient way. Use cases of patients demonstrate applicability, allowing the technology to be available also for the general population in the future.

tissue engineering, bioreactor, rapid prototyping, enthesis tissue, and Medicine

We report on the development of a bioreactor system for mechanical stimulation of musculoskeletal tissues. The ultimate object is to improve the quality of medical treatment following injuries of the enthesis tissue. To this end, the tissue formation process through the effect of mechanical stimulation is investigated. A six-well system was designed, 3D printed and tested. An integrated actuator creates strain by applying a force. A contactless position sensor monitors the travels. An electronic circuit controls the bioreactor using a microcontroller. An IoT platform connects the microcontroller to a smartphone, enabling the user to alter variables, trigger actions and monitor the system. The system was stabilised by implementing two PID controllers and safety measures. The results show that the bioreactor design is suited to execute mechanical stimulation and to investigate the tissue formation and regeneration process. The bioreactor reported here can now be implemented in tissue engineering applications including tissue specimen.

augmented smart insoles, gait monitoring, foot health, rehabilitation, and Medicine

The augmentation of smart insoles gained increased interest due to the possibilities in foot-related rehabilitation, medical treatment, and postural risk prevention. As shown by previous work, the technology offers a personalized solution for individual foot morphology and biomechanics, which can monitor the health status and healing process. However, the success of this mobile technology depends on its usability and acceptance by healthcare professionals and patients. Therefore, an exploratory qualitative user study was conducted to investigate the preferences of healthcare professionals and patients regarding augmented smart insoles (ASI) usage. In focus groups, experts and patients explored their needs and suggested potential design solutions. The thematic analysis of the participants’ feedback revealed useful information regarding user interface (UI) designs for the development of a mobile application supporting smart insoles. We found that patients and experts share similar data preferences for a mobile application supporting ASI and that both user groups desired the presence of complete pressure point monitoring, active feedback for posture correction, and personalized training videos for postural risk prevention. However, healthcare professionals expressed concerns regarding the lack of scientific evidence validating the effectiveness of this technology and suggested further research.

model driven development, internet of things, digital thread platform, domain specific languages, low-code/no-code, DIME, Electronics, and TK7800-8360

Software development cycles in the context of IoT! (IoT!) applications require the orchestration of different technological layers, and involve complex technical challenges. The engineering team needs to become experts in these technologies and time delays are inherent due to the cross-integration process because they face steep learning curves in several technologies, which leads to cost issues, and often to a resulting product that is prone to bugs. We propose a more straightforward approach to the construction of high-quality IoT applications by adopting model-driven technologies (DIME and Pyrus), that may be used jointly or in isolation. The presented use case connects various technologies: the application interacts through the EdgeX middleware platform with several sensors and data analytics pipelines. This web-based control application collects, processes and displays key information about the state of the edge data capture and computing that enables quick strategic decision-making. In the presented case study of a Stable Storage Facility (SSF), we use DIME to design the application for IoT connectivity and the edge aspects, MongoDB for storage and Pyrus to implement no-code data analytics in Python. We have integrated nine independent technologies in two distinct Low-code development environments with the production of seven processes and pipelines, and the definition of 25 SIBs in nine distinct DSLs. The presented case study is benchmarked with the platform to showcase the role of code generation and the reusability of components across applications. We demonstrate that the approach embraces a high level of reusability and facilitates domain engineers to create IoT applications in a low-code fashion.

3D‐printing, mammalian cell cultivation, microbial cultivation, online monitoring, Biotechnology, and TP248.13-248.65

Abstract In the field of bioprocess development miniaturization, parallelization and flexibility play a key role reducing costs and time. To precisely meet these requirements, additive manufacturing (3D‐printing) is an ideal technology. 3D‐printing enables rapid prototyping and cost‐effective fabrication of individually designed devices with complex geometries on demand. For successful bioprocess development, monitoring of process‐relevant parameters, such as pH, dissolved oxygen (DO), and biomass, is crucial. Online monitoring is preferred as offline sampling is time‐consuming and leads to loss of information. In this study, 3D‐printed cultivation vessels with optical prisms are evaluated for the use in upstream processes of different industrially relevant microorganisms and cell lines. It was shown, that the 3D‐printed optically modified well (OMW) is of benefit for a wide range of biotechnologically relevant microorganisms and even for mammalian suspension cells. Evaluation tests with Escherichia coli, Bacillus subtilis, Saccharomyces cerevisiae, and Chinese hamster ovary (CHO) cells were performed, providing highly reproducible results. Growth behavior of OMW cultures was comparable to behavior of shake flask (SF) cultivations and the signal to noise ratio in online biomass measurement was shown to be reduced up to 95.8% by using the OMW. Especially the cultivation phases with low turbidity respective optical densities below 1.0 rel.AU could be monitored accurately for the first time. Furthermore, it was demonstrated that the 3D‐printed optics are transferable to different well geometries and sizes, enabling efficient biomass monitoring for individual requirements with tailor‐made 3D‐printed cultivation vessels in small scale.

otolaryngology, three dimensional printing, four-dimensional printing, additive manufacturing, biomaterials, bioprinting, Biotechnology, and TP248.13-248.65

Three-dimensional (3D)/four-dimensional (4D) printing, also known as additive manufacturing or fast prototyping, is a manufacturing technique that uses a digital model to generate a 3D/4D solid product. The usage of biomaterials with 3D/4D printers in the pharma and healthcare industries is gaining significant popularity. 3D printing has mostly been employed in the domain of otolaryngology to build portable anatomical models, personalized patient-centric implants, biologic tissue scaffolds, surgical planning in individuals with challenging conditions, and surgical training. Although identical to 3D printing technology in this application, 4D printing technology comprises a fourth dimension of time. With the use of 4D printing, a printed structure may alter over time under various stimuli. Smart polymeric materials are also generally denoted as bioinks are frequently employed in tissue engineering applications of 3D/4D printing. In general, 4D printing could significantly improve the safety and efficacy of otolaryngology therapies. The use of bioprinting in otolaryngology has an opportunity to transform the treatment of diseases influencing the ear, nose, and throat as well as the field of tissue regeneration. The present review briefs on polymeric material including biomaterials and cells used in the manufacturing of patient centric 3D/4D bio-printed products utilized in management of otolaryngology.

atopic dermatitis, biometric data acquisition, clinical research study, eczema, inflammatory skin disease, mobile application, Medicine, Public aspects of medicine, RA1-1270, Electronic computers. Computer science, and QA75.5-76.95

IntroductionIn-person dermatology clinical research studies often face recruitment and participation challenges due to travel-, time-, and cost-associated barriers. Studies incorporating virtual/asynchronous formats can potentially enhance research subject participation and satisfaction, but few mobile health tools are available to enable remote study conduct. We developed SkinTracker, a patient-facing mobile app and researcher-facing web platform, that enables longitudinal collection of skin photos, patient reported outcomes, and biometric health and environmental data.MethodsEight design thinking sessions including dermatologists, clinical research staff, software engineers, and graphic designers were held to create the components of SkinTracker. Following iterative prototyping, SkinTracker was piloted across six adult and four pediatric subjects with atopic dermatitis (AD) of varying severity levels to test and provide feedback on SkinTracker for six months.ResultsThe SkinTracker app enables collection of informed consent for study participation, baseline medical history, standardized skin photographs, patient-reported outcomes (e.g., Patient Oriented Eczema Measure (POEM), Pruritus Numerical Rating Scale (NRS), Dermatology Life Quality Index (DLQI)), medication use, adverse events, voice diary to document qualitative experiences, chat function for communication with research team, environmental and biometric data such as exercise and sleep metrics through integration with an Apple Watch. The researcher web portal allows for management and visualization of subject enrollment, skin photographs for examination and severity scoring, survey completion, and other patient modules. The pilot study requested that subjects complete surveys and photographs on a weekly to monthly basis via the SkinTracker app. Afterwards, participants rated their experience in a 7-item user experience survey covering app function, design, and desire for participation in future studies using SkinTracker. Almost all subjects agreed or strongly agreed that SkinTracker enabled more convenient participation in skin research studies compared to an in-person format.DiscussionTo our knowledge, SkinTracker is one of the first integrated app- and web-based platforms allowing collection and management of data commonly obtained in clinical research studies. SkinTracker enables detailed, frequent capture of data that may better reflect the fluctuating course of conditions such as AD, and can be modularly customized for different skin conditions to improve dermatologic research participation and patient access.

visual disability, visually impaired, assistive technology (AT), user–centered design, human centred design, innovation, Other systems of medicine, RZ201-999, Medical technology, and R855-855.5

Despite scientific and technological advances in the field of assistive technology (AT) for people with visual impairment (VI), technological designs are frequently based on a poor understanding of the physical and social context of use, resulting in devices that are less than optimal for their intended beneficiaries. To resolve this situation, user-centred approaches in the development process of AT have been widely adopted in recent years. However, there is a lack of systematization on the application of this approach. This systematic review registered in PROSPERO (CRD42022307466), assesses the application of the ISO 9241-210 human-centred design principles in allegedly “user-centred designed” AT developments for persons with VI (see Supplementary PROSPERO Protocol). The results point to a wide variation of the depth of understanding of user needs, a poor characterization of the application of the User Centred Design (UCD) approach in the initial design phases or in the early prototyping, and a vague description of user feedback and device iteration. Among the principles set out in ISO 9241-210, the application of 5.6: “the design team includes multidisciplinary skills and perspectives” is the one for which the least evidence is found. The results show there is not enough evidence to fully assess the impact of UCD in (1) promoting innovation regarding AT products and practices, and (2) Judging if AT produced following such standards is leading to better user access, wellbeing outcomes and satisfaction. To address this gap it is necessary to, first, generate better implementation of UCD in AT development and second, to strengthen evidence regarding the implementation and outcomes of using UCD for AT. To better engage with the realities of persons with VI, we propose capacity building across development teams regarding UCD, its principles and components; better planning for UCD implementation; and cross-fertilization across engineering disciplines and social and clinical science.Systematic Review Registrationhttps://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=307466 PROSPERO (CRD42022307466).

Internet of Medical Things, blockchain, hyperledger fabric, healthcare, Information technology, and T58.5-58.64

The Internet of Medical Things (IoMT) has risen significantly in recent years and has provided better quality of life by enabling IoMT-based health monitoring systems. Despite that fact, innovative security mechanisms are required to meet the security concerns of such systems effectively and efficiently. Additionally, the industry and the research community have anticipated that blockchain technology will be a disruptive technology that will be able to be integrated into innovative security solutions for IoMT networks since it has the potential to play a big role in: (a) enabling secure data transmission, (b) ensuring IoMT device security, and (c) enabling tamper-proof data storage. Therefore, the purpose of this research work is to design a novel lightweight blockchain-based security architecture for IoMT-based health monitoring systems leveraging the features of the Hyperledger Fabric (HF) Platform, its utilities. and its lightweight blockchain nature in order to: (i) ensure entity authentication, (ii) ensure data confidentiality, and (iii) enable a more energy-efficient blockchain-based security architecture for IoMT-based health monitoring systems while considering the limited resources of IoMT gateways. While security mechanisms for IoT utilizing HF do exist, to the best of our knowledge there is no specific HF-based architecture for IoMT-based health monitoring systems.

3D printing, Hydroxyapatite, 4D printing, Polymer, Scaffold, Bone tissue engineering, Science (General), Q1-390, Social sciences (General), and H1-99

The osseous tissue can be classified as a nanocomposite that encompasses a complex interweaving of organic and inorganic matrices. This intricate amalgamation consists of a collagen component and a mineral phase that are intricately arranged to form elaborate and perforated configurations. Hydroxyapatite, whether synthesized artificially or obtained from natural sources, has garnered considerable attention as a composite material in the field of bone tissue engineering due to its striking resemblance to bone in terms of structure and characteristics. Hydroxyapatite (HA) constitutes the predominant ceramic biomaterial for biomedical applications due to its ability to replicate the mineral composition of vertebrate bone. Nonetheless, it is noteworthy that the present biomimetic substance exhibits unfavorable mechanical characteristics, characterized by insufficient tensile and compressive strength, thus rendering it unsuitable for effective employment in the field of bone tissue engineering. Due to its beneficial attributes, hydroxyapatite (HA) is frequently employed in conjunction with various polymers and crosslinkers as composites to enhance mechanical properties and overall efficacy of implantable biomaterials engineered. The restoration of skeletal defects through the use of customized replacements is an effective way to replace damaged or lost bone structures. This method not only restores the bones' original functions but also reinstates their initial aesthetic appearance. The utilization of hydroxyapatite-polymer composites within 3D-printed grafts necessitates meticulous optimization of both mechanical and biological properties, in order to ensure their suitability for employment in medical devices. The utilization of 3D-printing technology represents an innovative approach in the manufacturing of HA-based scaffolds, which offers advantageous prospects for personalized bone regeneration. The expeditious prototyping method, with emphasis on the application of 3D printing, presents a viable approach in the development of bespoke prosthetic implants, grounded on healthcare data sets. 4D printing approach is an evolved form of 3D printing that utilizes programmable materials capable of altering the intended shape of printed structures, contingent upon single or dual stimulating factors. These factors include aspects such as pH level, temperature, humidity, crosslinking degree, and leaching factors.

Additive manufacturing, 3D printing, Knowledge management, Business models, Roadmap, Technology roadmap, Science (General), Q1-390, Social sciences (General), and H1-99

Additive Manufacturing (AM) demonstrates significant potential with rapid growth and widespread industrial adoption. To support the integration and innovation of AM technologies, the development of guidance tools and support methods are crucial, and a technological roadmap can assist in this effort. Despite its widespread use in production processes, the need for further research on the potential impact of AM remains significant. The full impact of AM is still uncertain and lacks consensus, highlighting the need for increased knowledge and investment from the scientific community and organizations. While the benefits of AM are recognized, the challenges of its adoption are not entirely known. AM will bring changes in the way organizations create, distribute, and derive value. Thus, in this article, a roadmap for AM is proposed and presented as a tool to map technological knowledge on the implementation and evolution of AM and serve as a strategic guide for organizations. The methodology for its elaboration involves three phases: planning and preparation, roadmap development, and review and update. Through a literature review, database and project consultation, and questionnaires to Portuguese companies that use AM in their production process it was possible to characterize the AM technology and through the visual format, based on a time horizon, summarize in a common framework all the information about the current and future state of AM in Portugal. The results of this study show that research and development initiatives are essential to promote the evolution of knowledge of the AM technology. Throughout this study and with the development of the roadmap it is anticipated that in the near future the AM will be widely used for prototyping and manufacturing of components and may be used for direct production in the short to medium term. It was also found that the main obstacles to the implementation of AM are the economic/productivity factors and the shortage of professionals with knowledge and skills in the area.

agricultural tractor, digital twin, lumped parameter simulation, multibody, powertrain, tyre-soil interaction, Cybernetics, Q300-390, Electronic computers. Computer science, and QA75.5-76.95

Abstract Modern agricultural tractors are complex systems, in which multiple physical (and technological) domains interact to reach a wide set of competing goals, including work operational performance and energy efficiency. This complexity translates to the dynamic, multi‐domain simulation models implemented to serve as digital twins, for rapid prototyping and effective pre‐tuning, prior to bench and on‐field testing. Consequently, a suitable simulation framework should have the capability to focus both on the vehicle as a whole and on individual subsystems. For each of the latter, multiple options should be available, with different levels of detail, to properly address the relevant phenomena, depending on the specific focus, for an optimal balance between accuracy and computation time. The methodology proposed here by the authors is based on the lumped parameter approach and integrates the models for the following subsystems in a modular context: internal combustion engine, hydromechanical transmission, vehicle body, and tyre–soil interaction. The model is completed by a load cycle module that generates stimulus time histories to reproduce the work load under real operating conditions. Traction capability is affected by vertical load on the wheels, which is even more relevant if the vehicle is travelling on an uncompacted soil and subject to a variable drawbar pull force as it is when ploughing. The vertical load is, in turn, heavily affected by vehicle dynamics, which can be accurately modelled via a full multibody implementation. The presented lumped parameter model is intended as a powerful simulation tool to evaluate tractor performance, both in terms of fuel consumption and traction dynamics, by considering the cascade phenomena from the wheel–ground interaction to the engine, passing through the dynamics of vehicle bodies and their mass transfer. Its capabilities and numerical results are presented for the simulation of a realistic ploughing operation.