ENGINEERING, AEROSPACE, Frequency Selective Surface, Filter, Free-space measurement, and Measurement and prototyping

The design, prototyping, and free-space measurement of a 6-GHz Frequency Selective Surface filter is presented. The prototyping resolution of a large (A4 sheet size) Frequency Selective Surface with small loops as elements is checked, as well as the correlation with measurements performed with a 3-D full-wave solver. The test also involved the effect of cascading two different Frequency Selective Surfaces with a viewpoint towards a narrower frequency range, which provided good results.

ENGINEERING, BIOMEDICAL, Developmental dysplasia of the hip, Orthosis, and Rapid prototyping

Introduction Immobilization in a hip spica cast is required in surgical and nonsurgical treatments for children aged three months to four years diagnosed with developmental dysplasia of the hip. Skin complications are associated with the use of the spica cast in 30% of the cases. This research explores the use of photogrammetry and rapid prototyping for the production of a lighter, shower friendly and hygienic hip orthosis that could replace the hip spica cast. Methods Digitalized data of a plastic dool was used for design and fabrication of a customised hip orthosis following four steps: 1) Digitalization of the external anatomical structure by photogrammetry using a smartphone and open source software; 2) Idealization and 3D modeling of the hip orthosis; 3) Rapid prototyping of a low cost orthosis in polymer polylact acid; 4) Evaluation tests. Results Photogrammetry provided a good 3D reconstruction of the dool's hip and legs. The manufacture method to produce the hip orthosis was accurate in fitting the hip orthosis to the contours of the doll. The orthosis could be easily placed on the doll ensuring mechanical strength to immobilize the region of the hip. Conclusion A new approach and the feasibility of both techniques for hip orthosis fabrication were described. It represents an exciting advance for the development of hip orthosis that could be used in orthopedics. To test the effectiveness of this orthosis for developmental dysplasia of the hip treatment in newborns, material and mechanical tests, design optimization and physical tests with patients should be carried.

ENGINEERING, MANUFACTURING, Product engineering, Rapid prototyping, Decision making, Multiattribute criteria, Engenharia do produto, Prototipagem rápida, Tomada de decisão, and Critério multiatributos

A tecnologia de prototipagem de produtos por adição de material (Rapid Prototyping) e por remoção de material (Subtractive Rapid Prototyping) pode variar em: qualidade, tempo e custos, dependendo das características do produto. A escolha da tecnologia muitas vezes está condicionada à decisão empírica do designer/engenheiro ou operador, devido ao tipo de material, dimensão e precisão. Este artigo apresenta um método para tomada de decisão que auxilia a escolha da tecnologia de prototipagem rápida mais adequada na concepção de novos produtos. Foram utilizados os conceitos de DFM (Design for Manufacturing), CAD (Computer Aided Design), RPD (Rapid Product Development) e MAUT (Multiattribute Utility) em dois produtos de diferente estrutura e material (composto leve e simples maciço) para avaliar e validar o método proposto. Os resultados apresentam comparações entre as tecnologias de prototipagem rápida a partir de critérios para tomada de decisão, aperfeiçoando a concepção de protótipos mais eficientes.
The prototyping of products by additive material (Rapid Prototyping) and by subtractive material (Subtractive Rapid Prototyping) technology can vary in: quality, time and costs, depending on the product characteristics. The selection of technology often is conditioned to the designer/engineer or operator empirical decision due to the type of material, size and accuracy. This paper presents a method for decision making to assist the best choice of rapid prototyping technology on new product conception. We used the concepts of design for manufacturing (DFM), rapid product development (RPD) and computer aided design (CAD) for two products of different structure and material (lightweight dual and simple solid) to evaluate and validate the proposed method. The results show comparisons between the rapid prototyping technologies based on decision making, improving the conception of most efficient prototype.