Fábio Pinto da Silva

Design and milling manufacture of polyurethane custom contoured cushions for wheelchair users

BACKGROUND The design of custom contoured cushions manufactured in flexible polyurethane foams is an option to improve positioning and comfort for people with disabilities that spend most of the day seated in the same position. These surfaces increase the contact area between the seat and the user. This fact contributes to minimise the local pressures that can generate problems like decubitus ulcers. The present research aims at establishing development routes for custom cushion production to wheelchair users. This study also contributes to the investigation of Computer Numerical Control (CNC) machining of flexible polyurethane foams. METHOD The proposed route to obtain the customised seat began with acquiring the users contour in adequate posture through plaster cast. To collect the surface geometry, the cast was three-dimensionally scanned and manipulated in CAD/CAM software. CNC milling parameters such as tools, spindle speeds and feed rates to machine flexible polyurethane foams were tested. These parameters were analysed regarding the surface quality. The best parameters were then tested in a customised seat. The possible dimensional changes generated during foam cutting were analysed through 3D scanning. Also, the customised seat pressure and temperature distribution was tested. RESULTS The best parameters found for foams with a density of 50kg/cm(3) were high spindle speeds (24000 rpm) and feed rates between 2400-4000mm/min. Those parameters did not generate significant deformities in the machined cushions. The custom contoured cushion satisfactorily increased the contact area between wheelchair and user, as it distributed pressure and heat evenly. CONCLUSION Through this study it was possible to define routes for the development and manufacturing of customised seats using direct CNC milling in flexible polyurethane foams. It also showed that custom contoured cushions efficiently distribute pressure and temperature, which is believed to minimise tissue lesions such as pressure ulcers.

A digitalização tridimensional como método de verificação da deformação do MDF ocasionada pela absorção de água

A digitalizacao tridimensional consiste na captura de dados de superficies, e a partir disso, a construcao de objetos em modelos 3D virtuais. Esta tecnologia possui diversas aplicacoes, como: a producao de roupas, calcados e proteses personalizadas, criacao de dados 3D de modelos para animacao, jogos e filmes, reproducao de pecas de arte como esculturas, na engenharia reversa, entre outros. Sendo assim, neste trabalho, a digitalizacao tridimensional foi aplicada na caracterizacao de materiais. Desta forma, o estudo teve como objetivo a verificacao da deformacao do mdf ocasionada pela absorcao de agua a partir da digitalizacao tridimensional. Para isso, foram confeccionados corpos de prova de MDF de duas marcas diferentes e realizado o ensaio de absorcao de agua. A digitalizacao dos corpos de prova foi realizada antes da imersao em agua destilada, apos 2 h e 24 h de imersao. Os resultados evidenciaram que a digitalizacao tridimensional pode ser utilizada como metodo de verificacao da deformacao, pois demonstrou o inchamento dos corpos de prova submetidos ao ensaio de absorcao de agua.

AVALIAÇÃO DE MODELOS OBTIDOS POR DIFERENTES SISTEMAS DE DIGITALIZAÇÃO 3D PARA PRODUTOS PERSONALIZADOS

O objetivo e avaliar modelos obtidos por diferentes sistemas de digitalizacao tridimensional e verificar se as variacoes geometricas podem gerar implicacoes nas medidas antropometricas para o projeto de produtos personalizados. Para as comparacoes e analises, a perna direita de um sujeito foi digitalizada, pelo scanner 3D de luz branca (Artec Eva) e pelo scanner por infravermelho (kinect da Microsoft). Os modelos 3D obtidos foram comparados atraves do software Geomagic Q ualify . Tambem, atraves da usinagem CNC foram realizadas comparacoes de analises visuais, por mapeamento de pressao e por termografia. Os resultados obtidos foram satisfatorios tanto para o uso do scanner Kinect quanto para o Artec Eva. Porem, houve uma diferenca dimensional de aproximadamente 7 mm entre os modelos 3D, o que demonstra uma maior precisao de medidas nos modelos obtidos pelo scanner Artec Eva. No entanto, nao invalida o uso do Kinect para o desenvolvimento de projetos de produto personalizados. O que ira determinar qual o scanner 3D mais adequado para cada tipo de produto e a necessidade do grau de precisao para que o produto desempenhe sua funcao com maior conforto e eficiencia.

Development and Thermographic Analysis of Custom Seats for Wheelchairs

The design of Assistive Technology products has different technological routes such as massive products or custom products. These products aim at optimize the altered bodily functions. With that it can re-conduct these people to varied social activities. In this sense, the present article focuses on contribute in the construction of new technological routes for the manufacturing of wheelchair custom seats. The methodology includes the application of concepts such as tridimensional digitizing, CNC machining and thermography. Those techniques have the purpose of generating and analyzing seats made from user’s anthropometric data.

DISPONIBILIZAÇÃO DE EXERCÍCIOS E SUA CORREÇÃO ON-LINE EM AMBIENTES DE ENSINO A DISTÂNCIA

Neste artigo e apresentado o ambiente NdSM de disponibilizacao e correcao on-line de exercicios, uma ferramenta desenvolvida para completar a plataforma de EAD do NdSM/UFRGS.

Design and health care: a study of virtual design and direct metal laser sintering of titanium alloy for the production of customized facial implants

The increase in life expectancy and a great number of accidents lead to higher demand for medical products, including corrective implants. Patients with tumors or traumas need to replace injured areas in order to restore their aesthetic and structural function. Currently, the available craniofacial implants present a standard geometry and seldom generate satisfactory results. Customized implants, on the other hand, are designed to conform exactly to individual patient’s anatomy. This way, the use of customized implants can show beneficial effects to the patient and the surgical team. In this study, the design and manufacturing of customized implant prior to surgery were described. Implant shape and functional requirements were established by digital data based on CT-scans and mirroring operations. The design process of customized mandible prosthesis is illustrated as well as its manufacturing process (direct metal laser sintering) and quality control. Laser sintering process and its constraints for the production of customized implants in titanium alloy (Ti-6Al-4V) with complex geometry and internal structures are reported.