Advanced Applications of Rapid Prototyping Technology in Modern Engineering

Rapid prototyping (RP) technology has been widely known and appreciated due to its flexible and customized manufacturing capabilities. The widely studied RP techniques include stereolithography apparatus (SLA), selective laser sintering (SLS), three-dimensional printing (3DP), fused deposition modeling (FDM), 3D plotting, solid ground curing (SGC), multiphase jet solidification (MJS), laminated object manufacturing (LOM). Different techniques are associated with different materials and/or processing principles and thus are devoted to specific applications. RP technology has no longer been only for prototype building rather has been extended for real industrial manufacturing solutions. Today, the RP technology has contributed to almost all engineering areas that include mechanical, materials, industrial, aerospace, electrical and most recently biomedical engineering. This book aims to present the advanced development of RP technologies in various engineering areas as the solutions to the real world engineering problems

Modeling and Simulation in Engineering

This book provides an open platform to establish and share knowledge developed by scholars, scientists, and engineers from all over the world, about various applications of the modeling and simulation in the design process of products, in various engineering fields. The book consists of 12 chapters arranged in two sections (3D Modeling and Virtual Prototyping), reflecting the multidimensionality of applications related to modeling and simulation. Some of the most recent modeling and simulation techniques, as well as some of the most accurate and sophisticated software in treating complex systems, are applied. All the original contributions in this book are jointed by the basic principle of a successful modeling and simulation process: as complex as necessary, and as simple as possible. The idea is to manipulate the simplifying assumptions in a way that reduces the complexity of the model (in order to make a real-time simulation), but without altering the precision of the results

Estudo do processo de maquinagem de componente polimérico tibial de implante do joelho

A personalização de implantes do joelho é uma tendência crescente que permite aumentar a sua vida útil, exigindo processos de fabrico mais flexíveis do que os aplicados na produção em série. Esta tese analisa a viabilidade de produção personalizada através de maquinagem de alta velocidade com 3 ½ eixos, sendo o componente estudado aquele que é mais sujeito a desgaste na prótese do joelho. Deste modo, o trabalho desenvolvido teve como objetivos a modelação, o fabrico e o estudo do estado superficial do componente polimérico do implante do joelho, obtido por maquinagem a alta velocidade com recurso a ferramentas de corte convencionais. Esta interface de contacto entre o componente femoral e o prato tibial, foi modelada, a partir de modelos reais, em software 3D, recorrendo a técnicas da Engenharia Inversa. A otimização de parâmetros do processo levou à conceção de uma peça-teste com as superfícies mais importantes do espaçador, com principal ênfase para as cavidades dos côndilos. A simulação da maquinagem da peça-teste permitiu selecionar as seis trajetórias mais promissoras a estudar em testes experimentais. Os ensaios de maquinagem foram planeados através do método de Taguchi e realizados em várias fases, permitindo a sucessiva redução do número de trajetórias e de parâmetros considerados inicialmente, otimizando a qualidade das superfícies obtidas nesta operação de acabamento. No método proposto, a qualidade das superfícies foi avaliada quantitativamente através da leitura de alguns parâmetros de rugosidade, como o Ra (rugosidade média), e qualitativamente através de imagens de microscopia ótica. Modelaram-se a rugosidade média e a duração do acabamento em função dos parâmetros mais influentes, que são o incremento lateral entre passagens sucessivas da ferramenta de corte, ou a sua velocidade de avanço, consoante a trajetória. O melhor acabamento foi conseguido com a estratégia Blend obtendo-se um valor médio de Ra próximo de 1,1 µm e originando uma trajetória em espiral. Na produção do protótipo aplicaram-se os parâmetros otimizados na peça-teste recorrendo a uma máquina CNC com 3 ½ eixos e avaliou-se a precisão dimensional das superfícies maquinadas.Customized knee implants are a growing tendency which increases its lifetime, however it requires more flexible manufacturing processes than those applied in mass production. This thesis analyses the feasibility of customized production through high speed machining with 3 ½ axes. The knee prosthesis component studied is the one that is most subject to wear. Thus, the objectives of this work were modelling, manufacturing and studying the surface quality of the tibial insert, obtained by high-speed machining using conventional cutting tools. This interface, between the femoral component and the tibial plate, was modelled from real implants in 3D software, using reverse engineering techniques. The optimization of process parameters led to the design of a test piece with the most important surfaces of the tibial insert, with a primary accent on the condylar cavities. A machining simulation of the test piece allowed to select the six most promising trajectories to be studied in experimental tests. The machining tests were planned using the Taguchi method and carried out in several phases, allowing the reduction of the number of toolpaths and parameters considered initially, optimizing the roughness obtained in this finishing operation. The quality of the surfaces was measured by reading several roughness parameters, such as the arithmetic mean surface roughness (Ra), and through optical microscopy images. The average roughness (Ra) and the duration of the finish operations were correlated to the most influential parameters, which are the stepover and the feed rate. The best finish was achieved with the Blend strategy, with a spiral toolpath, obtaining a Ra value close to 1.1 µm. The optimized parameters were used in the production of the modelled tibial insert using a CNC machine with 3 ½ axes. The dimensional accuracy of the machined surfaces was evaluated.Programa Doutoral em Engenharia Mecânic

ROBUST ESTIMATION OF KNEE KINEMATICS AFTER TOTAL KNEE ARTHROPLASTY WITH EVOLUTIONAL COMPUTING APPROACH

ABSTRACT Analyzing knee kinematics after total knee arthroplasty (TKA) has been attracting considerable attentions because the knee kinematics can be used to evaluate TKA patients and to evaluate TKA operations and design of knee implants. Knee kinematics can be estimated by 2-D/3-D image registration from 3-D computer-aided design (CAD) models of knee implants to 2-D X-ray image. Although there are many studies for estimating knee kinematics, they have common problems that are dependency on initial pose/position and falling into local maxima. This study proposes a robust 2-D/3-D image registration method based on evolutional computing. The evolutional computing has both characteristics of global search performance and of local search performance. The characteristics are suitable for solving the problems of 2-D/3-D image registration. The proposed system has been evaluated by applying it to computer-synthesized images, X-ray images of phantoms, and X-ray images of TKA patients