Estudo e otimização do envoltório externo das próteses de antebraço

Abstract

Motor disability occurs in more than 13 million Brazilians, where 5.32% do not have a limb or part of it, also, levels of prosthesis use acceptance have very reduced values, mainly due to the high weight. The aim of this research is to study the external wrap of the forearm prosthesis, through the use of a material capable of resist to imposed demands and also the proposal of a geometric optimization to reduce mass, thickness, force and stress. The proposed methodology consist of using anthropometric techniques to collect accurate measurements of a human forearm and use them to develop a 3D model by software Inventor, then subject the model to an finite element analysis and also perform an optimization using the multi-objective genetic algorithm (MOGA) through Ansys Workbench software. The biomaterial used is the 316 austenitic stainless steel and the load applied in the simulation was equivalent to hold 10 kg in the hand, corresponding to a force of 98.1 N. The result of the initial simulation, for an arbitrary thickness of 4 mm, showed that the site of greatest stress is located in the part corresponding to the wrist, in the union between the forearm and the hand, with a value of 7.67 MPa. Thus, the next step was to use the MOGA optimization algorithm for an analysis of four proposed parameters: thickness, mass, maximum stress and maximum force. The results show points of convergence for values of 3,945 mm of thickness, 1,366 kg of mass, 100,25 N of maximum force and 4,09 MPa of maximum tension. Thus, it can be concluded that the analysis generated consistent results that meet the specifications of load and dimensions, attended the purposes of mass reduction and specification of a material capable of meeting imposed demands, and also opened opportunities for future work.