Influence of wall thickness on the stress distribution within transtibial monolimb

Abstract

一体化假肢是以聚合物为材料从接受腔到假腿一体成型的新型下肢假肢 ,它比传统型假肢更经济、美观、轻便 ,具有较大的应用前景。如同传统假肢 , 应力分析对于一体化假肢的构型设计和优化具有重要的意义。 由于假肢中的应力大小及分布与其所用材料的力学特性密切相关。 本文的工作是基于一实验用内骨架一体化小腿假肢的真实几何构型 ,考虑残端软组织和骨 ,建立一体化小腿假肢的三维有限元模型 ;在保持假肢的几何形状不变的前提下 ,建立三个不同壁面厚度的一体化小腿假肢的三维模型 ,应用有限元分析方法 ,计算这些模型在模拟 Heel Off步态时相的载荷作用下的应力分布 , 分析壁面厚度对一体化小腿假肢应力分布的影响 , 为一体化小腿假肢壁面厚度的设计标准提供参考。结果表明 ,可以通过适当增加壁面厚度来减小一体化假肢的应力及软组织表面的压力。 Monolimb is a new type of lower-limb prostheses made of macromolecule polymer,in which the socket and prosthetic shank are integrative. Compared with traditional prosthesis,monolimb is more economical,good-looking and portable, so it indicates a possible direction in the future. Biomechanical research on trans-tibial monolimb is necessary and helpful just like traditional prosthesis. In this article,a 3D FE model based on real geometry shape of an endoskeletal trans-tibial monolimb is established. Keeping the same geometrical shape,three 3D FE models of transtibial monolimbs with different wall thickness are established. The influence of wall thickness on the stress distribution is analyzed under the load corresponding to the subphase of stance of Heel Off. The results indicate that stress within transtibial monolimb and pressure on the surface of soft tissue could be decreased with wall thickness of transtibial monolimb increased. This study will be helpful for the standard of wall thickness in designing transtibial monolimb.