中国50th人体小腿有限元模型多工况优化建模方法

摘要

人体下肢是交通事故中最易受伤的部位之一,下肢有限元模型则成为研究下肢损伤机理和防护方法的重要工具,而要保证模型生物逼真度则需开展多工况全面验证.人体模型验证所需的生物力学试验数据由于样本尺寸、材料等多样性造成力学响应存在差异,难于用一个模型同时满足多个试验数据.中国人体与欧美人体在几何尺寸上的差异会造成生物力学响应的不同,因此有必要开发中国人体的有限元模型.通过CT、MRI扫描建立小腿几何模型,利用由胫骨关键尺寸确定的缩放系数,将小腿几何模型缩放至中国50百分位人体小腿.同样采用缩放方法,将生物力学试验数据缩放至小腿尺寸所对应的生物力学响应数据,以解决试验样本几何差异的影响.以胫骨和腓骨的弹性模量、应力-应变曲线、失效应变以及肉体体积模量为设计变量,采用优化方法,同时拟合胫骨和腓骨在准静态、动态载荷下不同加载位置的生物力学响应,以及小腿动态载荷下不同加载位置的生物力学响应,解决试验样本多样性造成的模型验证难题.当胫骨和腓骨皮质骨弹性模量分别取18.43和18.23 GPa、失效应变分别取1.2％和0.8％、小腿肉体体积模量取11.33 MPa时,所建小腿模型能够较好地同时满足多组试验中样本的生物力学响应,表明基于优化的多工况人体模型验证方法能够使有限元模型获得较好的生物逼真度.%The lower extremity of the human body is one of the most vulnerable parts in traffic accidents,and the finite element (FE) model of the lower limb has become an important tool to study mechanisms and protective methods of lower limb injuries.In order to ensure the fidelity of the model,it is necessary to carry out a comprehensive validation under multi-loading conditions.The biomechanical test data are different in the mechanical response due to the sample size and material diversity,so it is difficult to use one model to meet the multiple test data.The differences in geometric dimensions between Chinese and occidental human body would result in differences of biomechanical response,so it is necessary to develop the FE model of Chinese human body.In this paper,Geometry model based on the CT and MRI data was scaled to the 50 percentile male according to scaling factor derived from key dimensions of the tibia.The scaling method was also used to scale biomechanical test data to the biomechanical response data corresponding to the size of the leg.The elastic modulus,stress-strain curve,failure strain of the tibia and fibula and physical bulk modulus of the muscle were selected as design variables,the optimization method was used to fit tibia,fibula and calf biomechanical responses under different load positions in the quasi-static and dynamic loading conditions,which solved the problem with diversity caused by the test sample.When the elastic modulus of tibia and fibula were 18.43 and 18.23GPa,respectively,the failure strains were 1.156％ and 0.8％,respectively,and physical bulk modulus of the calf was 11.33MPa,the calf model could fit the biomechanical responses well in many groups of tests.The FE model verification methods based on the optimization of multi-loading conditionsmade the FE model acquire better biofidelity effectively.