骨骼肌生物力学特性多尺度建模与仿真

MULTI-SCALE MODELING AND SIMULATION OF SKELETAL MUSCLE BIOMECHANICAL PROPERTIES

针对肌纤维微观结构模型与显微镜下观察的图像存在一定差异、微观组分生物力学模型无法有效捕获骨骼肌剪切变形时的力学行为、骨骼肌多尺度数值模型计算成本高的问题,本文从实验、多尺度建模和仿真的角度研究骨骼肌被动力学特性,提出以曲边泰森多边形作为肌纤维截面形状,并建立骨骼肌微观尺度代表性体元RVE;提出新的生物力学模型(MMA模型),并将MMA模型作为肌纤维和结缔组织生物力学模型,MMA模型采用完全的应变不变量I_(4),I_(5),I_(6)和I_(7),使骨骼肌的剪切行为从材料属性层面得以体现;结合骨骼肌力学实验结果、RVE模型、肌纤维和结缔组织的生物力学模型,建立骨骼肌多尺度数值模型.根据实验结果确定生物力学模型参数,通过多尺度均匀化方法实现微观尺度和宏观尺度之间的连接,最终获得骨骼肌宏观力学行为,通过纵向拉伸、横向拉伸、平面外纵向剪切和平面内剪切4种变形形式的仿真结果验证骨骼肌多尺度数值模型的收敛性.研究了生物力学模型中模型参数、肌纤维体积分数和肌纤维结构对骨骼肌宏观力学行为的影响,最后通过实验验证多尺度数值模型的有效性.本文骨骼肌多尺度数值模型不仅能够用于研究骨骼肌微观因素对宏观力学行为的影响,也可用于研究疾病对骨骼肌生物力学特性的影响及模拟骨骼肌重塑和再生.

Aiming at the problems that there is a certain difference between the muscle fiber microstructure model and the image observed under the microscope,the microscopic component biomechanical model cannot effectively capture the mechanical behavior of skeletal muscle during shear deformation,and the high calculation cost of multi-scale numerical models of skeletal muscle.In this thesis,the mechanical properties of skeletal muscle are studied from the perspectives of experiment,multiscale modeling and simulation.Curved-edge Voronoi polygons are proposed as the cross-section of muscle fibers,and the corresponding representative volume element(RVE)is established at the microscale.A new biomechanical model(MMA model)is proposed,and the MMA model is used as the biomechanical model of muscle fibers and connective tissue,the MMA model adopts complete strain invariantsI_(4)、I_(5)、I_(6)、I_(7),so that the shear behavior of skeletal muscle is reflected at the level of material properties.Combine the experimental results of skeletal muscle,the RVE models,the biomechanical models of muscle fibers and connective tissue to establish a multiscale numerical model of skeletal muscle.According to the experimental results,the parameters of the biomechanical model are determined,the multiscale homogenization method are used to realize the connection between the microscale and the macro-scale,and the macroscopic mechanical behavior of skeletal muscle is finally obtained,four deformation forms of Longitudinal stretch,stretch laterally,out-of-plane longitudinal shear and in-plane shear are performed to verify the convergence of the model.This thesis research the effects of model parameters,muscle fiber volume fraction and muscle fiber structure on skeletal muscle on macroscopic mechanical behavior.Combined with experimental data,the effectiveness of the multiscale numerical model is verified.In this paper,the multi-scale numerical model of skeletal muscle can not only be used to study the influence of microscopic factors on the macroscopic mechanical behavior of skeletal muscle,but also to study the influence of diseases on the biomechanical properties of skeletal muscle and to simulate skeletal muscle remodeling and regeneration.