MULTI-SCALE MODELING AND SIMULATION OF SKELETAL MUSCLE BIOMECHANICAL PROPERTIES

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 invariants${I}_{4}、{I}_{5}、{I}_{6}、{I}_{7}$, 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.