Muscle and tendon tissues: constitutive modeling, numerical implementation and applications

Abstract

This work is concerned with the biological functioning and mechanical behavior of muscles and tendons. From the Mechanics viewpoint, muscles and tendons are \composite" materials that consist of ?bers, connective tissues, and bio°uids surrounding the ?bers. The idea of considering these ma- terials as \continuous media" is used and a \homogenization" process that accounts for the presence of the ?bers and the other material \phases" is developed. Thus, the main objective of this work is to propose a general and realistic constitutive model for the mechanical behavior of skeletal muscle and tendon when the materials are subjected to ?nite strains. The model accounts for all the essential information about the microstructure of the materials. Also, it is constructed in such a way that di®erent material properties of di®erent muscles can be altered easily when the behavior of a whole group of muscles is to be studied in the same time. Furthermore, a methodology to handle numerically the resulting non-linear and anisotropic con- stitutive equations in the context of ?nite element method is developed. The constitutive model is, then, implemented in a general-purpose ?nite element program. Finally, the developed model is used to study the behavior of several muscle-tendon complex cases. Firstly, the extension of a squid tentacle during the strike to catch prey is simulated in order to validate the proposed model with previous experimental and computational results. Next, the behavior of simpli?ed parallel ?bred and pennated muscles is studied. Also, the human semitendinosus muscle is simulated. The constitutive model is further applied to the muscles and tendons of the human leg and the plantar °exion of the ankle is achieved.