A VARIATIONAL CONSTITUTIVE MODEL FOR ACTIVE BEHAVIOR OF SKELETAL MUSCLES

Frederico Lagemann¹; Jakson Manfredini Vassoler¹

¹ PROMEC-UFRGS

doi:10.20906/CPS/COB-2015-1413

Resumo

Skeletal muscles are capable to provide force due to their components, which are formed mainly by bundles of specialized cells called muscle fibers. The mechanical response of skeletal muscle can be represented by two anisotropic contributions, a passive contribution that is related to the intrinsic muscle elasticity and an active contribution that dependents of an electrical stimulus of the muscle fibers. The numerical simulation of such materials have been studied for many years, but still it is a challenging task, where the development of an adequate constitutive model is a genuine challenge. Then, this paper propose an anisotropic model capable to take into account the muscle activation, when it is submitted to an electrical stimulus and finite strains. This approach is based on the Hill model. This model consists of an elastic element in series with a contraction component, and both in parallel with a second elastic element. The constitutive model is based on a variational framework, in which a local minimization provides the contractile variable updates for each load increment. The numerical results show that the proposed model can represent the muscle passive and active behavior, and may be used to represent skeletal muscles.

Palavras-chave: variational constitutive model; muscle activation; anisotropic model