A numerical model of passive and active behavior of skeletal muscles

In this paper a numerical model is developed for the simulation of the 3-D deformations of skeletal muscles. Muscles are distinct from other materials, particularly from other biological tissues, because of their capability of active contraction. The constitutive relation adopted in this work is a generalization of the model proposed by Humphrey and Yin for the passive behavior of cardiac muscle. This generalization is done in such a way as to make Humphrey's model compatible with Zajac's I-D model of the passive and active behavior of skeletal muscles. The finite element method is used to obtain numerical results for some simple tests.