Active finite element analysis of muscle-tendon complex

A three-dimensional active finite element analysis was conducted by using motor elements and large strain viscoleastic elements to study a skeletal a muscle-tendon complex. The active finite element was created through incorporation of a user-defined sub-program into ABAQUS finite element code. The method of creating the active finite element can also be applied in other commercially available finite element packages. The active finite element is controlled by the motor element that is activated by a mathematical function. The nonlinear passive behavior of the muscle was defined by the large strain viscoelastic elements and can be easily altered to other properties by using other elements in the material library without the need of re-defining the constitutive relation of the muscle. The motion and the stress-strain distribution of the muscle-tendon complex were simulated using the finite element model. With the active finite element method, realistic finite element simulation of not only skeletal muscle or any active structures may be carried out.