Biomechanical analysis of skeletal muscle in an interactive digital human system

Biomechanical analysis of skeletal muscles is an important task in digital human systems. The standard finite element method (FEM) can be used for muscle analysis; however, a full-scale FEM model can be overly complicated in a digital human system. In this work, we describe an efficient method of muscle analysis. The method is a combination of the Non-Uniform Rational B-spline (NURBS) geometric representation and the Galerkin methods. The basic idea is to establish the discrete equations of motion on the basis of NURBS geometry directly, without resorting to additional meshing. The method can adequately model muscle motion and stress while keeping the model size and complexity at a tractable level. As the first step towards interactive stress analysis in a digital human, we have developed NURBS FEM model for isolated muscles in human upper limb. The geometries of the muscles are extracted from the Visible Human Data Set [15], and the mechanical behavior is characterized by an active, anisotropic hyperelastic model. We also discuss how the muscle model will be implemented in and interacts with the virtual human (Santos) developed at the University of Iowa.