Graduation Year


Document Type




Degree Granting Department

Chemical and Biomedical Engineering

Major Professor

William Lee

Co-Major Professor

Don Hilbelink


Biomechanics, Finite Element Analysis, Kinesiology, Rotator Cuff, Shoulder


Computer generated three-dimensional (3-D) models are being used at increasing rates in the fields of entertainment, education, research, and engineering. One of the aspects of interest includes the behavior and function of the musculoskeletal system. One such tool used by engineers is the finite element method (FEM) to simulate the physics behind muscle mechanics. There are several ways to represent 3-D muscle geometry, namely a bulk, a central line of action and a spline model. The purpose of this study is to exmine how these three representations affect the overall outcome of muscle movement. This is examined in a series of phases with Phase I using primitive geometry as a simplistic representation of muscle. Phases II and III add anatomical representations of the shoulder joint with increasing complexity. Two methods of contraction focused on an applied maximal force (Fmax) and prescribed displacement. Further analyses tested the variability of material properties as well as simulated injury scenarios. The results were compared based on displacement, von Mises stress and solve time. As expected, more complex models took longer to solve. It was also supported that applied force is a preferred method of contraction as it allows for antagonistic and synergistic interaction between muscles. The most important result found in these studies was the consistency in the levels of displacement and stress distribution across the three different 3-D representations of muscle. This stability allows for the interchangeability between the three different representations of muscles and will permit researchers to choose to use either a bulk, central line of action or a spline model. The determination of which 3-D representation to use lies in what physical phenomenon (motion, injury etc.) is being simulated.