School of Engineering


Doctor of Philosophy in Engineering (PhD)


Mark Horstemeyer


Finite Element Analysis, Brain Damage, Football, Helmet


Biomedical Engineering and Bioengineering | Engineering


The objective of this research was to present a model for brain damage to investigate the head’s response to mechanical loadings. A Finite Element (FE) head and brain mesh used throughout this dissertation was constructed from Magnetic Resonance Imaging (MRI) scan data of one of the authors and validated in previous research. A computational modal analysis was first conducted on the whole head and an isolated brain to identify the resonant frequencies, mode shapes, and locations. A physics-based Internal State Variable (ISV) constitutive model for polymers was modified to include damage in the form of pore growth. The brain damage model was developed to capture pore growth influenced by both tensile pressure and shear strains. The damage model constants were calibrated to match intermediate strain rate (50 s-1) compression tests done on fresh porcine brain samples. The calibrated brain damage model was then used to evaluate the relationship between impact, brain pressure, brain strain, and damage using a 2D model of a helmeted head. The same boundary conditions were then applied to a 3D model of a helmeted head to study the differences in responses between 2D and 3D. Finally, a sensitivity analysis was conducted to study the influence of impact location, impact velocity, helmet shell material, helmet facemask material, helmet foam liner classification, and helmet foam liner general stiffness level. Both impact studies were carried out at low and high velocities intending to replicate a range of common impact magnitudes experienced by both linemen and skill positions. Based on the findings presented in this dissertation, a deeper understanding of brain damage resulting from head impacts is useful to help designers engineer safer helmet equipment.

Available for download on Friday, June 30, 2023