Finite Element Analysis of Humerus with Impact at Distal End and the Mechanical Effect of Bone Rehydration
Numerical modeling accuracy is dependent upon correct material property determination and input. This thesis demonstrates the importance in both numerical modeling and material characterization, two aspects of biomedical research that are intimately linked. The first study investigates the shear forces experienced on the humerus from a humeral impact on the distal end using 3D CAD model of a humerus and ANSYS for a finite element analysis. The humeral bone was analyzed with an impact on the distal end to signify falling on the elbow. A humeral model and a humeral model with a plate were both statically and dynamically simulated with the forces at the distal end and a fixed support at the proximal end. Maximum shear stresses were determined through the analysis in order to solve for the Tresca Failure Criterion shear stress. The results of this study determine that shear forces experienced on the medial and lateral diaphysis area of the humerus. The second part of this study investigates the rehydration of bone samples after they have been dehydrated and whether the rehydration of bone will restore the mechanical properties. A 20-month-old Sprague Dawley Rat femur was cut into three 1 mm transverse samples and one sagittal cut sample. The bone samples were mechanically tested using a micro-indenter before dehydration and after rehydration. The samples were dehydrated with increasing concentrations of (70%, 80%, 90%, and 100%) ethanol and were rehydrated using phosphate buffered saline (PBS) in a nebulizer for three hours. The results show no statistically significant differences between the pre-dehydrated samples and the post-rehydrated samples. Both studies show the importance of mechanical testing to determine the properties of bone at the macro-level.