1Department of Anthropology, University at Albany, 2Division of Basic Medical Sciences, Mercer University School of Medicine, 3Department of Biomedical Sciences, Baylor College of Dentistry, Texas A&M Health Sciences Center
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Finite element modeling has become increasingly important in studies of functional morphology, but the question remains: do our models realistically represent biological systems? Valid results are dependent upon valid input parameters and modeling assumptions such as geometry, material properties and boundary conditions. By comparing the results of experimentally collected strain data, we can better characterize the errors that have resulted from our modeling assumptions. This study assesses the accuracy of our finite element modeling techniques by comparing in vitro strain data to strain data extracted from a finite element model.
In vitro strain data was collected during non-physiological loading from rosette strain gages affixed to the rostrum, palate and zygomatic arch of a female chimpanzee (Pan troglodytes) cranium. The prepared cranium was secured in a testing rig comprised of steel rods and spherical joints; loads were applied incrementally on the dentition to 800N using an Instron universal testing machine. Following the loading experiments, material properties were collected from sites across the cranium using ultrasonic techniques. The specimen was then imaged via medical X-ray computed tomography and a finite element model was built by segmenting trabecular and cortical bone and converting the resultant stereolithographic files to yield a solid 3D model. The model was edited, meshed, assigned heterogeneous, orthotropic material properties derived from the ultrasonic analysis and then loaded and constrained to simulate the experimental conditions of the in vitro study. Experimental and model results were compared with respect to strain magnitude, orientation and mode.
This study was funded by the National Science Foundation Physical Anthropology HOMINID program (NSF BCS 0725126, NSF BCS 0725141).