Meeting Abstract

82.2  Friday, Jan. 7  Free body analysis, beam mechanics, and finite element modeling of the mandible of Alligator mississippiensis ROSS, C.F.*; PORRO, L.B.; HOLLIDAY, C.M.; ANAPOL, F.; OLIVEROS, L.C.; OLIVEROS, L.T.; University of Chicago; University of Chicago; University of Missouri School of Medicine, Columbia; University of Wisconsin, Milwaukee; University of Wisconsin, Milwaukee; University of Wisconsin, Milwaukee rossc@uchicago.edu

The mechanical behavior of mammalian mandibles is well-studied but a comprehensive biomechanical analysis of an extant archosaur mandible has never been carried out. We tested hypotheses regarding the mechanical behavior of the mandible of Alligator mississippiensis by analyzing reaction forces and stress regimes in: free body analysis using lever arm mechanics; beam models; and high-resolution finite element models of the Alligator mandible, incorporating, isotropic bone without sutures, anisotropic bone with sutures, anisotropic bone with sutures and contact between the mandible and the pterygoid flange. Compared to beam models, the Alligator finite element models exhibited less spatial variability in and lower peak values for dorsoventral bending and sagittal shear stress, suggesting that Alligator mandibular morphology reduces these stresses during biting. However, the Alligator models exhibited greater variability in the distribution of mediolateral and torsional stresses than the beam models. Incorporating anisotropic bone material properties and sutures into the model reduced dorsoventral and torsional stresses within the mandible, but led to elevated mediolateral stresses. These mediolateral stresses were mitigated by the addition of a pterygoid-mandibular contact, suggesting important contributions from, and trade-offs between, material properties and external constraints in Alligator mandible design. Beam modeling does not accurately represent the mechanical behavior of the Alligator mandible.