Meeting Abstract

78.2  Sunday, Jan. 6  Biomechanics of impact loading of goat horns (Capra hircus) using CT image based Finite Element Modelling YOO, E.*; BIEWENER, A.A.; Harvard University; Harvard University eyoo@oeb.harvard.edu

Intrasexual male combat is a critical determinant of social status and reproductive success for male goats (Capra hircus). Horn on horn collisions between male goats at speeds up to 2.5 m/s can pose a serious risk of brain and spinal cord injuries. Horn collisions have been modeled as concentrated quasi-static forces using curved beam theory but ignore the role of inertia and wave propagation on different components. Dynamic loading however might suggest otherwise. Furthermore, the horn bone cores resemble non-prismatic beams which may be a weight saving functional design. In addition, horns are composed of an inner bone core covered by an external keratin sheath with contrasting material properties. We present a finite element analysis of the dynamic response of this composite structure to impact loading using a CT scan image based model. We found that the maximum Von mises stress values are concentrated at the posterior base of the os cornu but the location and magnitude varies with the direction of loading. The Von mises stress values on the anterior surface of the horn bone core were less than half of the peak stresses on the posterior surface. In addition, the peak Von mises stress values on the anterior surface of the horn bone core were found at locations distal to the horn base, which was not predicted by previous studies estimating stress values using curved beam theory. The stress pattern on the anterior surface of the horn bone core suggests that the non-prismatic shape of the horn may be maintaining similar tensile stress values during impact loading.