Dynamic response of the muskox head: Experimental validation of a CT-based finite element model using Scanning Laser Dopler Vibrometry.

Abstract

Building on prior studies of Bovidae skull mechanics, this paper aims to validate the first finite element model (FEM) capable of capturing the dynamic response of the skull of an understudied species, the muskox (Ovibos moschatus). CT scans were used to capture the internal structure of the skull and create a detailed finite element model. Material properties were assigned using a density-based constitutive law, allowing us to account for stiffness gradients while keeping computation feasible. CT scans were used to capture the internal structure of the skull and create a detailed finite element model. Material properties were assigned using a density-based constitutive law, allowing us to account for stiffness gradients while keeping computation feasible, a method well establish in medical studies, but never used before on Bovidae skulls. A modal-based steady-state dynamic analysis was then performed to simulate the linear response of the skull to harmonic excitation. For experimental validation, the skull was mechanically excited over a frequency range of 10-10,000 Hz. Structural vibrations were measured on the left horn and nasal bone using a Scanning Laser Doppler Vibrometer (SLDV), enabling direct comparison with the numerical model. Transfer functions were constructed for both simulated and experimental data as the ratio of measured velocity to applied load, revealing the natural frequencies excited across the spectrum. The corresponding mode shapes were then extracted and compared. In the nasal bone, the complexity of the mode shapes required additional correlation analysis to reliably match resonance peaks and quantify frequency shifts between predicted and measured modes. Overall, the results validate the model up to 4 kHz, including both mode shapes and phase response, extending experimental and numerical validation to a frequency range not previously achieved in other Bovidae skull models.