Comparison of anisotropic models to simulate the mechanical response of facial skin

Physically-realistic models of the face can contribute to development in several fields including biomedicine, computer animation, and forensics. Face models have benefited from better anatomical representation of the mimetic muscles, and more realistic interactions between soft and bony tissues. These models can also benefit from improved characterisation of the skin layer by having more authentic deformation and wrinkling behaviour. The objective of this work is to compare and evaluate the ability of different constitutive models to simulate the mechanical response of facial skin subjected to a rich set of deformations using a probe. We developed a finite element model to simulate facial skin experiments. Several anisotropic constitutive equations were tested for their suitability to represent facial skin. The finite element model simulated the force-displacement response of facial skin under a rich set of deformations. The variance accounted for between the experimental data and model data ranged from 79% for the Gasser et al. (2006) model to 96% for the Bischoff et al. (2002) model. Estimated pre-stresses ranged from 7 kPa in the lip region to 53 kPa in the central cheek region.