A Continuum Fibre Network Model for the Anisotropic and Compressible Mechanics of Human Skin

We present a Continuum Fibre Network (CFN) formulation for modelling anisotropy, strain stiffening and volume change in fibrous soft tissues. The model combines a three-dimensional fibre orientation distribution, a bilinear tensile fibre law and a separate phenomenological volumetric potential. We calibrated the model using published uniaxial tensile and volume-change data for excised human skin from separate studies. Changes in cross-sectional area affected the tensile stress estimates for models that predicted volume change. Simulations of indentation, shear and biaxial tension illustrate predictions of the calibrated formulation under additional loading conditions. The CFN formulation included a weak isotropic neo-Hookean ground matrix with a prescribed shear modulus of 0.1 MPa.