A Elastic and Hyperelastic Material Model of Joint Cartilage - Calculation of the Pressure Dependent Material Stress in Joint Cartilage

In this paper we introduce a elastic and hyperelastic model to describe the pressure dependent material stress in joint cartilage. We used the pressure dependent E-modulus E = f(s) to calculate the material stress. E = f(s) is a degree 4 polynomial [1]. The indentor was pressed 0.4 mm into the tissue. The results show that the maximal stress at the contact zone between indentor and cartilage account for the elastic model is 1.8 MPa and for the hyperelastic model is 0.9 MPa. Also the stress distribution (sectional view) at the indentor, cartilage and bone at the loaded state for both models were calculated. For both models the stress decreases from the contact zone to the tide mark. The models can predict the deformation of tissue caused by short-term mechanical load as well as the resulting stress distribution within the tissue.