Material Characterization of Cardiovascular Biomaterials Using an Inverse Finite Element Method

Abstract

Being able to accurately model soft tissue behaviour, such as that of heart valvular tissue, is essential for developing effective numerical simulations of in-vivo conditions and determining patient-specific care options. Although several analytical material models, based on strain energy functions, have been successful in predicting soft tissue behaviour, complications arise when these models are implemented into finite element (FE) programs due to the incorporation of a penalty parameter for numerically enforcing material incompressibility. Specifically, material parameters determined through non-FE methods may no longer produce a material behaviour that reflects the experimental behaviour once they are used in an FE analysis. Based on commercial finite element software LS-DYNA, an inverse methodology was developed in MATLAB to simultaneously optimize the material parameters and the penalty parameter for the Guccione strain energy model. The methodology produced accurate predictions of the material behaviour under planar equibiaxial testing for five biomaterials used in heart valve cusp replacements.