Mixture models : validation and parameter estimation

Mixture models are used extensively for the description of the mechanical behaviour of biological tissues. Because of their increasing complexity there is a need for new methods to validate the models and to determine the material parameters in the constitutive equations of the individual components and their interaction.In the paper a mixed numerical experimental method to detennine the material parameters in bipllasic mixlure is summarized and a recursive estimat.ion algorithm is derived to estimate parameters for biphasic mixtures. In a simulation it is shown that an inverse analysis to determine 4 material parameters can be done in a CPU-time of the order of one single direct analysis. Moreover, some results of experiments with a synthetic model material are discussed. The latter were used to validate a tri-phasic material model and have shown that the theory according to Snijders [7) is not complete.