DETERMINATION OF A CONSTITUTIVE RELATION FOR PASSIVE MYOCARDIUM .2. PARAMETER-ESTIMATION

In the first paper ofthisseries, we proposed a new transversely isotropic pseudostrainenergy function W for describing the biomechanical behavior of excised noncontracting myocardium. The specific functional form of W was inferred directly from biaxial data to be a polynomial function of two coordinate invariant measures of the finite deformation and five material parameters. In this paper, best-fit values of the material parameters are determined from biaxial data using a nonlinear leastsquares regression. These values of the parameters are shown to be well-determined, and the final constitutive relation is shown to have good predictive capabilities. Since the proposed constitutive relation describes much broader classes of in-vitro biaxial data than previously proposed relations, it may be better applicable to analyses of stress in the passive heart. © 1990 by ASME.