On constitutive relations and finite deformations of passive cardiac tissue: I. A pseudostrain-energy function.
A three-dimensional constitutive relation for passive cardiac tissue is formulated in terms of a structurally motivated pseudostrain-energy function, W, while the mathematical simplicity of phenomenological approaches is preserved. A specific functional form of W is proposed on the basis of limited structural information and multiaxial experimental data. The material parameters are determined in a least-squared sense from both uniaxial and biaxial data. Our results suggest that (1) multiaxially-loaded cardiac tissue is nearly transversely-isotropic with respect to local muscle fiber directions, at least for a limited range of strain histories, (2) material parameters determined from uniaxial papillary muscle data result in gross underestimates of the stresses in multiaxially-loaded specimens, and (3) material parameters determined from equibiaxial tests predict the behavior of the tissue under various nonequibiaxial stretching protocols reasonably well.
Department of Mechanical Engineering, University of Maryland, Baltimore 21228.
J D
JD
Humphrey
F C
FC
Yin
D000818:Animals; D001696:Biomechanical Phenomena; D001698:Biomedical Engineering; D004285:Dogs; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D010210:Papillary Muscles / Q000502:physiology; D013314:Stress, Mechanical