Constitutive Model For Soft Tissue Research Articles

EDITORIAL

EDITORIAL

A composites-based hyperelastic constitutive model for soft tissue with application to the human annulus fibrosus

This paper presents a composites-based hyperelastic constitutive model for soft tissue. Well organized soft tissue is treated as a composite in which the matrix material is embedded with a single family of aligned fibers. The fiber is modeled as a generalized neo-Hookean material in which the stiffness depends on fiber stretch. The deformation gradient is decomposed multiplicatively into two parts: a uniaxial deformation along the fiber direction and a subsequent shear deformation. This permits the fiber–matrix interaction caused by inhomogeneous deformation to be estimated by using effective properties from conventional composites theory based on small strain linear elasticity and suitably generalized to the present large deformation case. A transversely isotropic hyperelastic model is proposed to describe the mechanical behavior of fiber-reinforced soft tissue. This model is then applied to the human annulus fibrosus. Because of the layered anatomical structure of the annulus fibrosus, an orthotropic hyperelastic model of the annulus fibrosus is developed. Simulations show that the model reproduces the stress–strain response of the human annulus fibrosus accurately. We also show that the expression for the fiber–matrix shear interaction energy used in a previous phenomenological model is compatible with that derived in the present paper.

A composites-based hyperelastic anisotropic constitutive model for soft tissue and its application to the human annulus fibrosus

A composites-based hyperelastic anisotropic constitutive model for soft tissue and its application to the human annulus fibrosus

On hyperelastic constitutive modeling of annulus fibrosus

Summary In a recent paper, Peng et. at. [I] developed an anisotropic hyperelastic constitutive model for the human annulus fibrosus in which fiber-matrix interaction plays a crucial role in simulating experimental observations reported in the literature. Later, Guo et. at. [2] used fiber reinforced continuum mechanics theory to formulate a model in which the fiber-matrix interaction was simulated using only composite effect. It was shown in these studies that, the classical anisotropic hyperelastic constitutive models for soft tissue which do not account for this shear interaction cannot accurately simulate the test data on human annulus fibrosus. In this study, we show that the microplane model for soft tissue developed by Caner and Carol [5] can be adjusted for human annulus fibrosus and the resulting model can accurately simulate the experimental observations without accounting for fiber-matrix inleraction. A comparison of results obtained from (i) a fiber-matrix paralic I coupling model which does not account for the fiber-matrix interaction (ii) the same model but enriched with fiber-matrix interaction, and (iii) microplanc model 1'01' soft tissue adapted to annulus fibrosus with 2 families of fiber distributions is presented.