Constitutive modeling of the time-dependent and cyclic loading of elastomers and application to soft biological tissues

The stress-strain behavior of both elastomeric materials and soft biological tissues exhibits time-dependence and hysteresis when subjected to cyclic loading. This paper discusses a new constitutive model capable of capturing the experimentally observed behavior under different general multiaxial loading conditions. The proposed model is a modification of the Bergstrom-Boyce model [J. Mech. Phys. Solids 46 (1998) 931] in which predictions of cyclic loading states have been improved by augmenting a reptation-based scaling law to include one additional material parameter that limits the maximum flow rate at any given deformation state. By direct comparison with experimental data on two rubber compounds and two soft biological tissues, the new material model is shown to capture the rate-dependence and the cyclic loading (ranging from positive to negative axial and shear loadings) in both elastomers and soft biological tissues. (C) 2001 Elsevier Science Ltd. All rights reserved.