Abstract

Two classes of constitutive models are widely used in the current literature to describe the general strain state of rubber under large deformations: the Invariant-based (Rivlin type) and the Principal-value based (Ogden type). However, their predictive capabilities, coupled with the finite element method, will greatly depend on the material coefficients determined from experimental stress-strain curves by nonlinear curve fitting. In addition, special care must be exercised in their numerical implementations, which is particularly true for the Ogden type models, when evaluating the material tangent stiffness coefficients. Several issues in connection with these are discussed and a number of simulations and test comparisons are presented.