A Nonlinear Theory of Viscoelasticity for Application to Elastomers

Abstract

A simple nonlinear theory of viscoelasticity has been developed for application to elastomers. The theory is the viscoelastic generalization of the kinetic theory of rubber elasticity, and it is used to model time and rate-dependent effects. The method of derivation reveals that the theory is applicable to stress-imposed rather than strain-imposed conditions. Thus the creep test provides the logical means for deducing the material properties of the theory, while the relaxation-test technique is not applicable. When the long time asymptotic state is at the same level of deformation for both tests, the sources and degree of nonlinearity in relaxation tests are shown to be more severe than those involved in creep tests. A simple means is deduced for obtaining the creep function from the nonlinear creep response of the elastomer.