A model for rubber-like materials with three parameters obtained from a tensile test

Based on our recent findings on the chains orientational distribution in deformed rubber-like materials, we present a novel, accurate and simple non-affine model for isotropic, incompressible polymers. The model has only three material parameters that are easily calibrated from the characteristic behaviour of a tensile test: the initial slope, the slope of the mid-range, and the locking stretch. Once calibrated, the proposal reproduces accurately the behaviour of the material under the general deformation states for moderately large stretches measured by Kawabata (rubber) and Kawamura (silicone), and at least for three deformation states approaching the locking behaviour (Treloar's tests on rubber).