Tuesday, 12 October 2004 - 4:20 PM

This presentation is part of : Wineman Symposium

The trousers test for fracture of rubber-like materials

Cornelius O. Horgan and Joseph G. Schwartz. University of Virginia, P. O. Box 400742, Charlottesville, VA 22904

The classical continuum mechanics modeling of incompressible hyperelastic materials such as vulcanized rubber involves strain-energy densities that depend on the first two invariants of the strain tensor. While these models accurately predict the mechanical behavior of rubber at moderate stretches, they fail to capture the strain-hardening and effects of limiting chain extensibility observed in experiments at large stretch. Gent(1996)proposed a simple new constitutive model that captures both these physical phenomena. The Gent model depends only on the first invariant and involves just two material parameters. A modification of this model that reflects dependence on the second invariant has been proposed recently by Horgan and Saccomandi. Here we discuss the stress response of the Gent and HS models for homogeneous deformations and apply the results to the fracture of rubber-like materials. Attention is focused on a particular fracture test, namely the trousers test where two legs of a cut specimen are pulled horizontally apart. It is shown that the cut position plays a key role in the fracture analysis, and that the effect of the cut position depends crucially on the constitutive model employed. It is also shown that the limiting chain extensibility models predict a finite fracture energy as the cut position gets closer to the edge of the specimen whereas the classical hyperelastic constitutive models predict unbounded energy in this limit. The results are relevant to the structural integrity of rubber components such as vibration isolators, vehicle tires, earthquake bearings, seals and flexible joints.

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