Analysis of deformation and fracture of ‘pure shear’ rubber testpiece

Abstract The ‘pure shear’ testpiece featured prominently in classical studies of elasticity and fracture mechanics of rubber. It consists of a thin, rectangular strip of rubber held by rigid clamps along its long edges. When the clamps are pulled apart, the deformation in the rubber is a close approximation to pure shear, except in regions near the free edges. Deviation from pure shear is usually neglected. In this paper, the effects of neglecting deviation from pure shear in the end regions have been evaluated using non-linear finite element analysis. The ‘pure shear’ testpiece is commonly used for studies of fracture in rubber because it is amenable to a simple fracture mechanics analysis provided the crack length is long relative to its height. An analysis for short cracks has also been accomplished but this solution is less well established. Finite element analysis results for the strain energy release rate are presented and agree with the published solution for long cracks. However, they disagree with the solution for short cracks. Differences were also found between a short crack located at the free edges and one located at the centre.