Influence of crack tip sharpness and radius on the strain distribution in rubbers analyzed by finite element simulation and experiments

摘要

The influence of the initial crack tip radius on the strain distribution in the vicinity of the blunted crack tip was determined experimentally by an optical full-field strain analysis method. These experimental results were compared to the calculations of the commercial finite element code ABAQUS 6.4-1. For the simulation a suitable hyperelastic material law was chosen and fitted to experimental data of three different tests (uniaxial tensile, planar tensile, biaxial tensile). Two different elastomer grades (SBR and EPDM) were selected for the experimental work. The utilized optical full-field strain analysis method based on the image correlation technique was found to be an effective tool to determine strains, strain distributions and gradients near to the crack tip for elastomeric materials. Different material behavior was observed for the two rubber types investigated. While the crack tip was regularly blunted (half circle shape) for EPDM and the strain gradient was low (less steep), the crack tip was sharp (less blunted) with a higher strain gradient for SBR.