Effects of crack propagation and strain rate on fracture resistance of carbon black reinforced rubber

This paper presents an investigation of examining the effects of crack propagation and strain rate on the fracture resistance of carbon black reinforced rubber. The strain rates chosen for the investigation are 10, 30, 50, 100, 200, 300 and 500 mm/min. The method of analysis is based on a quasistatic energy approach. The specimen geometry used is basically a double cantilever beam specimen (DCB) which satisfies the criteria of the stability of crack propagation, an essential requirement of producing subcritical crack growth. Due to low bending stiffness of the rubber, the DCB specimen is reinforced to circumvent the specimen buckling upon loading. The results indicate that there is no effect of the strain rates chosen on the fracture roughness of the carbon black reinforced rubber. The magnitude of the measured fracture toughness for crack propagation is, however, found to be about 40 times larger than that for crack initiation. The observation appears in agreement with those reported by earlier investigators.