Shear Fracture Propagation by DCB Testing

A shear fracture propagation in steel was investigated with the aid of spring-loaded DCB testing, that was developed as a laboratory simulation test of shear fracture propagation in pressurized gas pipelines. The dynamic aspects of fracture propagation were studied experimentally, mainly to obtain an average strain rate as well as strain distribution ahead of propagating shear crack with high velocity. Taking into account the influence of strain rate, experimental results were analyzed with a simple Dugdale model on steels of different toughness or of different ductility. Thus, an associated critical strain turned out to be a material resistance against shear fracture propagation, which is insensitive to propagation velocity. This material resistance was well correlated to uniform elongation in static tensile test. The correlation between material resistance and Charpy shelf energy is also discussed.