The dynamic motion of a circumferential through-crack in an axially stressed pipe was examined with a finite-difference shell code to determine the crack opening shapes and speed of extension of elastic-plastic crack propagation. Calculations were also performed with an additional hoop stress to examine the effect of earlier plastic deformation due to a biaxial stress state.

The results were compared with those obtained for elastic propagation of the circumferential crack and those obtained in a study of pressure-driven axially oriented cracks. As previously noted, in the study of the elastic fracture, the crack characteristics are primarily functions of the ratio of the dynamic crack intensity factor developed for a crack of fixed length to the crack initiation stress-intensity factor, K_IQ. Elastic-plastic circumferential cracks propagate slower than their elastic counterparts but substantially faster than comparably loaded axial cracks. Although slower moving, the crack openings are much larger. No effect of shell thickness was noted, and no edge flaps were found to exist.