Rate-dependent damage evolution and crack branching of pipe under internal gaseous detonation loading

Abstract

A rate-dependent damage evolution law was derived based on the thermally activated motion of dislocations. By writing the VUMAT subroutine, it was implemented to simulate the dynamic crack propagation and branching of pipe due to internal gaseous detonation. Also, the fluid-structure coupling between detonation wave and pipe was well achieved through immersed boundary method and “softened” contact formula. The predicted fracture profiles and pressure history inside the pipe were validated with experiments and compared with available results in literatures. Results demonstrated that the developed numerical model was more accurate in predicting the dynamic crack behaviors, especially the crack branching position relative to the main crack tip. The simulated average crack speed ranged from 171 m/s to 228 m/s, which well fell within the experimental range. Instead of dramatically decreasing, the speed of branched crack was comparable to that of the main crack. The damage field around the crack tip can reflect the direction of crack propagation or branching. The maximum strain rate always appeared at the right front of crack tip regardless of the subsequent crack behavior. It was further revealed that the high strain rate contributed to the straight propagation of crack, while branching was primarily governed by the particular strain pattern around the crack tip.