Mechanism of rippling deformation of pipe due to internal reflected detonation

The unique rippling deformation of pipe due to internal detonation and reflected shock was studied. Numerical model incorporating thermo-viscoplastic constitutive model and considering the fluid-structure coupling between detonation wave and pipe was developed. Two pipes made of 304 L steel and 6061-T6 aluminum with different diameter-to-thickness ratios were analyzed. The computed pressure histories, strain response and residual plastic strain patterns were in reasonably good agreements with experiments. Through detailed analysis of wave-pipe interaction and the propagation of incident and reflected flexural waves along the pipe, it is revealed that the rippling deformation is caused by two factors: 1) Plastic bugling deformation near the end wall due to reflected maximum peak pressure; 2) Interference between incident and reflected flexural waves. An analytical solution predicting the axial locations of the ripples was also derived. The ripple closest the reflecting end can be caused by only the reflected maximum pressure or together with the interference effect, which depends on the specific material parameter and diameter-to-thickness ratio of the pipe. The resulting plastic deformation was severer if the above two factors act together. The conclusions provide insights to this unique phenomenon.