Dynamics of interaction between converging shock waves and different defects in solids based on high-speed photography

The propagation of converging shock waves in solids and their interaction with defects are of fundamental importance in high-energy-density physics, shock compression science, inertial confinement fusion, and dynamic material response. However, in situ characterization of their transient evolution remains challenging under extreme loading conditions. In the present study, high-speed photoelectric imaging combined with a transparent polymethyl methacrylate surrogate is employed to visualize the propagation and focusing of converging shock waves and their interaction with circular holes, through-grooves, and annular gaps. Using the CJ-1 magnetic-drive flyer loading system, dynamic images are obtained at a temporal interval of 0.2 μs within a Ø30 mm field of view, and numerical simulations are performed to elucidate the underlying mechanisms. The results reveal distinct wave system topologies for different defects: circular holes generate a lagging diamond-shaped wave structure followed by petal-like reflected waves, through-grooves produce an X-shaped wave system and Mach stem, whereas annular gaps primarily delay shock wave focusing. The focusing pressure (obtained by numerical simulation) decreases by about 78%, 37%, and 18% for through-grooves, circular holes, and annular gaps, respectively. These differences arise from the competition between shock wave convergence and defect-induced attenuation. Penetrating grooves and circular holes substantially weaken the convergence effect, whereas this effect remains dominant for small-radius annular gaps. These findings clarify the defect-induced modulation mechanisms of converging shock waves and provide guidance for defect-tolerant structural design under extreme dynamic loading.