One‐dimensional theoretical analysis of polymethacrylimide foam sandwich structures subjected to underwater explosion impact using a dynamic shock wave model

Abstract Polymethacrylimide (PMI) foam, recognized for its excellent energy‐absorbing properties, demonstrates significant stress enhancement under dynamic compression. Accurately describing the behavior of PMI foam under dynamic impact is essential to predicting the dynamic response of PMI foam sandwich structures subjected to underwater explosion impact. The dynamic‐rigid‐plastic hardening (D‐R‐PH) shock wave model effectively characterizes the stress–strain relationship of foam materials under dynamic impact. A three‐dimensional (3D) mesoscale finite element (FE) model of PMI foam with four different densities was constructed using the Voronoi model. Simulations of PMI foam impacting a rigid wall at a specific initial velocity revealed the relationship between plastic shock wave velocity and impact velocity, enabling determination of parameters for the D‐R‐PH model. Using this model, a one‐dimensional theoretical framework incorporating cavitation effects was developed for PMI foam sandwich structures subjected to underwater explosion impact. FE simulations validated the model and comparisons with other shock wave models indicated that shock wave models based on quasi‐static compression data overestimated the panel motion behavior of PMI foam sandwich structures, as the stress enhancement phenomenon under dynamic compression was neglected. Parameter analysis revealed that, while core density and shock wave intensity significantly influenced impact resistance, the effects of panel thickness was relatively minor. Highlights A 3D mesoscale FE model for PMI foam based on the Voronoi model was developed. D‐R‐PH shock wave model parameters for PMI foam were obtained. A 1D underwater explosion FSI model was built based on D‐R‐PH. The dynamic response of PMI foam sandwich under underwater blast was investigated.