Dynamic response of composite tube reinforced porous polyurethane structures under underwater blast loading

The hyper-elastic porous structures show excellent acoustic stealth, impact isolation and underwater explosion protection properties when they are subjected to underwater blast loads. But the energy absorption ability of them needs to be improved, which is caused by premature densification. Therefore, the composite reinforced hyper-elastic porous polyurethane structure (CRHPP) filled with carbon fiber composite circular tubes are designed and fabricated in this paper. Based on quasi-static compression test results, it is shown that the CRHPPs has a 407% increase in energy absorption compared to the porous polyurethane structure. The dynamic responses and failure modes of the CRHPPs subjected to underwater blast loads are investigated by tests and simulations. The CEL (Coupled Eulerian-Lagrangian) method combined with the three-dimensional Hashin criterion are used to simulate the response process. In order to further improve the underwater explosion resistance of the CRHPPs, the effects of structural gradient on the responses are simulated and analyzed. The results show that the stiffness and energy absorption capacity of the hyper-elastic porous polyurethane structure can be significantly improved by adding composite tubes. There are no permanent damage and densification in the CRHPPs subjected to far-field underwater blast loads. Whether gradient or uniform in the other layers, these CRHPPs without reinforcement in the front first layer show better underwater explosion resistance and protection effect.