Underwater impulsive resistance of the foam reinforced composite lattice sandwich structure

The composite lattice sandwich structures with crushable foam core have exhibited outstanding potential in lightweight structures for underwater blast resistance. In this paper, the dynamic failure, energy absorption and associated mechanisms of the composite sandwich structures against the underwater impulsive loading are investigated experimentally and numerically. The underwater impulsive resistance of the composite lattice sandwich and the foam-reinforcement composite lattice sandwich are estimated by considering the varying impulsive intensities. With the reinforcement of the foam, the energy absorption capacity experiences a nearly 6 times of increase under the quasi-static compression. Although the influence on the deformed profile is limited, the effect of the impulsive intensity is fairly confirmed to have significant influences on the failure modes and energy absorption mechanisms of the sandwich structures. The impulsive resistance of the foam reinforced lattice sandwich structure is superior to the unreinforced counterpart in terms of the deflection resistance and structural integrity. The loading dispersion distribution, crushing, and cracking of the foam make the former optimize the energy absorption mechanism by highlighting the sacrifice of the front facesheet and decrease the back facesheet deflection. With the same areal mass with the lattice sandwich, the composite laminate exhibits inferior impulsive resistance to both the sandwich plates.