A combined experimental and numerical study has been performed to assess the potential of sandwich structures in resisting shock loading. The sensitivity of static and dynamic core strength to core topology is explored, and the effects of fluid-structure interaction is included in the finite element analysis. Experiments are performed on clamped beams and panels, using metal foam projectiles as a means of imposing the shock loading: the pressure-time transient is similar to that imposed by an underwater blast. The core topologies investigated include the corrugated core, Y-core, square honeycomb, diamond core and prismatic core. We take as specific examples here the dynamic response of the corrugated and Y-core. The dynamic response of fully clamped, monolithic and sandwich plates of equal areal mass has been measured by loading rectangular plates over a central patch with metal foam projectiles. All plates are made from AISI 304 stainless steel, and the sandwich topologies comprise two identical face-sheets and either Y-frame or corrugated cores. The resistance to shock loading is quantified by the permanent transverse deflection at mid-span of the plates as a function of projectile momentum. At low levels of projectile momentum both types of sandwich plate deflect less than monolithic plates of equal areal mass. However, at higher levels of projectile momentum, the sandwich plates tear while the monolithic plates remain intact. Three-dimensional finite element (FE) calculations adequately predict the measured responses, prior to the onset of tearing. These calculations reveal that the accumulated plastic strains in the front face of the sandwich plates exceed those in the monolithic plates. These high plastic strains lead to failure of the front face sheets of the sandwich plates at lower values of projectile momentum than for the equivalent monolithic plates.
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