Dynamic Hydroelastic Scaling of the Underwater Shock Response of Composite Marine Structures

Abstract

The hydroelastic scaling relations for the shock response of water-backed, anisotropic composite marine structures are derived and verified. The scaling analysis considers the known underwater explosion physics, previously derived analytical solutions for the underwater shock response of a water-backed plate, and elastic beam behavior. To verify the scaling relations, the hydroelastic underwater shock response of an anisotropic composite plate at several different scales is modeled as a fully coupled fluid-structure interaction (FSI) problem using the commercial Lagrangian finite element software ABAQUS/Explicit. Following geometric and Mach similitude, as well as proper scaling of the FSI parameter, scaling relations for the structural natural frequencies, fluid and structural responses are demonstrated for a variety of structural boundary conditions (cantilevered, fixed-fixed, and pinned-pinned). The scaling analysis shows that the initial response scales properly for elastic marine structures, but the secondary bubble pulse reload caused by an underwater explosion does not follow the same scaling and may result in resonant response at full scale.