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An experimental study on the underwater collapse of composite tubes with polymeric coatings is conducted in an attempt to mitigate the implosion pressure pulse released. Experiments are performed in a pressure vessel designed to provide constant hydrostatic pressure during collapse. Filament-wound carbon-fiber/epoxy tubes are studied with polyurea coatings of different thicknesses on the interior and exterior of the tube to explore the effects of these configurations on implosion pulse mitigation. 3-D Digital Image Correlation (DIC) technique is used to capture the full-field deformation and velocities during the implosion event. Local pressure fields generated by the implosion event are measured using dynamic pressure transducers to evaluate the strength of the emitted pressure pulses. Local pressure data and DIC results are used to obtain a measure of normalized energy released during implosion. Results show that thick interior coatings significantly reduce the energy released in the pressure pulse by slowing the collapse and softening the initial wall-to-wall contact. In contrast, thick exterior coatings increase this energy by suppressing damage, thereby reducing the energy absorption capacity of the structure. [ABSTRACT FROM AUTHOR]

An experimental and numerical study has been conducted to evaluate the underwater blast response of E-Glass/epoxy composite plates with polyurea coatings. The goal of the study is to determine the effects of these elastomeric coatings on the dynamic response of the plates, specifically the influence of coating thickness, location, and plate natural frequency. The composite material is a 0°/90° biaxial layup and the coatings are applied to either the loaded or non-loaded faces. A conical shock tube facility which produces shock loading conditions representative of the underwater detonation of an explosive charge is used to impart the shock loading to the plates during the experiments. The transient response of the plates is recorded using a three-dimensional (3D) digital image correlation system, consisting of high-speed photography and specialized post processing software. Computational models of the experiments are developed using the LS-DYNA finite element code. The simulations are shown to have a high level of correlation to the experimental data in terms of center point displacements and full field deformation profiles. Additional parametric studies using the correlated model show that the transient response of the composite plates is improved with increasing coating thickness, and that polyurea coatings located on the back face of the panels provide better performance than when located on the loaded surface. [ABSTRACT FROM PUBLISHER]