The Effects of Polyurea Coatings on the Underwater Explosive Response of Composite Plates

Abstract

The effects of polyurea coatings on the response of composite plates subjected to underwater explosive (UNDEX) loading have been studied. The investigation has been conducted through the use of both detailed laboratory experiments and corresponding fully coupled fluid structure interaction computational simulations. The primary parameters of interest are the influence of the coatings on (1) the overall transient response of the plates and (2) the overall damage experienced during loading. The study is comprised of two main sections: (1) The response of flat E-Glass/Epoxy plates subjected to near field blast loading and, (2) The response of flat E-Glass/Epoxy plates subjected to far field blast loading. The study utilizes two unique underwater explosion loading facilities to impart the loading to the specimens. The far field blast study utilizes a conical shock tube which imparts pressure loading representative of the far field, underwater detonation of a spherical charge. The near field experiments are conducted in a small-scale blast tank which provides a controlled environment for the test conduct. In both the near and far field experiments, the transient response of the plates is captured in real time through the use of ultrahigh-speed photography coupled with Digital Image Correlation (DIC). The computational models in each part of the study utilize the commercial finite-element code LS-DYNA, specifically the fluid structure interaction capability of the code. In each aspect of the study, comparisons are made between the experimental results and computational simulations with the models being shown to accurately simulate the dynamic response of the plates as well as the fluid structure interaction. The overall findings of the investigation are that polyurea coatings can have both positive and adverse effects on the shock response of the composite plates depending on coating thickness and coating location.