STUDY OF COMPOSITE STRUCTURES SUBJECTED TO UNDERWATER SHOCK LOADING

Underwater explosions (UNDEX) produce severe and complex loadings in naval applications. Increased use of composite materials in naval applications requires better understanding of how composite structures will respond and survive an UNDEX. A legacy underwater shock loading method, using liquid nitrogen, was implemented to study the dynamic structural response and failure of flat carbon composite plates. Pressure data was collected using different layouts to study directionality and to characterize the pressure profile of this loading method. A composite test rig was built and utilized to hold composite plates under different backing conditions, water-back (WB) and air-back (AB). Strain response data was collected and analyzed for each composite plate tested. A comparison of water-back and air-back backing conditions was made to better understand the effects of Fluid Structure Interaction in these contrasting backing conditions. Imagery of failure regions was collected, compared, and characterized. Further research is required to validate and more deeply explain the AB and WB comparison results obtained in this research. A compressed air shock pipe underwater release (CASPUR) system was designed and built. Successful initial operational testing of CASPUR was completed. Future pressure profile characterization of CASPUR is needed. Assessment of its efficacy in providing more consistent loading and structure response compared to that of the legacy loading system is required. Lieutenant, United States Navy Approved for public release. Distribution is unlimited.