An UNDEX response validation methodology

The assessment of the response of naval vessels to underwater shock creates a need for tools that can analyze and design such systems to withstand underwater explosions (UNDEX). This paper describes a preliminary attempt to develop a methodology for the assessment of structural systems to UNDEX effects. A methodology is proposed by which the response of a simplified structural component to UNDEX can be validated through the use of precision impact testing and numerical simulations. An iterative process was used where an UNDEX response, determined through previous results, preliminary UNDEX simulations, and impact simulations, provided the parameters necessary for a precision impact test that generates an equivalent response. Precision impact tests were performed, and the results correlated with the impact simulated data. The results from an UNDEX test were compared with the predictions from the validated numerical code. The structural component in both the tests and simulations was simplified to a flat rectangular panel. The numerical simulations were solved explicitly, and included either the impact loading environment - a hybrid impactor with an initial velocity - or the UNDEX loading environment - a plane shock wave applied to the surface of the target structure. Since close-in and early time UNDEX-related phenomena, such as gas bubble effects, are localized and very complicated, they were ignored in this preliminary phase of the study. Although the proposed methodology could require multiple iterations, the limited scope of this study only included one set of precision-impact tests on each type of material, one UNDEX test against an aluminum panel, and two UNDEX tests against composite panels. Once the methodology using precision shock testing and numerical simulations to validate the UNDEX response had been developed, it was used to develop a "design-for-shock" procedure. Published by Elsevier Science Ltd.