The whipping response of a submerged platform subjected to near-field, non-contact underwater explosions

An experimental investigation of an underwater explosion (UNDEX) induced whipping response was conducted on a submerged platform. The platform was subjected to eight near-field, non-contact UNDEX events, using two explosive charge sizes at three longitudinal positions along the hull length, coinciding with predetermined peak and node positions of the natural bending mode responses of the platform. We found that stand-off positions at amidships, coinciding with the peak response of the first bending mode, produced the most severe whipping response. Stand-off positions located at the node of the first bending mode had a greatly reduced whipping response for the same charge size and transverse stand-off distance. Stand-off positions away from amidships demonstrated multiple bending mode responses, which for the larger charge size resulted in the peak response occurring away from the initial stand-off position. These results have an implication on how navy platform assessments are undertaken, and suggests that whipping responses require more detailed consideration to understand a platform's limitations against an UNDEX event.