Shock Analysis of a Stern Ramp Using Dynamic Design Analysis Method

Shock load caused by underwater explosion in naval battles can lead to malfunction of the equipment on-board naval vessels. It makes the ships vulnerable and they can lose the ability to accomplish their missions. This study presents a shock analysis, using the dynamic design analysis method (DDAM), of a naval ship stern ramp subjected to a non-contact underwater explosion. The objective is to evaluate the performance of the ramp subjected to a shock load, identify areas for structural improvements and recommend design changes. The DDAM in the commercial software ANSYS is used in the evaluation of the ramp. The structural response to the shock load is estimated by combined modal and response spectrum analyses. The shock load is applied in three directions (vertical, fore and aft, athwart ships) and the results show that the vertical direction is the most severe loading direction and critical to the functionality of the ramp. A parametric study is presented which shows which parameters that influence the most the structural response. The results from this study are used to suggest improvements of the ramp structure to make it more resistant to shock loads.