Method for Predicting Damage Sustained by Air-Backed Plates Subjected to Impulsive Loading From Supersonic Torpedo Shock Wave

A method is presented to estimate the severity of damage on an air-backed plate caused by the shock wave of a passing supersonic underwater torpedo. Theory of compressible liquid flows is used to calculate the pre- to post-shock density ratio and peak shock pressure of the torpedo. A Newtonian impact theory approach is then employed to obtain the shock standoff distance to the torpedo. Utilizing the density ratio, peak shock pressure, and standoff distance, a novel method for predicting the damage sustained by the plate from the shock wave is presented by equating the peak shock pressure and standoff of a torpedo to that of an underwater detonation of TNT. Well known theory for the effects of shock waves generated by TNT detonation is then used to determine the shock factor, damage number, and deflection-thickness ratio. Using these parameters, a sample design change to a steel plate is provided to reduce the shock factor to a negligible value for a case of Mach 1.4 torpedo at 7.5 body radii distance. The herein-presented process offers insight into how to improve naval ship hull design to prevent lethal damage from shock effects.