An Experimental Study in the Hydroelastic Response of an Aluminum Wedge in Drop Tests

Slamming of high speed marine planing craft is an important part of their operating conditions. High hydrodynamic forces are inevitably induced causing the shell plating to deflect, which in turn can influence the flow physics surrounding the hull. In order to study the hull’s hydroelastic behavior due to a slamming event, the researchers performed wedge drop experiments with an aluminum wedge of 57 inches in length, 47 inches in breadth, and 20∘ deadrise with 1/4 inch thick unstiffened bottom panels. The elastic response of the bottom plating was measured via two methods. The first method uses a series of evenly-space, colinear strain gages, and the second method is a stereoscopic digital image correlation (S-DIC) technique. In this investigation, an S-DIC code has been developed and utilized to study the deflections and to advance the capabilities of future research. Drops have been made for four impact velocities: 4.8 ft/s, 6.8 ft/s, 8.4 ft/s, and 9.7 ft/s. Comparisons are made between the two methods at an impact velocity of 9.7 ft/s – only strain gages were used for the lesser impact velocities. The overall deflections of the deadrise panel are approximately 1/10 inch at an impact velocity of 9.7 ft/s. The predictions made using S-DIC and strain gages differ by approximately 23%.