Experimental and numerical study on shock reduction on thin plate with elastic patch

Abstract

A lamb wave is a guided wave that propagates along a plate-like structures in various systems. Particularly, in space structures where weight saving is very important, various vibrations are often transmitted as Lamb waves; therefore, control and mitigation of Lamb waves are important issue. Since the high frequency components included in the pyroshock can be fatal to electronic devices, many engineers have studied shock isolators for mounting and protecting such electronic devices. Lamb waves, as with light, are refracted with a certain angle due to the difference in wave speed between the two media. Using the refraction of the lamb waves, shock response for selected region can be reduced by changing direction of the wave. Theoretically, this effect can be achieved by simply attaching a thin elastic material on the host plate to change flexural stiffness. Thus, it would be a very efficient solution to reduce shock response in a specific area behind the patch on the wavefront path by attaching one elastic patch on the path of the Lamb wave. In this study, we proposed elastic patches of various shapes for shock reduction, and the shock reduction characteristics of several patches were numerically and experimentally confirmed. The plane Lamb waves generated from the array of piezoelectric disk attached to the thin metal plate were refracted when passing through the elastic patch; as a result, the shock response was decreased in the area behind the patch.