Simultaneous digital image correlation/particle image velocimetry to unfold fluid–structure interaction during air-backed impact

Abstract

Predicting the response of air-backed panels to impulsive hydrodynamic loading is essential to the design of marine structures operating in extreme conditions. Despite significant effort in this area of research, the lack of full-field measurement techniques of structural dynamics and flow physics hinders our understanding of the fluid–structure interaction. To fill this gap in knowledge, we designed a laboratory-scale experiment to elucidate fluid–structure interaction associated with impulsive hydrodynamic loading on a flexible plate. A combined experimental approach based on digital image correlation (DIC) and particle image velocimetry (PIV) was developed to afford spatially- and temporally-resolved measurements of the plate deflection and fluid velocity. From the velocity field measured through PIV, the hydrodynamic loading on the structure was estimated via a pressure-reconstruction algorithm. Experimental results point at a strong bidirectional coupling between structural dynamics and flow physics, which influence temporal and spatial patterns in counter-intuitive ways. While the plate deflection follows the fundamental in-vacuum mode shape of a clamped plate, the pressure exhibits a complex evolution. Not only does the location of the peak loading on the plate alternates between the clamp and the center as time progresses, but also the time evolution of the peak loading anticipated the peak displacement of the plate. This study contributes a new methodological approach to study fluid–structure interaction in three dimensions, offering insight in the physics of air-backed impact that could inform engineering design and scientific inquiry.