Structural response characteristics of a carbon fiber composite elastic plate induced by cavitation bubble collapse via POD method

This study investigates the modal and time–frequency response of an elastic composite plate subjected to single-bubble collapse at different normalized initial stand-off distances, η . Bubble evolution and full-field in-plane plate displacement are measured experimentally and analyzed using POD and CWT. Two dominant response modes are identified. The first mode is governed by y -direction displacement component and represents a global non-uniform displacement pattern that generally intensifies toward the free end, with energy mainly concentrated at 100–200 Hz. The second mode is governed by x -direction displacement component and exhibits a more spatially non-uniform response concentrated mainly near the plate center, with energy distributed primarily at 100–300 Hz and an additional component below 100 Hz. As η decreases, the high-energy response occurs earlier and the localized modal response becomes more pronounced. A key finding is that the plate response varies non-monotonically with stand-off distance. In the quasi-spherical collapse regime, the total POD energy generally decreases as η decreases from 2.5 to 1.5, whereas mushroom-shaped collapse at η =1.0 produces a renewed enhancement of the structural response. These results show that stand-off distance and collapse morphology jointly govern the response intensity, excitation timing, frequency distribution, and modal contribution of the elastic plate.