Linear vibration analysis of cantilever plates partially submerged in fluid

Abstract Dynamic characteristics, such as natural frequencies and mode shapes, of cantilever plates, partially in contact with a fluid, are investigated. In the analysis of the linear fluid–structure system, it is assumed that the fluid is ideal, and fluid forces are associated with inertial effects of the surrounding fluid. This implies that the fluid pressure on the wetted surface of the structure is in phase with the structural acceleration. Furthermore, the infinite frequency limit is assumed on the free surface. The in vacuo dynamic properties of the plates are obtained by use of a standard finite-element software. In the wet part of the analysis, it is assumed that the plate structure preserves its in vacuo mode shapes when in contact with the surrounding fluid and that each mode shape gives rise to a corresponding surface pressure distribution of the cantilever plate. The fluid–structure interaction effects are calculated in terms of the generalized added-mass values independent of frequency (i.e., infinite frequency generalized added-masses), by use of a boundary-integral equation method together with the method of images in order to impose the Φ = 0 boundary condition on the free surface. To assess the influence of the surrounding fluid on the dynamic characteristics, the wet natural frequencies and associated mode shapes were calculated, and they compared very well with the available experimental data and numerical predictions.