Hydroelastic criterion for an inclined flat plate in vertical and oblique impacts

Abstract

A two-dimensional semi-analytical model is applied for the analysis of hydroelastic effect during vertical and oblique impacts of flexible inclined plates with different boundary conditions (BCs). Hydrodynamic pressure is calculated using Wagner’s theory and the structural deformation is presented as a linear combination of dry normal modes. A longitudinal strip is used as an approximation of the longitudinal bending of a plate. Model predictions are validated by comparing with the available experimental data, semi-analytical model, and asymptotic approaches for vertical and oblique impacts of the plate with different BCs. The water impact is analyzed with two viewpoints of rigid and flexible plates. Maximum stress and deflection calculated using hydroelastic and rigid-quasi-static analyses are compared for different BCs. Based on the hydroelastic criterion, validity range of rigid-quasi-static analysis and the importance of dynamic response are determined. The effect of horizontal velocity is discussed. It is found that for a low value of hydroelastic criterion, the hydroelastic analysis yields lower values of maximum stress or deflection than rigid-quasi-static analysis, while for a moderate value of hydroelastic criterion is vice versa. As expected, for a high value of hydroelastic criterion both analyses yield the same results except in the case of a clamped-free plate. Evaluation of the hydroelastic and rigid-quasi-static analyses revealed that hydroelastic criterion and structural BCs are determinant in selecting one of them for the design process.