Dynamic Response of Axially Loaded Plates With Intermediate Fixities to Transient Hydrodynamic Impact Loads

Abstract

A dynamic analysis of axially loaded plates with intermediate fixities is presented. The underwater part of a craft is modeled as a lightly damped flexible plate, which rises out of the water and slams against it at a large vertical velocity. This causes highly localized hydrodynamic impact pressure moving at high velocities across the plate, setting it into high-frequency vibrations. The natural frequencies of the plate depend on the slenderness ratio, aspect ratio, axial load, and end fixities. The end fixities depend on the quality of welding, and type of bracketing. Normal mode summation method is used to analyze the vibratory response, which is generated for various impact speeds, deadrise angles, end fixities, axial loads, aspect ratios, and slenderness ratios. A parametric study is done to predict the location, instant, and magnitude of the maximum dynamic stresses on the structure. The hydrodynamic pressure is assumed to act on the equilibrium position of the plate, i.e. one-way coupling of the fluid and the structure is studied. The primary aim is to study the time-varying dynamic stress configurations and draw conclusions leading to sound structural designs.