On the transient responses of floating beams and the role of radiation damping

Abstract

The paper investigates the free vibration behaviour of a floating beam and its forced responses to transient wave packets. The analysis is based on the well-known simple model of a uniform Euler–Bernoulli beam, in which the coupled hydroelastic problem is solved directly. In principle the formulation is exact, within the context of linear theory and potential flow. The problem is discretised and complex eigenvalues of the system matrix are evaluated, in order to characterise the free vibration behaviour (the natural frequencies and radiation damping) over a range of dimensionless beam stiffnesses and mass ratios. The magnitudes of ‘resonant’ responses are shown to be linked to the imaginary parts of these eigenvalues. The model is then used to study the responses of the flexible beam in transient wave packets, such as the NewWave group.