A parametric study on the dynamic ultimate strength of a stiffened panel subjected to wave- and whipping-induced stresses

Abstract

ABSTRACT Although it is well known that the slamming-induced whipping can significantly increase the structural loading of ships, its consequence on the hull girder's collapse is still unclear. Moreover, the whipping-induced stresses are having a higher frequency than the wave-induced stresses. Hence some doubts are cast on the probability that the dynamic effects may provide additional strength reserves. This paper aims to investigate in a parametric way the dynamic ultimate strength of a stiffened panel, subjected to axial compression and lateral loads. The load amplitude curves for the axial stress are defined analytically by superimposing different components associated with several dominant load parameters, such as wave and whipping periods. In order to derive realistic loading scenarios, a broad range for each dominant load parameter is determined by analysing the hydro-elastic response of multiple container ships. The dynamic load factors are derived as the ratio between the dynamic capacity and the quasi-static one. Furthermore, it is shown that the dynamic effects are already existent in the wave loading scenarios, and this fact is attributable to some limitations of the Cowper–Symonds model. Thus the last section of this paper is dedicated to developing a new strain rate sensitivity model, which describes more accurately the strain rate sensitivity at low strain rates.