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.

摘要

虽然众所周知，砰击引起的摇晃会显着增加船舶的结构载荷，但其对船体梁倒塌的影响尚不清楚。此外，鞭打引起的应力比波浪引起的应力具有更高的频率。因此，对动态效应可能提供额外强度储备的可能性产生了一些怀疑。本文旨在以参数方式研究加筋板在轴向压缩和横向载荷下的动态极限强度。轴向应力的载荷幅值曲线是通过叠加与几个主要载荷参数（例如波浪和摆动周期）相关的不同分量来解析定义的。为了推导出真实的加载场景，通过分析多艘集装箱船的水弹性响应，确定每个主要载荷参数的广泛范围。动态负载系数是作为动态容量与准静态容量之间的比率推导出来的。此外，它表明在波浪加载场景中已经存在动力效应，这一事实归因于 Cowper-Symonds 模型的一些局限性。因此，本文的最后一部分致力于开发一种新的应变率敏感性模型，该模型更准确地描述低应变率下的应变率敏感性。结果表明，波浪载荷情景中已经存在动力效应，这归因于 Cowper-Symonds 模型的一些局限性。因此，本文的最后一部分致力于开发一种新的应变率敏感性模型，该模型更准确地描述低应变率下的应变率敏感性。结果表明，波浪载荷情景中已经存在动力效应，这归因于 Cowper-Symonds 模型的一些局限性。因此，本文的最后一部分致力于开发一种新的应变率敏感性模型，该模型更准确地描述低应变率下的应变率敏感性。