循环荷载作用下合成纤维系缆粘弹塑性应力应变关系

Stress-strain relationship of synthetic fiber mooring lines under cyclic loading

在循环载荷作用下,合成纤维系缆的应力应变关系表现出明显的非线性特性,直接影响系泊缆绳的动力响应。如何针对其在循环载荷作用下的应力应变关系进行准确的定量描述是有关绷紧式系泊系统设计的关键问题。国内外研究者之前的研究不能反映缆绳的载荷历史、蠕变特性以及刚度变化过程,因此提出一个粘弹性粘塑性模型来描述合成纤维系缆的应力应变关系。本模型能够反映合成纤维缆绳的时间变化特性以及在整个加载—卸载过程中的刚度变化。此外,提出了明确的参数确定方法及步骤,基于简单的蠕变实验可以确定模型的各个参数。将两种载荷条件下聚酯缆绳的实验结果与模型结果进行对比,二者吻合较好,证明了模型的有效性和可靠性。本研究对于绷紧式系泊系统的研发和工程应用具有重要意义。

The stress-strain relationship of synthetic fiber ropes under cyclic loading shows obvious nonlinear property, which directly influences the dynamic tension response of mooring lines. How to obtain the quantitative description of the stress-strain relationship of the synthetic fiber mooring lines under cyclic loading is a key problem relevant to the design of the taut-wire mooring system. The for- mer studies were insufficient to take into account the true loading history, creep behavior and the evolution of the dynamic stiffness. Thus a viscoelastic and viseoplastie model is developed herein to describe the stress-strain properties of synthetic fiber mooring lines. The time dependent property and the evolution of the dynamic stiffness during the loading and unloading processes can be fully consid- ered in the developed model. Besides, a specific method and a procedure for parameter identification are proposed and the parameters can be determined by simple creep experiments. The model is validated by comparison with the experimental results of polyester ropes under two loading conditions. The present work provides significant reference for the research and development and the engineering ap- plication of the taut-wire mooring systems.