聚酯系缆损伤对绷紧式系泊系统动力响应影响的数值分析

由于聚酯缆绳具备优异的力学性能,促使以其为主体系缆的绷紧式系泊系统得以广泛应用和发展。但聚酯系缆具有复杂的黏弹性和黏塑性,且由于在安装和使用过程中可能产生不同程度的损伤,使得聚酯系缆的动刚度特性发生演变,从而对系泊系统的动力响应产生直接影响。以一系泊于1 020 m水深的Spar平台为例,运用ABAQUS软件建立了由聚酯缆绳组成的系泊系统有限元模型,并利用ABAQUS子程序将损伤缆绳动刚度经验公式进行导入计算,以更好地反映系缆真实的动刚度变化。基于该有限元模型,计算了在相同水流、波浪工况下,不同损伤度、不同损伤系缆的系缆张力历程和平台的横荡、纵荡位移响应,分析了不同损伤度、不同损伤系缆对系缆张力及平台位移的影响。这些成果对把握绷紧式系泊系统在聚酯系缆有损伤情况下的非线性动力响应及其安全应用具有重要的参考价值。

Numerical investigation on the dynamic response of the taut-wire mooring system accounting for damaged polyester ropes

The taut-wire mooring system, which employs the polyester rope as the main part of mooring lines, is widely used due to the excellent mechanical properties of polyester ropes. However, the dynamic stiffness of mooring lines changes as a result of their complicated viscous elastic and viscous-plastic properties and the possible damage resulting from installation, mooring service, etc. And what is more, the dynamic stiffness evolution of mooring lines further affects the dynamic response of the mooring system. Therefore, it is necessary to delve into the nonlinear dynamic properties of damaged synthetic fiber ropes used as mooring lines. In this paper, the commercial finite element software ABAQUS is used to create a finite element model for a Spar platform with polyester mooring lines in 1 020 m water depth. A UMAT procedure of the damaged dynamic stiffness equation is developed to describe the stiffness evolution of mooring lines. Based on the finite element model, the tension history of mooring lines and the sway and surge displacement histories of the platform are calculated, which are in different degrees of damage and different locations of damage under the same condition of fluent and wave loadings. These results are of great value to the safe operation of taut-wire mooring systems.