Time Domain Simulation of the 3D Bending Hysteresis Behaviour of an Unbonded Flexible Riser
Time Domain Simulation of the 3D Bending Hysteresis Behaviour of an Unbonded Flexible Riser
复制标题
无粘结柔性立管 3D 弯曲滞后行为的时域仿真
DOI：
10.1115/omae2007-29315
复制
发表时间：
2007
影响因子：
7.2
通讯作者：
T. Sheldrake
中科院分区：
文献类型：
--
作者：
Z. Tan;P. Quiggin;T. Sheldrake
本文介绍了柔性隔水管在近海环境载荷作用下三维弯曲滞回行为的时域动态模拟的发展现状。主要的技术挑战是了解和模拟立管在弯曲大小和方向不断变化的情况下的拉伸装甲行为，以及它对立管弯曲滞后特性的影响。由于这一技术障碍，目前的行业实践是将立管建模为线性结构，并实施一定的保守性，然后将全局动态载荷提取到详细的局部模型中进行应力和寿命评估。本文介绍了Wellstream和Orcina分别开发的两种三维挠性立管弯曲滞回模型，以及它们在足尺试验中对弯曲滞回曲线的标定。这两个模型都是使用分析程序OrcaFlex实现的；Wellstream模型是一个详细的模型，它同时计算总弯矩和拉伸装甲中的应力；Orcina模型是一个更简单的模型，它只计算总弯矩。研究表明，在考虑和不考虑弯曲滞后行为的情况下，立管动态响应的差异，并评估Wellstream和Orcina 3D弯曲滞后模型的动态响应的差异。此开发允许在运动仿真中对立管结构特性进行更真实的建模，并报告立管强度组件的详细时间历史应力或应变结果。这将目前仅使用规则波法进行立管疲劳分析的做法扩展到使用采用雨量计数法的不规则波法。版权所有：Wellstream International Ltd.和Orcina Ltd.
This paper presents a ‘state of art’ in the development of the time domain dynamic simulation of 3D bending hysteresis behaviour of a flexible riser under offshore environment loading. The main technical challenge is to understand and model the riser tensile armour behaviour under continuous changes in both the magnitude and direction of bending, and its subsequent impact on the riser’s bending hysteresis characteristics. Because of this technical obstacle, the current industry practice is to model the riser as a linear structure, with certain conservatism enforced, and then to extract the global dynamic loads to a detailed local model for stress and life assessment. This paper introduces two 3D flexible riser bending hysteresis models, developed by Wellstream and Orcina respectively, and their calibrations against the bending hysteresis loops measured in full scale tests. Both models are implemented using the analysis program OrcaFlex; the Wellstream model is a detailed model that calculates both the total bending moment and the stresses in the tensile armour; the Orcina model is a simpler model that only calculates the total bending moment. A study is presented to illustrate the difference in the riser dynamic responses with and without consideration of the bending hysteresis behaviour, and to assess the difference in the dynamic responses between the Wellstream and Orcina 3D bending hysteresis models. This development permits more realistic riser structural properties to be modeled in the dynamic simulation, and reports detailed time history stress or strain results of the strength components of the riser. This expands the current practice of riser fatigue analysis of only using the regular wave approach, to using an irregular wave approach employing the rainflow counting method.Copyright © 2007 by Wellstream International Ltd. and Orcina Ltd.