基于极限承载能力分析的超深水水下分离器承压结构壁厚设计方法

摘要

Based on the analysis method for the ultimate bearing capacity of structures,a 3 000 m subsea gravity separator was taken as the research target in this paper.According to the formulas in ASMEVIII-Ⅰ code,the initial wall thickness was computed and the whole model was established using finite element software.The double nonlinear instability analysis and plastic ultimate analysis were carried out based on the 5 ％ maximum strain principle.Furthermore,the recursion arithmetic was proposed to optimize the wall thickness.Finally,the determination method for the wall thickness of ultra-deepwater subsea separators was established.A prototype was manufactured according to the optimized wall thickness and pressure tank crushing tests were conducted.The experimental result indicates that the model built in this paper is accurate,the errors of plastic analysis and instability analysis compared to the experimental results are 13.11％ and 8.80％ respectively.The determination method for the wall thickness of ultra-deepwater subsea separators proposed in this paper makes full use of material plasticity.In addition to guaranteeing the reliability,the determination method increases bearing capacity by 44.4％,and decreases wall thickness by 20％ in comparison with stress classification methods.%基于结构极限承载能力分析法,以3 000 m超深水重力式水下分离器为研究对象,根据ASMEVIII-Ⅰ基本公式计算结构初始壁厚,借助有限元软件建立了超深水水下分离器整体模型,开展了基于5％最大主应变准则的极限承载能力校核和双非线性稳定性极限承载能力校核,并在此基础上提出递归循环算法优化壁厚,最终构建了超深水水下分离器承压结构壁厚设计方法.根据最优壁厚制造了超深水水下分离器试验样机,开展了高压舱压溃试验,结果表明:本文所建立的超深水水下分离器整体模型具有较高精度,塑性极限分析和稳定性分析结果与试验结果的相对误差分别为13.11％、8.80％;本文所构建的超深水水下分离器承压结构壁厚设计方法充分利用了材料的极限承载能力,在保证结构高耐压和高可靠性的基础上,相比弹性应力分类法提高承载能力44.4％,并有效减小设计壁厚达20％.