点蚀损伤下海洋平台结构剩余强度的多尺度分析方法

MULTI-SCALE ANALYSIS OF RESIDUAL STRENGTH OF OFFSHORE PLATFORMS WITH PITTING CORROSION

均匀腐蚀损伤影响结构承载力的研究已趋于成熟,但点蚀损伤影响整体结构承载力的规律及其局部损伤的演化行为仍不明确。该文采用均匀分布的圆柱体点蚀损伤模型,探讨在宏观结构尺度中点蚀损伤的描述、多尺度区域的划分和跨尺度界面的连接以及结构非线性的求解方法,提出了研究考虑细观尺度点蚀损伤的海洋平台结构多尺度模型的构建和计算方法。计算结果表明:该文提出的多尺度模型构建策略有效地解决了细观尺度点蚀损伤在宏观结构尺度中的描述问题,且所建多尺度模型能够体现点蚀损伤削弱结构极限承载力的规律,为评估在役海洋平台结构的剩余强度提供了可行的方法。

Pitting corrosion is a common damage affecting the residual strength of offshore structures, whose deterioration mechanisms are not yet clear. In this study, a meso-scale corrosive pit model with cylindrically uniformly distributed pits on the surface of a pipe shell was adopted. The model was integrated into a macro-scale structure with pitting wastage damage. After studying key factors of mixed dimensional finite element model including the description method of the pits in the macro-scale structures, the partition principle of the structural multi-scale regions, the connection technique for the across-scale interface of the multi-scale region, and the nonlinear solution technique for the multi-scale model, a numerical approach addressing multi-scale modelling of offshore structures with pitting corrosion were proposed. Results of an aging offshore structure showed that the proposed multi-scale model can be successfully used to bridge the description gap between the meso-scale damage and the macro-scale structure. In addition, based on such multi-scale finite element models, the rule of the deterioration caused by corrosive pitting to the residual strength was remarkably reflected, providing a practical method for the evaluation of residual strength of offshore structures in engineering practice.