针对传统的Paris裂纹扩展模型在可靠性研究中不能考虑小裂纹扩展过程的问题，本文基于改进McEvily裂纹扩展模型，建立疲劳可靠性的极限状态计算方程，采用一次二阶矩验算点法对可靠度指标及其参数敏感性进行计算分析。通过与基于Paris裂纹扩展模型的可靠性结果对比表明：改进McEvily裂纹扩展模型下的可靠度指标为4.17，在Paris裂纹扩展模型下的可靠度指标为4.08，Paris模型只考虑了裂纹稳定扩展的过程，其可靠性计算结果更为保守；通过参数灵敏度分析得知，不确定变量中的材料参数m、初始裂纹尺寸a0、临界裂纹尺寸ac对可靠度指标有较大程度的影响。小裂纹扩展阶段的主要影响参数即裂纹闭合水平k，其变异系数对失效概率的影响较小但系数达到0.16时失效速率有进一步增长趋势。
Consideing traditional Paris crack propagation model in the study of reliability cannot consider the matter of small crack propagation process, in this paper, based on the improved McEvily crack propagation model of fatigue reliability calculation of the limit state equation is established, using a second-order moment checking point method of reliability index and the parameter sensitivity analysis, calculated, with the Paris based crack extension model show that the results of reliability of The reliability index of the improved McEvily crack growth model is 4.17, and that of the Paris crack growth model is 4.08. The model only considers the process of stable crack growth, and its reliability calculation results are more conservative. Through parameter sensitivity analysis, it is known that material parameters m, initial crack size and critical crack size in the uncertain variables have a great influence on the reliability index. Small crack growth stage of the main parameters influencing the level of crack closure k, but has little effect on the variation coefficient of failure probability coefficient reaches 0.16 a further increase of failure rate trend.
2021,43(1): 102-107 收稿日期：2019-12-17
DOI：10.3404/j.issn.1672-7649.2021.01.018
分类号：U664.1
基金项目：国家重点研发计划项目(2016YFC0300600)；国家自然科学基金资助项目(51709134，51879125)；江苏省自然科学基金资助项目(BK20160559)；江苏省“六大人才高峰”高层次人才资助项目(No.2018-KTHY-033)
作者简介：王珂(1979-),女,博士,副教授,研究方向为船舶与海洋结构物安全性
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