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疲劳应力监测是针对含缺陷压力容器进行结构健康监测和安全评估的重要手段。基于焊缝疲劳应力监测数据和其概率密度函数,可以详细了解压力容器的实际运营状况和准确评估结构剩余寿命。本文以直角光纤光栅(FBG)传感器对环焊缝结构应力时程监测数据为基础,分析研究疲劳裂纹热点区在随机载荷作用下的疲劳载荷谱特征。首先,基于三向应力监测数据样本计算其等效应力时程;然后采用雨流计数法处理等效应力时程,输出整个历程中各次应力循环的均值和幅值;最后,拟合均值和幅值的概率分布函数,并进行概率密度函数的参数估计和检验。研究结果表明:压力容器焊缝疲劳等效应力谱的均值循环次数呈正态分布,幅值循环次数呈Weibull分布。
Fatigue stress monitoring is an important means of structural health monitoring and safety assessment for defective pressure vessels. Based on the weld fatigue stress monitoring data and its probability density function, you can get a detailed understanding of the actual operating conditions of the pressure vessel and accurately estimate the residual life of the structure. In this paper, based on the time-history data of the ring weld structure, the FBG sensor was used to analyze the fatigue load spectrum characteristics of the fatigue cracked hotspot under random loading. First, the equivalent stress time history is calculated based on the three-dimensional stress monitoring data sample. Then the rain flow count method is used to process the equivalent stress time history and output the mean and amplitude of each stress cycle in the whole process. Finally, The probability distribution function of amplitude, and the parameter estimation and test of probability density function. The results show that the mean cyclic number of fatigue equivalent stress spectrum of pressure vessel weld is normal, and the amplitude cycles are Weibull distribution.