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疲劳应力监测是针对含缺陷设备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,可以详细了解焊接结构件高风险易裂区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)传感器对起重机械的典型焊缝结构进行监测,以其应力时程监测数据为基础,分析研究起重机疲劳裂纹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:起重机械典型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 tool for structural health monitoring and safety assessment of defective equipment. 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 high-risk frangible zones of welded structures and accurately estimate the residual life of the structure. In this paper, the typical weld structure of crane is monitored by FBG sensor. Based on the stress time history monitoring data, fatigue load spectrum characteristics of crane fatigue crack under random load are analyzed. 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 the average and amplitude of each stress cycle in the whole process are output. 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 the typical crane welder is normal, and the amplitude cycles are Weibull distribution.