压力容器焊缝疲劳应力概率分布研究
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摘要
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 to carry out structural health monitoring and safety assessment of pressure vessel. Based on the monitoring data of fatigue stress and its probability density function, the actual operation condition of pressure vessel can be fully understood and the remaining life of structure can be evaluated accurately. According to the monitoring data of the stress time history of the complex structure of pressure vessel with the fiber Bragg grating(FBG) stress monitoring system, the fatigue load spectrum characteristics of the fatigue structures under random loading are analyzed and studied. Firstly, the equivalent stress time history is calculated based on the triaxial stress monitoring data. Then, the equivalent stress time history is processed by the rain flow counting method, and the mean and amplitude of the stress cycles in the whole process are obtained. Finally, the probability distribution function of the mean and amplitude is fitted, and the characteristic parameters of the probability density function are tested. The results show that the mean of equivalent stress spectrum of pressure vessel is normal distribution, and the amplitude is Weibull distribution.
Fatigue stress monitoring is an important means to carry out structural health monitoring and safety assessment of pressure vessel. Based on the monitoring data of fatigue stress and its probability density function, the actual operation condition of pressure vessel can be fully understood and the remaining life of structure can be evaluated accurately. According to the monitoring data of the stress time history of the complex structure of pressure vessel with the fiber Bragg grating(FBG) stress monitoring system, the fatigue load spectrum characteristics of the fatigue structures under random loading are analyzed and studied. Firstly, the equivalent stress time history is calculated based on the triaxial stress monitoring data. Then, the equivalent stress time history is processed by the rain flow counting method, and the mean and amplitude of the stress cycles in the whole process are obtained. Finally, the probability distribution function of the mean and amplitude is fitted, and the characteristic parameters of the probability density function are tested. The results show that the mean of equivalent stress spectrum of pressure vessel is normal distribution, and the amplitude is Weibull distribution.
引文
[1]GB/T 19624-2004在用含缺陷压力容器安全评定[S].
[2]李振华.起重机金属结构疲劳寿命预测与疲劳可靠性研究[D].成都:西南交通大学,2009.
[3]赵雪峰.基于光纤光栅应变花的平面应变状态实验分析[J].光电子激光,2004,15(1):65-68.
[4]汪宏.基于MATLAB的疲劳寿命预测研究[D].西安:长安大学,2009.
[5]文彩,杨自春.结构疲劳寿命估计的概率和非概率混合模型研究[J].科学技术与工程,2009,9(17):5109-5112.
[6]徐钟济.蒙特卡罗方法[M].上海:上海科学技术出版社,1985.
[2]李振华.起重机金属结构疲劳寿命预测与疲劳可靠性研究[D].成都:西南交通大学,2009.
[3]赵雪峰.基于光纤光栅应变花的平面应变状态实验分析[J].光电子激光,2004,15(1):65-68.
[4]汪宏.基于MATLAB的疲劳寿命预测研究[D].西安:长安大学,2009.
[5]文彩,杨自春.结构疲劳寿命估计的概率和非概率混合模型研究[J].科学技术与工程,2009,9(17):5109-5112.
[6]徐钟济.蒙特卡罗方法[M].上海:上海科学技术出版社,1985.