管道疲劳寿命的可靠性分析

针对管道的疲劳失效分析,以概率论为基础,结合确定性的疲劳断裂力学估算方法,推导了管道的疲劳裂纹扩展寿命的计算公式.考虑到主要评定参数:初始裂纹尺寸、工况载荷、断裂韧性、机械强度、系数等的不确定性和随机性,应用蒙特卡罗模拟法对这些具有某种特定分布的随机变量进行了随机抽样计算.并利用数值积分法编制了计算机程序,求出在一定可靠度和置信度下的疲劳寿命,并与理论计算方法求得的疲劳寿命进行了比较.还比较了不同初始裂纹尺寸和断裂韧性对疲劳寿命的影响,并给出了算例.分析结果表明:蒙特卡罗模拟法真实地反映评定参数客观存在的不确定性,克服了确定性评定方法的缺点,具有良好的工程指导意义.

Reliability Analysis of Pipeline Fatigue Life

According to the fatigue failure analysis of pipeline,the formulas which were used to calculate the fatigue crack propagation lives of pipeline's components were derived by the method of probability and certain fatigue fracture mechanics.Considering mostly assessment parameters: the uncertain factors and randomness of initial crack size,practical working load,fracture toughness,mechanical intensity and coefficient,the random variables which had some certain distributions were calculated by Mote-Carlo simulation method.A computer program was developed by using numerical integration method,the fatigue life under given reliability and credit degree was gained,and it compared with the fatigue life which was gained by academic method.The fatigue life in different crack size and different fracture toughness was compared,and an example was given.By analyzing the result,the uncertainty of assessment parameters is reflected,and the shortcomings of certainty assessment methods are overcome.So it has great engineering significance.