汽包与管道疲劳损伤断裂可靠性分析

A Method Analysing Fatigue Damage Fracture of Steam Box and Pipe on Dependability

针对火电厂中汽包与管道在运行过程中发生疲劳损伤断裂失效这一类问题 ,提出一种概率疲劳损伤断裂失效分析方法 ,它以汽包与管道类压力容器结构的初始疲劳质量状态为基础 ,考虑了汽包或管道在疲劳条件下材质损伤衰变、萌生裂纹及其扩展时的随机性 ,采用概率统计方法 ,建立起以裂纹长度为准则的汽包与管道发生疲劳损伤断裂失效时的功能函数 ,同时还给出了按近似概率分析方法中的JC法与一次二阶矩法计算了汽包或管道在不同循环次数下的疲劳裂纹超过数概率。上述分析与计算 ,实质上反映了对汽包或管道疲劳损伤断裂失效时的疲劳寿命进行可靠性评估的概率分析新方法。本文中最后引用汽包与管道用耐热钢的疲劳试验结果 ,与上述分析方法得到的预测结果加以对比验证 ,表明提出的这一新方法是合理的和可靠的。

In connection with the fact that the boiler steam box and pipe in thermal power plant are deactivated while they work during their fatigue damage fracture.This paper suggests an analytic deactivating method to probability fatigue damage fracture.\;The initial fatigue quality state of structure of pressure vessel like steam box and pipe is prerequisite in the process of study.It is considered the randomness in which the material quality of steam box and pipe changes badly under fatigue and their cracks occur and expand.Therefore according to the crack length that is regarded as criterion,the function of fatigue damage fracture of steam box and pipe is estabalished with probability statistics.Furthermore this paper shows the probability of supernumber of the fatigue crakcs of steam box or pipe under different cycle numbers which is calculated with JC method of approximate probability analysis and one-row-tow-rank matrix.The analysis and calculation are acturally a new probability analysis method with which the fatigue life is evaluted at deactivation of steam box or pipe for fatigue damage fracture.Finally the fatigue test results of heat-resisting steel that is used in steam box and pipe are compared to the conclutions estimated with the new method.It is clear that the suggested new method is reasonable and dependable.