Crack growth analysis and fatigue life estimation in the piston rod of a Kaplan hydro turbine
Crack growth analysis and fatigue life estimation in the piston rod of a Kaplan hydro turbine
复制标题
轴流式水轮机活塞杆的裂纹扩展分析和疲劳寿命估算
DOI：
10.1111/ffe.12848
复制
发表时间：
2018
影响因子：
3.7
通讯作者：
Wang Z
中科院分区：
文献类型：
--
作者：
Liu X;Presas A;Luo Y;Wang Z
线弹性断裂力学（LEFM）方法很少用于分析水力压裂中的疲劳问题，通常考虑极其简化的疲劳模型。在世界上最大的轴流式水轮机中，作为重要的载荷传递部件的活塞杆在同一位置发生了两次断裂。这一事件导致了极高的直接维修费用和间接费用，是利用线性有限元法研究水轮机疲劳问题的一个非常有用的案例。为此，采用数值LEFM技术模拟了活塞杆裂纹扩展过程。初始缺陷尺寸的概率模型。一个可靠性标准，包括在没有一个关键的裂纹或断裂的活塞杆在特定的服务时间后的概率，被定义。在此基础上，讨论了机组初始裂纹形式和运行工况对机组可靠性的影响。计算的裂纹路径和预测的加载循环次数作为初始裂纹尺寸的函数与实际断裂截面和断裂操作时间一致。
Linear elastic fracture mechanics (LEFM) approaches are seldom used to analyze fatigue problems in hydraulic turbomachinery, where extremely simplified fatigue models are normally considered. In one of the largest Kaplan hydraulic turbines in the world, the piston rod, which is an important load transfer component, was found broken twice at the same location. This event, which leads to extremely high direct reparation costs and indirect costs, is a very useful case for research of fatigue problems in hydraulic turbines by means of LEFM. For this purpose, the crack growth progress in the piston rod is simulated with numerical LEFM techniques. A probabilistic model for the initial flaw size is considered. A reliability criterion, consisting in the probability of not having a critical crack or a fracture in the piston rod after a specific service time, is defined. Based on this model, the influence of initial crack models and operating services of the machine on the reliability of the unit is discussed. The calculated crack path and predicted number of loading cycles as a function of the initial crack size agree with the actual fracture section and operating time to fracture.