基于低周疲劳理论T型叶根转子轮槽寿命预测  

Life Prediction of T-Shaped Slot in Rotors Based on Low Cycle Fatigue Theory

作　　者：楼上游[1] 骆天舒[1] 应博芬[1] 徐旭岭[1] 

机构地区：[1]杭州汽轮机股份有限公司,杭州310022

出　　处：《热力透平》2015年第2期94-97,共4页Thermal Turbine

摘　　要：由于某些低压级组T型叶根轮槽圆角轮槽应力集中处应力超过屈服极限进入塑性区域,作用于其上的低周交变的离心力载荷会引起低周疲劳破坏,因此为了兼顾这类轮槽制造成本和整个转子安全寿命,需要预测T型叶根轮槽圆角的寿命。首先基于弹塑性理论,用非线性有限元方法定量计算了某级动叶叶根轮槽的加载-卸载-加载过程。从上述计算结果中得到应力集中处的八面体剪应变幅值和平均应力。然后将此数据代入改进后的Manson-Coffin关系式,用Newton迭代法求解该方程得到低周疲劳载荷循环次数。根据这个结果我们可以判断T型轮槽这类结构是否能在新设计机组中使用。As the peak stresses of the bladed disk T-shaped slot fillet in some low pressure stages are beyond yield,low cycle fatigue failure might be caused by low cycle load on the slot. Therefore, the life of T- shaped slot fillet must be predicted in order to obtain low cost of production of the slots and assure the safety of the whole rotor. The load-unload-load process of a slot is calculated by nonlinear FEM based on elastic-plastic theory. The amplitude of octahedral shear strain and the average stress in the peak stress area can be obtained from the above calculation. The results are substituted into an advanced Manson-Coffin equation, and then the equation is solved by Newtonian method. The solution is the permitted number of the cycles of fatigue load. Based on the solution, one could assert whether the T-shape slot can be used in a new designed turbine.

关 键 词：低周疲劳 塑性 叶根槽 屈服极限 有限元 

分 类 号：TK263.6[动力工程及工程热物理—动力机械及工程]