柴油机受热零件的低周热疲劳寿命预测

Low Cycle Fatigue Life Prediction of Diesel Engine Heating Components

本文首先分析船用柴油机热载荷的加载情况,然后确定强载零件的应力—应变迟滞循环;在此基础上用应变范围区分理论和滞回能范围理论,预测受热零件的低周热疲劳寿命.并和因低周热循环(起动和仃机)损坏的机器零件进行了比较,说明两个方法都具有一定的精确性.这是由于二者都考虑了疲劳和蠕变的交互作用.文中热疲劳和高温低循环疲劳的相当温度用的是最高温度T_2.在轴对称问题中,因为环向应力占主要地位,因此应力—应变范围以环向应力—应变范围为标志.

In this paper the thermal load condition of marine diesel engine is analysed, then the stress-strain hysterisis cycles are determined. On this basis the low cycle fatigue lives of heating components are calculated by the Strain-Range Partitioning Method and the Hysterisis Energy Method. By comparing the calculated results with the damaged component of a test machine due to starting and stopping in practical application, it is verified that both methods have a certain accuracy, because both are considered the interaction of fatigue and creep. During calculating and testing, the equivalent temperature of thermal fatigue and high temperature low-cycle fatigue is the maximum temperature T_2 and the stress-strain cycle is according to peripheral stress and strain, because the components are similar to the axisymmetric body.