高温合金材料时间相关热机械疲劳寿命预测技术

本文在变温非线性运动强化规律所描述的高温合金材料热机械疲劳应力-应变循环特性的基础上,重点讨论了应变控制的时间相关热机械疲劳寿命预测技术。对于温度循环的影响,采用由应变能密度表示的损伤参数,并且引入了温度损伤系数。对于循环时间的影响,引入了蠕变─疲劳相互作用的损伤机制,采用韧性耗散损伤模型。在确定模型的一些参数时,采用等温力学试验和疲劳试验的数据,把等温疲劳研究成果推广到变温疲劳分析领域。

LIFETME PREDICTION OF TIME-DEPENDENT THERMOMECHANICAL FATIGUE OF HIGH TEMPERATURE ALLOYS

paper discusses the lifetime prediction tecboques of time-dependent thermomechanical fatigue (TMF) of high temperatire alloys. It is based on the stress-strain cyclic behavior described by a non-linear kinematic hardening model in an irreversible thermodynamic system. In order to consider the influence of temperature cycles, a strain energy density combined with a temperature damage factor was deduced as a damage parameter. In the case of the time dependent fatigue, the application of a ductility exhaustion approach for creep-fatigue damage assessment was illustrated. In identifying parameters of the models, isothermal fatigue test results were applied A method using isothermal cycle data for predcting thermomechanical fatigue life bine was developed.