循环载荷下热疲劳裂纹的应力强度因子  

Stress Intensity Factor of Thermal Fatigue Crack under Cyclic Loading

作　　者：王世杰[1] 闫明[1] 佟玲[1] 刘勤 

机构地区：[1]沈阳工业大学机械工程学院,沈阳110178 [2]中国兵器工业系统总体部,北京100089

出　　处：《机械工程学报》2010年第10期64-68,共5页Journal of Mechanical Engineering

基　　金：辽宁省创新团队基金资助项目(2009T071)

摘　　要：为揭示循环温度载荷对热疲劳裂纹应力强度因子的影响规律,考虑材料的多线性塑性随动强化性质,用有限元法计算多种循环载荷作用下裂尖点的应力-应变和热疲劳裂纹的应力强度因子。该应力强度因子值由裂尖附近压缩塑性应变的累积量决定。压缩塑性应变对温度载荷的作用次序敏感,因此应力强度因子也受到温度载荷的作用次序的影响。恒温度幅循环条件下,如果不考虑裂纹扩展,热疲劳裂纹的应力强度因子不随循环次数变化。变温度幅循环条件下,低温循环不会影响其后的高温循环应力强度因子;高温循环却影响其后的低温循环应力强度因子,并使得低温循环的应力强度因子与高温循环的应力强度因子相同,因此突发的高温载荷严重威胁高温构件的寿命。热疲劳裂纹扩展试验证明了有限元计算结果的正确性。To reveal the rule of effect of cyclic temperature loading on the stress intensity factor of thermal fatigue crack,the stress-strain of crack tip under various cyclic loadings and the stress intensity factor of thermal fatigue crack are calculated by using finite element method in consideration of the multi-linear plastic kinematic hardening characteristic of a material.The stress intensity factor is dependent on the accumulation of plastic compression strain,which is sensitive to temperature loading sequence.Thus,the stress intensity factor is influenced by the temperature loading sequence,too.If crack propagation is not considered,the stress intensity factor of thermal fatigue crack will not change with cycles on condition that temperature amplitude is constant.However,when the temperature amplitude is variable,the low temperature cycle will not affect the stress intensity factor of latter high temperature cycles,but high temperature cycle will affect the stress intensity factor of latter low temperature cycles,and make it equal to that of high temperature cycle.Thus,a burst high temperature loading will badly threaten the lives of high temperature components.The thermal fatigue crack propagation testing proves that the calculated result by finite element method is correct.

关 键 词：热疲劳裂纹 应力强度因子 载荷顺序 有限元法 裂纹扩展试验 

分 类 号：TG113.25[金属学及工艺—物理冶金]