循环蠕变加载下疲劳裂纹扩展速率的探讨

根据循环蠕变加载下应力-应变迟滞徊线的周期性,提出了在一个循环周期内以应变能密度为损伤参量,并把材料的机械疲劳损伤和蠕变损伤统一处理的方法,以解决这两种损伤之间的交互作用问题;指出了在循环蠕变的加速现象中包含了这两种损伤之间的交互作用的效果;借助于等效杨氏模量概念,对静蠕变公式进行修正后用于循环蠕变的应变计算,进而对能量密度进行计算。然后参照单轴疲劳的研究过程,导出了循环蠕变加载下基于能量密度的疲劳裂纹扩展速率公式。

Research on the Fatigue Crack Growth Rate under Cyclic Creep Loading

Based on the periodicity of stress-stain hysteresis loop,a method is put forward to deal with the interaction between mechanical fatigue damage and creep damage by regarding the stain energy density as density damage in one cycle and integrating mechanical fatigue damage with creep damage.The acceleration of cyclic creep is proved to be the result of the interaction between mechanical fatigue damage and creep damage.The formula of static creep is modified to be applied to computing the stain of cyclic creep and stain energy density by virtue of equivalent Young modulus.Refer to the fatigue process uniaxial loading,the formula of fatigue crack growth rate under cyclic creep loading based on stain energy density is derived.