基于脆性损伤机制的高周疲劳模型

从不可逆热力学耗散理论出发,建立了一个高周疲劳各向同性连续损伤力学模型.与基于延性损伤机制的Lemaitre模型不同,本模型基于脆性损伤机制.它成功地将高周疲劳损伤纳入到统一的热力学框架之内.其损伤演化律考虑了应力比 R的影响.利用本模型,根据对称循环下(R=-1)的高周疲劳SN曲线,可以导出具有任意应力比R的 log S log N 曲线.模型应用于LC9高强度铝合金光滑试件的试验分析,理论计算与实验结果比较,符合良好.

High Cycle Fatigue Model Based on Brittle Damage Mechanism

An isotropic continuum damage mechanics model for high cycle fatigue derived from irreversible thermodynamic dissipative theory is presented.The model is different from Lemaitre model in damage mechanisms.The former is based on a brittle mechanism,and the later is ductile.The model incorporates successfully the high cycle fatigue into a unified thermodynamic framework.The effect of stress ratio R is considered in its damage evolution law.According to the high cycle fatigue SN curve under symmetrical loading,a Log S Log N curve for an arbitrary stress ratio R can be derived by using this model.The model has been applied to the smooth specimen of LC9 high strengthen aluminum alloy.A good agreement between theoretical Log S Log N curves and experimental ones is obtained.