High Cycle Fatigue Model Based on Brittle Damage Mechanism
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摘要: 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.Abstract: 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.
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