拉-压加载下纤维增强铝合金层板疲劳裂纹扩展的压载荷效应与预测模型

Effect of compression loading on the fatigue crack growth in fiber reinforced aluminium laminates and prediction model

基于增量塑性损伤理论与纤维增强金属层板疲劳裂纹扩展唯象方法,推导出在拉-压循环加载下,纤维增强金属层板疲劳裂纹扩展速率预测模型。并通过玻璃纤维增强铝合金层板在应力比R=-1,-2的疲劳裂纹扩展实验对预测模型进行验证。结果表明,纤维增强铝合金层板疲劳裂纹扩展的压载荷效应分为两种情况:在有效循环应力比RC>0时,表现为压载荷对铝合金层所承受残余拉应力的抵消作用;当RC<0时,表现为压载荷抵消残余拉应力后,对纤维增强铝合金层板金属层的塑性损伤,对疲劳裂纹扩展存在促进作用。纤维铝合金层板疲劳裂纹扩展的压载荷效应不可忽略,本文中得出的在拉-压循环加载下疲劳裂纹扩展速率预测模型与实验结果符合较好。

Using the incremental plastic damage theory and the phenomenological model for predicting fatigue crack growth in fiber reinforced metal laminates,a predicting model of fatigue crack growth in fiber reinforced aluminium alloy laminates under tension-compressive loading was deduced.The experiments of the fatigue crack growth in the glass fiber reinforced aluminium alloy laminates at the R=-1 and R=-2 were performed in order to verify the predicting model.The results show that the two cases of the effect of compression loading are pointed out that when the effective stress ratio RC〉0,it is characterized by counteracting the residual stress in the aluminium alloy layer,and when RC〈0,it is characterized by causing the plastic damage in the aluminium alloy layer and the promoting effect on the fatigue crack growth in fiber reinforced aluminium alloy laminates.The effect of compression loading should not be neglected.The model has been obtained good agreements with the experimental data.