疲劳损伤状态的模糊等效性试验研究

Experimental investigation on fuzzy equivalence under fatigue damage states

针对复杂载荷下以等效损伤假设为基础的材料疲劳寿命的估算误差较大的问题,基于模糊理论并结合耦合损伤概念提出模糊等效损伤假设,考虑加载顺序对疲劳损伤累积的影响来回避等效损伤假设。利用45钢材料进行了L-H和H-L加载顺序两级应力下的疲劳损伤累积规律验证,并选取16Mn材料的疲劳试验数据验证基于Miner线性损伤法则和本假设对材料疲劳寿命预测的准确性。结果表明,根据本假设计算的损伤量在两种加载顺序下均与试验值吻合良好,疲劳寿命估算结果比较接近于试验值,该假设以模糊理论为依据,为疲劳分析和寿命预测提供了一定的理论参考。

For issues of larger error in fatigue life estimation based on the equivalent damage assumption under complex loading,a fuzzy equivalent damage hypothesis was presented based on the fuzzy theory and the concept of coupled damage,in order to avoid the equivalent damage hypothesis by taking into account the influence of the loading sequence on cumulative fatigue damage.Two stages stress test on cumulative fatigue damage for 45 steel materials under sequence of L-H and H-L were performed.And the accuracy based on Miner linear damage rule and the hypothesis for predicting fatigue life of material has been verified by selecting fatigue test data of 16Mn.The results showed that the damage calculated with the fuzzy equivalent damage hypothesis are in good agreement with experimental data under two loading sequence,the life estimation results were closer to experimental values.The hypothesis based on the fuzzy theory provided a certain theoretical reference for fatigue analysis and life prediction under complex loading.