基于动态响应特性的点焊疲劳损伤参量

针对不同疲劳损伤累积量,研究了点焊疲劳试件的固有频率变化特性.研究结果表明,试件的固有频率与所承受的循环数比成非线性关系.提出了一个由固有频率相对变化来描述的疲劳损伤参量,并利用疲劳损伤理论,建立了非线性疲劳损伤演化模型.结果表明,所提出的疲劳损伤参量能够很好地描述点焊接头疲劳损伤特性,疲劳寿命预测误差在两个因子之内.

Fatigue Damage Parameter of Spot-welded Joints Based on Dynamic Response Characteristics

According to the different fatigue damage cumulative quantity, the dynamic response frequency is measured during the fatigue damage process. The results of experimental study show that the natural frequency varies nonlinearly with the fatigue damage fraction. A new fatigue damage parameter is proposed, which is described by the nonlinear relationship between the natural frequency of specimen and its cyclic ratio. On the basis of continuum fatigue damage theory, a nonlinear fatigue damage evolution model is developed. The results show that the proposed fatigue damage parameter can describe well the characteristics of fatigue damage. The predicted errors of fatigue life are within two factors.