半刚性基层疲劳损伤模型及寿命预估

Fatigue Damage Model and Fatigue Life Forecasting of Semi-rigid Base

基于临界损伤值DC不等于1的基本假定,借助损伤力学理论建立半刚性基层的疲劳损伤模型,并结合脆性材料S-N关系方程,得出了模型参数C的一个新的函数表达式C=1/(alnS+b)。通过疲劳试验对Dc值以及C表达式中的待定系数a、b进行测定,并对多个试件疲劳寿命进行了预估计算。研究结果表明半刚性基层材料Dc值约为0.6。利用建立的损伤模型,在当前损伤量仅为0.3至0.5倍临界损伤值时,即可较早地对试件疲劳寿命进行预估。预估结果与试验结果吻合较好。

A new fatigue damage model for semi-rigid base was established by means of damage mechanics based on the supposition of Dc unequal to 1, and a new formula C = 1/（ alnS ＋ b） of the parameter C in the model was obtained with the S-N equation. The value of Dc and indefinite coefficiens a and b were determined by doing fatigue experiments, furthermore, the fatigue life of several specimen were forecasted with this new damage model. The research results show that ： the Dc of the semi-rigid base is 0.6, the fatigue life of specimen can be early and effectively forecasted with the newlyestablished damage model as the value of D is just within 0.3 - 0.5 times of De, and the life forecasted is quite close to the experimental results.