基于TCD理论的缺口试样疲劳强度尺寸系数计算

为了建立疲劳强度尺寸系数计算公式，基于TCD理论对缺口试件的疲劳强度进行了研究．引入与材料疲劳强度以及疲劳裂纹扩展应力强度因子门槛值相关的临界距离，建立了试样缺口根部的应力幅函数．利用有限元计算结果对应力幅函数的参数进行拟合，并由此建立了缺口件的疲劳强度尺寸系数计算公式．最后，基于该方法针对两种材料(Q235和45#)以及不同缺口形状（U型和半圆型）分别进行了实例计算，所得结果与实验数据较为吻合．

Research of the Size Factor of Fatigue Strength Base on TCD Theory

In order to formulate the size factor of fatigue strength, this paper was focused on the fatigue strength of notched specimen based on the Theory of Critical Distances (TCD). The critical distance related to the fatigue strength of material and the threshold of crack propagation was introduced, and consequently the stress function of notch specimen root was established The FEM result was adopted for the fitting of stress function parameters. In the end, sample calculations for two distinctive materials Q235 and 45#, as well as V-shaped and U-shaped notch specimens, were performed based on the proposed method. It turns out that the numerical results are in good agreement with the experimental data.