基于三参数威布尔分布的自动调整臂疲劳寿命的P-S-N曲线研究

Research on the P-S-N Curve of Fatigue Life of Automatic Brake Adjuster Based on Three Parameter Weibull Distribution

通过疲劳试验研究了自动调整臂矩形压缩弹簧的疲劳寿命、疲劳变形以及破坏特征等。试验结果表明:疲劳应力载荷作用下,矩形压缩弹簧中间应力集中部位会产生裂纹,随着应力水平提高,裂纹变大,使得其传递转矩能力减弱;利用最小二乘法及最大相关系数法拟合自动调整臂疲劳寿命,可知其疲劳寿命服从三参数威布尔分布;根据三参数幂函数形式的S-N曲线方程,建立自动调整臂在不同应力下的P-S-N曲线,通过自动调整臂试验与理论疲劳极限寿命的比较表明,两者相对误差较小。

An experimental study on the fatigue properties of automatic brake adjuster is presented. The deflection ability,failure characteristics and fatigue life were investigated.It is observed when fatigue stress is applied,middle stress concentration parts of the rectangular compression spring will produce crack. While stress level increases,the crack becomes bigger,which makes its ability to transfer torque reduced. Using the method of least squares and maximum correlation coefficient fitting of the fatigue life of automatic brake adjuster,it was shown that its fatigue life obey the three parameter of Weibull distribution. According to the three parameters in the form of power function S-N curve equation, the automatic brake adjuster under different stress P-S-N curve is setd up. The automatic brake adjuster test was compared with the theoretical fatigue limit life which shown the relative error of the two is small.