双频激振下带V形缺口轴的疲劳寿命研究

针对金属轴类零件在实际复杂工况下易产生应力集中而发生疲劳破坏的问题,利用双频激振系统,研究带V形缺口轴的疲劳寿命随缺口几何参数的变化规律。首先,提出了促进轴疲劳裂纹萌生的激振频率控制曲线,同时采用响应曲面法中的Box-Behnken设计法对V形缺口的夹角、圆角半径和深度进行三因素三水平的实验设计;其次,建立了疲劳寿命多元回归预测模型,并采用方差分析法对模型进行可靠性评价;最后,利用响应曲面和等高线图分析了缺口的夹角、圆角半径和深度对轴疲劳寿命的影响规律,并进行了预测模型的应用。研究结果表明：疲劳寿命预测值与实测值之间的误差在4.2%以内,预测精度较高,预测模型可靠;缺口几何参数对疲劳寿命从大到小的影响次序是缺口深度、缺口圆角半径、缺口夹角,以圆角半径和深度的交互作用对轴疲劳寿命的影响最为显著。研究结果可为金属轴类零件的抗疲劳设计提供重要参考。

Study on fatigue life of shaft with V-notch under dual-frequency excitation

In view of the problem that metal shaft parts are prone to stress concentration and fatigue failure under actual complex working conditions, the variation of fatigue life of shaft with V-notch with notch geometric parameters was studied by using dual-frequency excitation system. Firstly, the excitation frequency control curve to promote the initiation of shaft fatigue crack was proposed. At the same time, the Box-Behnken design method in response surface method was used to carry out the experimental design of three factors and three levels of angle, fillet radius and depth of V-notch; secondly, a multiple regression prediction model of fatigue life was established, and the reliability of the model was evaluated by variance analysis; finally, the influence of the angle, fillet radius and depth of the notch on the fatigue life of the shaft was analyzed by using the response surface and contour map, and the prediction model was applied. The results showed that the error between the predicted and experimental values of fatigue life was within 4.2%, the prediction accuracy was higher, and the prediction model was reliable; the influence of the geometric parameters of the notch on the fatigue life from large to small was the depth, fillet radius, and the angle of notch. The interaction of fillet radius and depth had the most significant impact on the fatigue life of shaft. The research results can provide an important reference for the anti-fatigue design of metal shaft parts.