混凝土搅拌运输车副车架焊缝疲劳评估

Fatigue Strength Analysis of Sub-frame Weld of Truck Mixer

针对传统疲劳评估方法对焊接结构疲劳寿命计算精度和准确率不高的问题,提出采用等效结构应力法对副车架关键焊缝进行疲劳评估。通过车架静力学分析,确定了关键焊缝位置;利用惯性释放方法在车架与悬架各连接位置施加单位载荷进行分析,获得了车架在单位载荷单独激励下的应力响应;结合等效结构应力基本原理,选取存活率50%情况下的主S-N曲线对焊缝进行了疲劳寿命预测。结果表明:斜撑与纵梁焊接处焊缝的疲劳寿命为105.803次循环,与副车架实际作业过程中焊缝断裂位置一致,未能达到设计目标值。等效结构应力法具有网格不敏感性,相比传统疲劳评估方法能够较好地预测搅拌车副车架焊缝的疲劳寿命。

In view of the low accuracy of the traditional fatigue assessment method for the calculation of the fatigue life of the welded structure, the equivalent structural stress method was proposed for fatigue assessment of the welds of the sub-frame. Through the finite element analysis of the frame, the key weld position was researched. By using the inertial release method, the stress response of the frame under the single excitation of the unit load was obtained. Combined with the basic principle of equivalent structural stress, the stress at the weld position was calculated, and the main S-N curve with a survival rate of 50% was selected to predict the fatigue life of the weld. The results show that the fatigue life of the key weld is 105.803cycles, which consistent with actual product performance and fails to reach the design target value.Compared with traditional fatigue assessment methods, the equivalent structural stress method has the characteristics of grid insensitivity, it can better predict the fatigue life of the welded joints of the mixer truck sub-frame.