【摘要】 为得到固有频率随疲劳裂纹扩展的变化规律,在拉剪点焊试样有限元模型中,使用逐渐由少到多断开单元节点的方法模拟裂纹扩展过程.根据损伤力学原理和裂纹在横截面上的投影定义了损伤,建立了基于载荷幅和平均应力的疲劳寿命预测模型.利用此模型预测了实际试样的疲劳寿命.寿命预测结果与实验寿命结果对比表明,此疲劳寿命预测模型能较好地估算点焊结构的疲劳寿命.更多还原

【Abstract】 The effect of crack propagation on the changes of natural frequency was studied through simulation of crack propagation process by dispatching element nodes one by one in a finite element model.Based on the damage mechanics principle,the projection area of crack on cross-section was used to define the damage,and to establish the fatigue life prediction model with stress amplitude and mean stress.The fatigue life prediction by this model showed good agreement with experimental results.The proposed life prediction model can effec- tively predict the fatigue life of spot welded joints.更多还原