脉冲电流作用下熔孔尺寸对止裂性能影响的仿真研究

Simulation study on effect of weld hole size on crack-stopping performance under pulse current

采用有限元方法模拟带预制裂纹的构件在脉冲电流作用下的温度场,利用“生死单元”技术模拟脉冲作用出现的熔孔.在恒定载荷作用下产生熔孔现象时,建立求解应力强度因子模型,探究脉冲作用后熔孔尺寸对钝裂纹应力强度因子的影响.证明在恒定载荷作用下,随着熔孔尺寸增加,X轴最大应力位于裂纹尖端处呈下降趋势,修正后的应力强度因子呈上升趋势.在一定尺寸范围内,修正后的应力强度因子小于尖裂纹的应力强度因子,熔孔形成的钝裂纹对于裂纹尖端止裂才会有效果.研究结果可为含缺陷金属构件的修复机理研究提供科学参考.

The finite element method had been used to simulate the temperature field of the component with prefabricated cracks under the pulse current, and the "life and death unit" technique had been used to simulate the molten hole. A model of stress intensity factor had been established to solve the phenomenon of molten hole under constant load, the influence of the size of the hole on the stress intensity factor of the blunt crack had been investigated. It was proved that under constant load, the maximum stress of X-axis had been descending at the crack tip with the increase of the size of the weld hole, and the revised stress intensity factor had shown an upward trend. In a certain size range, the modified stress intensity factor was less than the stress intensity factor of the crack, the blunt crack formed by the molten hole would have an effect on crack tip stop crack, and the results could provide a scientific reference for the study on repair mechanism of metal components with defects.