继电器触点冷镦成形过程的有限元分析

Finite element analysis on cold upsetting process for relay contact

研究了Ag Sn O2类材料单体触点在镦制过程中的开裂问题,并将银丝材料拉伸试验曲线转化成真应力、应变数据,拟合得到银丝材料流变应力数学模型。应用有限元方法,模拟了银单体触点的冷镦成形过程,得到了冷镦成形过程中的等效应变、应力分布情况。研究结果表明,拉应力越靠近外层越大,而径向压应力则越靠近外层越小,变形物体的单位压力从外向内逐渐增大,因此,触点最大直径处为易开裂位置。此外,准确预测了成形过程中材料产生裂纹缺陷的位置及裂纹程度,当变形达到材料Damage值时,裂纹开始形成,Damage值随变形程度的增加而上升。通过试验,对开裂模拟结果进行了验证,模拟结果与试验吻合较好。

The crack of AgSnO2 single contact in the cold upsetting process was studied, and the flow stress mathematical model of silver wire material was fit by converting the tensile test curves of silver wire material into true stress-strain data. Then, the cold upsetting process of the AgSnO2 single contact was simulated by the finite element method, and the distributions of equivalent stress and strain dur- ing the cold upsetting process were gained. The results show that the bigger the tensile stress is closer to the outer layer, and the smaller the radial compressive stress is closer to the outer layer. Furthermore, the unit pressure of the deformed object increases gradually from the outside to the inside, so the position of the maximum diameter of contact is easy to crack. In addition, the position and extent of crack are predicted accurately. Thus, the crack begins to form when the deformation reaches the material Damage value, which increa- ses with the increasing of the deformation degree. Finally, the simulated results are verified by experiments, which are in good agree- ment with the test results.