Φ6 mm-2A10铝合金棒材电磁镦粗变形机理数值仿真研究

Numerical Simulation on Deformation Mechanism ofΦ6 mm-2A10 Aluminum Alloy Bars under Electromagnetic Upsetting

目的针对块体材料在高应变速率成形过程中应力、应变结果等很难获得的情况,通过数值模拟方法揭示其变形机理。方法将电磁成形技术和镦粗工艺相结合,建立电磁镦粗电磁场-力场数值耦合模型,同时进行相应的工艺试验,通过对比仿真和试验得到的鼓形特征验证模型的准确性,利用数值模型获得电磁镦粗的加载特性,分析电磁镦粗试样内部的应力和应变状态。结果电磁镦粗试样的数值模拟结果与试验结果的最大径向相对误差为5.1%,平均径向相对误差为2.84%;驱动片上磁压力的峰值在时间上大致位于第1个周期的1/4处,在空间上大致位于驱动片半径的5/8处;冲头的最大冲击速度达13.9 m/s,在该冲击速度下电磁镦粗试样内部的应变速率达7700 s^(-1);电磁镦粗试样内部的金属塑性流动不均、不同区域的应力状态差异和绝热温升所导致的应力-应变分布与常规镦粗的类似。结论证明了所建立的电磁镦粗电磁场-力场数值耦合模型的准确性和电磁镦粗工艺的可行性。

The work aims to reveal the deformation mechanism of bulk materials through numerical simulation aiming at that the stress and strain results of bulk materials are difficult to obtain in the process of high strain rate forming.A numerical coupling model of electromagnetic field-mechanical field for electromagnetic upsetting was established by combining electromagnetic forming technology and upsetting process,and the corresponding experiments were carried out.The accuracy of the model was verified by comparing the drum shape characteristics of simulation and test results.Then,the loading characteristics of electromagnetic upsetting were obtained by numerical simulation.The internal strain and stress status of the specimen under electromagnetic upsetting were analyzed.For the selected point on the drum edge,the maximum radial relative error between the numerical simulation results and the experimental results was 5.1%and the average radial relative error was 2.84%.The peak magnetic force on the driver plate approximately located temporally and spatially at 1/4 of the first cycle and the 5/8 of the radius of driver plate,respectively.The maximum impact velocity of the punch was 13.9 m/s,and the strain rate inside the upsetting specimen reached 7700 s^(-1) at this impact velocity.The distribution of strain and stress was similar to that of conventional upsetting due to uneven metal plastic flow,different stress states in different regions and adiabatic temperature rise.Thus,the accuracy of the established electromagnetic field-mechanical field coupling model for electromagnetic upsetting is verified and the feasibility of electromagnetic upsetting process is proved.