管材电液成形数值模拟与工艺试验研究

发布时间：2018-06-01 16:38

本文选题：电液成形 + 能量沉积速率　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：电液成形技术是脉冲成形工艺之一,可以提高材料成形性,减小工件回弹,在难变形材料成形、高精度成形以及校形领域得到越来越多的关注。本文以ANSYS/LS-DYNA程序为依托,将电液成形过程简化为等离子通道、水、受凹模限制的变形金属及周围空气模型。5052铝合金管材的电液成形工艺试验验证了模拟方案的准确性。当电极间隙完全等离子体化时,放电回路变成一个典型RLC衰减振荡回路。放电通道中的能量沉积模型采用工艺试验中测得的,并且根据放电通道两端电压的变化判断出用于变形的能量输入起点。采用绝热膨胀的理想气体模型定义等离子放电通道,受凹模约束的变形管坯采用各向同性模型。将等离子体、水和周围空气网格定义为ALE多物质流体组,变形材料与凹模为Lagrange固体组。对比退火态5052铝合金管材电液成形的数值模拟和工艺试验,分析冲击波载荷传递特点和管材变形规律。模拟结果表明,冲击波载荷使管材单元迅速获得很大移动速度;水流动压载荷分布均匀,使变形更均匀,同时减小了回弹。探究放电通道位置对管材成形的影响,发现竖直放置金属丝时,电极棒对冲击波传播的阻碍作用很小,提高了能量利用率,而且管材上应力应变更均匀。
[Abstract]:Electro-hydraulic forming is one of the pulse forming processes, which can improve the formability of materials, reduce the springback of workpiece, and get more and more attention in the field of difficult deformation material forming, high precision forming and shape calibration. In this paper, based on ANSYS/LS-DYNA program, the electrohydraulic forming process is simplified to plasma channel, water, deformed metal limited by concave die and surrounding air model .5052 aluminum alloy tube. The accuracy of the simulation scheme is verified. When the electrode gap is fully plasticized, the discharge loop becomes a typical RLC attenuation oscillation loop. The energy deposition model in the discharge channel is measured in the process test, and the energy input starting point for the deformation is determined according to the voltage variation at both ends of the discharge channel. The plasma discharge channel is defined by the adiabatic expansion ideal gas model and the isotropic model is used for the deformed tube billet constrained by the concave die. The plasma, water and surrounding air grids are defined as ALE multi-material fluid group, and the deformation material and concave mold are Lagrange solid group. The characteristics of shock wave load transfer and deformation of 5052 aluminum alloy tube were analyzed by comparing the numerical simulation and process test of the annealed 5052 aluminum alloy tube. The simulation results show that the shock wave load can make the tube element move rapidly and the pressure load of water flow is uniform, the deformation is more uniform, and the springback is reduced. The influence of discharge channel position on tube forming is investigated. It is found that the electrode rod has little hindrance to shock wave propagation when the wire is placed vertically, and the energy utilization rate is improved, and the stress and strain on the tube is more uniform.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG393

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