﻿ 2024-T3航空铝合金板材电磁V形弯曲应变分析
 文章快速检索 高级检索
2024-T3航空铝合金板材电磁V形弯曲应变分析

Analysis of strain in electromagnetic V-shaped bending of 2024-T3 aviation aluminum alloy plate
XIONG Weiren, WANG Wenping, WAN Min , LI Xinjun
School of Mechanical Engineering and Automation, Beijing University of Aeronautics and Astronautics, Beijing 100083, China
Abstract: The mechanical properties and service life of parts are influenced by the strain characteristics after metal forming process which causes plastic deformation. Meanwhile, the electromagnetic forming (EMF) gets more attention for the advantage that it can help to overcome the drawback of low formability of aluminum alloys at room temperature by improving the formability. Therefore, the aviation aluminum alloy plate of 2024-T3 was used as the study object. And, the experiments and numerical simulations of V-bending process by both EMF and conventional mechanical method were carried out. The influence of two forming methods on the strain characteristics at the V-shaped corner which is along the longitudinal direction of the specimen was studied. The results show that the tensile strain at the outside of the V-shaped corner of the numerical virtual part formed by EMF is smaller than that formed by mechanical method, and the peak value of tensile strain of actual part formed by EMF is lower by 13.9% as well. In addition, compared with mechanical method, a larger proportion of metal sheet formed by EMF gets involved in the bending deformation.
Key words: electromagnetic forming     V-bending     strain     performance     aluminum alloy

1 电磁成形原理

 图 1 金属平板EMF原理[4] Fig. 1 EMF principle of metal plate[4]

 图 2 EMF过程电路结构[4] Fig. 2 Circuit structure of EMF process[4]

2 实验材料及方法 2.1 实验材料与研究方法

 图 3 2024-T3准静态真实应力-真实应变曲线[13] Fig. 3 Quasi-static true stress-true strain curve of 2024-T3[13]

2.2 电磁V弯实验

 图 4 电磁成形线圈和V形凹模 Fig. 4 Tool coil and V-shaped die in EMF

 参数类型 参数值 电阻/Ω 0.001 电感/H 2×10 -6 横截面积/mm 2 2×4 层数 4 每层匝数 16 匝间距/mm 0.8 层间距/mm 0.4
 图 5 电磁V弯线圈、凹模和板料的实验设置 Fig. 5 Experimental set-up of coil,die and sheet metal in electromagnetic V-bending
2.3 机械V弯实验

 图 6 机械V弯实验装置 Fig. 6 Mechanical V-bending experiment set-up
3 数值模型 3.1 电磁V弯数值模型

ANSYS/Emag电磁场模型的单元类型和单元自由度选择如下:板料用SOLID97实体单元,AX、AY、AZ、VOLT自由度;线圈用SOLID97实体单元,AX、AY、AZ自由度;空气用SOLID97实体单元,AX、AY、AZ自由度;远场区域使用INFIN111单元,AX、AY、AZ自由度。线圈简化为同心圆环,使用BFE命令直接加载电流密度(JS)作为电磁场计算的激励源。电流密度由实验中实际测量的电流换算。图 7为用于电磁场计算的实际测量电流(充电电压18 kV)。电磁场模型中的板料和线圈网格如图 8所示。

 图 7 实际测量电流 Fig. 7 Measured actual currents
 图 8 电磁场中的板料与线圈网格 Fig. 8 Sheet metal and coil meshing in electromagnetic field

LS-DYNA结构场中板料、凹模和压边板都使用SOLID164显示动力单元,凹模和压边板均设定为刚体,且锁死凹模和压边板的位移和转动自由度。板料和模具之间设有很小的初始间隙以避免板料与模具出现网格初始穿透导致的接触问题。板料与模具的摩擦系数设定为0.25。结构场有限元网格如图 9所示。

 图 9 结构场有限单元网格 Fig. 9 Structural field finitc element mesh

3.2 机械V弯数值模型

 图 10 机械V弯数值模型 Fig. 10 Numerical model of mechanical V-bending
4 结果与讨论 4.1 电磁V弯试件的几何特征

 图 11 电磁V弯试件纵向轮廓 Fig. 11 Longitudinal profile of V-bending part formed by electromagnetic forming
 图 12 电磁V弯试件横向轮廓 Fig. 12 Transverse profile of V-bending part formed by electromagnetic forming

 图 13 试件几何参数 Fig. 13 Geometrical parameters of formed part

 试件类型 几何参数 R 1/mm R 2/mm R 3/mm Δ h/mm 实验 6.0 11.5 8.5 0.78 数值 - 9.5 - 0.39
 图 14 试件表面的电磁力分布云图 Fig. 14 Distribution contours of electromagnetic force on formed part surface

4.2 电磁与机械V弯应变特征对比 4.2.1 数值模型应变对比

 图 15 试件V形圆角外侧纵向拉应变 Fig. 15 Longitudinal component tensile strain at outer radius of V-shaped corner of formed part
 图 16 试件V形圆角内侧纵向压应变 Fig. 16 Longitudinal component of compressive strain at inner radius of V-shaped corner of formed part

1) 应变峰值大小

2) 变形区域大小

4.2.2 实际零件应变对比

 图 17 V形圆角外径相同的V弯试件 Fig. 17 Formed parts by V-bending with the same outer radius of V-shaped corner

 试件类型 纵向应变 电磁V弯 0.075 8 机械V弯 0.088 0
5 结 论

1) 相同弯曲半径下,电磁V弯试件V形圆角外侧拉应变峰值低于机械V弯试件。

2) 电磁V弯比机械V弯有更大范围的金属材料参与弯曲变形。

 [1] MAMALIS A G,MANOLAKOS D E,KLADAS A G,et al.Electromagnetic forming and powder processing:Trends and developments[J].Applied Mechanics Reviews,2004,57(4):299-324. Click to display the text [2] GOLOVASHCHENKO S F.Material formability and coil design in electromagnetic forming[J].Journal of Materials Engineering and Performance,2007,16(3):314-320. Click to display the text [3] SHANG J H,DAEHN G.Electromagnetically assisted sheet metal stamping[J].Journal of Materials Processing Technology,2011,211(5):868-874. Click to display the text [4] PSYK V,RISCH D,KINSEY B L,et al.Electromagnetic forming-A review[J].Journal of Materials Processing Technology,2011,211(5):787-829. Click to display the text [5] PARK H I,KIM D,LEE J,et al.Experimental study on electromagnetic forming of high strength steel sheets with different dimensions of aluminum driver plate[C]//Proceedings of ICHSF 2014.Dortmund:Forming Technology and Lightweight Construction,TU Dortmund University,2014:237-242. [6] IRIONDO E,ALCARAZ J L,DAEHN G S,et al.Shape calibration of high strength metal sheets by electromagnetic forming[J].Journal of Manufacturing Processes,2013,15(2):183-193. Click to display the text [7] IRIONDO E,GUTIERREZ M A,GONZALEZ B,et al.Electromagnetic impulse calibration of high strength sheet metal structures[J].Journal of Materials Processing Technology,2011,211(5):909-915. Click to display the text [8] LEE P S,PIEHLER H R,ADAMS B L,et al.Influence of surface texture on orange peel in aluminum[J].Journal of Materials Processing Technology,1998,80-81(3):315-319. Click to display the text [9] POLÁK J.Plastic strain-controlled short crack growth and fatigue life[J].International Journal of Fatigue,2005,27(10-12):1192-1201. Click to display the text [10] AL-RUBAIE K S,DEL GRANDE M A,TRAVESSA D N,et al.Effect of pre-strain on the fatigue life of 7050-T7451 aluminium alloy[J].Materials Science and Engineering:A,2007,464(1-2):141-150. Click to display the text [11] 刘大海,周文华,李春峰.电磁力体积力效应对AA5052板材动态成形性的影响[J].塑性工程学报,2013,20(6):62-67. LIU D H,ZHOU W H,LI C F.Influence of body force effect of the pulsed magnetic forces on the dynamic forming limits of AA5052 sheets[J].Journal of Plasticity Engineering,2013,20(6):62-67(in Chinese). Cited By in Cnki | Click to display the text [12] VANBENTHYSEN R,THIBAUDEAU E,KINSEY B L.Effect of specimen planar area on electromagnetic flanging[J].Journal of Manufacturing Processes,2013,15(2):194-200. Click to display the text [13] GAO X,KIM J.Modeling of ductile fracture:Significance of void coalescence[J].International Journal of Solids and Structures,2006,43(20):6277-6293. Click to display the text [14] BARTELS G,SCHÄTZING W,SCHEIBE H P,et al.Comparison of two different simulation algorithms for the electromagnetic tube compression[J].International Journal of Material Forming,2009,2(S1):693-696. Click to display the text [15] SOHONI G S,WALAME M V,TANDON V,et al.Dynamic behavior characterization of lead at high strain rates using high speed photography for finite element simulation[C]//Proceedings of IMECE 2005.New York:ASME,2005:1-6. Click to display the text [16] XIONG W R,WANG W P,WAN M,et al.Effect of the duration of electromagnetic pulse force on the rebound suppression in V-bend experiment[C]//Proceedings of ICHSF 2014.Dortmund:Forming Technology and Lightweight Construction,TU Dortmund University,2014:335-344. Click to display the text

#### 文章信息

XIONG Weiren, WANG Wenping, WAN Min, LI Xinjun
2024-T3航空铝合金板材电磁V形弯曲应变分析
Analysis of strain in electromagnetic V-shaped bending of 2024-T3 aviation aluminum alloy plate

Journal of Beijing University of Aeronautics and Astronsutics, 2016, 42(1): 158-164.
http://dx.doi.org/10.13700/j.bh.1001-5965.2015.0075