Eldorado Collection: 6th International Conference on High Speed Forming6th International Conference on High Speed Forminghttp://hdl.handle.net/2003/334052024-03-28T11:43:40Z2024-03-28T11:43:40ZA Numerical Investigation on Magnetic Pulse Cladding of Bi-Metal TubesFan, ZhisongYu, HaipingLi, Chunfenghttp://hdl.handle.net/2003/335182015-08-12T16:58:32Z2014-01-01T00:00:00ZTitle: A Numerical Investigation on Magnetic Pulse Cladding of Bi-Metal Tubes
Authors: Fan, Zhisong; Yu, Haiping; Li, Chunfeng
Editors: Huh, H.; Tekkaya, A. E.
Abstract: Bimetal tubes are widely applicable in refrigerating industry, liquid conduit systems and
other similar installations. Magnetic pulse cladding (MPC), based on a sequential
joining/welding of lapping portions of long tubes, is a novel approach to fabricate bimetal
tubes. This work presents an efficient numerical simulation of the MPC process to analyze
the dynamic deformation and its effect on cladding result from a numerical view. A 2D
axisymmetric model was established and a multi-steps cladding by forming was simulated
based on the models similar to an actual MPC process. Between two subsequent steps,
the stresses and strains were transferred from previous step to next one. The model
predictions and experimental results were compared by the contour of the clad tube and
showed an acceptable agreement. The advantages of a new field shaper with tile angle
α1 of 3° and angle α2 of 13° were presented, and the magnitude of the magnetic pressure,
the stress-strain field and velocity of collision were investigated. The numerical simulation
benefits the process knowledge and assists the design of the field shaper.2014-01-01T00:00:00ZStrain-rate effect on the dynamic behaviours of a rectangular conducting plateGao, Y.Huh, H.http://hdl.handle.net/2003/335112015-08-12T16:59:09Z2014-01-01T00:00:00ZTitle: Strain-rate effect on the dynamic behaviours of a rectangular conducting plate
Authors: Gao, Y.; Huh, H.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: This paper is concerned with thermo-elasto-plastic dynamic response of a conductive
plate in a magnetic pulse field. The influence of the strain rate effect and the temperature
effect are taken into account for the electromagnetic elasto-plastic dynamic transient
response and deformation of the conductive plate which made of strain-rate sensitive
materials. The Johnson-Cook model is employed to study the strain rate effect and the
temperature effect on the deformation of the plate. Basic governing equations are derived
for electro-magnetic field considering the eddy current. The analysis includes the elastoplastic
transient dynamic response and the heat transfer of a conductive rectangular plate,
and then an appropriate numerical code based on the finite element method to
quantitatively simulate the electro-magneto-elasto-plastic mechanical behaviors of the
conductive rectangular plate. The numerical results indicate that the strain rate effect has
to be considered for the conductive plates, especially for those with high strain rate
sensitivity. Comparison of the influence of the temperature effect on the deformation of the
plate with that of the strain rate effect shows that the influence of the temperature effect
on the deformation of a plate is not significant.2014-01-01T00:00:00ZPulsed Electromagnetic Attraction Processes for Sheet Metal ComponentsBatygin, Yuri V.Golovashchenko, Sergey F.Gnatov, Andrey V.Chaplygin, Evgeniy A.http://hdl.handle.net/2003/335102015-08-13T00:56:03Z2014-01-01T00:00:00ZTitle: Pulsed Electromagnetic Attraction Processes for Sheet Metal Components
Authors: Batygin, Yuri V.; Golovashchenko, Sergey F.; Gnatov, Andrey V.; Chaplygin, Evgeniy A.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: The work is dedicated to EMF attraction processes which can deform both ferromagnetic
and non-ferromagnetic sheet metal materials (low carbon steels, stainless steels and
aluminum alloys) using low frequency discharges. The analytical models of both tooling
configurations are based upon the solution of Maxwell equations in axially symmetrical
formulation. For ferromagnetic materials, the attraction effect is based upon magnetic
forces prevailing over the Lorentz forces for low frequency discharges. For nonferromagnetic
materials, the attraction forces are created by employing the auxiliary
screen which attracts the sheet metal blank. The concept of attraction in this inductor
system is based upon inducing currents flowing in the same directions in the screen and
in the sheet metal blank. In addition to the analytical models, the described concepts are
illustrated by the experimental results on attraction of sheet metal blanks employing a
single turn inductor.2014-01-01T00:00:00ZResearch on homogeneous deformation of electromagnetic incremental tube bulgingCui, XiaohuiMo, JianhuaLi, Jianjunhttp://hdl.handle.net/2003/335092015-08-12T16:59:05Z2014-01-01T00:00:00ZTitle: Research on homogeneous deformation of electromagnetic incremental tube bulging
Authors: Cui, Xiaohui; Mo, Jianhua; Li, Jianjun
Editors: Huh, H.; Tekkaya, A. E.
Abstract: The electromagnetic incremental forming (EMIF) method is used for tube forming process.
Suitable 2D FE models are designed to predict the forming process with a moving coil. In
comparison with experimental values, simulation method can obtain accurate results. Then,
effect factors named overlapping ration of adjacent discharge positions, discharge voltage,
forming sequence and die dimension on tube homogeneous deformation are discussed. The
result demonstrates that it is feasible to produce long-straight wall tubes using a small coil by
electromagnetic incremental tube bulging.2014-01-01T00:00:00ZAn experiment and simulation study of the rebound effect in electromagnetic forming processLiu, XianlongHuang, LiangLi, Jianjunhttp://hdl.handle.net/2003/335082015-08-12T20:58:26Z2014-01-01T00:00:00ZTitle: An experiment and simulation study of the rebound effect in electromagnetic forming process
Authors: Liu, Xianlong; Huang, Liang; Li, Jianjun
Editors: Huh, H.; Tekkaya, A. E.
Abstract: Electromagnetic forming (EMF) has been proved to be a useful method to form the
aluminium alloy sheet as it has so many advantages. As a high-speed forming process, it
can suppress crack, reduce springback, and improve the formability of material at room
temperature. But in the process of EMF, the rebound effect caused by high velocity impact
has an important effect on the flatness of the formed part. Then a spring damper system
has been added under the female stop block to eliminate this effect. The results of formed
shape, thickness distribution and stress and strain state are investigated by comparing with
free-forming process. On the other hand, the influence of spring stiffness and damping
coefficient is analysed by using of ANSYS loose-coupled method. The results shows that it
helps to improve the flatness of formed parts with a spring damper system used. Beside of
the changing of formed shape, the difference of stress strain state results in difference of
thickness distribution. And crack happened at the bottom is supressed, and this does
favour for further processing. Furthermore, the results also shows that low spring stiffness
and right damping coefficient are benefit for reducing the rebound effect.2014-01-01T00:00:00ZApplications of Pulsed Electromagnetic Fields in Powder Materials High Speed FormingMironovs, V.Lapkovskis, V.Kolbe, M.Zemcenkovs, V.Shishkin, A.http://hdl.handle.net/2003/335072015-08-12T16:34:27Z2014-01-01T00:00:00ZTitle: Applications of Pulsed Electromagnetic Fields in Powder Materials High Speed Forming
Authors: Mironovs, V.; Lapkovskis, V.; Kolbe, M.; Zemcenkovs, V.; Shishkin, A.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: In current article, applications of electromagnetic pulsed fields for processing of powder
materials are presented. The main attention is paid to the following applications of pulse
electromagnetic fields in powder metallurgy and allied industries: pressing of powders,
manufacturing of powder coatings, and conveying of ferromagnetic powders by means of
pulsed electromagnetic field.2014-01-01T00:00:00ZInfluence of the Boundary Layer in Magnetic Pulse Sheet Welds of Aluminium to SteelGeyer, M.Rebensdorf, A.Böhm, S.http://hdl.handle.net/2003/335062015-08-13T00:45:24Z2014-01-01T00:00:00ZTitle: Influence of the Boundary Layer in Magnetic Pulse Sheet Welds of Aluminium to Steel
Authors: Geyer, M.; Rebensdorf, A.; Böhm, S.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: In this paper, influential factors on the bonding strength of magnetic pulse welds between
Aluminium (A1050) and Steel (S235JR) sheets are shown. First, a process window
defined by varying charging energy and standoff distance for the welds. These welds will
be characterised by the means of weld length and shear strength. Sound parameters are
worked out at a standoff of 1.5 mm and a charging energy of 9 kJ. Nevertheless, no direct
correlation between archived weld length and weld strength can be seen for the specific
parameter set with a glass blasted, nearly polished surface. The achievable shear
strength for this parameter set varies in the magnitude of 30 %.
The chosen parameters are used to investigate the effect of surface preparation on the
weld. Surface preparation has an acceptable impact on the achievable weld length in the
interface and on the maximum shear strength. Furthermore, a controlled surface
appearance reduces the statistic deviation of the weld length. It is shown that machining,
which cuts grooves perpendicular to the collision direction, enhances the joint
performance as well as the achievable weld characteristics.
Furthermore, an acceptable impact of the rolling direction of the steel on the appearance
of the joint interface will be shown. A rolling direction which lies perpendicular to the
collision direction enhances the bulging of the steel into the aluminium.2014-01-01T00:00:00ZDevelopment of Space-Time-Controlled Multi-Stage Pulsed Magnetic Field Forming and Manufacturing Technology at the WHMFC*Li, LiangHan, XiaotaoCao, QuanliangChen, QiLai, ZhipengZhou, ZhongyuXiong, QiZhang, XiaoLi, XinFu, JiekaiLiu, Yuanhanghttp://hdl.handle.net/2003/335052015-08-12T16:59:01Z2014-01-01T00:00:00ZTitle: Development of Space-Time-Controlled Multi-Stage Pulsed Magnetic Field Forming and Manufacturing Technology at the WHMFC*
Authors: Li, Liang; Han, Xiaotao; Cao, Quanliang; Chen, Qi; Lai, Zhipeng; Zhou, Zhongyu; Xiong, Qi; Zhang, Xiao; Li, Xin; Fu, Jiekai; Liu, Yuanhang
Editors: Huh, H.; Tekkaya, A. E.
Abstract: In November 2011, the Project of Basic Research of Forming by Space-Time-Controlled
Multi-Stage Pulsed Magnetic Field (Stic-Must-PMF) was supported by the National Basic
Research Program of China (973 Project, 2011.11-2016.08). It is aimed at achieving
breakthroughs in manufacturing technology to solve current problems in forming largescale
and complex sheet and tube parts and components, imposed by the limitations of
existing equipment and materials forming properties. The objective of our research group
focuses on the design principles and structural layout optimization of Stic-Must-PMF
facility. And this paper will report the development of Stic-Must-PMF forming and
manufacturing technology at the Wuhan National High Magnetic Field Center (WHMFC)
including numerical modeling, experimental setup and experimental studies.2014-01-01T00:00:00ZDesign of Electromagnetic Pulse Crimp Torque JointsFaes, K.De Waele, W.Müller, M.Cramer, H.http://hdl.handle.net/2003/335042015-08-12T17:06:23Z2014-01-01T00:00:00ZTitle: Design of Electromagnetic Pulse Crimp Torque Joints
Authors: Faes, K.; De Waele, W.; Müller, M.; Cramer, H.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: Electromagnetic pulse crimping of form fit joints was investigated using tubes with a
diameter of 50 mm and a wall thickness of 1,5 mm, in the aluminium alloy EN AW-6060.
The tubes were crimped onto steel internal parts, which were designed to bear torsional
loads. Grooved, knurl rolled and knurl cut internal workpieces were used. To assess the
torque strength of the connections, a torque test set-up was designed and built.
In a first test series, grooved internal parts were used. The influence of the internal
workpiece design and the energy level on the torque resistance was investigated. Related
to the geometry of the internal workpiece, the following parameters were varied: the
groove depth, the groove width, the edge radius and the number of grooves.
In a second test series, knurl rolled and knurl cut internal workpieces were used. For the
joints with a knurl rolled internal part, the influence of the knurl pattern, defined by the
pitch, was investigated. For the connections with a knurl cut internal part, the influence of
the energy level was studied. The different joint failure mechanisms were determined.2014-01-01T00:00:00ZExperimental Study on Electromagnetic Forming of High Strength Steel Sheets with Different Dimensions of Aluminum Driver PlatePark, Hyeon IlKim, DaeyongLee, JinwooKim, Ji HoonLee, Myoung-GyuLee, YoungseonSong, Jung Hanhttp://hdl.handle.net/2003/335032015-08-13T00:29:34Z2014-01-01T00:00:00ZTitle: Experimental Study on Electromagnetic Forming of High Strength Steel Sheets with Different Dimensions of Aluminum Driver Plate
Authors: Park, Hyeon Il; Kim, Daeyong; Lee, Jinwoo; Kim, Ji Hoon; Lee, Myoung-Gyu; Lee, Youngseon; Song, Jung Han
Editors: Huh, H.; Tekkaya, A. E.
Abstract: Recently, the potential of the electromagnetic forming process has been introduced to
form the shallow longitudinal reinforcement ribs in the lateral walls of roll formed parts,
made of high strength steel sheets of 340MPa tensile stress grade [1]. However, it seems
that the application may not be easy for high strength steel sheet because of its high
tensile strength and low electric conductivity. In order to overcome this difficulty, aluminum
driver plate could be considered to enhance the formability of high strength steel sheets in
the electromagnetic forming process. In this paper, in order to investigate the effect of
aluminum driver plate on forming height of high strength steel sheet in electromagnetic
forming process, DP780 workpiece sheets were formed into a hemi elliptical protrusion
shape with Al1050 driver plate of various thicknesses and sizes. Experiments were
performed with a flat spiral coil actuator connected to an electromagnetic forming system.
The results, the aluminum driver plate helps to increase the forming height of high
strength steel sheets. In addition, the forming height of high strength steel sheet increases
as the thickness and size of a driver plate increases.2014-01-01T00:00:00ZExtension of formability of the magnesium wrought alloy AZ31B-O at room temperature by pulse magnetic formingUhlmann, E.Prasol, L.Kawalla, R.Schmidt, C.Becker, T.http://hdl.handle.net/2003/335022015-08-13T02:34:12Z2014-01-01T00:00:00ZTitle: Extension of formability of the magnesium wrought alloy AZ31B-O at room temperature by pulse magnetic forming
Authors: Uhlmann, E.; Prasol, L.; Kawalla, R.; Schmidt, C.; Becker, T.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: For having the lowest density of all metal construction materials of 1.75 kg/dm3, magnesium
wrought alloys are outstanding lightweight materials. The low formability at room temperature
limits the industrial use of magnesium AZ31B-O. In this paper the influence of
high strain rates was investigated with the aim to improve the formability of the alloy
AZ31B-O at room temperature.
The negative strain rate sensitivity of quasi-static strain rates causes an early loss of material
stability due to formation of local deformation zones on the work piece surface. This
leads to a low formability in the forming state of plane strain, in which the forming limit
(FLC) of magnesium alloy AZ31B-O has a critical minimum. For process illustration of
multi-axial stress states - which appear in conventional forming processes - the pulse
magnetic forming process is used. To create plane strain formability a flat coil is used. The
applied die is used to control the free formability. Hereby, a change of the maximum loads
on the power transfer zone to areas of plane strain formability occurs.
The results that have been achieved show that high strain rates at room temperature increase
the permitted loads of the material with plane strain formability significantly. High
speed forming is linked to a rising strain rate sensitivity which increases the flow resistance
in critical forming areas, in favor of a rising material stability. This fact is represented
by equally reduction of the sheet thickness on the power transfer area. The homogeneous
work piece stress clearly increases the formability of AZ31B-O at room temperature
compared to quasi-static forming process.2014-01-01T00:00:00ZBall Pad Mold Electromagnetic Forming Process for Aluminium Alloy SheetWang, Wen-PingWu, Xiang-DongWan, MinChen, Xiao-WeiXiong, Wei-Renhttp://hdl.handle.net/2003/335012015-08-12T16:58:59Z2014-01-01T00:00:00ZTitle: Ball Pad Mold Electromagnetic Forming Process for Aluminium Alloy Sheet
Authors: Wang, Wen-Ping; Wu, Xiang-Dong; Wan, Min; Chen, Xiao-Wei; Xiong, Wei-Ren
Editors: Huh, H.; Tekkaya, A. E.
Abstract: In order to meet requirements of lightweight technology in the field of aerospace, the new
forming technology for aluminium alloy skin parts and integral panel are brought to more
attention. Based on the principle of electromagnetic forming (EMF) and energy distribution,
a new electromagnetic forming process using ball as pad mold for aluminium alloy sheet
forming was suggested and test apparatus was designed. The new method was verified
by the finite element simulation and experimental technology, and all studies were carried
out on 2024-T3 aluminium alloy sheet. The results show that the new process of ball pad
mold electromagnetic forming is feasible to aluminium alloy sheet parts forming. Rubber
cushion thickness and electromagnetic pulse voltage are significant contributors to the
curvature radius of the test sample. Based on these observations, application advantages
and prospects of this new process were pointed out, and the subsequent research was
put forward.2014-01-01T00:00:00ZElectromagnetic Pulse Welding: Process Insights by High Speed Imaging and Numerical SimulationPabst, C.Groche, P.http://hdl.handle.net/2003/335002015-08-13T00:27:44Z2014-01-01T00:00:00ZTitle: Electromagnetic Pulse Welding: Process Insights by High Speed Imaging and Numerical Simulation
Authors: Pabst, C.; Groche, P.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: Most researches on the mechanisms of impact welding in general base their results on
the investigation of the joint area after the process, primarily by destructive testing. A
detailed analysis of the joining process itself, especially concerning electromagnetic pulse
welding, has not been performed yet and thus leads to a lack of understanding. As a
consequence of this, the design of the joint area and the process parameters are almost
exclusively found empirically.
With the help of a special image intensifier camera and a laser, which illuminates the joint
area, a new attempt is made to visualize the impact in electromagnetic pulse welding. The
results suggest that at least some mechanisms are currently not fully understood.
Explanations are developed, mainly concerning jet formation (surface cleaning during the
impact) and material behavior of the workpieces under the high strain rates of the
process. Areas of large strain rates (liquid-like behavior of the metal) and areas of
comparably small strain rates can be found within one workpiece. The question will be
discussed whether process parameters can be gained with the help of a simulation that is
sufficiently accurate at least in the macroscopic scale.2014-01-01T00:00:00ZEffect of the Duration of Electromagnetic Pulse Force on the Rebound Suppression in V-Bending ExperimentXiong, WeiRenWang, WenPingWan, MInPan, Longhttp://hdl.handle.net/2003/334992015-08-12T16:56:17Z2014-01-01T00:00:00ZTitle: Effect of the Duration of Electromagnetic Pulse Force on the Rebound Suppression in V-Bending Experiment
Authors: Xiong, WeiRen; Wang, WenPing; Wan, MIn; Pan, Long
Editors: Huh, H.; Tekkaya, A. E.
Abstract: Electromagnetic Forming (EMF) is one of the high speed forming technologies. The
spatial distribution and temporal evolution of electromagnetic body force and the
constraint imposed by the die on the sheet metal, are key factors which influence the
dynamic deformation behaviour of sheet metal. The great force induced by the collision at
high speed of the sheet and the die causes the rebound of the sheet off the die. The
rebound has a significant influence on the final shape of the part. On the basis of the
comparison of time relationship between the displacement of the sheet metal and the
amplitude of electromagnetic force, the study about the rebound phenomenon in an
electromagnetic V-bending experiment and its numerical simulation model is carried out in
this paper. Collision promotes deformation process, resulting in a drastic change of sheet
geometry in which a new distribution of electromagnetic force helps the part to fit the die.
The attenuation of force caused by distance increase is comparatively weak when forming
into a shallow die, so that the electromagnetic force maintains enough intensity which can
effectively suppress the rebound and help to calibrate the V-Shape of the part. Increasing
the duration of coil current pulse helps to suppress rebound effect of sheet metal when
forming into a shallow die.2014-01-01T00:00:00ZProcess reliability and reproducibility of pneumomechanical and electrohydraulic forming processesHomberg, W.Djakow, E.Damerow, O.http://hdl.handle.net/2003/334982015-08-12T16:58:57Z2014-01-01T00:00:00ZTitle: Process reliability and reproducibility of pneumomechanical and electrohydraulic forming processes
Authors: Homberg, W.; Djakow, E.; Damerow, O.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: A sufficiently high process reliability and reproducibility is mandatory if a high-speed
forming process is to be used in industrial production. A great deal of basic research work
into pneumo-mechanical and electrohydraulic forming has been successfully performed in
different institutions in the past. There, the focus has been more on process related
correlations, such as the influence and interaction of different parameters on the course
and result of those processes. The aspects of reliability and reproducibility have not been
examined to a sufficient extent. Hence, in the case of pneumo-mechanical forming,
insufficient investigations have been conducted into the effect that key parameters like the
kinetic energy level, the filling height of the working media or the conditions inside the
acceleration tube have on the reproducibility and course of the process. For
electrohydraulic forming, the repeatability has worsened on occasions up to now. To
improve the forming results and, in particular, the reputability of the process, it is
necessary to examine the tool parameters associated with the electrodes and the working
media. That is why research of this type is currently ongoing at the LUF. One important
issue here is examining the options that exist for visualising the way the spark takes hold
in the discharge chamber.2014-01-01T00:00:00ZMagnetic Pulse Welding of the “Tube – Plug” Pair of STS410 SteelKrutikov, V.Paranin, S.Ivanov, V.Spirin, A.Koleukh, D.Lee, J.-G.Lee, M.-K.Rhee, C.-K.http://hdl.handle.net/2003/334972015-08-12T16:59:13Z2014-01-01T00:00:00ZTitle: Magnetic Pulse Welding of the “Tube – Plug” Pair of STS410 Steel
Authors: Krutikov, V.; Paranin, S.; Ivanov, V.; Spirin, A.; Koleukh, D.; Lee, J.-G.; Lee, M.-K.; Rhee, C.-K.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: The research was focused on the magnetic pulse welding (MPW) of 12.5% Cr steel
STS410. The experiments were performed in the tube-plug geometry (both details were
made of the same steel). Magnetic pulse unit consisted of pulsed current generator (PCG)
loaded to a single-turn coil. Magnetic field amplitude of 40 T was generated in the coil
during experiments. The amplitude of pulsed current reached 750 kA.
The effects of energy storage capacity, charging voltage, and end plug shape were
studied. The welded samples were investigated by optical microscopy. The optimal
velocities of impact and contact front motion were evaluated as 300 m/s and 3-3.5 km/s,
respectively.
The paper includes the leakage test results as well. To date, the joints with a helium
leak rate of 10-9 mbar·l·s-1 have been produced.2014-01-01T00:00:00ZHigh Speed Forming Press Using Electromagnetic Pulse ForcePark, C. G.Choi, Y.Shim, J. Y.Kang, B. Y.http://hdl.handle.net/2003/334962015-08-13T00:26:42Z2014-01-01T00:00:00ZTitle: High Speed Forming Press Using Electromagnetic Pulse Force
Authors: Park, C. G.; Choi, Y.; Shim, J. Y.; Kang, B. Y.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: In this paper, the finite element analysis for the design of a high speed forming press
using electromagnetic pulse force has been performed. The punch of the press has been
fixed on a aluminium plate, which is driven by the electromagnetic pulse force. The force
is the repulsive force between aluminium plate and the coil. The coil has been supplied
with a high voltage AC current impulse from the capacitors and then the magnetized
aluminium plate has been forced to move upward with high speed. For the analysis of the
pressing, the coupled analysis of electromagnetic field and rigid-body dynamic of the
aluminium plate has been performed with a commercial FE-software, ANSYS and the
rigid-body dynamics theory.2014-01-01T00:00:00ZHigh speed joining process by laser shock forming for the micro rangeVeenaas, S.Vollersten, F.http://hdl.handle.net/2003/334952015-08-12T16:59:11Z2014-01-01T00:00:00ZTitle: High speed joining process by laser shock forming for the micro range
Authors: Veenaas, S.; Vollersten, F.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: The importance to implement more functionality on the same space pushes
miniaturization and makes hybrid joints under various conditions, also in the micro range,
necessary. Conventional joining processes, which are used in macro range, cannot be
easily transferred to micro range dimensions. In this work a new high speed joining
method for the micro range is presented, which is realized by a plastic forming process
based on TEA-CO2-Laser induced shockwaves. In a first step it is shown how sheet-sheet
joints can be realized with this method. The experimental results illustrate the possibilities
as well as the limits of the joining process by laser shock forming. Also the possible
defects which can occur during the joining process are presented. Especially fracture of
material at the edge. This is explained by the sharp edges in the joining area, which are
caused by the production process of the specimen.2014-01-01T00:00:00ZCollision Welding of Tungsten Alloy 17D and Copper Using Vaporizing Foil Actuator WeldingVivek, A.Liu, B. C.Daehn, G. S.http://hdl.handle.net/2003/334942015-08-12T16:58:13Z2014-01-01T00:00:00ZTitle: Collision Welding of Tungsten Alloy 17D and Copper Using Vaporizing Foil Actuator Welding
Authors: Vivek, A.; Liu, B. C.; Daehn, G. S.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: The objective of this study was to implement collision welding of tungsten alloy 17D (6.5% Ni,
3.3% Fe) and copper at a laboratory scale and subsequently investigate the relationship
between interfacial structure and mechanical properties. Vaporizing Foil Actuator (VFA) has
recently been demonstrated as a versatile tool for metalworking applications, such as impact
welding of dissimilar materials. Its implementation for welding is termed as VFA welding or
VFAW. With 8 kJ input energy into an aluminum foil actuator, a 0.5 mm thick Cu110 alloy
sheet was launched toward a tungsten alloy target resulting in a collision at a velocity of 580
m/s. The two sheets were found to be welded in the region where the collision velocity and
angle were optimal. This range, termed as the welding window was found to be narrow for
this combination of target and flyer materials. Scanning electron microscopy of sectioned
samples showed regions of wavy interface with significant plastic deformation on both sides.
Microhardness tests revealed significant increase in hardness near the interface.
Instrumented peel tests showed that the welds were quite strong with peel strength of 60
N/mm.2014-01-01T00:00:00ZControl of Velocity, Driving Pressure, and Planarity During Flyer Launch with Vaporizing Foil ActuatorHansen, S. R.Vivek, A.Daehn, G. S.http://hdl.handle.net/2003/334932015-08-12T16:56:12Z2014-01-01T00:00:00ZTitle: Control of Velocity, Driving Pressure, and Planarity During Flyer Launch with Vaporizing Foil Actuator
Authors: Hansen, S. R.; Vivek, A.; Daehn, G. S.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: Electrically-driven rapid vaporization of thin conductors produces a high-pressure pulse
which can be used to accelerate thin metal sheets to high velocities. Recently, vaporizing
foil actuators (VFA) have been applied toward a variety of impulse-based metalworking
operations such as collision welding, closed-die forming, embossing, and shearing. To
better apply VFA to different purposes, it is necessary to develop an understanding of how
variations on the characteristics of the foil actuator affect its mechanical impulse
generation. In this work, actuators made out of 0.0508, 0.0762, and 0.127 mm thick full
hard temper AA1145 foil were used to launch 0.508 mm thick AA2024-T3 sheets toward a
photonic Doppler velocimeter (PDV) probe. Launch velocities ranging between 300 and
1000 m/s were observed over a distance of less than 3 mm, and repeated trials
demonstrated repeatable results. Velocity, current and voltage traces were used to
examine the effect of deposited energy on average pressure and resulting velocity for foil
actuators of various thicknesses. The planarity of the flyer sheets’ launch and flight was
demonstrated with 0.0762 mm foil actuators by experiments that employed multiple PDV
probes simultaneously recording the velocity evolution at different locations across the
surface of the flyer.2014-01-01T00:00:00ZAnalysis of Strain Nonuniformity Index (SNI) in electrohydraulically formed sheet metal componentSalunke, S. K.Date, P. P.http://hdl.handle.net/2003/334922015-08-12T16:58:11Z2014-01-01T00:00:00ZTitle: Analysis of Strain Nonuniformity Index (SNI) in electrohydraulically formed sheet metal component
Authors: Salunke, S. K.; Date, P. P.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: In sheet metal parts formed by Electrohydraulic (free forming) process, a spherically
shaped reflector is predicted to result in a highly non-uniform thickness strain distribution. As
expected, the thickness strain (and hence thinning) is maximum at the top of the formed
dome. The probability of failure is therefore highest at this location. A finite element model is
formulated in ABAQUS explicit to generate the strain distribution in sheet metal. The model
considers a water filled chamber to transmit the pressure pulse. The effect of the electrical
discharge between the electrodes is modeled as a pressure wave of a certain magnitude
originating from the location of the electrodes. The constitutive relation for the sheet is
described by the Johnson-Cook model and non-deformable/ stiff tools are used.
The extent of non-uniformity in thickness strain distribution has been expressed in
terms of Strain Non-uniformity Index (SNI). It is the difference between the peak thickness
strain (PTS) and the average thickness strain (ATS). For successful forming, the value of SNI
should be as low as possible. This is enabled by an alternate design of the reflector which is
compared with the spherical shape. The pros and cons of using either shape of reflector are
examined in the paper.2014-01-01T00:00:00ZMagnetic Pulse Spot Welding: Application to Al/Fe JoiningManogaran, A. P.Manoharan, P.Priem, D.Marya, S.Racineux, G.http://hdl.handle.net/2003/334912015-08-12T16:59:07Z2014-01-01T00:00:00ZTitle: Magnetic Pulse Spot Welding: Application to Al/Fe Joining
Authors: Manogaran, A. P.; Manoharan, P.; Priem, D.; Marya, S.; Racineux, G.
Abstract: Magnetic pulse welding is a rapid process (takes place within few micro seconds) that
joins both homogeneous and heterogeneous materials in the solid state. The process
involves applying variable high current on an inductor to generate Lorentz forces on to the
conductive primary part (flyer). To realize the weld it is necessary to accelerate the flyer to
impact on to the secondary stationary part (base material) at a very high velocity attained
over the distance, called air gap, between the parts. It is typically possible to perform
welding of tubes and sheets provided there is an optimized air gap between the parts to
be welded. As part of our work we have developed an innovative approach (Magnetic
Pulse Spot Welding-MPSW) that eliminates the delicate task of maintaining the
aforementioned air gap between the plates. The proposed method opens better viable
perspectives for heterogeneous assembly of automotive structures or connecting batteries
in a quasi-cold state. The developed approach has been validated on the heterogeneous
assembly Al/Fe by tensile tests (quasi-static and dynamic) that attested the quality of
welds.2014-01-01T00:00:00ZExperimental Investigations on the Optimum Driver Configuration for Electromagnetic Sheet Metal FormingGies, S.Weddeling, C.Tekkaya, A. E.http://hdl.handle.net/2003/334902015-08-12T16:38:02Z2014-01-01T00:00:00ZTitle: Experimental Investigations on the Optimum Driver Configuration for Electromagnetic Sheet Metal Forming
Authors: Gies, S.; Weddeling, C.; Tekkaya, A. E.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: Electromagnetic forming is a high speed forming process especially suitable for materials
with high electrical conductivity such as copper or aluminum. In case of materials with
comparatively low electrical conductivity (e.g. stainless steel or titanium) the use of
so-called driver sheets is a common approach. Various publications proved that this way
materials with low electrical conductivity and even non-conductive materials can be
formed. Although the use of driver sheets is common practice, there are no or only
contradicting recommendations regarding the optimum driver sheet configuration.
Based on experimental investigations of the electromagnetic sheet metal forming process,
this paper investigates the optimum material and thickness of the driver sheet. The results
prove that aluminum should be favored over copper as driver material. The optimum
driver thickness was found to be dependent on thickness and electrical conductivity of the
workpiece. Even in case of a workpiece made of aluminum the use of a driver sheet could
enhance the efficiency of the process.2014-01-01T00:00:00ZInvestigation of Tailored Pressure Distributions by Vaporizing Tailored FoilsCai, S.Weddeling, C.Tekkaya, A. E.http://hdl.handle.net/2003/334892015-08-12T16:59:03Z2014-01-01T00:00:00ZTitle: Investigation of Tailored Pressure Distributions by Vaporizing Tailored Foils
Authors: Cai, S.; Weddeling, C.; Tekkaya, A. E.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: The rapid vaporization of thin metallic conductors can be used for innovative high speed
forming processes. Metal wires or foils are vaporized when a high current is applied. The
generated metal gas or plasma expands very rapidly with high pressure and impacts on
an intermediate polyurethane plate near the wires or foils. A shock wave is induced into
the polyurethane plate and provides the pressure pulse to the sheet metal, leading to a
deformation of the sheet. This process requires no expensive tool coils and no electrical
conductivity of the workpiece, which makes it attractive to multiple fields of application
such as forming and impact welding. In this study, the basic process parameters that
influence the shock pressure were experimentally identified including the charging energy
of capacitor bank, foil geometry (thickness and width) and thickness of polyurethane plate.
Based on the experiments of the parameter investigations, different new foil designs were
investigated in order to acquire a tailored pressure distribution. The results show that the
shock pressures can be located at different positions in a discontinuous way. Besides, the
pressure amplitudes and areas at different positions can also be varied, which depends
on the vaporized foil geometries at those positions.2014-01-01T00:00:00ZAvoiding Bending in Case of Uniaxial Tension with Electromagnetic FormingDemir, O. K.Weddeling, C.Ben Khalifa, N.Tekkaya, A. E.http://hdl.handle.net/2003/334882015-08-12T16:35:15Z2014-01-01T00:00:00ZTitle: Avoiding Bending in Case of Uniaxial Tension with Electromagnetic Forming
Authors: Demir, O. K.; Weddeling, C.; Ben Khalifa, N.; Tekkaya, A. E.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: During electromagnetic forming, excessive bending of the specimen takes place due to
high velocities and inertia. We show that the excessive bending can be prevented by
optimizing the coil geometry in case of uniaxial tension. The process is simulated with
various coil geometries, and the resulting amount of bending is compared to the case of
standard Nakajima Test. The comparison shows that the bending can be minimised to
acceptable levels to be able to call the method a decent way of determining forming limits.
The results should be verified experimentally.2014-01-01T00:00:00ZInfluence of Axial Workpiece Positioning during Magnetic Pulse Welding of Aluminum-Steel JointsLorenz, A.Lueg-Althoff, J.Göbel, G.Weddeling, C.Beyer, E.Tekkaya, A. E.http://hdl.handle.net/2003/334772015-08-13T00:25:28Z2014-01-01T00:00:00ZTitle: Influence of Axial Workpiece Positioning during Magnetic Pulse Welding of Aluminum-Steel Joints
Authors: Lorenz, A.; Lueg-Althoff, J.; Göbel, G.; Weddeling, C.; Beyer, E.; Tekkaya, A. E.
Editors: Huh, H.; Tekkaya, A. E.
Abstract: Magnetic Pulse Welding (MPW) offers a method to economically join similar and dissimilar
metals without the need for external physical or chemical binders, while avoiding the
adverse heating effects seen in many welding techniques. MPW allows for the fabrication
of joints via the harnessing of Lorentz forces, which result from discharging a current
pulse through a coil. In the process an outer piece (flyer) is accelerated onto an inner
piece (parent), and welding is achieved using propagating impact fronts. There are
several geometrical factors to be considered including the flyer-coil distance, the parentflyer
distance, as well as the axial relationship between flyer and coil (working length).
Various shapes of the front are possible and each configuration has its own advantages
and drawbacks. The goal of this work is to show not only how the aforementioned
parameters are related, but also ways to optimize front propagations, which are vital to the
welding result. This is done primarily by determining the influence of the working length of
tubular MPW specimens. It is shown that for steel-aluminum joints in the given
arrangements, three different front regimes exist, which are related to geometrical factors.
These results are especially useful to avoid seemingly favorable but nevertheless
suboptimal conditions for flyer movement that would reduce weld quality and energy
efficiency of the process.2014-01-01T00:00:00ZICHSF2014Huh, H.Tekkaya, A. E.http://hdl.handle.net/2003/334762015-12-12T11:31:36Z2014-07-08T00:00:00ZTitle: ICHSF2014
Authors: Huh, H.; Tekkaya, A. E.
Abstract: Since the first ICHSF, which was held in 2004 at the Technische Universität Dortmund,
Germany, this biannual conference has grown into one of the major events for high speed
forming technologies and its applications. This meeting series is now being organized with
the support of the International Impulse Forming Group (I2FG) that was formed in October
2008 through the vision of Professor Erman Tekkaya. His goal was to model this in many
ways after the International Cold Forging Research Group which has been instrumental in
applying cold forging to wide manufacturing practice. The public face of this site can be
found at http://www.i2fg.org with useful information as well as the proceedings of all the
ICHSF meetings. This 6th conference is organized as a joint event of the Department of
Mechanical Engineering of KAIST (Korea Advanced Institute of Science and Technology)
and the Institute of Forming Technology and Lightweight Construction of Technische
Universität Dortmund.2014-07-08T00:00:00Z