Eldorado Collection: 7th International Conference on High Speed Forming7th International Conference on High Speed Forminghttp://hdl.handle.net/2003/342292024-03-28T23:22:17Z2024-03-28T23:22:17ZA Study on the Critical Thickness of the Inner Tube for Magnetic Pulse Welding Using FEM and BEMGeng, H.Cui, J.Sun, G.Li, G.http://hdl.handle.net/2003/349502016-05-03T02:01:05Z2016-04-27T00:00:00ZTitle: A Study on the Critical Thickness of the Inner Tube for Magnetic Pulse Welding Using FEM and BEM
Authors: Geng, H.; Cui, J.; Sun, G.; Li, G.
Abstract: Due to high efficiency and quality in welding dissimilar metals, Magnetic Pulse Welding
(MPW) has attracted much attention. In this study, 3A21 aluminium alloy used as outer
tube was welded to 20Fe tube by MPW. In order to investigate the critical thickness of the
inner tube (20Fe) which is subjected to huge impact pressure from the outer tube (3A21),
both numerical simulations and experiments were carried out.
For the purpose of investigating the critical thickness of the inner tube under various
impact velocities, four discharge voltages (9 kV, 11 kV, 13 kV and 14 kV) were employed
in the MPW experiment. The diameters of inner tube at different locations were measured
to obtain its plastic deformation at various discharge voltages. The simulations
considering the coupled effects of the mechanical, thermal and electromagnetic process
were performed to research the impact velocity and deformation of tubular fittings in the
electromagnetic module (EM) in LS-DYNA. An inverse method was proposed to find the
dynamic yield stress of inner tube, and the predicted yield stress was then employed in
models with critical thickness. Both of the impact velocity and deformation were verified
experimentally.2016-04-27T00:00:00ZThe Influence of Thermal and Mechanical Effects on the Bond Formation During Impact WeldingPabst, C.Groche, P.http://hdl.handle.net/2003/349492016-05-03T02:01:01Z2016-04-27T00:00:00ZTitle: The Influence of Thermal and Mechanical Effects on the Bond Formation During Impact Welding
Authors: Pabst, C.; Groche, P.
Abstract: Impact welding, usually applied as explosion welding or electromagnetic pulse welding, is
a highly transient joining process. Strain rates in orders of magnitude far above 104 1/s and
resultant thermal effects occur and influence the formation of the joint significantly.
Experimental and microscopic investigations as well as analytical estimations are carried
out and presented in this paper in order to gain a more comprehensive understanding of the
effective mechanisms and their relevance. In addition to electromagnetic pulse welding, a
specially built test rig is used to identify the process window and its change due to modified
parameters. The test rig allows to change both impact parameters, angle β and velocity v_c ,
independently.
It will be shown that the actual formation of the joint and its characteristics are greatly
affected by the surrounding gaseous media. Strength and size of the joint can be influenced
as well as the location of the process window. Theories will be developed to explain these
results and to make them usable for the practical application. Furthermore, experimental
results indicate that the compression of the ambient atmosphere in the closing gap between
the two specimens evokes highly elevated temperature, which is in good accordance with
earlier findings.2016-04-27T00:00:00ZElectromagnetic Pulse Welded Aluminium to Copper Sheet Joints: Morphological and Mechanical CharacterizationFaes, K.Kwee, I.http://hdl.handle.net/2003/349482016-05-03T02:00:59Z2016-04-27T00:00:00ZTitle: Electromagnetic Pulse Welded Aluminium to Copper Sheet Joints: Morphological and Mechanical Characterization
Authors: Faes, K.; Kwee, I.
Abstract: This study investigated joining of Al to Cu sheets by electromagnetic pulse welding, which
is a solid-state welding process that uses electromagnetic forces to join materials. The
interfacial morphology and mechanical properties of the Al/Cu joints were analysed and
related to the welding process parameters. The centre section of the Al/Cu joints evolved
from a non-welded to a welded zone. The welded zone started with a wavy interface,
consisting of thick interfacial layers with defects and evolved to a relatively flat interface
without an interfacial layer. Interfacial phases resulted from solid-state mechanical mixing
and/or very localised interfacial heating. The interfacial layers had a thickness ranging
from 2-39 μm, an interface waviness amplitude up to 11 μm and contained 31-75 wt% Cu.
The interfacial layer thickness and the weld length are determined by both the discharge
energy and the stand-off distance. A trade-off existed between a homogeneous interface
and the maximum weld length when the stand-off distance is changed. The interfacial layer
exhibited an increased hardness compared to Al and Cu. A higher tensile force, up to
4,9 kN, was achieved at a higher energy and a lower stand-off distance. One of the factors
determining the tensile force was the width of the welded area.2016-04-27T00:00:00ZBenchmarking and Refining the Vaporizing Foil Actuator Spot Welding ProcessVivek, A.Wright, S. M.Liu, B. C.Hansen, S. R.Brune, R. C.Thurston, B. P.Taber, G. A.Lee, T.Mao, Y.Dittrich, T. J.Daehn, G. S.http://hdl.handle.net/2003/349472016-05-03T02:00:57Z2016-04-27T00:00:00ZTitle: Benchmarking and Refining the Vaporizing Foil Actuator Spot Welding Process
Authors: Vivek, A.; Wright, S. M.; Liu, B. C.; Hansen, S. R.; Brune, R. C.; Thurston, B. P.; Taber, G. A.; Lee, T.; Mao, Y.; Dittrich, T. J.; Daehn, G. S.
Abstract: Impact spot welding implemented by the vaporizing foil actuator welding method has been
studied. With significantly lower input energy levels as compared to resistance spot
welding, similar and dissimilar lap welding of aluminium alloys (AA) of types 5052 and
7075 was implemented. The dissimilar welds between 2 mm thick AA5052 and 2.3 mm
thick AA7075 were created with 4 kilojoules input energy, whereas the similar welds
between 1 mm thick AA5052 sheets required only 0.6 kilojoules. Flyer sheet velocities of
approximately 750 m/s were measured with a PDV system. Microhardness measurements,
performed across the dissimilar weld interfaces, showed no softening of the base materials
due to the welding process. A few distinct welding configurations were investigated for
improving process feasibility and obtaining the highest possible weld strength. Lap shear
tests and pry tests revealed that the configuration of the starting weld geometry greatly
affected weld quality.2016-04-27T00:00:00ZEffects of Surface Coatings on the Joint Formation During Magnetic Pulse Welding in Tube-to-Cylinder ConfigurationBellmann, J.Lueg-Althoff, J.Goebel, G.Gies, S.Beyer, E.Tekkaya, A. E.http://hdl.handle.net/2003/349462016-05-03T02:00:55Z2016-04-27T00:00:00ZTitle: Effects of Surface Coatings on the Joint Formation During Magnetic Pulse Welding in Tube-to-Cylinder Configuration
Authors: Bellmann, J.; Lueg-Althoff, J.; Goebel, G.; Gies, S.; Beyer, E.; Tekkaya, A. E.
Abstract: Magnetic Pulse Welding (MPW) is a joining technique favorable for the generation of
strong atomic bonded areas between different metals, e.g. aluminum and steel. Brittle
intermetallic phases can be avoided due to the high-speed collision and the absence of
external heat. The demand for the use of this technique in industries like automotive and
plant engineering rises. However, workpieces used in these fields are often coated, e.g. in
order to improve the corrosion resistance. Since the weld quality depends on the material’s
behavior at the collision zone, surface layers in that region have to be taken into account
as well.
This work investigates the influences of different coating types. Aluminum to steel
welding is used as an example system. On the inner steel part (C45) coatings like zinc,
nickel and chrome are applied, while the aluminum flyer tubes (EN AW-6060) are
anodized, chromated and passivated. Welding tests are performed using two different
welding systems with varying discharging frequencies and four geometrical part setups.
For all combinations, the flyer velocity during the process is measured by Photon Doppler
Velocimetry (PDV). By using the uncoated material combination as a reference, the
removal of surface layers due to jetting is analyzed. Finally, the weld quality is
characterized in peel tests, shear-push tests and by the help of metallographic analysis. It
is found that certain coatings improve the joint formation, while others are obstructive for
the performance of MPW. Some coatings have no influence on the joining process at all.2016-04-27T00:00:00ZImpact Welding Structural Aluminium Alloys to High Strength Steels Using Vaporizing Foil ActuatorLiu, B.Vivek, A.Daehn, G. S.http://hdl.handle.net/2003/349452016-05-03T02:00:54Z2016-04-27T00:00:00ZTitle: Impact Welding Structural Aluminium Alloys to High Strength Steels Using Vaporizing Foil Actuator
Authors: Liu, B.; Vivek, A.; Daehn, G. S.
Abstract: Dissimilar Al/Fe joining was achieved using vaporizing foil actuator welding. Flyer
velocities up to 727 m/s were reached using 10 kJ input energy. Four Al/Fe combinations
involving AA5052, AA6111-T4, JAC980, and JSC1500 were examined. Weld samples were
mechanically tested in lap-shear in three conditions: as-welded, corrosion-tested with ecoating,
and corrosion-tested without coating. In all three conditions, the majority of the
samples failed in the base aluminium instead of the weld. This shows that the weld was
stronger than at least one of the base materials, both before and after corrosion testing.
Galvanic corrosion was not significant since the differences in open cell potential, which
represent the driving forces for galvanic corrosion, were small among these materials—no
more than 60 mV in all cases. Nonetheless, through corrosion testing, the base materials
suffered general corrosion, which accounted for the weakening of the base materials.2016-04-27T00:00:00ZInfluence of the Wall Thicknesses on the Joint Quality During Magnetic Pulse Welding in Tube-to-Tube ConfigurationLueg-Althoff, J.Schilling, B.Bellmann, J.Gies, S.Schulze, S.Tekkaya, A. E.Beyer, E.http://hdl.handle.net/2003/349442016-05-03T02:00:52Z2016-04-27T00:00:00ZTitle: Influence of the Wall Thicknesses on the Joint Quality During Magnetic Pulse Welding in Tube-to-Tube Configuration
Authors: Lueg-Althoff, J.; Schilling, B.; Bellmann, J.; Gies, S.; Schulze, S.; Tekkaya, A. E.; Beyer, E.
Abstract: The implementation of multi-material concepts, for example, in automotive engineering or
aerospace technologies, requires adequate joining techniques. The Magnetic Pulse Welding
(MPW) process allows for joining both similar and dissimilar materials without additional
mechanical elements, chemical binders, or adverse influences of heat on the joining partners.
In this process, an electro-conductive at (‘flyer’) part is accelerated by Lorentz forces
and impacts the inner (‘parent’) part under high velocity and high pressure, leading to the
formation of a metallurgical joint. Besides joining of sheets and tubes to solid cylinders, the
connection of two tubes is of particular interest due to the increased lightweight potential.
The present paper focuses on the MPW of aluminum (EN AW-6060) to steel (C45) tubes. An
experimental study was performed, in which the wall thickness of the parent part was reduced
successively. The deformation behavior of both the flyer and parent parts was recorded
during the experiments by a two-probe Photon Doppler Velocimeter (PDV). The final
shape of the joined specimens was analyzed by a 3D digitizer. An instrumented peel test was
used for the determination of the weld quality. It was found that defect-free MPW of aluminum
tubes on steel tubes without supporting mandrel is possible.2016-04-27T00:00:00ZInfluence of Different Strain Rates on the Flow Curve and the Formability of Thin Aluminium and Tinplate SheetsLinnemann, M.Lieber, T.Scheffler, C.Psyk, V.Müller, R.Landgrebe, D.http://hdl.handle.net/2003/349432016-05-03T02:00:50Z2016-04-27T00:00:00ZTitle: Influence of Different Strain Rates on the Flow Curve and the Formability of Thin Aluminium and Tinplate Sheets
Authors: Linnemann, M.; Lieber, T.; Scheffler, C.; Psyk, V.; Müller, R.; Landgrebe, D.
Abstract: Due to this high number of produced units and the very thin sheet metals used for beverage
cans, precise production processes with high production volumes are necessary. To save
expenses, while optimising these processes, numerical simulation methods are exploited.
Considering this, it is indispensable to identify the material behaviour as exactly as possible.
In practise, often results of quasi static tensile tests are used, although these are insufficient
for the precise modelling of the material behaviour during can production, since strain rates
of up to 10³ s-1 can occur, here. Therefore, quasi static and high speed tensile test have been
done on specimens featuring the typical materials and thicknesses of semi-finished parts
used for beverage can production. The results were compared with similar materials at
higher sheet metal thicknesses and authenticated by numerical simulation. It was shown that
there is an influence of the strain rate on the material behaviour and it is necessary to
determine material characteristics at strain rates, which are close to the process speed.
Furthermore, the results were classified in their signification for beverage can production
and forming technologies in general.2016-04-27T00:00:00ZExperimental and Numerical Prediction of the Static and Dynamic Forming Properties of Ti6Al4VVerleysen, P.Galan-Lopez, J.http://hdl.handle.net/2003/349422016-05-03T02:00:49Z2016-04-27T00:00:00ZTitle: Experimental and Numerical Prediction of the Static and Dynamic Forming Properties of Ti6Al4V
Authors: Verleysen, P.; Galan-Lopez, J.
Abstract: The strain rate dependence of the plastic yield and failure properties displayed by most
metals affects energies, forces and forming limits involved in high speed forming processes.
In this contribution a technique is presented to assess the influence of the strain rate on the
forming properties of Ti6Al4V sheet. In a first step, static and dynamic tensile experiments
are carried out using a classical tensile test device and a split Hopkinson tensile bar facility
respectively. Next to uniaxial tensile, also purpose-developed plain strain and shear stress
samples are tested. The experimental results clearly show that the mechanical behaviour of
Ti6Al4V is strain rate dependent. Indeed, with increasing strain rate, plastic stress levels
increase, however, this occurs at the expense of the deformation capacity. Subsequently, to
allow simulation of forming processes, Johnson-Cook, Swift and Voce material model
parameters are determined. Finally, the influence of the strain rate on the forming limits is
assessed using the uni-axial tensile test results. Prediction of the initiation of necking in the
Ti6Al4V sheets subjected to multi-axial strain states is based on the Marciniak-Kuczynski
model. The thus obtained forming limit diagrams (FLDs) show a non-negligible effect of the
strain rate. The reduced ductility at higher strain rates is reflected into an unfavourable
downward shift of the FLD. Compared with the experimental data, the static FLD is clearly
conservative.2016-04-27T00:00:00ZDevelopment of Vibration During the Electromagnetic Ring Expansion TestYang, K.Taber, G.Sapanathan, T.Vivek, A.Daehn, G. S.Raoelison, R. N.Buiron, N.Rachik, M.http://hdl.handle.net/2003/349412016-05-03T10:57:12Z2016-04-27T00:00:00ZTitle: Development of Vibration During the Electromagnetic Ring Expansion Test
Authors: Yang, K.; Taber, G.; Sapanathan, T.; Vivek, A.; Daehn, G. S.; Raoelison, R. N.; Buiron, N.; Rachik, M.
Abstract: Magnetic pulse forming (MPF) techniques work on the principle of Lorentz force induced
by eddy current which can cause plastic deformation in a metal workpiece. Lorentz force
depends on parameters such as frequency and amplitude of input current, electromagnetic
properties of materials and distance between the work piece and coil. The development of
vibration as a consequence of elastic strain recovery in a ring expansion process using a
MPF technique has been identified and presented in this paper. Coupled mechanicalelectromagnetic
3D simulations were carried out to investigate the effect of various
magnetic pulse currents in the development of reversal of motion during the MPF process
using LS-DYNA package. Ring expansion using a multi-turn helix coil with an applied
pulse current, with the rings made of aluminum alloy AA6061 –T6 is investigated for the
effect of vibration during the process. The numerical results show good agreement with
the experimental work for various currents. The underlying principle of vibration and
formability has respectively been studied using force analysis and stress analysis. The
results also show that the 5.6kJ energy already increased the formability by ~66 percent in
comparison with the quasi-static formability value from the literature.2016-04-27T00:00:00ZDevelopment of an Interrupted Pulse Expanding Ring TestImbert, J.Worswick, M.http://hdl.handle.net/2003/349402016-05-03T02:00:45Z2016-04-27T00:00:00ZTitle: Development of an Interrupted Pulse Expanding Ring Test
Authors: Imbert, J.; Worswick, M.
Abstract: An interrupted pulse electromagnetic (EM) expanding ring test is being developed at the
University of Waterloo to study the high rate behaviour of sheet metals. In a classic EM
expanding ring test, a ring is expanded radially using the forces induced on the ring by a
high frequency high intensity current flowing in a nearby coil. If the driving force and the
acceleration of the ring are known, then the stress-strain history of the ring can be
determined. Coil currents are typically generated by large capacitor banks that produce a
current discharge in the shape of a damped sinusoid. To properly determine the stress of the
ring, the forces induced on the ring by the current pulse must be known, which is difficult to
do in practice. The approach taken in this work is to interrupt the current by means of an
exploding wire switch to eliminate the Lorentz forces and achieve a free flight condition,
where the stress can be determined using only the measured velocity and density of the ring.
The velocity of the rings was measured using a photon Doppler velocimeter (PDV). With
this technique significant periods of free-flight were obtained, with the corresponding stressstrain
data. Results for 1.5 mm sheet of AA 5182-O are presented.2016-04-27T00:00:00ZA New Experimental Technique for Applying Impulse Tension LoadingFan, Z. S.Yu, H. P.Su, H.Zhang, X.Li, C. F.http://hdl.handle.net/2003/349392016-05-03T02:00:44Z2016-04-27T00:00:00ZTitle: A New Experimental Technique for Applying Impulse Tension Loading
Authors: Fan, Z. S.; Yu, H. P.; Su, H.; Zhang, X.; Li, C. F.
Abstract: This paper deals with a new experimental technique for applying impulse tension loads.
Briefly, the technique is based on the use of pulsed-magnetic-driven tension loading.
Electromagnetic forming (EMF) can be quite effective in increasing the forming limits of
metal sheets, such as aluminium and magnesium alloys. Yet, why the forming limit is
increased is still an open question. One reason for this is the difficulty to let forming
proceed on a certain influence monotonically: the main phenomena causing this increase
in formability are considered to due to “body force” effect, inertia effect, changes in strain
rate sensitivity. In this study, an impulse tension loading setup is presented. “Body force”
effect and strain rate, which are known to be the two key factors leading to higher
formability, can now be separated freely by our designed device. Reproducible and
adjustable loading rate (80s-1~3267s-1) can be achieved by adjusting the discharge
voltage and capacitance. The relation between the discharge voltage and strain rate was
obtained with the help of finite element calculations and high-camera measurement results.
The results of an exploratory experiment carried out on the designed device are presented
for aluminum alloy AA5052 sheet. It shows that this technique could be used to study the
dynamic response of sheets.2016-04-27T00:00:00ZA Study to Improve the Crash Performance of Plastic Materials Considering the Strain Rate and Fracture CharacteristicKim, H. Y.Lee, C. A.Bamg, J. H.Cho, B. C.Kim, D. Y.Ha, D. Y.http://hdl.handle.net/2003/349382016-05-03T02:00:42Z2016-04-27T00:00:00ZTitle: A Study to Improve the Crash Performance of Plastic Materials Considering the Strain Rate and Fracture Characteristic
Authors: Kim, H. Y.; Lee, C. A.; Bamg, J. H.; Cho, B. C.; Kim, D. Y.; Ha, D. Y.
Abstract: The numerical simulation of structural parts made from plastics is becoming increasingly
important nowadays. The fact that almost any structural requirement can be combined in a
lightweight, durable and cost effective structure is the driving force behind its widespread
application. More and more structural relevant parts are being constructed and
manufactured from plastics. It is difficult accurately to predict the reliability according to
finite element analysis, because plastics materials show the complex material behaviour.
Thus, it is demanded for reliable and obvious methods to design these parts and to predict
their material behaviour. For the finite element simulations of polymeric materials
mathematical models are needed which cover all the phenomena of the material.
In this paper, it is possible to describe accurately the mechanical behaviour of
thermoplastic materials using a new constitutive model termed as SAMP-1(Semi-
Analytical Model for Polymers) in LS-dyna. We performed the high speed tension tests
(strain rate: 0.001/s, 0.1/s, 1/s, 50/s, 100/s) for the characterisation of the plastics
material. Also, the parameters of the SAMP-1 model were identified by using multidirectional
mechanical tests such as uniaxial tension, simple shear, and compression tests.
As validation purpose, the SMAP-1 model was compared to the existing models for
predicting the stress-strain behaviour in the test specimens and the dynatup impact test.2016-04-27T00:00:00ZMaterial Constitutive Behavior Identification at High Strain Rates Using a Direct-Impact Hopkinson DeviceGuo, X.Sow, C.Khalil, C.Heuzé, T.Racineux, G.http://hdl.handle.net/2003/349372016-05-03T02:00:38Z2016-04-27T00:00:00ZTitle: Material Constitutive Behavior Identification at High Strain Rates Using a Direct-Impact Hopkinson Device
Authors: Guo, X.; Sow, C.; Khalil, C.; Heuzé, T.; Racineux, G.
Abstract: Modern numerical simulation techniques allow nowadays obtaining accurate solutions of
magnetic pulse and electrohydraulic forming/welding processes. However, one major
difficulty persists: the identification of material constitutive equations behavior at levels of
high strain rates reached by these processes, and which varies between 103 and 105 s-1.
To address this challenge, a direct-impact Hopkinson system was developed at ECN.
It permits to perform dynamic tests at very high strain rates exceeding the range of the
traditional Split Hopkinson Pressure Bars and hence enable us to identify constitutive
models for a wide range of strain rates. The alloy used to test this device was Ti-6Al-4V.
Strain rates up to 2.5×103 s-1 were attained.2016-04-27T00:00:00ZQualification of CuCr1Zr for the SLM ProcessUhlmann, E.Tekkaya, A. E.Kashevko, V.Gies, S.Reimann, R.John, P.http://hdl.handle.net/2003/349362016-05-03T02:00:40Z2016-04-27T00:00:00ZTitle: Qualification of CuCr1Zr for the SLM Process
Authors: Uhlmann, E.; Tekkaya, A. E.; Kashevko, V.; Gies, S.; Reimann, R.; John, P.
Abstract: Working coils for electromagnetic forming processes need to comply with a wide list of
requirements such as durability, efficiency and a tailored pressure distribution. Due to its
unique combination of high strength and high electrical conductivity CuCr1Zr meets these
requirements and is a common material for coil turns. In combination with conventional coil
production processes like winding or waterjet cutting the use of this material is state of the
art. A promising approach for coil production is the use of additive manufacturing (AM)
processes. In comparison to conventional manufacturing processes, AM offers tremendous
advantages such as feature-integration e.g. undercuts or lattice structures. However, this
increased design freedom only leads to improved working coils if copper alloys with high
strength and high electrical conductivity such as CuCr1Zr can be processed. Due to the high
thermal conductivity and reflectivity the use of suchlike materials in additive manufacturing
processes is challenging. Considering the effects of the required pre- and post-processing
treatments for additive manufactured parts the need for research is further increased. The
objective of this paper is to develop a method for the qualification of CuCr1Zr for the
selective laser melting (SLM) process. This comprises the powder characterization, the
process parameter identification and the microstructure investigation of the generated test
geometries.2016-04-27T00:00:00ZElectrodynamics of Magnetic Pulse Welding Machines: Global and Local Electrical AnaloguesBouzerar, R.Bougrioua, F.Tekaya, I.Foy, N.Hamzaoui, M.Bourny, V.Durand-Drouhin, O.Jouaffre, D.Haye, D.http://hdl.handle.net/2003/349352016-05-03T02:00:22Z2016-04-27T00:00:00ZTitle: Electrodynamics of Magnetic Pulse Welding Machines: Global and Local Electrical Analogues
Authors: Bouzerar, R.; Bougrioua, F.; Tekaya, I.; Foy, N.; Hamzaoui, M.; Bourny, V.; Durand-Drouhin, O.; Jouaffre, D.; Haye, D.
Abstract: In this paper, a theoretical, experimental and numerical study of MPW machines is carried
out. While it is known that such machines are very complex by nature because of the coupling
between different parts, we used simple electrical analogues to describe its dynamics. A RLC
circuit modeling the whole machine is depicted and experimental results are shown. A
further study including numerical simulations allows to compute the current distribution and
estimate the magnetic field within the coil but also the magnetic pressure generated in the
process, all using a 2D model and reasonable assumptions. A late theoretical study opens
the way for innovative experimental measurements regarding the kinetics of the
deformations of metallic tubes, but also their mechanical behavior before the welding
process, making use of their capacitive properties.2016-04-27T00:00:00ZEfficient Coil Design by Electromagnetic Topology Optimization for Electromagnetic Sharp Edge Forming of DP980 Steel SheetChoi, M. K.Huh, H.Seo, M. H.Kang, Y.http://hdl.handle.net/2003/349342016-05-03T02:00:36Z2016-04-27T00:00:00ZTitle: Efficient Coil Design by Electromagnetic Topology Optimization for Electromagnetic Sharp Edge Forming of DP980 Steel Sheet
Authors: Choi, M. K.; Huh, H.; Seo, M. H.; Kang, Y.
Abstract: This paper proposes a design method of the tool coil by topology optimization for the
electromagnetic sharp edge forming process. Topology optimization is an approach that
optimizes material configuration in a given domain to meet the design requirements. The
design problem for the tool coil is defined as enhancing efficiency of the forming process
and optimization problem is set to be maximization of the Lorentz force induced on the tool
coil. A new topology optimization formulation based on the numerical methods for
electromagnetism using FEM and BEM is developed for maximization of the Lorentz force.
Optimum design of the tool coil is obtained by the topology optimization using the element
density approach. The optimized result is compared with other coils which have different
configurations to show the effectiveness of the proposed method. The idea of applying
topology optimization to the design of the tool coil is successful and this formulation deals
effectively for the optimization problems.2016-04-27T00:00:00ZEffect of Conductivity of the Inner Rod on the Collision Conditions During a Magnetic Pulse Welding ProcessSapanathan, T.Yang, K.Raoelison, R. N.Buiron, N.Jouaffre, D.Rachik, M.http://hdl.handle.net/2003/349332016-05-03T02:00:31Z2016-04-27T00:00:00ZTitle: Effect of Conductivity of the Inner Rod on the Collision Conditions During a Magnetic Pulse Welding Process
Authors: Sapanathan, T.; Yang, K.; Raoelison, R. N.; Buiron, N.; Jouaffre, D.; Rachik, M.
Abstract: The Magnetic Pulse Welding (MPW) process involves a high speed collision between the
flyer and inner rod. Conductivity of the inner rod may play a significant role in the collision
speed and collision angle. The collision conditions were investigated with varying
conductivity of the inner rod in this study. Coupled mechanical-electromagnetic 3D
simulations were carried out using LS-DYNA package to investigate the effect of
conductivity of the inner rod on the collision patterns during the MPW process. The
simulation involves a welding process with a tube and a rod using a one turn coil with a
separate field shaper. The electrical conductivity was varied to a wide range to investigate
the influence on the collision condition. Moreover, in order to verify the independency of the
collision condition with the mechanical properties of the inner rod, two cases including
aluminum alloy AA2024-T351 and copper with appropriate Johnson-Cook parameters were
used for the rod. In the entire simulations aluminum alloy was used as the tube material. It
was identified that the impact velocity is almost consistent for each case and the impact
angles vary between negative and positive values according to the angular measurement
convention used in this study. Although, influence of the conductivity of the inner rod is not
significant for the investigated current flow while it may sometime delay the incidence of
collision at lower frequencies than the critical frequency (FCrit). Optimizing the collision
conditions in the MPW process can help to identify the suitable materials for prescribed
welding conditions.2016-04-27T00:00:00ZA Coupled 3D/2D Axisymmetric Method for Simulating Magnetic Metal Forming Processes in LS-DYNAL‘Eplattenier, P.Çaldichoury, I.http://hdl.handle.net/2003/349322016-05-03T02:00:35Z2016-04-27T00:00:00ZTitle: A Coupled 3D/2D Axisymmetric Method for Simulating Magnetic Metal Forming Processes in LS-DYNA
Authors: L‘Eplattenier, P.; Çaldichoury, I.
Abstract: LS-DYNA is a general purpose explicit and implicit finite element program used to analyse
the non-linear dynamic response of three-dimensional solids and fluids. It is developed by
Livermore Software Technology Corporation (LSTC). An electromagnetism (EM) module
has been added to LS-DYNA for coupled mechanical/thermal/electromagnetic simulations,
which have been extensively performed and benchmarked against experimental results for
Magnetic Metal Forming (MMF) and Welding (MMW) applications. These simulations are
done using a Finite Element Method (FEM) for the conductors coupled with a Boundary
Element Method (BEM) for the surrounding air, hence avoiding the need of an air mesh.
More recently, a 2D axisymmetric version of the electromagnetic solver was
introduced for much faster simulations when the rotational invariance can be assumed.
In many MMF and MMW applications though, the rotational invariance exists only
for part of the geometry (typically the coil), but other parts (typically the workpiece or the
die) may not have this symmetry, or at least not for the whole simulation time.
In order to take advantage of the partial symmetry without limiting the geometry to
fully symmetric cases, a coupling between 2D and 3D was introduced in the EM. The user
can define the parts that can be solved in 2D and the ones which need to be solved in 3D
and the solver will assume the rotational invariance only on the 2D parts, thus keeping the
results accurate while significantly reducing the computation time.
In this paper, the coupling method will be presented along with benchmarks with fully
3D and fully 2D simulations, comparing the accuracy of the results and the simulation times.2016-04-27T00:00:00ZIncrease of the Reproducibility of Joints Welded with Magnetic Pulse Technology Using Graded Surface TopographiesRebensdorf, A.Boehm, S.http://hdl.handle.net/2003/349312016-05-03T02:00:33Z2016-04-27T00:00:00ZTitle: Increase of the Reproducibility of Joints Welded with Magnetic Pulse Technology Using Graded Surface Topographies
Authors: Rebensdorf, A.; Boehm, S.
Abstract: The reproducibility of individual welding methods depends to large extents on the material
properties. This is especially the case for impact welding as tests have shown that the surface
properties influence the joint formation. With the aim to influence the formation and position
of the lower curve of the welding process window, this paper focuses on how the surface
topography influences an asymmetrical impact. Additionally, relevant process parameters
(e.g. collision speed, collision angle, jet formation) will be included and disturbance
contours that are placed transversely to the collision vector will be examined. A high-speed
camera was used to measure the collision speed as well as the collision angle. The specific
surface topographies were created using belt grinding (cutting with geometrically undefined
edges) and laser ablation (non-cutting process, local vaporization of materials through
pulsed laser beams). The tests exemplarily show a strong correlation between the surface
geometries and the joint. The disturbance contours that were introduced transversely to the
collision vector shift the lower weld seam boundary, whereas a reduction of the discharge
energy leads to a relative strength of the joint of 1.0.
In sum, this paper offers fundamental insights into the mechanisms of the joint
formation when using magnetic pulse welding and shows the influence of the surface
topographies on the conflict between relevant procedural parameters and the possibility to
shift the lower procedural window.2016-04-27T00:00:00ZElectrohydraulic Forming of Light Weight Automotive PanelsMamutov, A. V.Golovashchenko, S. F.Bonnen, J. J.Gillard, A. J.Dawson, S. A.Maison, L.http://hdl.handle.net/2003/349302016-05-03T02:00:26Z2016-04-27T00:00:00ZTitle: Electrohydraulic Forming of Light Weight Automotive Panels
Authors: Mamutov, A. V.; Golovashchenko, S. F.; Bonnen, J. J.; Gillard, A. J.; Dawson, S. A.; Maison, L.
Abstract: This paper describes the results of development of the electrohydraulic forming (EHF)
process as a near-net shape automotive panel manufacturing technology. EHF is an
electro-dynamic process based upon high-voltage discharge of capacitors between two
electrodes positioned in a fluid-filled chamber. This process is extremely fast, uses lowercost
single-sided tooling, and potentially derives significantly increased formability from
many sheet metal materials due to the elevated strain rate. Major results obtained during
this study include: developing numerical model of the EHF; demonstrating increased
formability for high-strength materials and other technical benefits of using EHF;
developing the electrode design suitable for high volume production conditions;
understanding the limitations on loads on the die in pulsed forming conditions; developing
an automated fully computer controlled and robust EHF cell; demonstration of
electrohydraulic springback calibration and electrohydraulic trimming of stamped panels;
full scale demonstration of a hybrid conventional and EHF forming process for automotive
dash panel.2016-04-27T00:00:00ZDetermination of Forming Speed at a Laser Shock Stretch Drawing ProcessVeenaas, S.Vollertsen, F.Krüger, M.Meyer, F.Hartmann, M.http://hdl.handle.net/2003/349292016-05-03T02:00:29Z2016-04-27T00:00:00ZTitle: Determination of Forming Speed at a Laser Shock Stretch Drawing Process
Authors: Veenaas, S.; Vollertsen, F.; Krüger, M.; Meyer, F.; Hartmann, M.
Abstract: Laser shock forming is a new high speed forming process based on TEA-CO2-laser induced
shock waves. In former publications laser shock forming was already presented as a process
which can be used for deep drawing, stretch drawing and cutting of thin copper and
aluminum sheets. The process utilizes an initiated plasma shock wave on the target surface,
which leads to the sheets forming. Several pulses can be applied at one point in order to
achieve a high forming degree without increasing the energy density beyond the ablation
limit. During the process, pressure peaks in the range of some MPa can be achieved. In
order to classify the process in the framework of high speed forming processes, the temporal
varying deformation velocity due to different materials have been identified based on a
stretch drawing process by using different pulse energies. Therefore a new high speed
measurement system based on the shadowing effects is designed and its suitability is shown.
The determined strain rate of 520 s-1 meets one of the criteria for the classification of laser
shock stretch drawing as a high-speed forming process.2016-04-27T00:00:00ZAnalytical and Numerical Investigation of Tube Compression with a Multi-Turn, Axisymmetric CoilNassiri, A.Zhang, S.Reisert, K.Kinsey, B.http://hdl.handle.net/2003/349282016-05-03T02:00:27Z2016-04-27T00:00:00ZTitle: Analytical and Numerical Investigation of Tube Compression with a Multi-Turn, Axisymmetric Coil
Authors: Nassiri, A.; Zhang, S.; Reisert, K.; Kinsey, B.
Abstract: While some Finite Element software packages exist that are capable of modelling the
electromagnetic forming process and estimating the corresponding process parameters
(e.g., magnetic pressure and workpiece velocity), there is a lack of simplified and accuracy
analytical modelling tools for this purpose. In this study, a coupled analytical model was
created to predict the magnetic pressure generated by a multi-turn, axisymmetric coil and
the corresponding tube radial displacement and velocity. In the proposed model, at each
time increment, the magnetic field geometry is updated in response to the tube deformation.
To assess the proposed analytical model, numerical simulations were conducted where the
pressure distribution from the analytical model was applied. The results show good
agreement between analytical and numerical results.2016-04-27T00:00:00ZAnalytical 1D-calculation of a 1-turn Coil Parameters for the Magneto-Forming TechnologyMansouri, O.Maloberti, O.Jouaffre, D.Hamzaoui, M.Derosiere, J.Haye, D.Leonard, J. P.Pelca, P.http://hdl.handle.net/2003/349272016-05-03T02:00:24Z2016-04-27T00:00:00ZTitle: Analytical 1D-calculation of a 1-turn Coil Parameters for the Magneto-Forming Technology
Authors: Mansouri, O.; Maloberti, O.; Jouaffre, D.; Hamzaoui, M.; Derosiere, J.; Haye, D.; Leonard, J. P.; Pelca, P.
Abstract: In this paper, we will present an analytical modelling of a one-turn coil dedicated to
magnetic-pulse technologies. The goal is to be able to determine the main useful parameters
of an inductor by calculating the magnetic vector potential “A” diffusion. The concerned
parameters are electromagnetic (electromagnetic fields, magnetic flux and electric current
densities), electrical (resistance and inductance, maximum field coefficient) and
electromechanical (Lorentz force density and maximum force coefficient). The results
obtained will then be compared to numerical computations performed onto some test cases.
In order to get an approximate but robust analytical solution, it is proposed to assume an
axial symmetry and to solve the problem in the harmonic working condition before studying
the transient state.2016-04-27T00:00:00ZDetachment of Conductive Coatings by Pulsed Electromagnetic FieldMironov, V.Tatarinov, A.Kolbe, M.Gluschenkov, V.http://hdl.handle.net/2003/349262016-05-03T02:00:20Z2016-04-27T00:00:00ZTitle: Detachment of Conductive Coatings by Pulsed Electromagnetic Field
Authors: Mironov, V.; Tatarinov, A.; Kolbe, M.; Gluschenkov, V.
Abstract: The paper presents results of studies on the detachment of conductive coatings from the
metal substrate by pulsed electromagnetic field (PEMF). It is known that at the boundary of
a metal substrate and an electrically conductive coating having different electrical
conductivities sharp changes of PEMF strength arise. This effect has been used to remove a
copper layer from a steel substrate. Experimental studies were carried out in the Riga
Technical University (Latvia), West Saxony University of Applied Science Zwickau,
(Germany) and the Samara Aerospace University (Russia). Generators of pulsed current
with power capacity from 1 to 60 kJ with discharge rates from 10 to 100 kHz were used.
Treatment of coatings was performed using both flat and cylindrical inductors. The influence
of a number of factors on the efficiency of the separation of conductive coating (Cu, Al),
such as the thickness and material properties of the coating and substrate, the strength of
adhesion of the coating to the substrate, the electrical parameters of the equipment and the
inductor system, are shown. Examples demonstrating the main application potential of the
method include: deleting of a thin conductive coating induced on metallic and non-metallic
products by spraying; separation of layers of metal sheets after their joint rolling or
punching; removal of conductive membranes used in the magnetic pulse compression of
powders.2016-04-27T00:00:00ZNumerical and Experimental Investigation of Joining Aluminium and Carbon Fiber Reinforced Composites by Electromagnetic Forming ProcessZajkani, A.Salamati, M.http://hdl.handle.net/2003/349252016-05-03T02:00:18Z2016-04-27T00:00:00ZTitle: Numerical and Experimental Investigation of Joining Aluminium and Carbon Fiber Reinforced Composites by Electromagnetic Forming Process
Authors: Zajkani, A.; Salamati, M.
Abstract: Carbon fiber reinforced composites became so popular in automotive, aerospace, marine
and military industries in past years, because of their high strength, low weight and
subsequently high specific strength. The basic challenges of producing the CFRP
components are their forming and joining techniques. In this study, a finite element analysis
is carried out by the purpose that the optimum geometries to be selected for manufacturing
an electromagnetically assisted joining by forming system of two aluminium and CFRP
sheets. Electromagnetic forming is one of the high speed forming technologies that uses the
Lorentz force as a forming pressure. High speed and usually one-step forming process are
some of its advantages while, the necessity of high electrical conductivity of the work-piece
is an important restriction. Aluminium deformed in this study, so that its behaviour is
assumed to be dependent on the strain rate. Also, the hardening behaviour of aluminium is
described by the Johnson-Cook material model. The joining by forming system is modelled
in the finite element code by means of the ABAQUS 6.13 FEM software. The magnetic
pressure pulse of the coil is described by the VDLOAD subroutine to apply it to the lower
surface of the aluminium field shaper. Under influence of this force, the punch bulges the
aluminium sheet into the hole on the CFRP sheet and a cavity on die helps the bulged region
to form a mechanical interlock. In the experimental investigations, predrilled CFRP sheets
with different diameter holes and locations are used. The effect of geometrical parameters
such as metal thickness are studied on the quality of joints. The most important parameter
to be considered here, is the tensile strength of the joints. Therefore, the joint samples had
been applied under tensile test in order to consider failure modes, experimentally.2016-04-27T00:00:00ZProcess Design for Electromagnetic Forming of Magnesium Alloy AZ31 Using FE SimulationUhlmann, E.Prasol, L.Roehrs, H.http://hdl.handle.net/2003/349242016-05-03T02:00:16Z2016-04-27T00:00:00ZTitle: Process Design for Electromagnetic Forming of Magnesium Alloy AZ31 Using FE Simulation
Authors: Uhlmann, E.; Prasol, L.; Roehrs, H.
Abstract: Magnesium wrought alloys are outstanding lightweight materials due to their low density
and high specific strength. The low formability of magnesium wrought alloy AZ31 at room
temperature is increased by electromagnetic forming in comparison to quasi-static
forming. For a detailed study of electro-magnetic process a coupled FE simulation must be
performed. In this paper the process design for electromagnetic forming of magnesium
wrought alloy AZ1 using FE simulation is presented.
The complexity of an electromagnetic forming process requires the illustration of
magnetic, thermal and structural dynamic domains. Moreover, it is also necessary to
illustrate the electromagnetic resonant circuit RLC. Short processing time and the strong
dependence of the physical domains to each other requires a coupled FE simulation.
The illustration of resonant circuit and the resulting formation of magnetic field is
carried out in two-dimensional rotationally symmetric model in ANSYS MAPDL using a
suitable material model. As a result time-dependent and location-dependent eddy currents
and Lorentz forces are estimated.
Subsequently, the transmission of the estimated Lorentz forces and joule heat
generation rates to ANSYS LS-DYNA is done. Due to the rotational symmetry of 2D ANSYS
MAPDL model a transformation of the loads on 3D structures can be realized. The
formation of an optimum deformation of a work piece in dependence of a defined die has
been carried out. Here, the influence of different coil designs, die materials and geometries
and RLC parameters was investigated.2016-04-27T00:00:00ZCombined Working Media-Based Forming on a Pneumo-Mechanical High Speed Forming MachineDjakow, E.Homberg, W.Tabakajew, D.http://hdl.handle.net/2003/349232016-05-03T02:00:14Z2016-04-27T00:00:00ZTitle: Combined Working Media-Based Forming on a Pneumo-Mechanical High Speed Forming Machine
Authors: Djakow, E.; Homberg, W.; Tabakajew, D.
Abstract: Quasi-static working media-based forming processes (WMF) permit the production of
complex sheet metal parts with relatively little expense. The associated need for very high
pressures and hence complex tools and machines for the production of fine geometrical
details is often problematic. The use of high speed forming processes (HSF) can offer many
benefits, including a reduced financial outlay on equipment and better part properties in this
case. But these processes also have disadvantages, of course, such as if they are used for the
production of complex large-surface parts. Consequently, a combination of both approaches
would be ideal. This paper describes a new approach to combining high pressure sheet metal
forming (HPF) and pneumo-mechanical HSF for the production of complex sheet metal
parts.2016-04-27T00:00:00ZMathematical Optimization for the Virtual Design of Process Chains with Electromagnetic FormingRozgic, M.Stiemer, M.http://hdl.handle.net/2003/349222016-05-03T02:00:11Z2016-04-27T00:00:00ZTitle: Mathematical Optimization for the Virtual Design of Process Chains with Electromagnetic Forming
Authors: Rozgic, M.; Stiemer, M.
Abstract: In this work, a framework for virtual process design for coupled processes including
electromagnetic impulse forming is presented. Virtual process design is here understood as
the computer based identification of suitable geometry and process parameters to reach a
predefined forming result via physically feasible process paths. Implementation of this
concept relies on three pillars: a physical process model, its implementation within a
numerical simulation, and a mathematical optimization algorithm. This methodology is
particularly applied to a combination of deep drawing and subsequent electromagnetic
forming (EMF). In this case, the model is given by an anisotropic elasto-viscoplastic
material model augmented by damage evolution and coupled with the magneto-quasistatic
approximation to Maxwell's equations. For constrained mathematical optimization, an inner
point algorithm is applied. With this method for virtual process design at hand, several
technological problems are addressed including tool coil design and the identification of
ideal electrical parameters of the tool coil circuit. Employing this framework requires the
identification of the material model described above. It turns out that a high precision
identification of material parameters can be achieved with basically the same mathematical
algorithm as derived for process identification.2016-04-27T00:00:00Z3D Impacts Modeling of the Magnetic Pulse Welding Process and Comparison to Experimental DataCuq-Lelandais, J.-P.Avrillaud, G.Ferreira, S.Mazars, G.Nottebaert, A.Teilla, G.Shribman, V.http://hdl.handle.net/2003/349212016-05-03T02:00:12Z2016-04-27T00:00:00ZTitle: 3D Impacts Modeling of the Magnetic Pulse Welding Process and Comparison to Experimental Data
Authors: Cuq-Lelandais, J.-P.; Avrillaud, G.; Ferreira, S.; Mazars, G.; Nottebaert, A.; Teilla, G.; Shribman, V.
Abstract: Magnetic Pulse Welding (MPW) is a solid state (cold) welding process known to present
several advantages. When properly designed, such an assembly is stronger than the
weakest base material even for multi-material joining. These high quality welds are due to
an almost inexistent Heat Affected Zone which is not the case with fusion welding
solutions. Another advantage is a welding time that is under a millisecond. In order to
define the MPW parameters (mainly geometry, current and frequency), recent
developments have made it possible to adapt welding windows from the Explosive Welding
(EXW) for use in MPW. Until now, these welding windows have been simulated only in 2D
geometries showing how the impact angle and the radial velocities progress in a welding
window. The aim of this paper is to present our most recent development, which builds on
this analysis to develop a 3D model in order to deal for example with local planar MPW.
Simulation results will be presented and then compared to experimental data for a multimaterial
join case.2016-04-27T00:00:00ZHigh Speed Forming 2016 - Proceedings of the 7th International Conferencehttp://hdl.handle.net/2003/349202016-05-04T12:32:27Z2016-04-27T00:00:00ZTitle: High Speed Forming 2016 - Proceedings of the 7th International Conference
Editors: Tekkaya, A. E.; Kleiner, M.
Abstract: The “International Conference on High Speed Forming” has developed into a major event for
impulse forming, its processes, and its applications. Since the first ICHSF in Dortmund in 2004, the
latest developments in the analysis of high speed forming and joining processes, tools and machines
as well as material characterization have been introduced at the biannual conferences with growing
interest and impact. I am especially proud to recognize that the last ICHSF 2014 in Daejeon/Korea
has strengthened the ties between the European, American, and Asian impulse forming communities. The objectives of the 7th ICHSF are to offer a platform for innovative presentations from international
universities, research institutes, and companies and to support discussions and the informal exchange
of experiences and knowledge between scientists, practicing engineers, manufacturers, and industrial
operators.2016-04-27T00:00:00Z