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Javidi Shirvan, AlirezaORCID iD iconorcid.org/0000-0002-7897-621X
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Publications (10 of 12) Show all publications
Javidi Shirvan, A., Choquet, I., Nilsson, H. & Jasak, H. (2018). Coupling boundary condition for high-intensity electricarc attached on a non-homogeneous refractory cathode. Computer Physics Communications, 31-45
Open this publication in new window or tab >>Coupling boundary condition for high-intensity electricarc attached on a non-homogeneous refractory cathode
2018 (English)In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, p. 31-45Article in journal (Refereed) Published
Keywords
Coupling boundary
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-9356 (URN)10.1016/j.cpc.2017.09.010 (DOI)000418969900003 ()
Note

Ingår i doktorsavhandling

Available from: 2016-05-31 Created: 2016-05-31 Last updated: 2019-11-15Bibliographically approved
Choquet, I., Javidi Shirvan, A. & Nilsson, H. (2016). A predictive model for gas tungsten arc heat source. In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016. Paper presented at 7th International Swedish Production Symposium, SPS16, Lund, Sweden, October 25–27, 2016 (pp. 1-10). Lund: Swedish Production Academy
Open this publication in new window or tab >>A predictive model for gas tungsten arc heat source
2016 (English)In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Academy , 2016, p. 1-10Conference paper, Published paper (Refereed)
Abstract [en]

Gas tungsten arcs are used as heat sources in production processes such as welding and metal deposition.However, the most advanced of the existing gas tungsten arc models still lack predicting the arc temperature observed experimentally, unless imposing a priori the extent of the cathode arc attachment.Possible causes of this problem were investigated. It was concluded that the physical state of the arcing gas tungsten cathode was too simplified by the existing models. This oversimplification results in an overestimation of the cathode arc attachment area and an underestimation of the arc temperature field.An improved model was developed based only on physical criteria. It was tested by comparison with experimental measurements available in the literature. Good agreement with the temperature measured on the cathode surface and within the arc were obtained.

Place, publisher, year, edition, pages
Lund: Swedish Production Academy, 2016
Keywords
Electric arc, temperature distribution, welding heat source, metal deposition heat source
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-10247 (URN)
Conference
7th International Swedish Production Symposium, SPS16, Lund, Sweden, October 25–27, 2016
Available from: 2016-12-08 Created: 2016-12-08 Last updated: 2018-08-12Bibliographically approved
Javidi Shirvan, A. & Choquet, I. (2016). A review of cathode-arc coupling modeling in GTAW. Welding in the World, 60(4), 821-835
Open this publication in new window or tab >>A review of cathode-arc coupling modeling in GTAW
2016 (English)In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 60, no 4, p. 821-835Article in journal (Refereed) Published
Abstract [en]

Material properties of welds are strongly influenced by the thermal history, including the thermo-fluid and electromagnetic phenomena in the weld pool and the arc heat source. A necessary condition for arc heat source models to be predictive is to include the plasma column, the cathode, and the cathode layer providing their thermal and electric coupling. Different cathode layer models based on significantly different physical assumptions are being used. This paper summarizes today’s state of the art of cathode layer modeling of refractory cathodes used in GTAW at atmospheric pressure. The fundamentals of the cathode layer and its physics are addressed. The main modeling approaches, namely (i) the diffusion approach, (ii) the partial LTE approach, and (iii) the hydrodynamic approach are discussed and compared. The most relevant publications are systematically categorized with regard to the respective physical phenomena addressed. Results and process understanding gained with these models are summarized. Finally, some open questions are underlined.

Keywords
GTA Welding, Cathodes, Mathematical models, Tungsten electrodes, Reviews, Simulating, Plasma, Heat flow
National Category
Applied Mechanics Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-9268 (URN)10.1007/s40194-016-0319-7 (DOI)000385025900020 ()2-s2.0-84975709499 (Scopus ID)
Funder
Knowledge Foundation
Note

First online: 21 March 2016

Available from: 2016-04-13 Created: 2016-03-30 Last updated: 2019-02-11Bibliographically approved
Javidi Shirvan, A., Choquet, I. & Nilsson, H. (2016). Effect of cathode model on arc attachment for short high-intensity arc on a refractory cathode. Journal of Physics D: Applied Physics, 49(3 November 2016), 1-17, Article ID 485201.
Open this publication in new window or tab >>Effect of cathode model on arc attachment for short high-intensity arc on a refractory cathode
2016 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 49, no 3 November 2016, p. 1-17, article id 485201Article in journal (Other academic) Published
Abstract [en]

Various models coupling the refractory cathode, the cathode sheath and the arc at atmospheric pressure exist. They assume a homogeneous cathode with a uniform physical state, and differ by the cathode layer and the plasma arc model. However even the most advanced of these models still fail in predicting the extent of the arc attachment when applied to short high-intensity arcs such as gas tungsten arcs. Cathodes operating in these conditions present a non-uniform physical state. A model taking into account the first level of this non-homogeneity is proposed based on physical criteria. Calculations are done for 5 mm argon arcs with a thoriated tungsten cathode. The results obtained show that radiative heating and cooling of the cathode surface are of the same order. They also show that cathode inhomogeneity has a significant effect on the arc attachment, the arc temperature and pressure. When changing the arc current (100 A, 200 A) the proposed model allows predicting trends observed experimentally that cannot be captured by the homogeneous cathode model unless restricting a priori the size of the arc attachment. The cathode physics is thus an important element to include to obtain a comprehensive and predictive arc model

Keywords
activated tungsten cathode, arc attachment, electron emission, gas tungsten arc, modelling, thermal plasma
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-9357 (URN)10.1088/0022-3727/49/48/485201 (DOI)000404349900001 ()2-s2.0-84997269626 (Scopus ID)
Funder
Knowledge Foundation
Note

Ingår i doktorsavhandling

Funders: Sustainable Production Initiative and the Production Area of Advance at Chalmers.

Available from: 2016-05-31 Created: 2016-05-31 Last updated: 2019-05-20Bibliographically approved
Javidi Shirvan, A. (2016). Modelling of cathode-plasma interaction in short high-intensity electric arc: Application to Gas Tungsten Arc Welding. (Doctoral dissertation). Göteborg: Chalmers University of Technology
Open this publication in new window or tab >>Modelling of cathode-plasma interaction in short high-intensity electric arc: Application to Gas Tungsten Arc Welding
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In arc welding the quality of the weld is strongly influenced by the thermal history of the workpiece which is itself governed by the electric arc heat source. The models for predicting weld properties thus need a good evaluation of the distribution of the heat input from thearc to the workpiece. To have a predictive model of arc heat source it is necessary to take into account the cathode and its coupling with the plasma. The coupling allows to calculate the temperature and current density distributions along the cathode surface rather than prescribing them. This thesis focuses on the arc-cathode coupling for a plasma assumed to be in local thermal equilibrium. A self-consistent coupling boundary model for high-intensity electric arc on a refractory cathode (thoriated tungsten) was developed accounting for the physics of the sub-layers of the cathode layer and the non-uniformity of the cathode surface physical state. The cathode layer model accounts for the non-equilibria in the cathode layer. It was tested in one-dimensional calculations and then extended to a cathode-plasma coupling boundary condition for gas tungsten arc implemented in OpenFOAM. Different modelling assumptions commonly used for developing the model were questioned and investigated. It was checked that the secondary electron emission is negligible compared to the effect of emitted electrons and ions. It was verified that it is justified to neglect the space charge of emitted electron when calculating the cathode surface electric field. It was verified that Richardson-Dushman electron emission law supplemented with Schottky correction is used within its domain of validity in GTA applications even for low work function emitters. It was shown that the radiative absorption of the cathode surface is not negligible compared to the radiative emission. The cathode layer model was also further developed to take into account the in homogeneity of the cathode material. It was shown that the cathode in homogeneityhas a significant effect on the size of the arc attachment and consequently on the cathode surface and the plasma temperature. Good agreement was obtained with the measured cathode surface and plasma temperatures without imposing any adjustable parameters. The results showed that the proposed model, which is only based on physical principles, is ableto predict the trends observed experimentally.

Place, publisher, year, edition, pages
Göteborg: Chalmers University of Technology, 2016. p. 78
Series
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie, ISSN 0346-718X ; 4062
Keywords
Electric arc discharge, sheath, pre-sheath, Knudsen layer, doped refractory cathode, arc-cathode coupling, Gas Tungsten Arc simulation, OpenFOAM.
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-9358 (URN)9789175973814 (ISBN)
Public defence
2016-06-10, VDL, Chalmers Tvärgata 4C, Chalmers, Göteborg, 10:00 (English)
Opponent
Supervisors
Available from: 2016-05-31 Created: 2016-05-31 Last updated: 2018-07-25Bibliographically approved
Javidi Shirvan, A., Choquet, I. & Nilsson, H. (2014). Modelling of electrode-arc coupling in electric arc welding. In: Johan Stahre, Björn Johansson,Mats Björkman (Ed.), Proceedings of The 6th International Swedish Production Symposium 2014 16-18 September 2014: . Paper presented at The 6th International Swedish Production Symposium 201416-18 September 2014 (pp. 1-8).
Open this publication in new window or tab >>Modelling of electrode-arc coupling in electric arc welding
2014 (English)In: Proceedings of The 6th International Swedish Production Symposium 2014 16-18 September 2014 / [ed] Johan Stahre, Björn Johansson,Mats Björkman, 2014, p. 1-8Conference paper, Published paper (Refereed)
Abstract [en]

Modelling of the arc in electric arc welding is significant to achieve a better pro-cess understanding, thus gain better weld quality and a more efficient production process.It requires knowing the conditions at the surfaces of the anode and cathode. These condi-tions are very difficult to set from measurements and should be calculated. This requiresmodelling the complex physics of the electrode layer coupling electrode and arc. Thispaper presents a self-consistent electrode layer model that 1) is suited to welding applica-tions, 2) accounts for the known physics taking place, and 3) satisfies the basic conservationrequirements. The model is tested for different conditions. Its potentiality for welding ap-plications is shown through calculations coupling plasma arc, electrode and cathode layermodels. The calculations are done for both tungsten and thoriated tungsten electrode.

Keywords
thermal plasma, arc welding, electrode layer, sheath, electrode surface temperature, numerical simulation, OpenFOAM.
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-6622 (URN)978-91-980974-1-2 (ISBN)
Conference
The 6th International Swedish Production Symposium 201416-18 September 2014
Projects
SUMMAN
Funder
Knowledge Foundation
Available from: 2014-09-11 Created: 2014-09-11 Last updated: 2018-08-12Bibliographically approved
Choquet, I., Javidi-Shirvan, A. & Nilsson, H. (2013). Magnetic field models for high intensity arcs, applied to welding: A comparison between three different formulations. In: ASM Proceedings of the International Conference: Trends in Welding Research 2013: . Paper presented at 9th International Conference on Trends in Welding Research; Chicago, IL; United States; 4 June 2012 through 8 June 2012; Code 97902 (pp. 876-885). Chicago, IL: ASM International
Open this publication in new window or tab >>Magnetic field models for high intensity arcs, applied to welding: A comparison between three different formulations
2013 (English)In: ASM Proceedings of the International Conference: Trends in Welding Research 2013, Chicago, IL: ASM International, 2013, p. 876-885Conference paper, Published paper (Refereed)
Abstract [en]

Most simulation studies done to deeper understand high-intensity welding arcs address axi-symmetric configurations and use the electric potential formulation. This formulation involves the assumption of a one-dimensional magnetic field. The assumption is justified in its original frame: rather long arcs (about 10 mm), and when the electrode tip is excluded from the computational domain. However, arcs applied to welding are shorter, and the electrode geometry is important to take into account. The present work questions the assumption of a one-dimensional magnetic field for simulating short welding arcs. We have compared three different approaches for modeling the magnetic field: three-dimensional, two-dimensional axi-symmetric, and the electric potential formulation. These models have been applied to water cooled anode Gas Tungsten Arc Welding (GTAW) test cases with truncated conical electrode tip (tip radius of 0.5 and 0.2 mm) and various arc lengths (2, 3 and 5 mm). For the axi-symmetric cases studied in the present work, the three- and two-dimensional models give exactly the same results. The one-dimensional simplification of the magnetic field turns out to have a significant unfavorable effect on the simulation results. For axi-symmetric welding applications, it is argued that the two-dimensional axi-symmetric formulation should be used. Copyright © 2013 ASM International® All rights reserved.

Place, publisher, year, edition, pages
Chicago, IL: ASM International, 2013
Keywords
Work-integrated Learning, WIL, Robotics, Welding, AIL
National Category
Robotics
Research subject
ENGINEERING, Manufacturing and materials engineering; Work Integrated Learning
Identifiers
urn:nbn:se:hv:diva-5566 (URN)2-s2.0-84880664004 (Scopus ID)9781627089982 (ISBN)
Conference
9th International Conference on Trends in Welding Research; Chicago, IL; United States; 4 June 2012 through 8 June 2012; Code 97902
Available from: 2013-10-18 Created: 2013-08-13 Last updated: 2018-07-25Bibliographically approved
Javidi Shirvan, A. (2013). Modelling of Electric Arc Welding: arc-electrode coupling. (Licentiate dissertation). Gothenburg: Chalmers University of Technology
Open this publication in new window or tab >>Modelling of Electric Arc Welding: arc-electrode coupling
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Arc welding still requires deeper process understanding and more accurateprediction of the heat transferred to the base metal. This can be provided by CFD modelling.Most works done to model arc discharge using CFD consider the arc corealone. Arc core simulation requires applying extrapolated experimental data asboundary conditions on the electrodes. This limits the applicability. To become independent of experimental input the electrodes need to be included in the arcmodel. The most critical part is then the interface layer between the electrodesand the arc core. This interface is complex and non-uniform, with specific physicalphenomena.The present work reviews the concepts of plasma and arc discharges that areuseful for this problem. The main sub-regions of the model are described, andtheir dominant physical roles are discussed.The coupled arc-electrode model is developed in different steps. First couplingsolid and fluid regions for a simpler problem without complex couplinginterface. This is applied to a laser welding problem using the CFD softwareOpenFOAM. The second step is the modelling of the interface layer betweencathode and arc, or cathode layer. Different modelling approaches available inthe literature are studied to determine their advantages and drawbacks. One ofthem developed by Cayla is used and further improved so as to satisfy the basicprinciples of charge and energy conservation in the different regions of thecathode layer. A numerical procedure is presented. The model, implementedin MATLAB, is tested for different arc core and cathode conditions. The maincharacteristics calculated with the interface layer model are in good agreementwith the reference literature. The future step will be the implementation of theinterface layer model in OpenFOAM.

Place, publisher, year, edition, pages
Gothenburg: Chalmers University of Technology, 2013. p. 88
Series
Thesis for the degree of Licentiate of Engineering, ISSN 1652-8565 ; 2013:12
Keywords
electric welding, arc welding simulation, electrode, plasma, cathode layer, sheath, arc discharge
National Category
Applied Mechanics Fluid Mechanics and Acoustics Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-5826 (URN)
Presentation
2013-05-24, Chalmers University of Technology, Göteborg, 11:34 (English)
Opponent
Supervisors
Available from: 2014-01-20 Created: 2013-12-20 Last updated: 2018-07-25Bibliographically approved
Javidi Shirvan, A., Choquet, I. & Nilsson, H. (2012). Numerical modelling of shielding gas flow and heat transfer in laser welding process. In: The Swedish Production Academy on October 2012 (Ed.), Proceedings of the 5th International Swedish Production Symposium, SPS12: . Paper presented at The 5th International Swedish Production Symposium, SPS12,6th - 8th of November 2012, Linköping Sweden (pp. 1-7). Linköping
Open this publication in new window or tab >>Numerical modelling of shielding gas flow and heat transfer in laser welding process
2012 (English)In: Proceedings of the 5th International Swedish Production Symposium, SPS12 / [ed] The Swedish Production Academy on October 2012, Linköping, 2012, , p. 7p. 1-7Conference paper, Published paper (Refereed)
Abstract [en]

In the present work a three-dimensional model has been developed to study shieldinggas flow and heat transfer in a laser welding process using computational fluid dynamics.This investigation was motivated by problems met while using an optical system totrack the weld path. The aim of this study was to investigate if the shielding gas flowcould disturb the observation area of the optical system. The model combines heatconduction in the solid work piece and thermal flow in the fluid region occupied by theshielding gas. These two regions are coupled through their energy equations so asto allow heat transfer between solid and fluid region. Laser heating was modelled byimposing a volumetric heat source, moving along the welding path. The model wasimplemented in the open source software OpenFOAM and applied to argon shieldinggas and titanium alloy Ti6Al4V base metal. Test cases were done to investigate theshielding gas flow produced by two components: a pipe allowing shielding the melt,and a plate allowing shielding the weld while it cools down. The simulation results confirmedthat these two components do provide an efficient shielding. They also showedthat a significant amount of shielding gas flows towards the observation area of the opticalsystem intended to track the weld path. This is not desired since it could transportsmoke that would disturb the optical signal. The design of the shielding system thusneeds to be modified.

Place, publisher, year, edition, pages
Linköping: , 2012. p. 7
Keywords
laser welding, shielding gas, volumetric heat source, coupling boundary
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-4854 (URN)978-91-7519-752-4 (ISBN)
Conference
The 5th International Swedish Production Symposium, SPS12,6th - 8th of November 2012, Linköping Sweden
Available from: 2012-12-10 Created: 2012-12-05 Last updated: 2019-02-27Bibliographically approved
Choquet, I., Javidi Shirvan, A. & Nilsson, H. (2012). On the choice of electromagnetic model for shorthigh-intensity arcs, applied to welding. Journal of Physics D: Applied Physics, 45(20), 205203
Open this publication in new window or tab >>On the choice of electromagnetic model for shorthigh-intensity arcs, applied to welding
2012 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 45, no 20, p. 205203-Article in journal (Refereed) Published
Abstract [en]

Four different approaches were considered for modelling the electromagneticfields of high-intensity electric arcs: i) the three-dimensional model, ii) the twodimensionalaxi-symmetric model, iii) the electric potential formulation, and iv) themagnetic field formulation. The underlying assumptions and the differences betweenthese models are described in detail. Models i) to iii) reduce to the same limit for anaxi-symmetric configuration with negligible radial current density, contrary to modeliv). Models i) to iii) were retained and implemented in the open source CFD softwareOpenFOAM. The simulation results were first validated against the analytic solutionof an infinite electric rod. Perfect agreement was obtained for all the models tested.The electromagnetic models i) to iii) were then coupled with thermal fluid mechanicsin OpenFOAM, and applied to the calculation of an axi-symmetric Gas Tungsten ArcWelding (GTAW) test case with short arc (2mm) and truncated conical electrode tip.Models i) and ii) lead to the same simulation results, but not model iii). Model iii)is suited in the specific limit of long axi-symmetric arc, with negligible electrode tipeffect. For short axi-symmetric arc, the more general axi-symmetric formulation ofmodel ii) should instead be used.

Keywords
thermal plasma, electric arc, magnetic field, short arc, welding, MIG, TIG
National Category
Engineering and Technology Natural Sciences
Research subject
ENGINEERING; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-3785 (URN)10.1088/0022-3727/45/20/205203 (DOI)000303815000010 ()2-s2.0-84860734043 (Scopus ID)
Available from: 2011-10-17 Created: 2011-10-17 Last updated: 2019-02-27Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-7897-621X

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