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Modelling of Electric Arc Welding: arc-electrode coupling
Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för maskinteknik. (Welding, PTW)ORCID-id: 0000-0002-7897-621X
2013 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
Gothenburg: Chalmers University of Technology , 2013. , s. 88
Serie
Thesis for the degree of Licentiate of Engineering, ISSN 1652-8565 ; 2013:12
Nyckelord [en]
electric welding, arc welding simulation, electrode, plasma, cathode layer, sheath, arc discharge
Nationell ämneskategori
Teknisk mekanik Strömningsmekanik och akustik Bearbetnings-, yt- och fogningsteknik
Forskningsämne
TEKNIK, Produktions- och materialteknik
Identifikatorer
URN: urn:nbn:se:hv:diva-5826OAI: oai:DiVA.org:hv-5826DiVA, id: diva2:681677
Presentation
2013-05-24, Chalmers University of Technology, Göteborg, 11:34 (Engelska)
Opponent
Handledare
Tillgänglig från: 2014-01-20 Skapad: 2013-12-20 Senast uppdaterad: 2018-07-25Bibliografiskt granskad
Delarbeten
1. Numerical modelling of shielding gas flow and heat transfer in laser welding process
Öppna denna publikation i ny flik eller fönster >>Numerical modelling of shielding gas flow and heat transfer in laser welding process
2012 (Engelska)Ingår i: Proceedings of the 5th International Swedish Production Symposium, SPS12 / [ed] The Swedish Production Academy on October 2012, Linköping, 2012, , s. 7s. 1-7Konferensbidrag, Publicerat paper (Refereegranskat)
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.

Ort, förlag, år, upplaga, sidor
Linköping: , 2012. s. 7
Nyckelord
laser welding, shielding gas, volumetric heat source, coupling boundary
Nationell ämneskategori
Bearbetnings-, yt- och fogningsteknik
Forskningsämne
TEKNIK, Produktions- och materialteknik
Identifikatorer
urn:nbn:se:hv:diva-4854 (URN)978-91-7519-752-4 (ISBN)
Konferens
The 5th International Swedish Production Symposium, SPS12,6th - 8th of November 2012, Linköping Sweden
Tillgänglig från: 2012-12-10 Skapad: 2012-12-05 Senast uppdaterad: 2019-02-27Bibliografiskt granskad

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