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Dissertations / Theses on the topic 'Arc welding'
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Javidi, Shirvan Alireza. "Modelling of Electric Arc Welding : arc-electrode coupling." Licentiate thesis, Högskolan Väst, Avd för maskinteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-5826.
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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.
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Goodarzi, Massoud. "Mathematical modelling of gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) processes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27936.pdf.
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Erener, Yavuz. "Analysis Of Welding Parameters In Gas Metal Arc Welding By A Welding Robot." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607766/index.pdf.
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ANALYSIS OF WELDING PARAMETERS IN GAS METAL ARC
WELDING BY A WELDING ROBOT
Erener, Yavuz
M.S., Department of Mechanical Engineering
Supervisor : Prof. Dr. R. Tuna Balkan
Co-Supervisor : Prof. Dr. M. A. Sahir Arikan
September 2006, 130 pages
In Robotic Gas Metal Arc Welding process, the welding parameters controlled by the welder (travel speed of the welding torch, wire feed speed, current, voltage, wire diameter, etc.) should be considered to obtain a desired welding quality. To design an appropriate welding model for the used equipment, the effects of each parameter should be studied by carrying out an adequate number of experiments. The welding process is described by analyzing the experimental data to define the relationships between the welding parameters and process variables. Various regressional models can be suggested to establish the analytical relationships.
In this study, the relationship between bead geometry and voltage, current, travel speed and wire feed speed is established by using a specific computer program developed for this purpose.
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Jönsson, Pär Göran. "Arc parameters and metal transfer in gas metal arc welding." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12470.
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Haas, Edmund Joseph. "Arc-augmented laser welding of aluminum /." Full text open access at:, 1986. http://content.ohsu.edu/u?/etd,123.
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Liratzis, Theocharis. "Tandem gas metal arc pipeline welding." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/5686.
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Energy consumption has grown by 2% per year worldwide over the past ten years. In 2005 worldwide 900,000 barrels of oil and 7.6 billion cubic metre of natural gas were produced daily. The exploitation of fields to meet the increased demands in energy requires the presence of adequate infrastructures. High strength pipeline steels(X100) have been developed to operate at higher pressures allowing a greater volume of fuel to be transported. Additional advantages arising from the reduction in wall thickness contribute to reduction in construction costs and steel volume.
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Clark, Stephen. "Vision monitoring systems in arc welding." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237511.
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Li, Ping. "Neural networks for automatic arc welding." Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284264.
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Talkington, John Eric. "Variable polarity gas metal arc welding." Connect to resource, 1998. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1130352747.
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Thesis (M.S.)--Ohio State University, 1998.Advisor: Richard W. Richardson, Welding Engineering Program. Includes bibliographical references (leaves 111-113). Available online via OhioLINK's ETD Center
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Weimann, David Herbert. "A study of welding procedure generation for submerged-arc welding process." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317488.
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Phillips, David Harper. "Magnetically Impelled Arc Butt (MIAB) Welding of Chromium-Plated Steel Tubular Components Utilizing Arc Voltage Monitoring Techniques." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1204567657.
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Lamas, Javier. "Analysis of laser arc hybrid welding experiments." Licentiate thesis, Luleå tekniska universitet, Produkt- och produktionsutveckling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26147.
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The thesis is about the analysis of experimental results on the laser arc hybrid welding (LAHW) process as well as about the methodology and tools behind. Due to the high potential on weld penetration and welding speed, the industrial importance of LAHW techniques has been increasing in the recent years. However the massive use of them is constrained because of high investment costs, complexity and novelty. These obstacles provoke a lack of experienced operators and they desire a base of knowledge related to optimal parameters to obtain good quality welds. In this scenario, understanding of the physical LAHW phenomena has been proven useful for better control of the process,particularly to predict and avoid groups of parameters that can originate defects. For this reason, it is valuable to carry out experiments and to systematize the analysis methods.The presented work is focused on the impact of geometrical joint fit-up properties on the weld surface quality. The papers included here are organized as a comprehensive study of the effects and impact of various geometrical aspects of the laser-arc-workpiece arrangement on the surface quality of the welds, i.e. tracking from joint fit-up tolerances like gap width to critical weld shape aspects like undercuts via observation of fluid flow at the weld pool surface. Three frequent and critical geometrical aspects were identified from industrial edge preparation, namely gap width variations, vertical edgemismatch and vertical plate position to the laser-arc tool. These aspects can cause defects when the surface is bended or when the LAHW tool is automatically moved. Although in production they arise all simultaneously, to understand the respective contribution, systematic experiments were designed. These experiments were carried out to measure and surpass the stability threshold related to each aspect, to observe the flow behaviour and to evaluate the physical phenomena related to weld bead formation.The three Papers I, II, III describe a systematic methodology based on High Speed Imaging, HSI, on quantitative weld surface measurement obtained from a laser triangulation scanner and on statistical analysis of different experimental results. This methodology is based on the observation, measurement, automatic location and calculation of fundamental bead variables (top and root undercuts, reinforcement, melt pool length, pool width and flow speed, or mass balance) related to the melt flow.In Paper I, using a pulsed arc mode, the effects of increasing the standoff between the LAHW tool and the workpiece are described and a mechanism is identified to explain the flow behaviour and its consequences on the resulting weld pool shape. In Paper II, again using pulsed arc mode in LAHW, the effects of the vertical edge mismatch and of the gap width on the weld pool shape are described, again followed by a theoretical description. Paper III compares the pulsed arc mode with the CMT mode in LAHW,again for the effect of the gap width on the weld surface shape, in particular the top bridging phenomenon that was identified. Also these results are theoretically described, explaining the mechanisms via HSI.Altogether, the three papers comprise a theoretical description of the LAHW weld shape behaviour and weld quality depending on the fit-up tolerances, based on experimental evidence and analysis. From this chain of evidence and associated understanding, conclusions were drawn and practical guidelines were derived.Godkänd; 2014; 20141112 (alka); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Javier Lamas Ämne: Produktionsutveckling/Manufacturing Systems Engineering Uppsats: Analysis of Laser Arc Hybrid Welding Experiments Examinator: Professor Alexander Kaplan, Institutionen för teknikvetenskap och matematik, Luleå Tekniska universitet Diskutant: Professor Petri Vuoristo, Tammerfors tekniska universitet Tid: Torsdag den 18 december 2014 kl 09.30 Plats: E206, Luleå tekniska universitet
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LANGENOJA, MARKUS, and KARLSSON VINCENT ÖHRVALL. "Next generation high productivity submerged arc welding." Thesis, KTH, Maskinkonstruktion (Inst.), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148055.
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The task of designing concepts for the next generation of submerged arc welding heads was given by ESAB. ESAB is a global company manufacturing welding equipment for a wide span of industries and uses. In October 2011, ESAB introduced a new technology called Integrated Cold Electrode™, abbreviated and trademarked as ICE™. ICE™ is a technique which utilizes three electrodes in a highly productive and stable process. The current state of the ICE™ technique focuses on welding thick plates with conventional joint types such as x- and v-joints. The next phase in the development of the technique is to be able to weld milled 16/8°-joints which are developed by German company Graebner. This kind of joint determines the requirements of the next generation of ESAB’s equipment for submerged arc welding.Simultaneously as designing the welding torch being able to weld the 16/8°-joint, a concept for a highly customizable modular head was developed enabling the possibility to tailor the submerged arc welding process according to the customer’s precise needs.A progressive conceptual development has been conducted in close collaboration with ESAB. Theoretical models have been developed to evaluate thermal-electric behavior of the welding torches to obtain plausible dimensions for the electric conductors to withstand the effects caused by joule heating. Deliverables for the project has been well defined 3D CAD-models while a prototype was not included in the scope of the project.One concept for the 16/8° joint is presented as the Narrow Joint Concept, NJC, which fulfills the requirements specified. The NJC is developed with focus on smart design with low manufacturing cost as well as ease-of-use for the operator. NJC brings ICE™ into narrow joints.The Modular Head Concept, MHC, presents an idea how to create a fully customizable process with the possibility to emulate the ICE™ techniqueUppdraget att utveckla nästa generation pulverbågsutrustning gavs av företaget ESAB. ESAB är ett globalt företag som tillverkar svetsutrustning för ett brett spann av branscher och användningsområden. I oktober 2011 lanserade ESAB en ny teknik vid namn Integrated Cold Electrode™, ICE™. ICE™ är en teknik som utnyttjar tre stycken elektroder i en högproduktiv och stabil svetsprocess. I dagsläget fokuserar ICE™-tekniken på att svetsa konventionella fogtyper såsom x- och v-fogar i tjocka plåtar. Nästa fas i utvecklingen av tekniken är möjligheten att svetsa frästa 16/8°-fogar som det tyska företaget Graebner utvecklar. Denna typ av foggeometri ger kraven för ESAB’s nästa generation pulverbågsutrustning.Simultant togs koncept fram för att möjliggöra skräddarsydd utrustning efter kunders specifika processbehov.En progressiv konceptutveckling har utförts i nära sammarbete med ESAB. Teoretiska modeller har tagits fram för att utvärdera de termo-elektriska egenskaperna hos de utvecklade svetshuvudena så att dessa kan motstå den resistiva uppvärmningen som sker i de elektriska ledarna. Då en prototypframtagning ej låg inom ramen för arbetet har detaljerade 3D CAD-modeller producerats.Konceptet för 16/8°-fogen kallas Narrow Joint Concept, NJC, och uppfyller de uppställda kraven. NJC är framtaget med fokus på smart konstruktion där låg tillverkningskostnad och enkel användning har premierats. NJC sammanfogar ICE™ och smala fogar.Det modulära konceptet kallat Modular Head Concept, MHC, representerar en idé för att skapa skräddarsydda lösningar efter kunders behov. MHC äger förmågan att fungera som ett ICE™-huvud.
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Zhao, Jing. "Computer vision systems for automated arc welding." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399073.
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Philpott, M. L. "Direct arc sensing for robot MIG welding." Thesis, Cranfield University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376205.
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Kim, Yong-Seog. "Metal transfer in gas metal arc welding." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14199.
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Joaquim, M. "Through-the-arc sensing for automated welding." Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/11121.
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Joaquim, Marco. "Through-the-arc sensing for automated welding." Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/11121.
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WALLACE, MARJORIE EDMONDS. "CONTROL TECHNOLOGY ASSESSMENT OF ARC WELDING OPERATIONS." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin975336281.
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Adonyi-Bucuroiu, Ioan. "A study of arc force effects during submerged gas tungsten-arc welding /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487671108304733.
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Gil, Teixeira Lopes Agostinho. "Arc-based sensing in narrow groove pipe welding." Thesis, Cranfield University, 2006. http://dspace.lib.cranfield.ac.uk/handle/1826/1514.
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Big gains in productivity are found in tandem and dual tandem pipeline welding but require highly skilled operators who have to control the position of the torch very accurately for long periods. This leads to high demands on the skills and stamina of the operators of mechanised pipeline welding systems. There is a very strong motivation to fully automate the welding process in order to reduce the required skills and to improve consistency. This project focuses on the use of through-the-arc sensing for seam following and contact-tip-workpiecedistance (CTWD) control. A review of literature reveals very little development work on arc sensing for Pulsed Gas Metal Arc Welding (GMAW-P) in narrow grooves. GMAW-P is often used to achieve optimum properties in weld quality and fusion characteristics and also positional welding capability, all of which are important factors for pipeline welding. The use of through-the-arc sensing for narrow groove pipe welding applications poses specific challenges due to the steep groove sidewalls and the use of short arc lengths, producing very different behaviour compared to V-groove arc sensing techniques. Tandem welding is also quite different from single wire techniques with both wires working in close proximity producing mutual interferences in arc signals. An investigation was conducted in order to assess GMAW-P arc signals and it was found that improved consistency, higher sensitivity and less noise was present in voltages in the peak current period (peak voltages) used for torch position control. As a result of this investigation, a CTWD and cross-seam control system was developed and tested for single and tandem GMAW-P, using a 5º narrow groove. The test results have revealed accuracies for both controls of better than 0.2 mm. CTWD control was developed by following the existent welding procedure voltage average and cross-seam control by peak voltage comparison between maximum torch excursions. Experiments were also performed to evaluate the influence of torch oscillation frequency on arc voltage behaviour and sensitivity, along with weld bead characteristics and fusion profiles. The resultant arc signal sensitivity was consistent with the results found in the literature for conventional GMAW. For GMAW-P, although no data was available from the literature for comparison, the results have shown no increase in sensitivity with the increase of oscillation frequency with the welding setup used. Bead profile analysis performed at different sidewall proximities indicated that optimum wire to sidewall proximities can be found between 0 mm and +0.2 mm, measured from the outer edge of the wire to the sidewall corner. Accurate control is required since +1 mm proximity produced poor sidewall fusion and no signal differentiation for control recognition of groove width. This work showed that negative proximities or wire proximity beyond the sidewall produce wire burn back and hence very long arc lengths, resulting in poor depths of penetration and shallower beads, with major undercut defects. In addition, this work has also shown the importance of torch oscillation width control, in order to produce accurate cross-seam control. A method is proposed to achieve torch oscillation width control by a continuous peak voltage comparison between centre and sidewall torch positions, using the optimum values of wire to sidewall proximity found and the resultant peak voltage value. This control will also provide a clear indication of actual groove width. Clearly this data can also be used to implement a system which adapts welding parameters to groove width.
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Shepherd, Philip R. "A contribution to adaptively controlled robotic arc welding." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/11032.
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Mathematical models have been devised expressing the levels of controllable welding factors as a function of the joint geometry, such that acceptable weld beads are produced. Weld beads were required to be both geometrically acceptable and mechanically sound despite changes in the root face thickness (0.5 mm - 2.5 mm) and root gap (0 - 1.5 mm). The equations are intended to form part of an adaptively controlled robotic arc welding system. Simulation was used to develop the adaptive expressions. The study was applied to the root weld bead of the closing seam of railway bogie side frames fabricated from structural steel. The self shielding flux cored electrode arc welding process was used to weld single J preparations orientated in the horizontal-vertical position. Single sided full penetration welds with underbeads were required. The weld bead geometry was defined in terms of ten responses. Mathematical models derived from factorially designed experiments were used to relate the weld bead geometry, incidence of porosity and the occurrence of electrode stubbing to a function of upto seven factors. A data base of almost 1000 test welds was generated, in which each test was characterised by 76 pieces of information. Analysis of variance was used to determine which factors most influenced each of the responses. Multiple regression enabled an expression for each response to be derived as a function of the welding factor levels. The weld bead geometry model consisted of ten equations, each a function of upto six factors, whilst the soundness model related the optimum welding voltage to a function of three factors so that porosity and electrode stubbing would not be encountered.
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Xu, Lei. "Plasma arc welding fabrication using thin titanium sheet." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.605800.
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This work was motivated by the industrial and academic needs for process development of automated keyhole plasma arc welding (K-PA W) in thin Ti- 6AI-4V sheet and the control required for the process to be suitable for aerospace components. K-PAW, is a high energy density precision welding process which is a lowcost alternative to laser and electron beam welding. It is potentially capable of fabricating high integrity titanium alloy welds in aero-engine thin panel structures. However, the process has always represented a challenge owing to the complexity of welding torch configurations and the associated large number of process parameters to take into consideration. Three types of weld joint, which represent the welding fabrications in a simplified aero-engine casing component, were manufactured in the work: flat bead-on-plate, flat Tjoint and curved T -joint. A new welding procedure was developed to produce thin sheet T-joints by K-PAW, which has overcome the difficulty of operating the structurally complicated welding torch in limited space. An analytical model was experimentally validated and was employed to identify the process parametric envelopes for valid keyhole welding modes from the numerous possible parameter combinations. Weld joints were characterised in tenns of thermal history, micro-hardness and metallurgical microstructure. Distortion and residual stresses are maJor concerns associated with fusion welding fabrication. While distortions can lead to geometrical inaccuracy, paIticularly in the thin panel stl11ctures, residual stresses can combine with applied stresses to reduce the life of components. In this thesis, the out-of-plane l distortions of welded thin Ti-6AI-4V bead-on-plate and T-joint welds were measured using contact and non-contact coordinate-measuring techniques, from which the effects of welding sequence on the distortions can also be identified. Residual stress distributions in the welded sheet were detennined by synchrotron X-ray and neutron diffraction techniques. The use of synchrotron X-ray methods is relatively newly developed as titanium alloys respond weakly to neutron beams. These not only have provided improved understanding of residual stresses in thin sheet welds but also have greatly contributed to validation of finite element (FE) modelling work undertaken by other researchers.
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Peters, Daniel Joseph. "Submerged arc welding consumables for HSLA-100 steel." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26280.
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Absi, Alfaro Sadek Crisostomo. "Mathematical modelling of narrow gap submerged arc welding." Thesis, Cranfield University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.232955.
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Jones, Lawrence Anthony. "Dynamic electrode forces in gas metal arc welding." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11287.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (p. 306-313).
by Lawrence Anthony Jones.
Ph.D.
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Cronje, M. "Finite element modelling of shielded metal arc welding." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/2649.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005.This study involved the modelling and verification of the Shielded Metal Arc Welding of mild steel with the focus on displacement and temperature distribution prediction of welded plates. The project was divided into three phases namely; the literature survey into finite element modelling of welding processes, the modelling of a welding process and verification of the modelling with experimental results. A working welding model was created using a commercial finite element software package with the capabilities to model welding processes. The welding model was systematically developed from a two-dimensional model into a threedimensional full physics process model. Experimental measured welding heat input parameters were applied in the model, temperature dependent material properties were applied and actual structural restraints from the experiments were modelled. Displacement and temperature distributions were measured on mild steel plates welded with the Shielded Metal Arc Welding process. The plate temperature was measured at various locations with K-type thermocouples spot welded onto the plates. Plate deformation was measured at various stages of the manufacturing process. Tendencies in plate displacement were investigated with a change in certain welding parameters. The finite element model was verified and good correlations were found, especially for the temperature distribution in the welded plates.
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Ho, Yeu-Chuan 1960. "DESIGN OF ARC WELDING PROCESSES: A CAUSAL PERSPECTIVE." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/291663.
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The ability to make rational decisions based on the synthesis of various pieces of information and to eventually arrive at an integrated design plays a very important role in everyday engineering practice. In this paper, a conceptual framework for manufacturing design is obtained through a causal perspective. This framework is used in developing a knowledge-based system that gains insight into the process of arc welding from a few detailed analyses and experiments on simplified models and rationally arrives at an integrated design of the actual process using a hybrid axiomatic-algorithmic approach for design synthesis. The design strategy presented here may also be applied to any manufacturing process in general.
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Sen, Debamoy. "Coupled Field Modeling of Gas Tungsten Arc Welding." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/38820.
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Welding is used extensively in aerospace, automotive, chemical, manufacturing, electronic and power-generation industries. Thermally-induced residual stresses due to welding can significantly impair the performance and reliability of welded structures. Numerical simulation of weld pool dynamics is important as experimental measurements of velocities and temperature profiles are difficult due to the small size of the weld pool and the presence of the arc. From a structural integrity perspective of welded structures, it is necessary to have an accurate spatial and temporal thermal distribution in the welded structure before stress analysis is performed. Existing research on weld pool dynamics simulation has ignored the effect of fluid flow in the weld pool on the temperature field of the welded joint. Previous research has established that the weld pool depth/width (D/W) ratio and Heat Affected Zone (HAZ) are significantly altered by the weld pool dynamics. Hence, for a more accurate estimation of the thermally-induced stresses it is desired to incorporate the weld pool dynamics into the analysis. Moreover, the effects of microstructure evolution in the HAZ on the mechanical behavior of the structure need to be included in the analysis for better mechanical response prediction. In this study, a three-dimensional model for the thermo-mechanical analysis of Gas Tungsten Arc (GTA) welding of thin stainless steel butt-joint plates has been developed. The model incorporates the effects of thermal energy redistribution through weld pool dynamics into the structural behavior calculations. Through material modeling the effects of microstructure change/phase transformation are indirectly included in the model. The developed weld pool dynamics model includes the effects of current, arc length, and electrode angle on the heat flux and current density distributions. All the major weld pool driving forces are included, namely surface tension gradient, plasma drag force, electromagnetic force, and buoyancy. The weld D/W predictions are validated with experimental results. They agree well. The effects of welding parameters (like welding speed, current, arc length, etc.) on the weld D/W ratio are documented. The workpiece deformation and stress distributions are also highlighted. The transverse and longitudinal residual stress distribution plots across the weld bead and their variations with welding speed and current are also provided. The mathematical framework developed here serves as a robust tool for better prediction of weld D/W ratio and thermally-induced stress evolution and distribution in a welded structure by coupling the different fields in a welding process.Ph. D.
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Campbell, Stuart William. "Shielding gas parameter optimisation in arc welding processes." Thesis, University of Strathclyde, 2015. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25988.
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This thesis is focussed on shielding gas optimisation in gas shielded arc welding processes, and has been conducted along two themes; deriving conditions in which the shielding gas flow rate can be safely reduced, and through the highly novel process of alternating shielding gases. The correct shielding gas flow rate is essential for providing adequate protection to the weld metal during the heating, liquid and solidification stages. Hence, there is an optimum shielding gas flow rate, but this is difficult to define and is often decided on the basis of preference or experience. A multi-disciplined, systematic study has been conducted, which has shown that there is considerable scope to reduce the shielding gas flow rate. Experimental trials have shown that the shielding gas flow rate can be reduced, in a draft-free environment, to 6 l/min, with no degradation in weld quality for the worst draft conditions measured in a typical shipyard fabrication hall, at 10 l/min. This study has resulted in shielding gas flow controllers, preset at 12 l/min, being installed in a large shipyard environment, removing the welding operatives ability to increase the shielding gas flow rate. The application of alternating shielding gases offers clear manufacturing cost reduction benefits which arise from measurable increases in productivity, improved distortion control and re-work reduction, and overall improvements to the mechanical properties of the weld. Arc pressure measurements, and the subsequent derivation of forces acting on the liquid weld metal, have indicated that flow vectors for helium are opposite in direction to that produced by argon, creating a dynamic action within the weld pool. Schlieren visualisation has shown that there is a greater degree of helium entrainment in the primary jet due to a constriction of its flow in the secondary jet, influencing the arc's behaviour and inferring more of the associated benefits.
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Abu, Bakar Nooh. "ESWELPD : an expert system for the generation of welding procedure of arc welding processes." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/33209.
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The research is focused on the development of an expert system to generate welding procedures for arc welding processes. The system has been developed on an IBM AT microcomputer, using an expert system shell KES (Knowledge Engineering System), a product of Software Architecture & Engineering Inc. The system is primarily intended for novice users, hence good 'help' facilities and graphical representations are provided in the system.
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Shen, Hao. "Seam position detection in pulsed gas metal arc welding." Access electronically, 2003. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20040823.125740/index.html.
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Ludick, Mark. "Experimental sensitivity analysis of welding parameters during transition from globular to spray metal transfer in gas metal arc welding." Thesis, Peninsula Technikon, 2001. http://hdl.handle.net/20.500.11838/1269.
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Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, Cape Town, 2001Since the discovery of arc welding at the beginning ofthe century, metal transfer has been a topic ofresearch interest. Metal transfer can, in fact be related to weld quality, because it affects the arc stability. Furthermore, it determines the weld spatter, penetration, deposition rate and welding position. Gas Metal Arc Welding (also known as Metal Inert Gas- or MIG welding) is the most co=on method for arc welding steels and aluminurn alloys. Approximately 40% of the production welding in the country is accomplished by this process in which the thermal phenomena and melting ofthe solid electrode are coupled to the plasma arc and the weld pool. Thus the therrno- fluid behaviour of the electrode and detaching drops can have significant effects on the subsequent weld quality and production rate. The knowledge of how metal transfer affects this arc welding process is important for welding control and process automation, as well as in the development of improved welding consumables. Gas metal arc welding has a distinct feature, indicated by the results of Lesnewich [24], [23], that for most gases, there is a discrete metal droplet formation change between low and high current operations. Naturally the droplet size will have a significant influence on the properties ofthe welds. In globular transfer which occurs at low current, the welding electrode melts and produces large droplets (usually larger in diameter than the electrode wire diameter). This mode of transfer is associated with high spatter levels and thus undesirable in terms of welding economics. An increase in welding current will, for most welding! shielding gases, produce metal transfer with smaller droplets, which is termed spray transfer. This mode oftransfer is associated with high voltage and amperage settings, thus producing high deposition rates limited to the flaUhorizontal position.
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Cho, Min Hyun. "Numerical simulation of arc welding process and its application." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1155741113.
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Liu, Xiaopei. "Dual Bypass Gas Metal Arc Welding Process and Control." UKnowledge, 2008. http://uknowledge.uky.edu/gradschool_diss/664.
Full textAbstract:
GMAW (Gas Metal Arc Welding) is one of the most important arc welding processes being adopted in modern manufacturing industry due to its advantages in productivity, energy efficiency and automation. By monitoring and improving some of the important properties of GMAW such as production rate, metal transfer and base metal heat input, researchers could bring the process efficiency and stability to a new level. In recent years, some innovative modifications of GMAW such as Twins, Tandem and laser-MIG hybrid welding have been adopted into many industrial applications for better productivity.
In this dissertation, a novel GMAW called DB-GMAW (Dual Bypass Gas Metal Arc Welding) using two GTAW torches and one GMAW torch to construct a welding system, is proposed and developed. In DB-GMAW, two GTAW torches perform the bypass system which decouples the total welding current into base metal current and bypass current after the melt down of filler wire. Compared to conventional GMAW, DB-GMAW has many advantages in droplet formation, base metal heat input and penetration achievement due to its unique characteristics in welding arc and current flow. In the first place of the research, experimental system of DB-GMAW is constructed. Then, sufficient experiments under different parameters are performed to provide us a good understanding of the behaviors and characteristics of this novel GMAW process. Observation about metal transfer formation and base metal heat input is studied to verify its theoretical analysis. Full penetration of work piece via DB-GMAW is achieved based on a series of parameter testing experiments. Moreover, image processing techniques are applied to DB-GMAW to monitor the welding process and construct a feedback system for control.
Considering the importance of maintaining stable full penetration during many welding applications, a nonlinear model of DB-GMAW full penetration is developed in this dissertation. To do that, we use machine vision techniques to monitor the welding profile of the work piece. A control algorithm based on the nonlinear model using adaptive control technique is also designed. The achievement of this dissertation provides a fundamental knowledge of a novel welding process: DB-GMAW, and a good guidance for further studies about DBGMAW.
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Sedy, Eugene B. "Validation of a computational model for autogenous arc welding." Thesis, Monterey, California. Naval Postgraduate School, 1990.
Find full textAbstract:
Approved for public release, distribution is unlimitedA three dimensional transient computational model of heat transfer are welding is generalized, and then validated by comparison to Rosenthal's solution for moving point sources of heat. The current version of the code allows much greater flexibility in the specification of the thermal input from the arc. The resulting surface temperature profiles and fusion zone shapes are compared to those measured experimentally for several input power levels ofr autogenous gas tungsten arc welding. Arc efficiency is experimentally determined using change of phase of a liquid fluorocarbon. The model is shown to be useful for modeling autogenous welding of thick plates. Weld seam misalignment and surface flaw detection are shown to be possible ahead of hte arch with accurate surface temperature detection methods. The potential of the model are creating a database of fusion and heat zone sizes, temperature profiles, and coding rates for various materials, processes, and power levels is indicated.
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Yan, Ming. "WeldSim : a model for simulating gas metal arc welding." Thesis, The University of Sydney, 2001. https://hdl.handle.net/2123/27861.
Full textAbstract:
The aim of the project described in this thesis is to develop a theoretical model to predict the performance of gas metal arc welding, also known as metal inert gas welding (MIG) and achieve a better understanding of the mechanism and the physical processes involved.
The gas metal arc welding simulation model - WeldSim is an electrical circuit developed from a basic circuit model. It incorporates results from a free-burning arc model to describe the arc and a second order differential equation to describe one-dimensional energy conservation in the welding anode.
WeldSim considers the effects of droplet formation, change of the liquid metal amount at the tip of stickout as well as the bridge formed during short circuits. The liquid metal at the tip is detached as a droplet only when the amount of the liquid is enough to form a droplet. To take the bridge formed after short circuits into account, WeldSim assumes that the arc won't be generated if the calculated arc length is less than the bridge length and the liquid amount at the tip is greater than the liquid left after each shorting.
Predictions from WeldSim in short circuiting mode are compared with the experimental results collected during bead-on-plate argon-shielded gas metal arc welding. WeldSim successfully predicts the decrease in short circuiting frequency with increasing supply voltage and the existence of droplet transfer between each pair of short circuits, which is observed experimentally. At low voltage supply, droplet formation rate is low and most of the liquid filling metal is transferred to the welding pool through short circuit. Therefore the short circuiting frequency is high at lower voltage supply and the droplet formation rate increases with increasing arc voltage.
Commercial circuit analysis software is used to solve the circuit model. WeldSim provides a fast and useful technique to predict the overall welding behaviour. The model can be used to optimize welding parameters and guide the actual manufacturing processes.
In this thesis, Chapter One introduces the development history of welding processes and gives a general introduction to gas metal arc welding process. Chapter Two introduces the development of modelling of GMAW processes. The third chapter details WeldSim and clarifies the differences between WeldSim and the original model. Chapter Four compares and discusses the predicted and the experimental results. Some conclusions are drawn in Chapter Five.
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Xu, Pu. "A circuit model for simulating gas metal arc welding." Thesis, The University of Sydney, 1999. https://hdl.handle.net/2123/27678.
Full textAbstract:
An electrical circuit was developed to model the behaviour of gas metal arc welding (GMAW), also known as metal inert gas welding (MIG). The model incorporates results from a one-dimensional free-burning arc model to describe the arc and a second order differential equation to describe one—dimensional energy conservation in the welding anode.
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Erabelli, Prasad Rao 1962. "EXPERT SYSTEM FOR DESIGN OF ARC WELDING (ARTIFICIAL INTELLIGENCE)." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/291579.
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Hansen, James Christopher. "Rotating Electrode Pulse Gas Metal Arc Welding for Improved Aluminum Shipbuilding Quality." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1606991932450895.
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Thornton, M. F. "Spectroscopic determination of temperature distributions for a TIG arc." Thesis, Cranfield University, 1993. http://dspace.lib.cranfield.ac.uk/handle/1826/10551.
Full textAbstract:
Argon TIG arc temperatures have been measured for a wide range of
arc
parameters using the 'Fowler-Milne' spectroscopic method. Prompted by
widespread disagreement amongst temperatures published by previous
groups, a detailed investigation has been carried out into those experimental
and theoretical
aspects of the measurement process that may have led to
incorrect results. The tests have included the variation of
experimental
parameters, the choice of Abel inversion procedure, and the calculation of
argon species number densities and partition functions.
The existence of
equilibrium within the TIG arc has been investigated by
determining temperatures with a number of argon emission lines. Significant
differences 'in derived values of the
temperatures were observed within 1mm
of the
tungsten cathode tip, smaller variations were observed over the
remainder of the arc. The results indicate that
large scale departures from a
Boltzmann distribution
amongst argon atom excited states exists close to the
tungsten tip, deviations decrease with increasing distance from the tip but do
not
disappear completely. lt is believed that the breakdown of equilibrium
within the
argon TIG arc may help to explain the disagreement in temperatures
obtained
by past groups that have used spectroscopic methods.
Despite evidence for non-equilibrium within the arc. results from
previous groups suggest that derived values of .the temperatures are
substantially correct in the main body of the arc. The detailed temperature
maps provide useful information on temperature changes with arc parameters
for the
purposes of modelling and understanding of the arc.
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Hendricks, Brian Reginald. "Simulation of plasma arc cutting." Thesis, Peninsula Technikon, 1999. http://hdl.handle.net/20.500.11838/1245.
Full textAbstract:
Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, 1999The simulation of Plasma Arc Cutting is presented in this study. The plasma arc cutting process employs a plasma torch with a very narrow bore to produce a transferred arc to the workpiece. A technique for modelling plasma arc cutting has been developed by applying the thermo-metallurgical model to the process and integrating a model of material removal to this model. The model is solved using the finite element method using the FE package SYSWORLD, more specifically SYSWELD. The objective is to determine the minimum energy required to cut a plate of some thickness using this virtual model. The characteristics of the cut need to exhibit the characteristics of a "high quality cut". The model presented can predict the kerf size given certain process variable settings. The numerical results obtained are assessed by conducting experiments. By maintaining Ill1rumum energy input cost savings can be made through energy savings, limiting additional finishing processes and reducing expense of shortening the electrode and nozzle lifetimes. The modelling of the PAC process using virtual design techniques provides a cost-effective solution to the manufacturing industries with respect to process specification development. This plays an important role in South Africa's transition into a competitive global market. It is envisaged that the model will provide an alternative more efficient, non-destructive means of determining the optimum process variable settings for the plasma arc cutting process.
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Davies, Mark H. "Numerical modelling of weld pool convection in gas metal arc welding /." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phd2563.pdf.
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Smailes, Allan J. "Thermal modelling of gas metal arc welding using finite element analysis /." Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09ENS/09enss635.pdf.
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Mazidi, Aimal. "Comparison of a new, high precision, energy efficient welding method with the conventional Gas Metal Arc Welding on high carbon steel base metal." Thesis, Högskolan Väst, Avd för tillverkningsprocesser, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-6860.
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CMT+P welding is less susceptible to hot cracking than the MAG welding process due to use of low heat input properties. Solidification cracking was found in all weld specimens that had greater 0.39KJ/mm heat inputs. Cracking occurs because of the contraction stresses generates during cooling. Hydrogen cracking is found in HAZ with low heat input parameters, this type of cracking occurred because of very rapid cooling and therefore not enough time to allow the hydrogen to dissipate from the specimen. To eliminate this type of cracking the experiment could be repeated by adding heating during welding to control and reduce the cooling rate. Due to high carbon content in the steel and very fast cooling the microstructure of the weld is martensitic in the base metal as well as the HAZ. Microstructure in the weld and base metal is martensitic due to high carbon con-tent and rapid cooling. At low heat inputs dilution is less and therefore lower carbon content in weld pool. Better weld appearance and weld quality is achieved with CMT+P welding process than the conventional GMA welding processes because of the new wire movement technology during welding
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Cave, W. R. "Investigation of the constricted plasma arc process for hyperbaric welding at pressures 1 to 100bar." Thesis, Cranfield University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360220.
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Lindmark, Terese. "Welding parameter window for Tandem gas-shielded metal arc welding and fatigue in welded T-joints." Thesis, University West, Department of Technology, Mathematics and Computer Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-828.
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Lin, Yanping. "Improvement of HAZ in multi-pass NG submerged arc welding." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39376.
Full textAbstract:
The study emphasizes the effects of multi-pass narrow gap (NG) Submerged-Arc welding (SAW) on the Heat Affected Zone (HAZ). The differences between the HAZ of single-pass welds and multi-pass welds are radical and are caused by the subsequent thermal cycles which only exist in multi-pass welding.A series of experiments were carried out to establish the relationship between the welding thermal cycles and the mechanical and microstructural properties of a HAZ. Both real and Gleeble simulated HAZ's were investigated.
Theoretical and experimental analyses indicate that the HAZ's in multi-pass welds can be improved significantly by the welding process itself. However, multi-pass welding does not always improve its HAZ. To realize the improvement, some special criteria must be met. The most important parameters are heat input, welding speed, deposit thickness and inter-pass temperature. This study establishes the relations between these parameters and the effects of HAZ refinement. There are some domains of the parameters in which HAZ refinement can be realized. The research reveals that in multi-pass NG welding, a set of welding parameters can always be found to fulfill the conditions for HAZ improvement.
Real welding processes, with welding parameters optimized according to the analyses, were performed and a totally refined HAZ was achieved under laboratory conditions. It is suggested that the method can be applied to in situ welding situations.
High heat input does not necessarily lead to inferior microstructural and mechanical properties in multi-pass NG welding. As long as the conditions for HAZ refinement are satisfied, an improved HAZ will be obtained no matter how high the heat input is. This also leads to the conclusion that the HAZ in multi-pass NG welding is less sensitive to heat input than that in single pass welding.
The tempering parameter, which has been used to evaluate the tempering effects at constant temperature, is successfully introduced into welding (non-isothermal) conditions. The effects of precipitates in 2.25Cr-1Mo steel are theoretically investigated.
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Wang, Ge. "NUMERICAL ANALYSIS OF METAL TRANSFER IN GAS METAL ARC WELDING." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_diss/538.
Full textAbstract:
In gas metal arc welding (GMAW), metal transfer plays a crucial role in determining the quality of the resultant weld. In the present dissertation, a numerical model with advanced computational fluid dynamics (CFD) techniques has been developed first in order to provide better numerical results. It includes a two-step projection method for solving the incompressible fluid flow; a volume of fluid (VOF) method for capturing free surface; and a continuum surface force (CSF) model for calculating surface tension. The Gauss-type current density distribution is assumed as the boundary condition for the calculation of the electromagnetic force. The droplet profiles, electric potential and velocity distributions within the droplet are calculated and presented for different metal transfer modes. The analysis is conducted to find the most dominant effects influencing the metal transfer behavior. Comparisons between calculated results and experimental results for metal transfer under constant current are presented and show good agreement. Then, our numerical model is used to study a proposed modified pulsed current gas metal arc welding. This novel modified pulsed current GMAW is introduced to improve the robustness of the welding process in achieving a specific type of desirable and repeatable metal transfer mode, i.e., one drop per pulse (ODPP) mode. This new technology uses a peak current lower than the transition current to prevent accidental detachment and takes advantage of the downward momentum of the droplet oscillation to enhance the detachment. The calculations are conducted to demonstrate the effectiveness of the proposed method in achieving the desired metal transfer process in comparison with conventional pulsed current GMAW. Also, the critical conditions for effective utilization of this proposed method are identified by the numerical simulation. The welding operational parameters and their ranges are also calculated and the calculated results further demonstrate the robustness of this new GMAW technique in achieving high quality welding.
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Ule, Robert L. "A study of the thermal profits during autogenous arc welding." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26277.
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