Numerical Simulation and Visualization of Material Flow in Friction Stir Welding via Particle Tracing

Dialami, Narges; Chiumenti, Michele; Cervera, Miguel; Saracibar, C. Agelet de; Ponthot, Jean‐Philippe; Bussetta, Philippe

doi:10.1007/978-3-319-06136-8_7

Cited by 23 publications

(24 citation statements)

References 17 publications

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“…Agelet de Saracibar et al [106], Chiumenti et al [116], and Dialami et al [117][118][119] To model the plastic deformation and thermal analysis.…”

Section: Authors Objectives Resultsmentioning

confidence: 99%

“…By using a sub-grid scale stabilized mixed velocity, both the pressure and the temperature in different coupled thermo-rigid-plastic models, the thermal modelling of the FSW process was investigated by Agelet de Saracibar et al [106] Chiumenti et al [116], and Dialami et al [117][118][119]. In all models, the Eulerian and the Arbitrary Lagrangian Eulerian (ALE) approaches were employed.…”

Section: Local Scalementioning

confidence: 99%

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A Comparison of Different Finite Element Methods in the Thermal Analysis of Friction Stir Welding (FSW)

Meyghani

Awang

Emamian

et al. 2017

Metals

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Friction Stir Welding (FSW) is a novel kind of welding for joining metals that are impossible or difficult to weld by conventional methods. Three-dimensional nature of FSW makes the experimental investigation more complex. Moreover, experimental observations are often costly and time consuming, and usually there is an inaccuracy in measuring the data during experimental tests. Thus, Finite Element Methods (FEMs) has been employed to overcome the complexity, to increase the accuracy and also to reduce costs. It should be noted that, due to the presence of large deformations of the material during FSW, strong distortions of mesh might be happened in the numerical simulation. Therefore, one of the most significant considerations during the process simulation is the selection of the best numerical approach. It must be mentioned that; the numerical approach selection determines the relationship between the finite grid (mesh) and deforming continuum of computing zones. Also, numerical approach determines the ability of the model to overcome large distortions of mesh and provides an accurate resolution of boundaries and interfaces. There are different descriptions for the algorithms of continuum mechanics include Lagrangian and Eulerian. Moreover, by combining the above-mentioned methods, an Arbitrary Lagrangian-Eulerian (ALE) approach is proposed. In this paper, a comparison between different numerical approaches for thermal analysis of FSW at both local and global scales is reviewed and the applications of each method in the FSW process is discussed in detail. Observations showed that, Lagrangian method is usually used for modelling thermal behavior in the whole structure area, while Eulerian approach is seldom employed for modelling of the thermal behavior, and it is usually employed for modelling the material flow. Additionally, for modelling of the heat affected zone, ALE approach is found to be as an appropriate approach. Finally, several significant challenges and subjects remain to be addressed about FSW thermal analysis and opportunities for the future work are proposed.

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“…Agelet de Saracibar et al [106], Chiumenti et al [116], and Dialami et al [117][118][119] To model the plastic deformation and thermal analysis.…”

Section: Authors Objectives Resultsmentioning

confidence: 99%

Section: Local Scalementioning

confidence: 99%

A Comparison of Different Finite Element Methods in the Thermal Analysis of Friction Stir Welding (FSW)

Meyghani

Awang

Emamian

et al. 2017

Metals

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“…There have been attempts to model the CFSW process using numerical simulation, e.g., as a thermo-mechanical phenomenon [30,31], but these efforts have not yet yielded a consolidated theory for the development of defects. The numerical simulation approach tends to assume a fluid continuum, which is intrinsically limiting since it is evident that the material is transported around the tool in batches (for tools with flats), and the voids are failures in packing (rather than negative pressure regions per se).…”

Section: Literaturementioning

confidence: 99%

“…The speed ratio is representative of revolutions per tool traverse distance (rev/mm) which can be a key factor for integrity of the flow regimes during the stirring process between the A.S and R.S [31]. An incompatible speed ratio can cause the failure of the weld in the early stages of the process or cause structural defects through the weld-line such as tunnel void or macro-cracks.…”

Section: Entry Zonementioning

confidence: 99%

Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding

Tamadon

Pons

Sued

et al. 2018

Metals

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Bobbin friction stir welding (BFSW) is an innovative variant for the solid state welding process whereby a rotating symmetrical tool causes a fully penetrated bond. Despite the process development, there are still unknown variables in the characterization of the process parameters which can cause uncontrolled weld defects. The entry zone and the exit zone consist of two discontinuitydefects and removing them is one of the current challenges for improving the weld quality. In the present research, the characteristic features of the entry and exit defects in the weld structure and formation mechanism of them during the BFSW processing was investigated. Using stacked layers of multi-colour plasticine the material flow, analogous to metal flow, can be visualised. By using different colours as the path markers of the analogue model, the streamline flow can be easily delineated in the discontinuity defects compared with the metal welds. AA6082-T6 aluminium plates and multi-layered plasticine slabs were employed to replicate the entry-exit defects in the metal weld and analogue samples. The fixed-bobbin tool utilized for this research was optimized by adding a thread feature and tri-flat geometry to the pin and closed-end spiral scrolls on both shoulder surfaces. Samples were processed at different rotating and longitudinal speeds to show the degree of dependency on the welding parameters for the defects. The analogue models showed that the entry zone and the exit zone of the BFSW are affected by the inhomogeneity of the material flow regime which causes the ejection or disruption of the plastic flow in the gap between the bobbin shoulders. The trial aluminium welds showed that the elimination of entry-exit defects in the weld body is not completely possible but the size of the defects can be minimized by modification of the welding parameters. For the entry zone, the flow pattern evolution suggested formation mechanisms for a sprayed tail, island zone and discontinuity-channel. For the exit zone a keyhole-shaped discontinuity is discussed as a structural defect.

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“…The Arbitrary Lagrangian Eulerian (ALE) formalisms have been proposed to deal with non-cylindrical pin shapes (see [1][2][3][4][5][6][7][8][9]). A mixed stabilized sub-grid scale finite technology has been adopted to solve coupled thermo-mechanical problems with a rigidviscoplastic constitutive behavior [4].…”

mentioning

confidence: 99%

Local–global strategy for the prediction of residual stresses in FSW processes

Dialami

Cervera

Chiumenti

et al. 2016

Int J Adv Manuf Technol

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The final publication is available at Springer via http://dx.doi.org/10.1007/s00170-016-9016-3This work describes the local–global strategy proposed for the computation of residual stresses in friction stir welding (FSW) processes. A coupling strategy between the analysis of the process zone nearby the pin tool (local level analysis) and the simulation carried out for the entire structure to be welded (global level analysis) is implemented to accurately predict the temperature histories and, thereby, the residual stresses in FSW. As a first step, the local problem solves the material stirring as well as the heat generation induced by the pin and shoulder rotation at the heat affected zone. The Arbitrary Lagrangian Eulerian (ALE) formulation is adopted to deal with the rotation of complex pin shapes. A thermo-rigid-viscoplastic constitutive law is employed to characterize the viscous flow of the material, driven by the high-strain rates induced by the FSW process. A mixed temperature–velocity–pressure finite element technology is used to deal with the isochoric nature of the strains. The output of this local analysis is the heat generated either by plastic dissipation or by friction, and it is used as the power input for the welding analysis at structural (global) level. The global problem is tackled within the Lagrangian framework together with a thermo-elasto-viscoplastic constitutive model. In addition, in this case, the mixed temperature–displacement–pressure format is introduced to deal with the deviatoric nature of the plastic strains. The outcomes of this analysis are the distortions and the residual stresses after welding. The material used in this work is stainless steel 304 L; however, the methodology presented is applicable to a wide range of materials. The proposed numerical strategy is validated by the experimental evidence.Peer ReviewedPostprint (author's final draft

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Numerical Simulation and Visualization of Material Flow in Friction Stir Welding via Particle Tracing

Cited by 23 publications

References 17 publications

A Comparison of Different Finite Element Methods in the Thermal Analysis of Friction Stir Welding (FSW)

A Comparison of Different Finite Element Methods in the Thermal Analysis of Friction Stir Welding (FSW)

Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding

Local–global strategy for the prediction of residual stresses in FSW processes

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