Numerically modelled study of the plunge stage in friction stir spot welding using multi-tiered mesh partitions

2021 ◽  
Author(s):  
Arindom Baruah ◽  
Jayaprakash Murugesan ◽  
Hemant Borkar
Keyword(s):  
Spot Welding ◽  
Material Model ◽  
Friction Stir Spot Welding ◽  
Frictional Heat ◽  
Complex Behaviour ◽  
Friction Stir ◽  
Spot Joining ◽  
Solid State Joining ◽  
Joining Process ◽  
Significant Attention

Abstract Friction stir spot welding is a solid-state joining process that has attracted significant attention particularly in the field of joining of lightweight, low melting alloys. These materials include alloys of Aluminium and Magnesium amongst many others which are of great importance to the aerospace and the automobile industries. The friction stir spot welding is a complex thermo-mechanical multiphysics phenomenon and is currently a field of intense research. The motivation of the current study is to understand this complex behaviour of the joining process by simulating it in the ABAQUS CAE environment. In the friction stir spot joining technique, the plunge stage is identified as the critical stage of operation as it involves a highly transient and dynamic zone for material and temperature flows. The plunge stage was studied in detail using the finite element based model. The plasticity of the material was simulated by the Johnson-Cook material model while the frictional heat generation was captured by applying a penalty-based frictional contact between the rotating tool and the workpiece contact surfaces. Considering the reasonable assumptions made, the results obtained by the numerical simulation model were found to agree with the past experimental and numerically modelled studies.

Friction Self-Piercing Riveting (F-SPR) of AA6061-T6 to AZ31B

2013 ◽  
Author(s):  
YongBing Li ◽  
ZeYu Wei ◽  
YaTing Li ◽  
ZhaoZhao Wang ◽  
Xiaobo Zhu
Keyword(s):  
Magnesium Alloys ◽  
Spot Welding ◽  
High Speed ◽  
Dissimilar Materials ◽  
Friction Stir Spot Welding ◽  
Friction Stir ◽  
Riveting Process ◽  
Solid State Joining ◽  
Joining Process ◽  
Vehicle Bodies

Implementation of lightweight low-ductility materials such as aluminum alloys, magnesium alloys and composite materials has become urgently needed for automotive manufacturers to improve the competitiveness of their products. However, the hybrid use of these materials poses big challenges to joining processes. Self-piercing riveting (SPR) is currently the most popular technique for joining dissimilar materials and has been widely used in joining all-aluminum and multi-material vehicle bodies. However, in riveting magnesium alloys, cracks always occur for its low ductility. In this paper, a hybrid joining process named friction self-piercing riveting (F-SPR), which combines mechanical joining mechanism of SPR with solid-state joining mechanism of friction stir spot welding (FSSW) by making rivet rotating at high speed in riveting process, was proposed aiming at joining the low ductility materials. 1-mm-thick AA6061-T6 and 2-mm-thick AZ31B were used to validate the effectiveness of the F-SPR process. The results showed that the F-SPR process could significantly improve the rivetability of magnesium alloys, and greatly increase the joint strength, comparing with traditional SPR process.

Thermo-mechanical modelling of the Friction Stir Spot Welding process: Effect of the friction models on the heat generation mechanisms

2022 ◽  
pp. 146442072110709
Author(s):  
Nasra Hannachi ◽  
Ali Khalfallah ◽  
Carlos Leitão ◽  
Dulce Rodrigues
Keyword(s):  
Numerical Simulation ◽  
Heat Generation ◽  
Spot Welding ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Frictional Heat ◽  
Contact Conditions ◽  
Friction Stir ◽  
Friction Models ◽  
Generation Mechanisms

Friction Stir Spot Welding involves complex physical phenomena, which are very difficult to probe experimentally. In this regard, the numerical simulation may play a key role to gain insight into this complex thermo-mechanical process. It is often used to mimic specific experimental conditions to forecast outputs that may be substantial to analyse and elucidate the mechanisms behind the Friction Stir Spot Welding process. This welding technique uses frictional heat generated by a rotating tool to join materials. The heat generation mechanisms are governed by a combination of sliding and sticking contact conditions. In the numerical simulation, these contact conditions are thoroughly dependent on the used friction model. Hence, a successful prediction of the process relies on the appropriate selection of the contact model and parameters. This work aims to identify the pros and cons of different friction models in modelling combined sliding-sticking conditions. A three-dimensional coupled thermo-mechanical FE model, based on a Coupled Eulerian-Lagrangian formulation, was developed. Different friction models are adopted to simulate the Friction Stir Spot Welding of the AA6082-T6 aluminium alloy. For these friction models, the temperature evolution, the heat generation, and the plastic deformation were analysed and compared with experimental results. It was realized that numerical analysis of Friction Stir Spot Welding can be effective and reliable as long as the interfacial friction characteristics are properly modelled. This approach may be used to guide the contact modelling strategy for the simulation of the Friction Stir Spot Welding process and its derivatives.

Effect of Tool Shape on Temperature Field in Friction Stir Spot Welding

2013 ◽  
Vol 58 (2) ◽  
pp. 595-599 ◽  
Author(s):  
P. Lacki ◽  
Z. Kucharczyk ◽  
R.E. Śliwa ◽  
T. Gałaczyński
Keyword(s):  
Temperature Field ◽  
Solid State ◽  
Spot Welding ◽  
Plastic Material ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Frictional Heat ◽  
Maximum Temperature ◽  
Tool Geometry ◽  
Friction Stir

Friction stir welding (FSW) is one of the youngest methods of metal welding. Metals and its alloys are joined in a solid state at temperature lower than melting points of the joined materials. The method is constantly developed and friction stir spot welding (FSSW) is one of its varieties. In the friction stir spot welding process a specially designed tool is brought into rotation and plunged, straight down, in the joined materials. Heat is generated as a result of friction between the tool and materials, and plastic deformation of the joined materials. Softening (plastic zone) of the joined materials occurs. Simultaneously the materials are stirred. After removal of the tool, cooling down the stirred materials create a solid state joint. Numerical simulation of the process was carried out with the ADINA System based on the finite element method (FEM). The problem was considered as an axisymmetric one. A thermal and plastic material model was assumed for Al 6061-T6. Frictional heat was generated on the contact surfaces between the tool and the joined elements. The model of Coulomb friction, in which the friction coefficient depends on the temperature, was used. An influence of the tool geometry on heat generation in the welded materials was analysed. The calculations were carried out for different radiuses of the tool stem and for different angles of the abutment. Temperature distributions in the welded materials as a function of the process duration assuming a constant value of rotational tool speed and the speed of tool plunge were determined. Additionally, the effect of the stem radius and its height on the maximum temperature was analysed. The influence of tool geometry parameters on the temperature field and the temperature gradient in the welded materials was shown. It is important regarding the final result of FSSW.

Friction Self-Piercing Riveting of Aluminum Alloy AA6061-T6 to Magnesium Alloy AZ31B

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
YongBing Li ◽  
ZeYu Wei ◽  
ZhaoZhao Wang ◽  
YaTing Li
Keyword(s):  
Magnesium Alloys ◽  
Spot Welding ◽  
High Speed ◽  
Dissimilar Materials ◽  
Friction Stir ◽  
Magnesium Alloy Az31b ◽  
Riveting Process ◽  
Solid State Joining ◽  
Joining Process ◽  
Vehicle Bodies

Implementation of lightweight low-ductility materials such as aluminum alloys, magnesium alloys and composite materials has become urgently needed for automotive manufacturers to improve the competitiveness of their products. However, hybrid use of these materials poses big challenges to traditional joining process. Self-piercing riveting (SPR) is currently the most popular technique for joining dissimilar materials and has been widely used in joining all-aluminum and multimaterial vehicle bodies. However, in riveting magnesium alloys, cracks always occur for its low ductility. In this paper, a hybrid joining process named friction self-piercing riveting (F-SPR), which combines mechanical joining mechanism of SPR with solid-state joining mechanism of friction stir spot welding (FSSW) by making rivet rotating at high speed in riveting process, was proposed aiming at joining the low-ductility materials. The effectiveness of the F-SPR process was validated via riveting 1 mm thick AA6061-T6 and 2 mm thick AZ31B. The results showed that the F-SPR process could significantly improve the rivetability of magnesium alloys, and greatly increase the joint strength, comparing with the traditional SPR process.

Microstructural Factors Governing Mechanical Properties in Friction Stir Welds

2007 ◽  
Vol 345-346 ◽  
pp. 1493-1496 ◽  
Author(s):  
Yutaka S. Sato ◽  
Hiroyuki Kokawa
Keyword(s):  
Mechanical Properties ◽  
High Reliability ◽  
Local Region ◽  
Frictional Heat ◽  
Hardness Profile ◽  
Friction Stir ◽  
Precise Understanding ◽  
Weld Properties ◽  
Solid State Joining ◽  
Joining Process

Friction stir welding (FSW) is a solid-state joining process. During FSW, microstructure drastically changes in local region of the workpiece by introduction of frictional heat and severe plastic deformation arising from rotation of the welding tool, which results in inhomogeneous microstructural distribution in the welds. To maintain high reliability of the structure produced by FSW, precise understanding of microstructural factors governing weld properties is required. In the present paper, microstructural factors governing mechanical properties, especially hardness profile and tensile properties, of friction stir welded Al and Mg alloys are reviewed.

Application of Solid State Joining Technologies in Aerospace Parts

2020 ◽  
Vol 837 ◽  
pp. 69-73
Author(s):  
Ho Sung Lee ◽  
Jong Hoon Yoon ◽  
Joon Tae Yoo
Keyword(s):  
Solid State ◽  
Diffusion Bonding ◽  
Plastic Material ◽  
Welding Process ◽  
Bonding Process ◽  
Fusion Welding ◽  
Frictional Heat ◽  
Friction Stir ◽  
Solid State Joining ◽  
Joining Process

This study presents manufacturing lightweight aerospace components by solid state joining technologies. The advantages of solid state joining are due to the lack of hot cracking from solidification, since there is no liquid phase involved in joining process. This produces a high quality joint as compared to that from conventional fusion welding process. In diffusion bonding process, two different surfaces are matched together at elevated temperature under a low pressure without macroscopic plastic deformation in the interface. In friction stir welding process, the rotating shoulder of the tool generates frictional heat on the surface. As the pin rotates it forces the plastic material to mix mechanically in the vicinity of the pin and produces a heavily deformed microstructure around the pin. In this study, solid state joining processes of diffusion bonding and friction welding, are applied to manufacture several launcher components with lightweight, efficient and cost saving.

scholarly journals Evaluation of mechanical property predictions of refill Friction Stir Spot Welding joints via machine learning regression analyses on DoE data

2021 ◽  
Author(s):  
Frederic E. Bock ◽  
Tino Paulsen ◽  
Nikola Brkovic ◽  
Lennart Rieckmann ◽  
Dennis Kroeger ◽  
...  
Keyword(s):  
Machine Learning ◽  
Mechanical Property ◽  
Process Parameters ◽  
Spot Welding ◽  
Friction Stir Spot Welding ◽  
Regression Analyses ◽  
Friction Stir ◽  
Joint Properties ◽  
Process Property ◽  
Solid State Joining

The high-potential of lightweight components consisting of similar or dissimilar materials can be exploited by Solid-State Joining techniques. Whereas defects such as pores and hot cracking are often an issue in fusion-based joining processes, via solid-state joining processes they can be avoided to enable high-quality welds. To define an optimal process window for obtaining anticipated joint properties, numerous time and cost consuming experiments are usually required. Building a predictive model based on regression analysis enables the identification and quantification of process-property relationships. On the one hand, mechanical property and performance predictions based on specific process parameters are needed, on the other hand, inverse determination of required process parameters for reaching desired properties or performances are demanded. If these relations are obtained, optimized process parameter sets can be identified while vast numbers of required experiments can be reduced, as underlying physical mechanisms are utilized. In this study, different regression analysis algorithms, such as linear regression, decision trees and random forests, are applied to the refill Friction Stir Spot Welding process for establishing correlations between process parameters and joint properties. Experimental data sets used for training and testing are based on a Box-Behnken Design of Experiments (DoE) and additional test experiments, respectively. The machine-learning based regression analyses are benchmarked against linear regression and DoE statistics. The results illustrate a decryption of relationships along the process-property chain and its deployment to predict mechanical properties governed by process parameters.

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