A New Approach to Measure Strain During Friction Stir Welding Using Visioplasticity

2011 ◽  
Author(s):  
Mohamadreza Nourani ◽  
Abbas S. Milani ◽  
Spiro Yannacopoulos
Keyword(s):  
Friction Stir Welding ◽  
Plastic Strain ◽  
Shape Change ◽  
Equivalent Plastic Strain ◽  
Leading Edge ◽  
Strain Range ◽  
New Approach ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Tool Pin

During modeling of the friction stir welding (FSW) process, the prediction of strain range experienced by the material is important as it affects the microstructure and mechanical properties of the final weld [1–7]. For aluminum alloys, this range has been reported very scarcely and/or scattered widely in the literature (the range of the maximum equivalent plastic strain has been reported to be from 2.4 to 184 [8–24]). A new approach is proposed in this article for measuring strain during friction stir welding using visioplasticity. In this approach, strains are calculated from changes in the boundaries of a small cylindrical Al-30% SiC composite marker mounted in the advancing side of mid-plane of adjacent plates during welding. The marker shape change is observed by a “stop action” (freeze-in) technique midway the process. COMSOL numerical modeling is then used to compute the strain distribution using the observed boundary changes compared to the initial marker boundaries. As an illustrative example, the method is applied to the results reported by London et al. [25] for the friction stir welding of 6.35 mm thick 7050 aluminum plates, welded with tool RPM of 350, welding speed of 1.69 mm/sec, tool pin diameter of 8 mm, tool shoulder diameter of 24 mm, and tool tilt angle of 3 degrees. A lower and upper bound of cumulative equivalent plastic strain of 14.1 and 20.3, respectively, were found to be in the neighborhood where the marker enters the severe deformation zone at mid-plane of plates in front of the leading edge of the pin.

scholarly journals Analysis of the tool plunge in friction stir welding - comparison of aluminium alloys 2024 T3 and 2024 T351

2016 ◽  
Vol 20 (1) ◽  
pp. 247-254
Author(s):  
Darko Veljic ◽  
Bojan Medjo ◽  
Marko Rakin ◽  
Zoran Radosavljevic ◽  
Nikola Bajic
Keyword(s):  
Friction Stir Welding ◽  
Plastic Strain ◽  
Heat Generation ◽  
Aluminium Alloys ◽  
Three Dimensional ◽  
Equivalent Plastic Strain ◽  
Fe Model ◽  
Arbitrary Lagrangian Eulerian ◽  
Friction Stir ◽  
Tool Pin

Temperature, plastic strain and heat generation during the plunge stage of the friction stir welding (FSW) of high-strength aluminium alloys 2024 T3 and 2024 T351 are considered in this work. The plunging of the tool into the material is done at different rotating speeds. A three-dimensional finite element (FE) model for thermomechanical simulation is developed. It is based on arbitrary Lagrangian-Eulerian formulation, and Johnson-Cook material law is used for modelling of material behaviour. From comparison of the numerical results for alloys 2024 T3 and 2024 T351, it can be seen that the former has more intensive heat generation from the plastic deformation, due to its higher strength. Friction heat generation is only slightly different for the two alloys. Therefore, temperatures in the working plate are higher in the alloy 2024 T3 for the same parameters of the plunge stage. Equivalent plastic strain is higher for 2024 T351 alloy, and the highest values are determined under the tool shoulder and around the tool pin. For the alloy 2024 T3, equivalent plastic strain is the highest in the influence zone of the tool pin.

Influences of Tool pin Profile and Tool Shoulder Curvature on the Formation of Friction Stir Welding Zone in AA6061 Aluminium Alloy

2012 ◽  
Vol 445 ◽  
pp. 789-794 ◽  
Author(s):  
Vahid Moosabeiki ◽  
Ghasem Azimi ◽  
Mostafa Ghayoor
Keyword(s):  
Friction Stir Welding ◽  
Aluminium Alloy ◽  
Frictional Heat ◽  
Welding Parameters ◽  
Zone Formation ◽  
Friction Stir ◽  
Tool Pin Profile ◽  
Tool Shoulder ◽  
Aa6061 Aluminium Alloy ◽  
Tool Pin

Friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a non-consumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force, etc., and tool pin profile play a major role in deciding the weld quality. Friction stir tool plays a major role in friction stir welding process. In this investigation, it is tried to evaluate the effect of tool pin thread and tool shoulder curvature on FSW zone formation in AA6061 aluminium alloy. In this regard, six different tool pin geometries (threadless triangular pin with/without conical shoulder, threaded triangular pin with conical shoulder, threadless square pin with/without conical shoulder, threaded square pin with conical shoulder) are used to fabricate the joints. The formation of FSP zones are analyzed macroscopically. Tensile properties of the joints are evaluated and correlated with the FSP zone formation. Consequently, it is obtained that welding creates a higher quality compared to other tool pin profiles using the square tool with curved shoulder and having threaded pin.

A thermal-plastic model of friction stir welding in aluminum alloy

2017 ◽  
Vol 24 (3) ◽  
pp. 439-446
Author(s):  
Zhang Peilei ◽  
Yan Hua ◽  
Li Chonggui ◽  
Yu Zhishui ◽  
Lu Qinghua
Keyword(s):  
Plastic Deformation ◽  
Friction Stir Welding ◽  
Three Dimensional ◽  
Transfer Model ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Moving Coordinate ◽  
Model Of Friction ◽  
Tool Pin ◽  
Good Agreement

AbstractA three-dimensional heat transfer model for friction stir welding is presented in this paper. A moving coordinate was introduced to reduce the difficulty of modeling the moving tool. Heat input from the tool shoulder and the tool pin were considered in the model. The plastic deformation heat was introduced into the model, too. It is clear that the heat production increased owing to plastic deformation, and this process depends on the stress level. Temperature measurement experiments were done to validate the calculated results. The calculated results were in good agreement with the experimental results. Preheating the workpiece is beneficial to obtain a good weld seam.

scholarly journals Analysis of Tools used in Friction Stir Welding process

2018 ◽  
Vol 8 (6) ◽  
Author(s):  
Akshansh Mishra ◽  
Adarsh Tiwari ◽  
Mayank Kumar Shukla ◽  
A. Razal Rose
Keyword(s):  
Friction Stir Welding ◽  
Critical Role ◽  
Base Material ◽  
Welding Process ◽  
Tool Geometry ◽  
Work Piece ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Tool Pin ◽  
Joining Process

A relatively new joining process, friction stir welding (FSW) produces no fumes; uses no filler material; and can join aluminium alloys, copper, magnesium, zinc, steels, and titanium. FSW sometimes produces a weld that is stronger than the base material. The tool geometry plays a critical role in material flow and governs the transverse rate at which FSW can be conducted. The tool serves three primary functions, i.e., (a) heating of the work piece, (b) movement of material to produce the joint, and (c) containment of the hot metal beneath the tool shoulder. Heating is created within the work piece by friction between both the rotating tool pin and shoulder and by severe plastic deformation of the work.

scholarly journals Parameters Optimization of Dissimilar Friction Stir Welding for AA7079 and AA8050 through RSM

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
M. Kavitha ◽  
V. M. Manickavasagam ◽  
T. Sathish ◽  
Bhiksha Gugulothu ◽  
A. Sathish Kumar ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Friction Stir Welding ◽  
Aluminium Alloy ◽  
Engineering Application ◽  
Parameters Optimization ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Dissimilar Friction Stir Welding ◽  
Constituent Elements ◽  
Tool Pin

Aluminium alloy is widely used in engineering application, and it can be classified based on the constituent elements or alloying elements. Aluminium alloy is preferred for the nature of its tensile strength, ductility, and corrosion resistance in this research to make a dissimilar friction stir welding joint of aluminium alloys 7079 and 8050 materials. The tensile strength of the weld joint is estimated by the influence of the response surface methodology approach. The welding is carried out by preferred process parameters with a tool speed of 1000–2500 rpm, tool pin diameter of 2–6 mm, welding speed of 50–300 mm/min, and tool shoulder diameter of 10–20 mm. The ANOVA analysis and the prediction of tensile strength were conducted efficiently. From the RSM analysis, the tool pin diameter mostly modified the output of the result.

scholarly journals Temperature Monitoring and Material Flow Characteristics of Friction Stir Welded 2A14-t6 Aerospace Aluminum Alloy

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3387 ◽  
Author(s):  
Tingke Wu ◽  
Fengqun Zhao ◽  
Haitao Luo ◽  
Haonan Wang ◽  
Yuxin Li
Keyword(s):  
Friction Stir Welding ◽  
Material Flow ◽  
Flow Model ◽  
Welding Process ◽  
Temperature Monitoring ◽  
Measuring System ◽  
Welding Parameters ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Tool Pin

Aiming at the problems that the temperature in the welding area of friction stir welding (FSW) is difficult to measure and the joints are prone to defects. Hence, it is particularly important to study the material flow in the welding area and improve the welding quality. The temperature of the tool shoulder and the tool pin was monitored by the wireless temperature measuring system. The finite element model of friction stir welding was established and the welding conditions were numerically simulated. The flow law of material of the friction stir welding process was studied by numerical simulation. The material flow model was established by combining the microstructure analysis results, and the forming mechanism of the defects was analyzed. The results show that the temperature in the welding zone is the highest at 1300 rpm, and the temperature at the tool shoulder is significantly higher than that at the tool pin in the welding stage. When high-rotation speeds (HRS) are chosen, the material beneath the tool shoulder tends to be extruded into the pin stirred zone (PSZ) after flowing back to the advancing side. This will cause turbulence phenomenon in the advancing side of the joint, which will easily lead to the formation of welding defects. In the future, temperature monitoring methods and the flow model of material can be used to optimize the welding parameters.

Numerical and experimental study of the heat transfer process in friction stir welding

2003 ◽  
Vol 217 (1) ◽  
pp. 73-85 ◽  
Author(s):  
M Song ◽  
R Kovacevic
Keyword(s):  
Heat Transfer ◽  
Friction Stir Welding ◽  
Transfer Process ◽  
Three Dimensional ◽  
Heat Transfer Process ◽  
Frictional Heat ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Tool Pin ◽  
Good Agreement

A mathematical model to describe the detailed three-dimensional transient heat transfer process in friction stir welding (FSW) is presented. This work is both theoretical and experimental. An explicit central differential scheme is used in solving the control equations, the heat transfer phenomena during the tool penetrating, the welding and the tool-removing periods that are studied dynamically. The heat input from the tool shoulder is modelled as a frictional heat and the heat from the tool pin is modelled as a uniform volumetric heat generated by the plastic deformation near the pin. The temperature variation during the welding is also measured to validate the calculated results. The calculated results are in good agreement with the experimental data.

scholarly journals Influence of material velocity on heat generation during linear welding stage of friction stir welding

2016 ◽  
Vol 20 (5) ◽  
pp. 1693-1701
Author(s):  
Alin Murariu ◽  
Darko Veljic ◽  
Dragana Barjaktarevic ◽  
Marko Rakin ◽  
Nenad Radovic ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Friction Stir Welding ◽  
Heat Generation ◽  
Welding Process ◽  
Slip Rate ◽  
Frictional Heat ◽  
Al Alloy ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Tool Pin

The heat generated during friction stir welding (FSW) process depends on plastic deformation of the material and friction between the tool and the material. In this work, heat generation is analysed with respect to the material velocity around the tool in Al alloy Al2024-T351 plate. The slip rate of the tool relative to the workpiece material is related to the frictional heat generated. The material velocity, on the other hand, is related to the heat generated by plastic deformation. During the welding process, the slippage is the most pronounced on the front part of the tool shoulder. Also, it is higher on the retreating side than on the advancing side. Slip rate in the zone around the tool pin has very low values, almost negligible. In this zone, the heat generation from friction is very low, because the material is in paste-like state and subjected to intensive plastic deformation. The material flow velocity around the pin is higher in the zone around the root of the pin. In the radial direction, this quantity increases from the pin to the periphery of the tool shoulder.

Overview of Texture Evolution during Friction Stir Welding of Stainless Steel Using Crystal Plasticity and EBSD

2007 ◽  
Vol 550 ◽  
pp. 479-484 ◽  
Author(s):  
Jae Hyung Cho ◽  
Donald E. Boyce ◽  
Paul R. Dawson
Keyword(s):  
Stainless Steel ◽  
Friction Stir Welding ◽  
Crystal Plasticity ◽  
Texture Evolution ◽  
Three Dimensional ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Eulerian Formulation ◽  
Material Points ◽  
Tool Pin

Texture evolution during friction stir welding of stainless steel was investigated using both predictions by crystal plasticity and EBSD measurements. Two- and three-dimensional Eulerian formulations are used to model friction stir welding. Plane strain deformation is assumed in a two-dimensional model, and an initial uniform texture changes into a torsion texture with monoclinic sample symmetry after deformation. Around the tool pin, the texture strengthens, weakens and restrengthens repeatedly. It is found from a simple circular streamline model that the relative magnitudes of the deformation rate and spin along the streamlines decide textural stability. In order to consider more complicated material behaviors, such as movement along the thickness direction due to a threaded tool pin and a tool shoulder, a three-dimensional Eulerian formulation is also implemented. Materials starting under the tool shoulder travel down to the bottom, producing the longest material streamlines. Those material points are predicted to have stronger texture components than others. EBSD results are compared with the predictions.

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