A Mathematical Formulation for Calculating Temperature Dependent Friction Coefficient Values: Application in Friction Stir Welding (FSW)

2017 ◽  
Vol 379 ◽  
pp. 73-82 ◽  
Author(s):  
Bahman Meyghani ◽  
Mokhtar Awang ◽  
Sattar Emamian
Keyword(s):  
Friction Stir Welding ◽  
Friction Coefficient ◽  
Mathematical Formulation ◽  
Governing Equations ◽  
Temperature Dependent ◽  
Element Analysis ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Precise Calculation ◽  
The Finite Element Analysis

High rotational motion from the welding tool generates a significant amount of the heat during friction stir welding (FSW). Basically, during FSW the heat is mostly coming from the frictional force between the tool shoulder and the plates. Therefore, a precise calculation of the friction coefficient can increase the accuracy of the finite element analysis (FEA) of the process. However, researchers have applied constant values, and that causes a gap between the reality and the simulated model especially after the welding plunging step. In this study, a mathematical formulation is proposed in order to calculate the temperature dependent values of the friction coefficient and also to explore the influence of the temperature in the friction coefficient. To solve the governing equations of the process, the MATLAB®software is used. The results indicate that, from 25°C to the AA 6061-T6 melting point (580°C), the values of the friction coefficient fall steadily in a range of 0.207089 to 0.000582. Furthermore, the material shear stress and the material yield stress decrease consistently as the temperature rises. Consequently, the influence of the temperature in the contact input parameters and the material properties are discussed in detail and a good correlation with the published results is achieved.

Effects of Heat Dissipation from Friction Stir Welding to Microstructures of Semi-Solid Cast 6063 Al Alloy

2021 ◽  
Vol 904 ◽  
pp. 70-75
Author(s):  
Chaiyoot Meengam ◽  
Kittima Sillapasa ◽  
Yotsakorn Pratumwal ◽  
Somboon Otarawanna
Keyword(s):  
Friction Stir Welding ◽  
Heat Dissipation ◽  
Maximum Temperature ◽  
Al Alloy ◽  
Element Analysis ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Measurement Results ◽  
6063 Al Alloy ◽  
Semi Solid

In this work, temperature distribution in semi-solid cast 6063 aluminum alloy workpieces during friction stir welding (FSW) was determined by finite element analysis (FEA). The FEA results were validated by comparing them with the measurement results from thermocouples. The maximum temperature of 534.2oC was predicted at the workpiece surface contacted with the tool shoulder. The temperature profiles obtained from FEA were used to explain microstructural changes during FSW. It was observed that relatively high temperature made α-Al grains became elongated and Mg2Si intermatalics turned into a rod-like morphology with round edges.

Coupled Thermo-Mechanical Modelling of Friction Stir Welding

2007 ◽  
Author(s):  
Hongjun Li ◽  
Donald Mackenzie
Keyword(s):  
Friction Stir Welding ◽  
Material Properties ◽  
Numerical Models ◽  
Transient Temperature ◽  
Temperature Dependent ◽  
Element Analysis ◽  
Significant Development ◽  
Friction Stir ◽  
Welding Technology ◽  
Ale Formulation

The significant development in welding technology for the last decade is the emergence of Friction Stir Welding (FSW). This paper investigates the thermo-mechanical phenomena involved in the FSW welded plates by Finite Element Analysis. The numerical models are fully thermo-mechanically coupled in that heat generated by material plastic deformation and temperature dependent mechanical material properties are taken into account. The whole FSW process is divided into three distinct stages: plunge, dwell and transverse. The transient temperature, stress and velocity of material particles around the tool are reported from the numerical models. It is found that temperature plays an important role in obtaining a sound weld, and only when a proper temperature field is established can the FSW process proceed to next stage. It is also found that it is not possible to fully simulate the FSW process using the ALE formulation without full remeshing during the travel stage of the process due to excessive element distortion.

Thermo-Mechanical Modelling of Friction Stir Welding Process

2013 ◽  
Vol 774-776 ◽  
pp. 1155-1159 ◽  
Author(s):  
Xiao Cong He
Keyword(s):  
Finite Element Analysis ◽  
Friction Stir Welding ◽  
Mechanical Behaviour ◽  
Material Flow ◽  
Welding Process ◽  
Element Analysis ◽  
Friction Stir ◽  
Mechanical Modelling ◽  
Major Factors ◽  
Realistic Prediction

Friction stir welding (FSW) is a solid-state welding process where no gross melting of the material being welded takes place. Numerical modelling of the FSW process can provide realistic prediction of the thermo-mechanical behaviour of the process. Latest literature relating to finite element analysis (FEA) of thermo-mechanical behaviour of FSW process is reviewed in this paper. The recent development in thermo-mechanical modelling of FSW process is described with particular reference to two major factors that influence the performance of FSW joints: material flow and temperature distribution. The main thermo-mechanical modelling used in FSW process are discussed and illustrated with brief case studies from the literature.

A Thermo-Fluid Analysis of the Friction Stir Welding Process

2007 ◽  
Vol 539-543 ◽  
pp. 3832-3837 ◽  
Author(s):  
D. Jacquin ◽  
Christophe Desrayaud ◽  
Frank Montheillet
Keyword(s):  
Friction Stir Welding ◽  
Bulk Material ◽  
Welding Process ◽  
Vertical Motion ◽  
Velocity Fields ◽  
Fluid Simulation ◽  
Metal Sheet ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Fluid Analysis

The thermo-mechanical simulation of Friction Stir Welding focuses the interest of the welding scientific and technical community. However, literature reporting material flow modeling is rather poor. The present work is based on the model developed by Heurtier [2004] and aims at improving this thermo-fluid simulation developed by means of fluid mechanics numerical and analytical velocity fields combined together. These various velocity fields are investigated separately and especially according to the power dissipated during the flow. Boundary conditions are considered through a new approach based on the kinematic analysis of the thread of the pin. An equilibrium is established between the vertical motion of the bulk material dragged in the depth of the metal sheet, and its partial circulation around the pin. The analyses of the obtained velocity fields enable the understanding of the welded zone asymmetry and highlights the bulk material mixing between the welded coupons in the depth of the sheet. A regression is performed on the relative sliding velocity of the aluminium according to the surface of the tool: shoulder and pin. Two dimension flow lines in the depth of the metal sheet are then obtained and successfully compared with the results obtained by Colegrove (2004) [1].

scholarly journals 3D-Printed Tool Shoulder Design for the Analogue Modelling of Bobbin Friction Stir Weld Joint Quality

2021 ◽  
Vol 21 (1) ◽  
pp. 27-42
Author(s):  
A. Tamadon ◽  
D. J. Pons ◽  
K. Chakradhar ◽  
J. Kamboj ◽  
D. Clucas
Keyword(s):  
Friction Stir Welding ◽  
Cross Sections ◽  
Weld Joint ◽  
Flow Patterns ◽  
Friction Stir Weld ◽  
Butt Weld ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Analogue Modelling ◽  
3D Printed

Abstract A variety of tool shoulder designs comprising three families i.e. blade, spiral and circular shaped scrolls, were produced to improve the material flow and restrictions to avoid the tunnel void. The bobbin tools were manufactured by 3D printing additive manufacturing technology using solid filament. The butt weld joint was produced by each tool using plasticine as the workpiece material. The apparent surface features and bi-colour cross-sections provided a physical flow comparison among the shoulder designs. For the bobbin friction stir welding (BFSW), the tool shoulder with a three-spiral design produced the most stability with the best combination of the flow patterns on surface and cross-sections. The circular family tools showed a suitable intermixing on the surface pattern, while the blade scrolls showed better flow features within the cross-sections. The flow-driven effect of the shoulder features of the bobbin-tool design (inscribed grooves) was replicated by the 3D-printed tools and the analogue modelling of the weld samples. Similar flow patterns were achieved by dissimilar aluminium-copper weld, validating the accuracy of the analogue plasticine for the flow visualization of the bobbin friction stir welding.

Effects of Tool Pin Profile and Tool Shoulder Diameter on the Tensile Behaviour of Friction Stir Welded Joints of Aluminium Alloys

2014 ◽  
Vol 984-985 ◽  
pp. 586-591 ◽  
Author(s):  
R. Ashok Kumar ◽  
M.R. Thansekhar
Keyword(s):  
Friction Stir Welding ◽  
Aluminium Alloy ◽  
Tensile Properties ◽  
Welded Joints ◽  
Tensile Behaviour ◽  
Light Weight ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Shoulder Diameter ◽  
Weight Structures

— For fabricating light weight structures, it requires high strength-to weight ratio. AA6061 aluminium alloy is widely used in the fabrication of light weight structures. A356 aluminium alloy has wide spread application in aerospace industries. Friction stir welding is solid state joining process which is conducting for joining similar and dissimilar materials. The friction stir welding parameters play an important role for deciding the strength of welded joints. In this investigation, A356 and AA6061 alloys were friction stir welded by varying triangular, square, hexagonal pin profiles of tool keeping the remaining parameters same and AA6061 alloys were friction stir welded by varying tool shoulder diameter as 12mm,15mm,18mm without changing other parameters. Tensile properties of each joint have been analyzed microscopically. From the experimental results, it is observed that hexagonal pin profiled tool and 15mm shoulder diameter tool provides higher tensile properties when compared to other tools.

On the problem of tool destruction when obtaining fixed joints of thick-walled aluminum alloy blanks by friction welding with mixing

2021 ◽  
Vol 23 (3) ◽  
pp. 72-83
Author(s):  
Kirill Kalashnikov ◽  
◽  
Andrey Chumaevskii ◽  
Tatiana Kalashnikova ◽  
Aleksey Ivanov ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Friction Welding ◽  
Welding Process ◽  
High Strength ◽  
Heterogeneous Structure ◽  
Adhesive Interaction ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Electric Erosion

Introduction. Among the technologies for manufacturing rocket and aircraft bodies, marine vessels, and vehicles, currently, more and more attention is paid to the technology of friction stir welding (FSW). First of all, the use of this technology is necessary where it is required to produce fixed joints of high-strength aluminum alloys. In this case, special attention should be paid to welding thick-walled blanks, as fixed joints with a thickness of 30.0 mm or more are the target products in the rocket-space and aviation industries. At the same time, it is most prone to the formation of defects due to uneven heat distribution throughout the height of the blank. It can lead to a violation of the adhesive interaction between the weld metal and the tool and can even lead to a destruction of the welding tool. The purpose of this work is to reveal regularities of welding tool destruction depending on parameters of friction stir welding process of aluminum alloy AA5056 fixed joints with a thickness of 35.0 mm. Following research methods were used in the work: the obtaining of fixed joints was carried out by friction welding with mixing, the production of samples for research was carried out by electric erosion cutting, the study of samples was carried out using optical metallography methods. Results and discussion. As a result of performed studies, it is revealed that samples of aluminum alloy with a thickness of 35.0 mm have a heterogeneous structure through the height of weld. There are the tool shoulder effect zone and the pin effect zone, in which certain whirling of weld material caused by the presence of grooves on tool surface is distinctly distinguished. It is shown that the zone of shoulders effect is the most exposed to the formation of tunnel-type defects because of low loading force and high welding speeds. It is revealed that tool destruction occurs tangentially to the surface of the tool grooves due to the high tool load and high welding speeds.

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