Computational Analysis on Weld Formation Mechanism during Self-Reacting Friction Stir Welding

2020 ◽  
pp. 1-15
Author(s):  
Chenyu Zhao ◽  
Xun Liu
Keyword(s):  
Boundary Condition ◽  
Shear Stress ◽  
Friction Stir Welding ◽  
Shear Layer ◽  
Formation Mechanism ◽  
Fluid Model ◽  
Three Dimensional ◽  
Welding Process ◽  
Weld Formation ◽  
Friction Stir

Abstract Three-dimensional computational fluid dynamics models are developed to understand physical principles of self-reacting friction stir welding process. A novel approach of predicting the weld microstructure based on plastic strain distribution at cross-section behind the tool is proposed and verified with experimental results. Limitations and credibility of shear stress and velocity tool/workpiece boundary condition are evaluated from the perspective of the weld formation mechanism. The importance of the shear layer and its sticking/sliding transition state in weld formation mechanism is emphasized. From modeling perspective, shear stress boundary, which only represents a sliding condition, neglects the movement and effects of this shear layer. When shear layer is formed, due to the velocity discontinuity which could not be captured in fluid model, velocity boundary condition, which represents an averaging effect of sticking/sliding transition between tool and shear layer, is needed.

Mathematical Model for Multi-Component Forces and Torque Determination in Friction Stir Welding

2011 ◽  
Vol 230-232 ◽  
pp. 1255-1259
Author(s):  
T. Khairuddin Jauhari ◽  
I.P. Almanar ◽  
Hussain Zuhailawati
Keyword(s):  
Mathematical Model ◽  
Friction Stir Welding ◽  
Early Stage ◽  
Three Dimensional ◽  
Welding Process ◽  
Temperature Dependent ◽  
Metallic Material ◽  
Friction Stir ◽  
Work Material ◽  
Force Components

Major works concentrated on the energy conversion from mechanical friction work to heat; emphasized on the immediate contact surface of work material and rotating welding tool but with no in-depth analytical study to relate the loads that are transferred to the work material and the welding fixture especially at early stage of heat generation. In this work, a mathematical model is developed to predict three-dimensional force components and axial torque of the rotating tool based on contact mechanic principle in relation to Al6061 temperature-dependent material properties. The model shows the ability to be possibly adapted for different metallic material and physical properties. It suggests the exerted torque and loads calculation endured by work material involving friction and shear mechanism of two static-dynamic contacting surface; rotating rotational tool and the fixed work material, to be used as one of the option for optimization of the welding process such as to determine the ratio of slip, non-slip contact condition through comparisons of experimental and computer simulation on the Friction Stir Welding process.

Numerical Simulations of Friction Stir Welding Process and Subsequent Post Weld Cold Rolling Process

2009 ◽  
Vol 419-420 ◽  
pp. 433-436 ◽  
Author(s):  
Yu Jie Sun ◽  
Yong Zang ◽  
Qing Yu Shi
Keyword(s):  
Residual Stress ◽  
Friction Stir Welding ◽  
Three Dimensional ◽  
Welding Process ◽  
Rolling Process ◽  
Mechanical Analysis ◽  
Fusion Welding ◽  
Work Piece ◽  
Friction Stir ◽  
Longitudinal Residual Stress

A sequential coupled three-dimensional thermo-mechanical analysis was conducted first to simulate friction stir welding (FSW) of aluminum alloy. In thermal analysis, the model included adaptive heat source, contact heat transfer both between work piece and clamps and between work piece and backing board etc; in the mechanical analysis, the model involved contact interaction both between work piece and clamps and between work piece and backing board, mechanical load of tool etc. The simulation results indicate that the longitudinal residual stress is unsymmetrical about weld centerline; the magnitude of longitudinal residual stress for FSW process is lower than that for fusion welding process. Based on simulated results of FSW process, a three-dimensional elastic-plastic analysis was then carried out to simulate rolling process, the simulation result show that rolling process not only causes a marked reduction in the longitudinal tensile residual but also reverse the sign of the longitudinal residual stress.

scholarly journals An Alternative Pressure-dependent Friction Boundary Condition for Modeling Self-reacting Friction Stir Welding

2021 ◽  
Author(s):  
CHENYU ZHAO ◽  
Xun Liu
Keyword(s):  
Boundary Condition ◽  
Friction Stir Welding ◽  
Cross Section ◽  
Welding Speed ◽  
Defect Formation ◽  
Computational Results ◽  
Weld Formation ◽  
Void Defect ◽  
Friction Stir ◽  
Cross Section Geometry

Abstract A pressure-dependent friction boundary condition is developed based on wear theory for modeling self-reacting friction stir welding using computational fluid dynamics approach. The importance of shear layer in weld formation is emphasized. Effects of welding speed on the weld cross section geometry can be robustly captured with this newly developed boundary condition. Computational results showed at higher welding speed, the distance between the TMAZ boundary and the pin periphery at the advancing side is reduced, which corresponds to the experimental observations. This tendency could serve as a numerical criterion to predict void defect formation.

scholarly journals Technology and equipment for friction stir preweld edge preparation

2021 ◽  
Vol 21 (2) ◽  
pp. 163-170
Author(s):  
Y. G. Lyudmirsky ◽  
А. N. Soloviev ◽  
М. V. Soltovets ◽  
R. R. Kotlyshev ◽  
I. V. Mironov ◽  
...  
Keyword(s):  
Finite Element ◽  
Theoretical Model ◽  
Friction Stir Welding ◽  
Geometric Model ◽  
Three Dimensional ◽  
Welding Process ◽  
Element Model ◽  
Element Mesh ◽  
Laboratory Equipment ◽  
Friction Stir

Introduction. Friction stir welding is widely used due to certain advantages of this method. Factors that reduce the strength of joints made of high-strength aluminum alloys are considered. When welding flat sheets, an effective way to increase the strength of the weld is edge thickening. The paper proposes a method for such thickening. A device is developed, calculations and experiments are carried out. Materials and Methods. Laboratory equipment has been developed to provide simultaneous thickening of two edges to be welded. The main component of this equipment is a steel roller, which is rolled along the edges of two blanks and thickens them due to plastic deformation. The same setup can be used for the friction stir welding process. To calculate the geometry of the thickened edges and the parameters of the deforming roller depending on the value of the edge settlement, a mathematical model based on the contact problem for elastic (roller) and elastoplastic (blank) bodies with a bilinear hardening law has been developed. A three-dimensional simplified geometric model of the facility with account of its symmetry has been constructed. On the contact surfaces, special contact finite elements were selected and the finite element mesh was refined. The numerical implementation of the model was carried out in the ANSYS package. Results. The theoretical model provides assessing the stress-strain state of interacting elements. On the basis of the developed finite element model, the parameters of the thickened edges are calculated, and the geometry of the thickened edges is defined. Using the developed laboratory equipment, full-scale experiments on thickening the edges of the blanks were carried out. The experimental results confirm the adequacy of the developed theoretical model and calculations based on it. The possibility of adjusting the size of the thickened edges is shown.Discussion and Conclusion. A technology for obtaining thickened edges in places of welds is proposed. It will reduce the metal consumption of structures and ensure the bearing capacity of welded joints not lower than similar characteristics of the base metal. A theoretical model of the process is developed, and a numerical experiment providing the selection of the process parameters is carried out. 

scholarly journals A Robust Numerical Procedure for the Thermomechanical Flow Simulation of Friction Stir Welding Process Using an Adaptive Element-Free Galerkin Method

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
C. T. Wu ◽  
Wei Hu ◽  
Hui-Ping Wang ◽  
Hongsheng Lu
Keyword(s):  
Friction Stir Welding ◽  
Galerkin Method ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Welding Process ◽  
Element Free Galerkin Method ◽  
Convex Approximation ◽  
Friction Stir ◽  
Element Free Galerkin ◽  
Element Free

A meshfree modeling technique of material flow in the three-dimensional multiphysics thermomechanical friction stir welding process is presented. In this numerical model, the discretization in space is derived by the Element-Free Galerkin method using a Lagrangian meshfree convex approximation. The discrete thermal and mechanical equations are weakly coupled as the time advances using a forward difference scheme. A mortar contact algorithm is employed to model the stirring effect and heat generation due to frictional contact. Heat conductance between contacting bodies is considered as a function of contact pressure. A two-way adaptive procedure is introduced to the coupled thermomechanical system to surpass potential numerical problems associated with the extensive material deformation and spatial discretization. In each adaptive phase, a consistent projection operation utilizing the first-order meshfree convex approximation is performed to remap the solution variables. Finally, a three-dimensional multiphysics thermomechanical coupled friction stir welding problem is analyzed to demonstrate the effectiveness of the present meshfree numerical procedure.

3-D Finite Element Simulation of Friction Stir Welding Process of Non Similar Aluminum-Copper Sheets

2011 ◽  
Vol 312-315 ◽  
pp. 953-958 ◽  
Author(s):  
A. Alimoradi ◽  
M. Loh-Mousavi ◽  
R. Salekrostam
Keyword(s):  
Finite Element ◽  
Friction Stir Welding ◽  
Heat Input ◽  
Three Dimensional ◽  
Welding Process ◽  
Process Conditions ◽  
Friction Stir ◽  
Two Parameters ◽  
Tool Pin ◽  
The Relationship

The Friction Stir Welding (FSW), a relatively new welding process, was developed in 1991 at the Welding Institute near Cambridge, England. There are two tool speeds to be considered in friction-stir welding; how fast the tool rotates and how quickly it traverses the interface. These two parameters have considerable importance and must be chosen with care to ensure a successful and efficient welding cycle. The relationship between the welding speeds and the heat input during welding is complex. In this paper the friction stir welding (FSW) process of stainless steel alloys has been modeled using a three dimensional finite element method. A coupled thermal viscoplastic model was used for the simulation. Tool speeds and temperature distribution are coupled and solved together using this method. The relationship between the welding speeds and the heat input during welding is obtained by numerical analysis, and the stress contour occurred by temperature field and tool force is surveyed. In addition, the effects of FSW process conditions on heating mainly near the tool pin are investigated in this paper.

Evaluation of Thermal Distribution in Friction Stir Welding on Dissimilar Materials (Cu-Al) Using Infrared Thermography and Numerical Simulation

2016 ◽  
Vol 1138 ◽  
pp. 113-118
Author(s):  
Monica Iordache ◽  
Eduard Nitu ◽  
Claudiu Badulescu ◽  
Doina Iacomi ◽  
Lia Nicoleta Boţilă ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Infrared Thermography ◽  
Three Dimensional ◽  
Welding Process ◽  
Dissimilar Materials ◽  
Element Model ◽  
Fe Model ◽  
Friction Stir ◽  
Solid State Joining ◽  
Joining Process

Friction Stir Welding (FSW) is a solid state joining process realized by the interaction between a non-consumable welding tool that rotates on the contact surfaces of the combined parts. Welding dissimilar materials aluminum and copper by FSW are of great interest because Al and Cu are two most common engineering materials widely used in many industries. This paper presents an investigation concerning the influence of the rotation of the tool on temperatures during the welding process. Also, the welding of copper and aluminum materials by FSW process was simulated using a finite element model. Three-dimensional FE model has been developed in ABAQUS/Explicit using the Coupled Eulerian Lagrangian method, the Johnson–Cook material law and the Coulomb’s Law of friction and was validated by infrared thermography method and thermocouple measurement.

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