Modeling Damage Evolution in Friction Stir Welding Process

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Youliang He ◽  
Paul R. Dawson ◽  
Donald E. Boyce
Keyword(s):  
Friction Stir Welding ◽  
Void Growth ◽  
Evolution Equations ◽  
Volume Fraction ◽  
Welding Process ◽  
Three Dimensions ◽  
Element Formulation ◽  
Operational Parameters ◽  
Friction Stir ◽  
Welding Processes

The evolution of voids (damage) in friction stir welding processes was simulated using a void growth model that incorporates viscoplastic flow and strain hardening of incompressible materials during plastic deformation. The void growth rate is expressed as a function of the void volume fraction, the effective deformation rate, and the ratio of the mean stress to the strength of the material. A steady-state Eulerian finite element formulation was employed to calculate the flow and thermal fields in three dimensions, and the evolution of the strength and damage was evaluated by integrating the evolution equations along the streamlines obtained in the Eulerian configuration. The distribution of internal voids within the material was qualitatively compared with experimental results, and a good agreement was observed in terms of the spatial location of voids. The effects of pin geometry and operational parameters such as tool rotational and travel speeds on the evolution of damage were also examined.

Numerical Study of the Tool Rake Angle Effect on the Material Flow in Friction Stir Welding Process

2007 ◽  
Author(s):  
Hosein Atharifar ◽  
Radovan Kovacevic
Keyword(s):  
Friction Stir Welding ◽  
Material Flow ◽  
Numerical Study ◽  
Welding Process ◽  
Rake Angle ◽  
Heat Transfer Analysis ◽  
Tool Geometry ◽  
Friction Stir ◽  
Tool Pin ◽  
Welding Processes

Minimizing consumed energy in friction stir welding (FSW) is one of the prominent considerations in the process development. Modifications of the FSW tool geometry might be categorized as the initial attempt to achieve a minimum FSW effort. Advanced tool pin and shoulder features as well as a low-conductive backing plate, high-conductive FSW tools equipped with cooling fins, and single or multi-step welding processes are all carried out to achieve a flawless weld with reduced welding effort. The outcomes of these attempts are considerable, primarily when the tool pin traditional designs are replaced with threaded, Trifiute or Trivex geometries. Nevertheless, the problem remains as to how an inclined tool affects the material flow characteristics and the loads applied to the tool. It is experimentally proven that a positive rake angle facilitates the traverse motion of the FSW tool; however, few computational evidences were provided. In this study, numerical material flow and heat transfer analysis are carried out for the presumed tool rake angle ranging from −4° to 4°. Afterwards, the effects of the tool rake angle to the dynamic pressure distribution, strain-rates, and velocity profiles are numerically computed. Furthermore, coefficients of drag, lift, and side force and moment applied to the tool from the visco-plastic material region are computed for each of the tool rake angles. Eventually, this paper confirms that the rake angle dramatically affects the magnitude of the loads applied to the FSW tool, and the developed advanced numerical model might be used to find optimum tool rake angle for other aluminum alloys.

Solid State Welding Process for Aerospace Components

2015 ◽  
Vol 1119 ◽  
pp. 597-600
Author(s):  
Hyun Ho Jung ◽  
Ye Rim Lee ◽  
Jong Hoon Yoon ◽  
Joon Tae Yoo ◽  
Kyung Ju Min ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Solid State ◽  
Structural Integrity ◽  
Welding Process ◽  
Diffusion Welding ◽  
Intimate Contact ◽  
Friction Stir ◽  
Base Materials ◽  
Welding Processes ◽  
And Diffusion

Since solid state welded joint is formed from an intimate contact between two metals at temperatures below the melting point of the base materials, the structural integrity of welding depends on time, temperature, and pressure. This paper provides some of examples of friction stir welding and diffusion welding process for aerospace components. Friction stir welding process of AA2195 was developed in order to study possible application for a large fuel tank. Massive diffusion welding of multiple titanium sheets was performed and successful results were obtained. Diffusion welding of dissimilar metals of copper and stainless steel was necessary to manufacture a scaled combustion chamber. Diffusion welding of copper and steel was performed and it is shown that the optimum condition of diffusion welding is 7MPa at 890°C, for one hour. It is shown that solid state welding processes can be successfully applied to fabricate lightweight aerospace parts.

Modeling of the Plastic Characteristics of AA6082 for the Friction Stir Welding Process

2015 ◽  
Vol 639 ◽  
pp. 309-316
Author(s):  
Sergio Pellegrino ◽  
Livan Fratini ◽  
Marion Merklein ◽  
Wolfgang Böhm ◽  
Hung Nguyen
Keyword(s):  
Friction Stir Welding ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Flow Behavior ◽  
Welding Process ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Friction Stir ◽  
Friction Stir Welding Process ◽  
Welding Processes

Focus of this paper is to model the plastic forming behavior of AA6082, in order to develop the numerical FE analysis of the friction stir welding processes and the simulation of subsequent forming processes. During the friction stir welding process, the temperatures reached are until 500 °C and have a fundamental role for the correct performance of the process so the material data has to show a temperature dependency. Because of the tool rotation a strain rate sensitivity of the material has to be respected as well. In this context, the general material characteristics of AA6082 were first identified for different stress states. For the uniaxial state the standard PuD-Al used in the automotive industry was applied, for the shear state the ASTM B831-05 was used and for biaxial states the ISO 16842 was exploited. To characterize the plastic flow behavior of the AA6082 at elevated temperatures tensile tests were performed according to DIN EN ISO 6892-2 from 25 °C until 500 °C with a strain rate from 0.1 s-1up to 6.5 s-1.

scholarly journals A Multi-attribute Control Chart for Monitoring Friction Stir Welding Process Considering Small Sample Sizes

2018 ◽  
Vol 23 (4) ◽  
pp. 474-484
Author(s):  
Esmeralda Ramírez-Méndez ◽  
Mario Cantu-Sifuentes ◽  
David Salvador González-González ◽  
Argelia Fabiola Miranda-Pérez ◽  
Rolando Javier Praga-Alejo
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Control Chart ◽  
Welding Process ◽  
Small Sample ◽  
Sample Sizes ◽  
Process Data ◽  
Friction Stir ◽  
Small Sample Sizes ◽  
Welding Processes

Abstract Often, welding processes used in the industry affect the mechanical properties of materials and quality of a manufactured product. There is, however, an alternative process named Friction Stir Welding (FSW), which is an solid state welding process developed to weld light alloys without compromising their mechanical properties. It is of interest to monitor the performance of FSW process to detect loss of quality. In practice, superficial and internal defects can be found; they can be identified through simple visual inspection and through visual recognition on destructive testing respectively, both procedures represent inspection by attributes. Therefore a multi-attribute control chart is assessed to monitor the process. Commonly, multi-attribute control charts involve high sampling rates to ensure accurate monitoring. In this paper, a multi-attribute control chart is proposed, considering the use of empirical control limits, instead of the theoretical ones, in order to improve its accuracy and lessen the small sample sizes effect. The performance of proposed approaches is analyzed by means of Monte Carlo simulation. The results suggest that the performance of the empirical designs is better than the theoretical ones in all tested cases. Finally, the results of monitoring FSW process data are detailed.

Empirical Dynamic Modeling of Friction Stir Welding Processes

2007 ◽  
Author(s):  
Xin Zhao ◽  
Prabhanjana Kalya ◽  
Robert G. Landers ◽  
K. Krishnamurthy
Keyword(s):  
Steady State ◽  
Friction Stir Welding ◽  
Process Parameters ◽  
Dynamic Models ◽  
Welding Process ◽  
Recursive Least Squares ◽  
Finite Difference Schemes ◽  
Power Relationship ◽  
Friction Stir ◽  
Welding Processes

Current Friction Stir Welding (FSW) process modeling research is concerned with the detailed analysis of local effects such as material flow, heat generation, etc. These detailed thermo-mechanical models are typically solved using finite element or finite difference schemes and require substantial computational effort to determine temperature, forces, etc. at a single point in time. Dynamic models describing the total forces acting on the tool throughout the entire welding process are required for the design of feedback control strategies and improved process planning and analysis. In this paper, empirical models relating the process parameters (i.e., plunge depth, traverse rate, and rotation speed) to the process variables (i.e., axial, traverse, and lateral forces) are developed to understand their dynamic relationship. First, the steady-state relationship between the process parameters and variables is constructed, and the relative importance of each process parameter on each process variable is determined. Next, the dynamic process response characteristics are determined using Recursive Least-Squares. The results indicate that the steady-state relationship between the process parameters and variables is well characterized by a nonlinear power relationship, and the dynamic responses are well characterized by low-order linear equations. Experiments are conducted that validate the developed FSW dynamic models.

Friction Stir Welding of Composite Materials with Metallic Matrix: A Brief Review

2015 ◽  
Vol 809-810 ◽  
pp. 449-454 ◽  
Author(s):  
Ana Boşneag ◽  
Marius Adrian Constantin ◽  
Eduard Niţu ◽  
Monica Iordache ◽  
Alin Rizea
Keyword(s):  
Composite Materials ◽  
Friction Stir Welding ◽  
Welded Joint ◽  
Metallic Matrix ◽  
Welding Process ◽  
Fusion Welding ◽  
Industrial Environment ◽  
Friction Stir ◽  
Current State ◽  
Welding Processes

Composite materials with metallic matrix are increasingly require more than traditional materials metallic, being lighter, more reliable and with their superior properties like: rigidity, tensile strength, flexural strength, fatigue strength, modulus of elasticity, hardness, etc. Due to these advantages, above mentioned, this process has largely penetrated industrial environment. Despite these advantages, there are restrictions on their combination through traditional fusion welding methods so that was passed at the solid-state welding processes, respectively at Friction Stir Welding (FSW). Our researches presents in this brief review: some general ideas about composite materials with metallic matrix and Friction Stir Welding process, appearance and benefits, basic information about the process and composite materials welded by this process, shows the current state of the research with respect to behaviour macrostructure, microstructure, microhardness, tensile properties and defects of the welded joint between composite materials with metallic matrix.

Design and Implementation of Nonlinear Force Controllers for Friction Stir Welding Processes

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Xin Zhao ◽  
Prabhanjana Kalya ◽  
Robert G. Landers ◽  
K. Krishnamurthy
Keyword(s):  
Friction Stir Welding ◽  
Axial Force ◽  
Welding Process ◽  
Smith Predictor ◽  
Pole Placement ◽  
Communication Delays ◽  
Nonlinear Feedback ◽  
Friction Stir ◽  
Design And Implementation ◽  
Welding Processes

In friction stir welding (FSW) processes, force control can be used to achieve good welding quality. This paper presents the systematic design and implementation of FSW force controllers. The axial and path forces are modeled as nonlinear functions of the FSW process parameters (i.e., plunge depth, tool traverse rate, and tool rotation speed). Equipment models, which include communication delays, are constructed to relate the commanded and measured actuator signals. Based on the dynamic process and equipment models, nonlinear feedback controllers for the axial and path forces are designed using the polynomial pole placement technique. The controllers are implemented in a Smith predictor-corrector structure to compensate for the inherent equipment communication delays, and the controller parameters are tuned to achieve the best closed loop response possible given equipment limitations. In the axial force controller implementation, a constant axial force is maintained, even when gaps are encountered during the welding process. In the path force controller implementation, a constant path force is maintained, even in the presence of gaps, and wormhole generation during the welding process is eliminated by regulating the path force.

Investigation of the effects of welding variables on the welding defects of the friction stir welded high density polyethylene sheets

2021 ◽  
pp. 009524432110588
Author(s):  
Mustafa Kemal Bilici
Keyword(s):  
Friction Stir Welding ◽  
High Density Polyethylene ◽  
Welding Process ◽  
High Strength ◽  
High Density ◽  
Welding Parameters ◽  
Friction Stir ◽  
Wide Range ◽  
Welding Defects ◽  
Welding Processes

Modern thermoplastic materials are used in an expanding range of engineering applications, such as in the automotive industry, due to their enhanced stress-to-weight ratios, toughness, a very short time of solidification, and a low thermal conductivity. Recently, friction stir welding has started to be used in joining processes in these areas. There are many factors that affect weld performance and weld quality in friction stir welding (FSW). These factors must be compatible with each other. Due to the large number of welding variables in friction stir welding processes, it is very difficult to achieve high strength FSW joints, high welding performance, and control the welding process. Welding variables that form the basis of friction stir welding; machine parameters, tool variables, and material properties are divided into three main groups. Each welding variable has different effects on the weld joint. In this study, friction stir welds were made on high density polyethylene (HDPE) sheets with factors selected from machine parameters and welding tool variables. Although the welding performance, quality, and strength gave good results in some conditions, successful joints could not be realized in some conditions. In particular, welding defects occurring in the combination of HDPE material with FSW were investigated. Welding quality, defects, and performances were examined with macrostructure. In addition, the tensile strength values of some the joints were determined. The main purpose of this study is to determine the welding defects that occur at the joints. The causes of welding defects, prevention methods, and which weld variables caused were investigated. Welding parameters and welding defects caused by welding tools were examined in detail. In addition, the factors causing welding defects were changed in a wide range and the changes in the defects were observed.

scholarly journals Influence of Tool Tilt Angle on Material Flow and Defect Generation in Friction Stir Welding of AA2219

2018 ◽  
Vol 68 (5) ◽  
pp. 512-518 ◽  
Author(s):  
Suresh Meshram ◽  
Madhusudhan Reddy
Keyword(s):  
Friction Stir Welding ◽  
Process Parameters ◽  
Tilt Angle ◽  
Material Flow ◽  
Critical Role ◽  
Welding Process ◽  
Fusion Welding ◽  
Friction Stir ◽  
Tool Tilt Angle ◽  
Welding Processes

Heat treatable aluminium alloy AA2219 is widely used for aerospace applications, welded through gas tungsten and gas metal arc welding processes. Welds of AA2219 fabricated using a fusion welding process suffers from poor joint properties or welding defects due to melting and re-solidification. Friction stir welding (FSW) is a solid-state welding process and hence free from any solidification related defects. However, FSW also results in defects which are not related to solidification but due to improper process parameter selection. One of the important process parameters, i.e., tool tilt angle plays a critical role in material flow during FSW, controlling the size and location of the defects. Effect of tool tilt angle on material flow and defects in FSW is ambiguous. A study is therefore taken to understand the role of tool tilt angle on FSW defects. Variation in temperature, forces, and torque generated during FSW as a result of different tool tilt angles was found to be responsible for material flow in the weld, controlling the weld defects. An intermediate tool tilt angle (1o-2o) gives weld without microscopic defect in 7 mm thick AA2219 for a given set of other process parameters. At this tool tilt angle, x-force, and Z- force is balanced with viscosity and the material flow strain rate sufficient for the material to flow and fill internal voids or surface defects in the weld.

Friction Stir and Gas Tungsten Arc Welding of ZM21 Magnesium Alloy

2014 ◽  
Vol 909 ◽  
pp. 77-82
Author(s):  
Hari Krishna Kallipudi ◽  
Rama Koteswara Rao Sajja ◽  
Venkata Subba Rao Veera
Keyword(s):  
Friction Stir Welding ◽  
Magnesium Alloy ◽  
Arc Welding ◽  
Welding Process ◽  
Gas Tungsten Arc Welding ◽  
Friction Stir ◽  
Friction Stir Welding Process ◽  
Gas Tungsten Arc ◽  
Gas Tungsten ◽  
Welding Processes

Magnesium alloy ZM21 plates were welded using friction stir welding, a solid state process and gas tungsten arc welding which is a fusion welding process. Defect free, full penetration welds were obtained after several trials using different process parameters. The effect of welding processes on mechanical properties of Mg-Zn-Mn joints were evaluated using tensile tests, bend test, vickers micro hardness measurements and optical microscopy. Welds produced by Friction stir welding process exhibited superior tensile properties compared to Gas Tungsten Arc Welding process. Hardness reduction in the weld metals were observed for both the welding techniques. Friction stir welds showed finer grains in the weld nugget and in the heat affected zone. Both types of welds exhibited good bend ductility comparable to that of the base material. It has been concluded that both the processes are well suited to obtain sound welds of the magnesium alloy ZM21 and Friction stir welding process offers stronger welds.

Sign in / Sign up

Export Citation Format

Share Document