Search results for "FSW"
showing 10 items of 73 documents
Material Flow in FSW of AA7075 - T6 butt joint: numerical simulations and experimental verifications
2006
Friction stir welding (FSW) has reached a large interest in the scientific community and in the recent years also in the industrial environment, owing to the advantages of such solid state welding process with respect to the classic ones. Advanced finite element method tools are needed in order to develop an effective engineering of the processes; quantitative results can be acquired from numerical simulations once the basic information such as the material flow is certain. A 3D Lagrangian implicit coupled rigid viscoplastic model has already been developed by the authors to simulate FSW of butt joints. In the present paper the material flow in the FSW of AA7075–T6 butt joints is investigat…
Experimental Characterization of FSW T-Joints of Light Alloys
2007
Welding is playing a growing role in transport industry due to relevant advantages it allows. Friction Stir Welding is considered one of the most promising joining technologies, especially when it is applied to light alloys. Focusing attention on FSW of T-joints, several parameters have to be considered, and due to thermo-mechanical features of process, T joints need a dedicated approach. A set of previously developed experiments has shown that the tilt angle plays a relevant role in the joint strength. Furthermore it should be observed that T-joints are very often utilized in aerospace industries since the produced structures are composed of joined skins and stingers. Numerous data are rep…
Residual stresses in friction stir welded parts of complex geometry
2011
Residual stresses play a key role on the mechanics underlying the fatigue crack growth propagation of welded joints. Indeed, compressive residual stresses may induce a beneficial enhancement of the fatigue life under loading condition whereas tensile residual stresses may act to increase the stress distribution at crack tip, resulting in a life-threatening condition of the welded structure. In-process distortion and final geometry of welded joints are also affected by residual stresses. In this paper, the longitudinal residual stress distributions in friction stir welding (FSW) joints were investigated for butt and skin–stringer geometries, including lap and T configurations. To measure res…
A new fixture for FSW processes of titanium alloys
2010
FSW of titanium alloys is nowadays one of the most challenging welding operations, even with a solid state process, due to the thermo-mechanical and thermo-chemical characteristics of such materials. Due to the relevant application of titanium alloys in the aeronautic and aerospace industries, in the recent years few attempts were carried out to develop FSW processes aimed to maximize the mechanical performances of the welded parts. In the paper a new fixture is presented allowing obtaining effective FSW joints of titanium blanks, which were investigated through mechanical and metallurgical tests highlighting the peculiarities of FSW of titanium alloys.
The role of thermal contribution in the design of AA2024 friction stir welded butt and lap joints: mechanical properties and energy demand
2022
Although in recent times the use of solid-state welding processes as friction stir welding (FSW) has become increasingly widespread, for some joint morphologies, as lap joints, there are still signifcantly less data available on both process parameters optimization and energy consumption. In the present paper, the authors investigated the possibility of enhancing the joint quality in two diferent confgurations, i.e. lap and butt joints, taking into account specifc thermal contribution (STC) conferred to the weld. Strength, micro-hardness and microstructure were evaluated on the produced AA2024 aluminum alloys butt and lap joints. The surface response method (RSM) was used to investigate the…
Female sex workers' use of mobile phones in India: Lessons in effective engagement
2019
Despite the widespread impact of mobile phone technology, research on female sex workers’ (FSWs) access and use of this technology is sparse. This study aimed to document FSWs’ subjective perceptions of the benefits of mobile phone technology as well as examine the potential for its use by nongovernmental organizations (NGOs). Employing a phenomenological study built on in-depth qualitative interviews and focus group discussions with 67 FSWs and 18 staff and leaders from local NGOs in Mumbai and various locations of the Karnataka State in India between January and May 2015. Findings revealed complex trajectories for FSWs regarding accessing, learning about, and using mobile phone technology…
Finite Element Studies On Friction Stir Welding Processes of Tailored Blanks
2008
Although friction stir welding (FSW) has been successfully used to join materials that are difficult-to-weld or unweldable by fusion welding methods, it is still in its early development stage and, therefore, its potential has not been fully exploited yet. FSW appears to be a very promising process for tailor-welded blanks to overcome the difficulties encountered in traditional fusion welding processes for obtaining a sound welding with good nugget integrity. In this paper the friction stir welding process for tailored blanks of aluminum alloy is investigated through a FEM developed by the authors. In particular FSW for sheets with different thicknesses is studied. For each setup a differen…
Influence of material characteristics on plastomechanics of the fsw process for T-joints
2009
Abstract The potential of friction stir welding (FSW) has thoroughly been investigated by several authors, however their focus has primarily been on butt joints. T-joints are of paramount interest for transportation industries especially due to their capacity to straighten panels. Welding of T-joints is very challenging due to thin walls, poor location of the rib–web interface and the requirements for corner-fillets. This paper investigates FSW of T-joints of two popular aluminum alloys, i.e. 2024-T4 and 6082-T6, and the role played by the material characteristics on joining. First, an experimental study is carried out with specially designed fixture to determine the effect of process condi…
An Innovative Friction Stir Welding Based Technique to Produce Dissimilar Light Alloys to Thermoplastic Matrix Composite Joints
2016
Abstract Aluminum sheets can be joined to composite materials with different techniques. Each of them has advantages and weak points over the others. In literature, new techniques and patents are continuously developed to overcome these difficulties. In the paper a new Friction Stir Welding based approach is proposed to mechanically join AA6082-T6 to self-reinforced polypropylene. The aluminum sheet is pre-holed along both the sides of the weld line. A pinless tool generates the heat and pressure needed to activate back-extrusion of the composite. Joints have been produced with varying hole diameter and pitch. The mechanical resistance of the joint has been evaluated and the different failu…
Numerical Simulation of Friction Stir Welding by Natural Element Methods
2008
In this work we address the problem of numerically simulating the Friction Stir Welding process. Due to the special characteristics of this welding method (i.e., high speed of the rotating pin, very large deformations, etc.) finite element methods (FEM) encounter several difficulties. While Lagrangian simulations suffer from mesh distortion, Eulerian or Arbitrary Lagrangian Eulerian (ALE) ones still have difficulties due to the treatment of convective terms, the treatment of the advancing pin, and many others. Meshless methods somewhat alleviate these problems, allowing for an updated Lagrangian framework in the simulation. Accuracy is not affected by mesh distortion (and hence the name mes…