Abstract
Friction Stir Welding (FSW) is a novel kind of welding for joining metals that are impossible or difficult to weld by conventional methods. Three-dimensional nature of FSW makes the experimental investigation more complex. Moreover, experimental observations are often costly and time consuming, and usually there is an inaccuracy in measuring the data during experimental tests. Thus, Finite Element Methods (FEMs) has been employed to overcome the complexity, to increase the accuracy and also to reduce costs. It should be noted that, due to the presence of large deformations of the material during FSW, strong distortions of mesh might be happened in the numerical simulation. Therefore, one of the most significant considerations during the process simulation is the selection of the best numerical approach. It must be mentioned that; the numerical approach selection determines the relationship between the finite grid (mesh) and deforming continuum of computing zones. Also, numerical approach determines the ability of the model to overcome large distortions of mesh and provides an accurate resolution of boundaries and interfaces. There are different descriptions for the algorithms of continuum mechanics include Lagrangian and Eulerian. Moreover, by combining the above-mentioned methods, an Arbitrary Lagrangian–Eulerian (ALE) approach is proposed. In this paper, a comparison between different numerical approaches for thermal analysis of FSW at both local and global scales is reviewed and the applications of each method in the FSW process is discussed in detail. Observations showed that, Lagrangian method is usually used for modelling thermal behavior in the whole structure area, while Eulerian approach is seldom employed for modelling of the thermal behavior, and it is usually employed for modelling the material flow. Additionally, for modelling of the heat affected zone, ALE approach is found to be as an appropriate approach. Finally, several significant challenges and subjects remain to be addressed about FSW thermal analysis and opportunities for the future work are proposed.
Highlights
For many years welding has been used as a very common method for joining materials
The Eulerian approach was found as an appropriate method for modelling the material flow and the fluid flows, because in this method nodes remain fixed and the material points can move inside the mesh
In experimental observations the costs and time needed, are relatively high, in order to reduce costs and times, the numerical modelling approach of the Friction Stir Welding (FSW) process is very common between researchers and it is reflected by the number of published literature covering this topic
Summary
For many years welding has been used as a very common method for joining materials. During the historical investigations, for the first time the welding was used by the Sumerian civilization in order to weld copper utensils. After the 20th century the significance of the welding was increased sharply, because after the First World War, in the Treaty of Versailles, building ships heavier than 10,000 tons was prohibited for all countries. The study on the use of the advanced joining methods for warships was began by German engineers [1] and after a while they could reduce 1000’s of tons of the ship. Metals 2017, 7, 450; doi:10.3390/met7100450 www.mdpi.com/journal/metals methods for warships was began by German engineers [1] and after a while they could reduce 1000's of tons of the ship weight. Without violating the treaty, Germany could build large warships while their weight was still less than 10,000 tons. The weight was becoming as a Metals 2017, 7, 450 significant factor in designing and building ships, though the motivation for Germany was ill suited; the thought process was leading the industry of manufacturing to a new heightened level of thinking
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