Monitoring of the friction stir welding process by means of thermography

Abstract:Friction welding is one of the foremost welding processes for similar and dissimilar metals. Previously, the process has been modeled utilizing the rudimentary techniques of constant friction and slip-stick friction. The motivation behind this article is to present a new characteristic for temperature profile estimation in modeling of the rotary friction welding process. For the first time, a unified model has been exhibited, with an implementation of the phase transformation of similar and dissimilar materials. The model was generated on COMSOL Multiphysics ® and thermal and structural modules were used to plot the temperature curve. The curve for the welding of dissimilar metals using the model was generated, compared and analyzed with that of practical curves already acquired through experimentation available in the literature, and then the effect of varying the parameters on the welding of similar metals was also studied.

Section: Discussionsupporting

confidence: 58%

Thermal Model of Rotary Friction Welding for Similar and Dissimilar Metals

Dawood

Butt

Hussain

et al. 2017

“…Moreover, some researchers [45][46][47] were focused on the thermography method which has been defined as a modern method for investigating the thermal field through online monitoring of the process, inspection and research. It should be mentioned that, this method is mainly used to determine the thermal field variations, when the measurements are difficult or impossible to record (i.e., inside the weld).…”

Section: Thermal Analysis Of Fsw (Friction Stir Welding)mentioning

confidence: 99%

A Comparison of Different Finite Element Methods in the Thermal Analysis of Friction Stir Welding (FSW)

Meyghani

Awang

Emamian

et al. 2017

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.

“…Thermography is a non-contact and potentially full-field methodology, making it a good candidate for in-line monitoring. Due to the heat generation mechanisms which occur in the FSW process [81], thermographic techniques can be used to find defects in real-time during the welding process [82]. In such real-time monitoring, thermal behavior of joints can be correlated to process parameters and thermography can hence be used to perform online monitoring of the FSW process.…”

Section: Thermographymentioning

confidence: 99%

Investigation of Nondestructive Testing Methods for Friction Stir Welding

Taheri

Kilpatrick

Norvalls

et al. 2019

Friction stir welding is a method of materials processing that enables the joining of similar and dissimilar materials. The process, as originally designed by The Welding Institute (TWI), provides a unique approach to manufacturing—where materials can be joined in many designs and still retain mechanical properties that are similar to, or greater than, other forms of welding. This process is not free of defects that can alter, limit, and occasionally render the resulting weld unusable. Most common amongst these defects are kissing bonds, wormholes and cracks that are often hidden from visual inspection. To identify these defects, various nondestructive testing methods are being used. This paper presents background to the process of friction stir welding and identifies major process parameters that affect the weld properties, the origin, and types of defects that can occur, and potential nondestructive methods for ex-situ detection and in-situ identification of these potential defects, which can then allow for corrective action to be taken.