A Mathematical Formulation for Calculating Temperature Dependent Friction Coefficient Values: Application in Friction Stir Welding (FSW)

Materialwissenschaft Werkst

Awang

Emamian

et al. 2018

One of the most intriguing joining techniques in aerospace and automotive industries is friction stir welding. In this welding, temperature has an important effect on the quality and the integrity of the weld. Welding parameters, on the other hand, highly affect the temperature. Many authors used finite element methods to study the effect of the process parameters on thermal behavior by using constant Young's modulus, while, it should decrease as the temperature increases. Therefore, the proper definition of the Young's modulus during the study of the effect of the process parameters on thermal behavior, will increase the accuracy of the model. In this paper, to properly investigate thermal behavior, temperature dependent and constant Young's modulus values are applied in different models to examine the accuracy of those models. In addition, the influence of the process parameters on thermal behavior is studied. More accurate results are obtained from the model in which temperature dependent values of the Young's modulus is used. The effect of the welding parameters and different Young's modulus values on the size, shape and temperature of the welding string zone is studied and reported in detail.

Section: Methodsmentioning

confidence: 99%

A comparison between temperature dependent and constant Young's modulus values in investigating the effect of the process parameters on thermal behaviour during friction stir welding

Materialwissenschaft Werkst

Awang

Emamian

et al. 2018

“…Friction between solid objectives involves a complicated behavior, thus to achieve a high accuracy modeling of the process during complex welding conditions the implementation of an accurate contact condition is required [48][49][50][51]. The first important point in implementing an appropriate contact condition during FSW process is the selection of the contact model.…”

Section: Sliding and Sticking Conditions At The Contact Interfacementioning

confidence: 99%

“…A main limitation in the model was the long processing time for reaching the steady-state condition. In fully coupled thermomechanical models, the classical and the modified Coulomb laws were used for modeling the FSW process [51,59]. The gap between numerical models was not wide at lower rotational velocities.…”

Section: Sliding and Sticking Conditions At The Contact Interfacementioning

confidence: 99%

Progress in Thermomechanical Analysis of Friction Stir Welding

2020

Chin. J. Mech. Eng.

Self Cite

This article reviews the status of thermomechanical analysis of the friction stir welding (FSW) process for establishing guidelines for further investigation, filling the available research gaps, and expanding FSW applications. Firstly, the advantages and applications of FSW process are introduced, and the significance and key issues for thermomechanical analysis in FSW are pointed out. Then, solid mechanic and fluid dynamic methods in modeling FSW process are described, and the key issues in modeling FSW are discussed. Different available mesh modeling techniques including the applications, benefits and shortcomings are explained. After that, at different subsections, the thermomechanical analysis in FSW of aluminum alloys and steels are examined and summarized in depth. Finally, the conclusions and summary are presented in order to investigate the lack of knowledge and the possibilities for future study of each method and each material.

“…For the simulation process, the probe is allowed to plunge until the shoulder contacts with the workpiece. Consideration is given to the contact surfaces between the tool and workpiece using the Coulomb's law of friction with the friction coefficient obtained from the dependent temperature values [23]. Then, Johnson-Cook law (where the yield stress is a function of strain rate and temperature) is used to determine the material behaviour [4].…”

Section: Fig 1 the Model And The Meshmentioning

confidence: 99%

Prediction of the Temperature Distribution During Friction Stir Welding (Fsw) With A Complex Curved Welding Seam: Application In The Automotive Industry

Awang

2018

MATEC Web Conf.

Self Cite

Advanced welding of complex geometries promises significant development in the automotive industry. Friction Stir Welding (FSW) as a solid-state welding technique has spread quickly since its initial development by TWI in 1991. It has found applications in various industries, including railway, automotive, maritime and aerospace. Temperature during FSW plays a significant role, therefore thermal analysis of the process provides the opportunity to understand the process in detail, and also allows one to save energy and cost as well. However, experimental investigation of the thermal behaviour is challenging, because of inaccuracy in the measuring instruments. Thus, Finite Element Methods (FEMs) offer an appropriate approach for thermal modelling of the process. There is also a dilemma in defining the perpendicular movement of the tool on a curved surface. To clarify the problem, the tool needs to follow a regular pattern during curved movement, and it should have a perpendicular position to the surface at each point. However, previous literature modelled only a single point movement for the tool. Thus, the finite element package needs to be modified to develop a precise perpendicular movement for the tool. In this paper, a VDISP user defined subroutine is used to modify Abaqus® software for thermal analysis of a complex curved plate. The results of the paper show that the problem of the perpendicular movement of the tool is resolved and the thermal behaviour of the FSW is done with remarkable accuracy.