Modeling of Friction Stirring

Abstract

The last two decades have witnessed significant advances in friction stir welding (FSW). This solid-state welding process was originally used for joining Aluminum alloys before being extended to other metallic and non-metallic materials. The high complexity in FSW stems from the complex interactions between highly coupled physical phenomena. As experimental procedures are costly and time-consuming, numerical simulations were used extensively in an effort to develop a comprehensive understanding of the process. This research consists of two parts: one part provides a critical review of the three fundamental components of the numerical simulation of FSW; which are the numerical method, the constitutive model, and the contact model. The second part contains the detailed development of the finite element model to study the FSW process and submerged FSW process (SFSW), with emphasis on the effect of submerging on the temperature profile and thermal history. The finite element model is developed using the Coupled Eulerian-Lagrangian modeling technique and is validated against previous experimental work for the Aluminum 5083 alloy. Temperature profiles for different welding conditions are investigated to validate the model. The developed finite element model is able to predict the temperature profile in both FSW and SFSW processes. It also captures the dissymmetrical temperature distribution around the welding line; and the effect of using the SFSW process on peak temperatures, cooling rates, and size of the heat affected zone. Moreover, flash formation and the material flow patterns are successfully captured. The results show that increasing the rotational speed from 1000 rpm to 1700 rpm for the SFSW of the Aluminum 5083 alloy resulted in an increase in peak temperature by 200%. This temperature rise yields to material softening, improved the material flow, and higher weld quality.