A 3D numerical simulation of different phases of friction stir welding

Abstract

An adaptive arbitrary Lagrangian–Eulerian formulation is developed to compute the material flow and the temperature evolution during the three phases of the friction stir welding (FSW) process. It follows a splitting approach: after the calculations of the velocity/pressure and temperature fields, the mesh velocity is derived from the domain boundary evolution and from an adaptive refinement criterion provided by error estimation, and finally state variables are remapped. In this way, the unilateral contact conditions between the plate and the tool are accurately taken into account, so allowing one to model various instabilities that may occur during the process, such as the role played by the plunge depth of the tool on the formations of flashes, the possible appearance of non-steady voids or tunnel holes and the influence of the threads on the material flow, the temperature field and the welding efforts. This formulation is implemented in the 3D Forge3 FE software with automatic remeshing. The non-steady phases of FSW can so be simulated, as well as the steady welding phase. The study of different process conditions shows that the main phenomena taking place during FSW can be simulated with the right sensitivities.

Numerical modeling of friction stir welding process: a literature review

“…It means that very high pressures lead to overheating and thinning of the joint, whereas very low pressures lead to insufficient heating and voids. The tilt angle of the tool, measured with respect to the workpiece surface, is also an important parameter, especially to help producing welds with "smooth" tool shoulders [5].…”

Optimization of Friction Stir Weld Joint Quality Using a Meshfree Fully-Coupled Thermo-Mechanics Approach

“…Schmicker [21] had good success with FEM adaptive re-meshing algorithms in 2D for the rotary friction welding process. Other researchers [16,[22][23][24][25] have focused on coupled Eulerian-Lagrangian (CEL) and arbitrary Lagrangian-Eulerian (ALE) approaches. These methods have advantages over FEM with re-meshing when it comes to dealing with large deformation.…”

Experimental and numerical investigation of aluminium lap joints made by RFSSW

“…The smooth circumferential distribution of heat is the consequence of the high rotational speed and convective heat flow by motion of the material [9,10]. Computation of the thermo-mechanical fields during all the FSW phases (plunge, friction, retraction) without information about the process, only relying on accurate constitutive and friction models, is presented in [11,12]. Based on the numerical and experimental investigations, the results of the model are found to be very sensitive to small variations of the friction coefficient.…”