Meshless Simulation of Friction Stir Welding

I Alfaro,F Micari,L Fratini,F Chinesta,E Cueto

doi:10.1063/1.2740812

Abstract

This paper encompasses our first efforts towards the numerical simulation of friction stir welding by employing a Lagrangian approach. To this end, we have employed a meshless method, namely the Natural Element Method (NEM). Friction Stir welding is a welding process where the union between the work pieces is achieved through the extremely high deformation imposed by a rotating pin, which moves between the two pieces. This extremely high strain is the main responsible of the difficulties associated with the numerical simulation of this forming process. Eulerian and Arbitrary Lagrangian‐Eulerian (ALE) frameworks encounter difficulties in some aspects of the simulation. For instance, these approaches need additional techniques for the description of the boundary between materials, such as level sets, boundary markers or similar. In this paper we address the issue of employing a Lagrangian framework, which adequately describes the evolution in time of the interphase. The meshless character of the technique also ensures that no degeneracy on the accuracy is obtained due to mesh distortion. Some examples are presented that show the potential of the technique in simulating such a process.

Highlights

Friction stir welding (FSW) is a process that, in its development stage, has been successfully used to join pieces of materials with poor weldability
It achieves welding of the pieces by employ ing a rotating ping that provoques both extremely high plastic deformation and a high heat generation. It is schematically represented inFig. 1. In this papers we focus on the numerical simulation of such a process, rather than the experimental characteri zation
The rate of heat generation in the aluminium billet due to plastic deformation is given by r=f3cr:d where f3 represents the fraction of mechanical energy transformed to heat and is assumed to be 0.9 [12]

Summary

Introduction

Friction stir welding (FSW) is a process that, in its development stage, has been successfully used to join pieces of materials with poor weldability. The extremely large deformation present during the process, very localized in a more or less region around the pin, always introduced numerical problems. Two nodes sharing a facet of their Voronoi cell are called natural neighbours and the name of the technique.

Results

Conclusion