Numerically modelled study of the plunge stage in friction stir spot welding using multi-tiered mesh partitions

Abstract

Friction stir spot welding is a solid-state joining process that has attracted significant attention particularly in the field of joining of lightweight, low melting alloys. These materials include alloys of Aluminium and Magnesium amongst many others which are of great importance to the aerospace and the automobile industries. The friction stir spot welding is a complex thermo-mechanical multiphysics phenomenon and is currently a field of intense research. The motivation of the current study is to understand this complex behaviour of the joining process by simulating it in the ABAQUS CAE environment. In the friction stir spot joining technique, the plunge stage is identified as the critical stage of operation as it involves a highly transient and dynamic zone for material and temperature flows. The plunge stage was studied in detail using the finite element based model. The plasticity of the material was simulated by the Johnson-Cook material model while the frictional heat generation was captured by applying a penalty-based frictional contact between the rotating tool and the workpiece contact surfaces. Considering the reasonable assumptions made, the results obtained by the numerical simulation model were found to agree with the past experimental and numerically modelled studies.