3-Dimensional Nonlinear Finite Element Analysis of both Thermal and Mechanical Response of Friction Stir Welded 2024-T3 Aluminum Plates

Abstract

This paper attempt to predict numerically both the temperature distribution during friction stir welding process of 2024-T3 aluminium plates and the resulting thermal residual stress by sequentially coupling the thermal histories into the mechanical model assuming elastic-perfectly plastic metal behaviour in accordance with the classical metal plasticity theory. The commercial code ANSYS 14 is used in Thermomechanical modelling of friction stir welding of aluminium 2024-T3.  Heat input from the tool shoulder and the tool pin are considered in the finite element analysis model. A moving heat source with a heat distribution simulating the heat generated from the friction between the tool shoulder and the work piece is used in the heat transfer analysis The longitudinal stress components are found to be the highest tensile stress components and correspond to the temperature profiles within the heat affected zone of the weld. The through-thickness (normal) stresses are found to be negligible compared with the longitudinal and transverse stress components. To facilitate simulation runs of the proposed model an APDL (ANSYS Parametric Design Language) code is developed to extract the thermal history and the subsequent thermal stresses. The effects of various heat transfer conditions at the bottom surface of the workpiece, thermal contact conductances at the work-piece and the backing plate interface on the thermal profile in the weld material are taken into considerations. The results of the simulation are compared to other published experimental results and the agreement was good.

Keywords: Friction stir welding, Finite element, Three dimensional modeling, Thermal stresses.