Numerical simulation of residual stresses for friction stir welds in copper canisters

In an attempt to map the residual stress distributions after friction stir welding of copper canisters, a three-dimensional thermo-mechanical model has been formulated by coupling heat transfer and elasto-plasticity analyses. The transient temperature field around the tool is simulated by a moving heat source. The simulation shows that the residual stress distribution in a thick-wall copper canister is sensitive to the circumferential angle and asymmetrical to the weld line. Both tensile and compressive stresses emerge along the weld line and its vicinity. The maximum tensile stress appears in the circumferential direction on the outer surface. The maximum tensile stress, whether it is predicted by the finite element method or measured by the hole-drilling technique and the X-ray diffraction method, does not exceed 50 MPa in general.

► A finite element model has been formulated to map the residual thermal stress for friction stir welded copper canister. ► Satisfactory temperature cycles are simulated by a moving heat source with thermo-pseudomechanical description. ► Computational results show good agreements with hole-drilling measurements albeit there are deviations in some positions. ► Distribution of residual stresses in a canister is sensitive to circumferential angle and asymmetrical to the weld line. ► Both FEM-results and measurements show a maximum tensile stress of 50 MPa in the hoop direction on the outer surface.