Thermal fields in dissimilar 7055 Al and 2197 Al-Li alloy FSW T-joints: numerical simulation and experimental verification

A 3D transient computational thermal model is developed to investigate the heat transfer effects arising during friction stir welding (FSW) in dissimilar alloys with a T-joint. Specifically, a dual-heat-source-based mathematic model is derived on the basis of theories of classical as well as adhesive friction while using the actual fixture geometry adopted in the corresponding FSW experiment. A sliding mesh method is used to represent the positions of the dynamic heat source to capture the complex motion of the rotational smooth pin, and the FSW-T process of the stiffener with the corresponding thermal physical properties being obtained by JMAT software and simulated by APDL programming codes in ANSYS. The actual FSW experiment is carried out on alloy plates with a T-joint whose temperature histories were recorded at by the embedded thermocouples (Ps) placed at specified positions. The transient temperature profiles predicted are found to be in good agreement with those monitored during FSW-T. This has confirmed the validity and the reliability of the thermal model, thus indicating that it could be used to reflect the heat transfer process of FSW-T rather than resorting to an actual test.