A coupled statistical and numerical analysis of the residual properties of AA6063 friction stir welds

Abstract

In the current study, four process parameters were selected to investigate their individual and combined effects on three residual properties of AA6063 friction stir welds. The input parameters were the rotational speed, traverse speed, sheet length, and clamping ratio. The output responses were the longitudinal tensile residual stress, longitudinal compressive residual stress, and out-of-plane distortion. The main objective herein was to determine the most significant parameters and interactions affecting each response at a 95 % confidence level via the Design of Experiments. Experimental design trials were conducted with the aid of finite element simulation to reduce research time and cost. Linear regression models were developed to help predict the residual properties within the selected study domain. They were constructed in terms of the significant variables only. For longitudinal tensile residual stress, all four parameters plus the sheet length-clamping ratio interaction were proven statistically significant at the prescribed confidence level. Meanwhile, thermal distortion was found to be highly dependent on the rotational speed, sheet length, and their interaction only. None of the variables had statistical significance in affecting the longitudinal compressive residual stress. Therefore, this response could not be expressed by a mathematical formula.

Keywords

• Friction stir welding
• Design of experiments
• Numerical modeling
• Longitudinal residual stress
• Thermal distortion
• Aluminum alloys