Constitutive Model Parameter Identification for 6063 Aluminum Alloy Using Inverse Analysis Method for Extrusion Applications

Hot compression tests of the 6063 aluminum alloy were conducted using a Gleeble-3500 thermal simulation testing machine, and the stress-strain curves at different temperatures and strain rates were obtained. The Kocks-Mecking-Estrin (KME) constitutive model was used to describe the rheological properties, and the initial parameters were identified based on experimental data. The final parameters were identified by the inverse analysis method. The KME model was embedded in a plane compression finite element model by the ABAQUS UHARD subroutine. The multidisciplinary optimization design software ISIGHT was used to integrate the finite element method simulation and relative error calculation. A minimal relative error between the experimental and simulated results was set as the objective, and a multi-island genetic optimization algorithm was used to identify the constitutive parameters. The results showed good agreement between the simulated and measured compression specimen shapes, and the global error between the numerical and measured force-displacement data was only 3.8%. The inverse analysis method was more accurate than the fitting method in identifying the constitutive parameters. The extrusion of a round bar was simulated, and both temperature and extrusion force were accurately predicted by using this constitutive model, further proving that the inverse analysis method used in the present study is effective in identifying the constitutive parameters.