Mechanism Of Thermal Forming And Optimization Of Process Parameters For 2124 Aluminum Alloy

2124 aluminum alloy is an ideal lightweight material,and its application in the manufacture of product parts can effectively reduce product weight and improve product performance.This paper analyzed the thermal deformation mechanism of 2124 aluminum alloy through uniaxial tensile tests and metallographic tests,established the constitutive equation of 2124 aluminum alloy,and studied the optimization of process parameters of2124 aluminum alloy sheet forming based on the optimization strategy with Kriging surrogate model.The main work is as follows:Taking 2124 aluminum alloy as the research object,the influence of different deformation conditions on the deformation of the material was analyzed through uniaxial tensile tests and metallographic tests.The test results showed that 2124 aluminum alloy had significant temperature sensitivity.As the temperature rises,the flow stress of the material gradually decreases,and the grains continue to refine;In addition,as the strain rate decreases,the flow stress of the material gradually decreases,and the crystal grains gradually become smaller.Based on the stress-strain curves obtained from the uniaxial tensile tests,the Hansen-Spitel constitutive equation of 2124 aluminum alloy was established,and the parameters of the constitutive equation were identified through intelligent algorithms,so that the constitutive equation could better reflect thermal deformation law of 2124 aluminum alloy.Based on the ABAQUS user material subroutine interface,the 2124 aluminum alloy user material subroutine VUMAT was written in Fortran language,which realized the secondary development of the Hansen-Spitel constitutive equation of 2124 aluminum alloy,and provided a numerical simulation basis for thermal forming of 2124 aluminum alloy.Based on the maximum expectation improved sampling criterion,the trust region method and the minimum response surface sampling criterion were used to improve it,an improved hybrid sampling addition criterion was proposed,and then an improved dynamic Kriging optimization strategy was developed,which could improve the optimization efficiency and convergence accuracy.Taking NUMISHEET2002 fender as the research object,the Kriging model between process parameters and forming quality was established,the Kriging model was dynamically updated using the improved hybrid sampling criterion,and the improved particle swarm algorithm was used to obtain the optimal process parameters,eliminated the cracking defects of sheet metal forming and improved the forming quality.Based on the established Hansen-Spitel constitutive equation of 2124 aluminum alloy,a finite element model of double C was established in the finite element simulation software ABAQUS.The key forming process parameters were used as design variables,and the maximum thinning rate of the formed part was selected as target value to build a Kriging model.The Kriging model was dynamically updated using the improved hybrid plus point criterion,and then an improved particle swarm algorithm was used to optimize the model to obtain the optimal process parameters.The simulation results showed that the optimized process parameters could eliminate the cracking defects in the forming of the double C parts with 2124 aluminum alloy.In order to verify the reliability of the 2124 Hansen-Spitel constitutive equation and the validity of the optimized process parameters,the stamping test of double C parts was carried out,and the simulation results were basically consistent with the test results.The optimized process parameters could improve the quality of the formed parts.