Research On Parameter Indentification Of Anisotropic Yield Criterion For AA5086 Aluminium Alloy Sheet

Aluminum alloy has many advantages such as low density,high specific strength and specific rigidity,strong corrosion resistance,and easy recovery,and it is widely used in high-end manufacturing such as aerospace and automobile industry.Aluminum alloy sheet has obvious anisotropy,and it has certain influence on the contour shape and forming accuracy of the parts in the forming process.The Yld2000-2D anisotropic yield criterion can accurately describe the anisotropy of the material and can provide guidance for the forming of the aluminum alloy.The accuracy of the yield criterion parameter identification is the key to predicting the material anisotropy and optimizing the forming process.In this paper,the parameters of the anisotropic yield criterion of Yld2000-2D are identified based on the traditional method,the direct method and the reverse method,and the recognition accuracy of the three identification methods is verified by the cylindrical piece deep drawing test.The main contents are as follows:(1)Based on the DIC technology,uniaxial tensile tests and isostatic tensile tests at different angles were carried out.The Hill48 yield criterion and the Yld2000-2D anisotropic yield criterion parameters were identified by the traditional method,and the single pull was predicted based on the identified parameters.Yield stress,anisotropy coefficient and yield trajectory study.The study shows that the prediction accuracy of the anisotropic yield criterion of Yld2000-2D is higher than the Hill48 yield criterion.At the same time,the influence of weight coefficients on the recognition accuracy in the loss equation is studied.The results show that when the weight coefficients are random,the recognition accuracy is better,and the predictability of the single-pull yield stress,anisotropic coefficient and yield trajectory is better.(2)Based on the DIC technique,a double cross-pull test was carried out under different loading ratios to establish a test yield trajectory.Based on the yield stress,anisotropy coefficient,yield stress,and anisotropy coefficient,respectively,the Yld2000-2D orientation was identified.The parameters of the yield criterion of the opposite sex,based on the identified parameters,predict the anisotropic coefficient and the yield trajectory.The results show that when the yield criterion is identified based on the yield stress and the anisotropic coefficient,the recognition accuracy is higher and the prediction of the relevant parameters is higher.(3)Based on the cross tensile test and the Pottier bulging test,the Yld2000-2D anisotropy yield criterion was reversed and the yield trajectory was predicted based on the identified parameters.The study found that the parameters identified from the reverse of the two tests were highly accurate in predicting the yield trajectory and were highly consistent with the test values.(4)Based on the self-designed molds,the deep-drawing test of cylindrical parts was carried out,and the lug height of the cylindrical parts was measured using an altimeter,and the finite element model of the cylindrical part deep-drawing test was built,which was identified by different methods.The parameters of the yield criterion were substituted into the finite element model to calculate the height of the simulated ear.The effect of different parameter identification methods on the recognition accuracy was studied by comparing the height of the ear system with the height of the ear system.The results show that the identification accuracy of the yield criterion parameter identified by the reverse tensile test is high.