Numerical Simulation And Experimental Study On Springback Of High Strength Steel Plate Based On Yoshida-uemori Model

Because the rapid development of automobile industry in the fields of lightweight and driving safety,the requirements for the use of materials are becoming higher and higher.And high strength steel can meet the requirements of lightweight and safety of automobile structure at the same time,it has become the preferred material for automobile steel.Meanwhile,the serious springback problem of high-strength steel after forming,it is more difficult to simulate sheet metal forming.Among them,Yoshida-Uemori material hardening model can comprehensively and accurately describe the deformation behavior of metal sheet in the process of cyclic large plastic deformation,and has become one of the important models to simulate sheet metal forming.However,the model parameters can only be obtained by cyclic loading test and regression operation.At the same time,in the process of cyclic loading test,the thin plate is prone to warpage and instability,which makes it difficult for the actual test operation,resulting in the dilemma that there is no suitable Yoshida uemori material hardening model parameters available.In this paper,the cyclic tensile compression test is successfully completed by the self-designed fixture.The parameters of Yoshida uemori material hardening model are obtained through the software written by PYTHON.The stamping forming of U-shaped parts is simulated and analyzed by DYNAFORM finite element software,and finally verified by experiments.The main research contents of this paper are as follows:The effect of rolling direction on the mechanical properties of DP980 high strength steel plate was studied by uniaxial tensile test at room temperature.The test results show that the anisotropy difference of DP980 high strength steel plate is very small.At the same time,the mechanical properties data such as yield strength,tensile strength,anisotropy coefficient and hardening index were obtained.A fixture suitable for cyclic tensile compression test of metal materials is independently designed.The large strain cyclic tensile compression test of DP980 high strength steel plate is successfully carried out with the fixture,and the cyclic stress-strain curve of the plate is obtained,which provides test data for solving the Yoshida-Uemori material model parameters of DP980 high strength steel plate.Use PYTHON programming language,a YUMP software for quickly solving the parameters of Yoshida-Uemori material hardening model of metal sheet is written.Solving the parameters of Yoshida-Uemori material hardening model by software can improve the solution speed and reduce the parameter solution time.In the ANSYS finite element analysis software,the Yoshida-Uemori material hardening model parameters solved by YUMP software are used to simulate the sheet metal cyclic tension and compression process,and the cyclic stress-strain curve of the sheet metal is obtained.Compared with the cyclic stress-strain curve obtained by the test,it is verified that the Yoshida-Uemori material hardening model parameters of the sheet metal solved by YUMP software are accurate.Then,according to the data obtained from the cyclic tensile compression test of DP980 high strength steel plate,the parameters of Yoshida-Uemori material hardening model are obtained.Through DYNAFORM finite element analysis software,the finite element model of stamping forming of U-shaped parts is established.Two material models MAT 37 and MAT 125 are used to analyze the springback of U-shaped parts.The simulation results show that the MAT125 material model with Yoshida-Uemori material hardening model parameters solved by YUMP software has a greater prediction result for the springback of U-shaped parts.Through the stamping test,the effects of stamping speed and blank holder force process parameters on the springback of U-shaped parts of DP980 high strength steel plate are studied.The simulation and prediction results of springback of U-shaped parts by comparative test and two material models show that the springback prediction results of MAT 125 material model using Yoshida-Uemori material hardening model are closer to the test results.At the same time,the test shows that the springback of U-shaped parts first decreases and then increases with the increase of stamping speed,and decreases slowly with the increase of blank holder force.