Study On Springback Prediction And Anisotropy Parameters Inverse Base On Deep-drawing Split-ring Test

Springback is one common phenomenon in sheet metal forming process. In orderto reduce development cycle of new product and improve the product quality, how topredict accurately and control effectively the springback has become the focus ofresearch.What’s more, as a strong geometric, material and boundary conditionnonlinear problem, springback is a diffcult research problem, too.With the extensiveapplication of high strength steel, the springback has attracted wide attention in theworld.For a long time,tring to improve the accuracy of springback prediction, peoplehave carried out a lot of research in the aspects of algorithm, element theory, materialmodel, process parameters and so on.Now, the prediction on simple2-D springbackhas already maken a great progess which can get a certain accuracy.But the predictionaccuracy of the complex3-D springback can not meet the engineering needs.In this paper,3-D springback model-Demeri model and anvance high strengthsteel-DP800were choosed for the study. Using experiments-numerical simulationhybrid method, the study focuses on the prediction accuracy of FEM simulation forhigh strength steel3-D springback.The main content of this thesis is as follows:(1) The springback mechanism of the Demeri model has been illustrated. Themodel is different from he commonly used2-D model, which can be used to study thespringback under the more complex srain and stress state.(2) Experiment was designed using uniform experiment design, which choosingthe punch speed, binder hold force, sheet diameter, drawing-cup height as the designparameters. And the sensitivity analysis of these four parameters has been carried outfrom two aspects-one single parameter floating and muti-parameters interaction.(3) Based on the design of experiment, the drawing-cup experiment was carriedon, and the drawing-cups were splited. While a large number of finite elementnumertical simulations were carried out. Through comparing diferences of thesplit-ring springback between experiment and simulation in the aspects of the fictionand lubricant, element size and its distribution, virtual punch speed, the mumber ofthick integration points, material model, et al.(4) Based on flange edge of drawing cup，an inverse approach to identifyanisotropy parameters is presented. This inverse approach takes the coefficient of normal anisotropy r0，r45，r90as the inverse variables, the differences of flange edgebetween the simulation and experiment as the objective function. And verify thevalidity of the method from the aspect of the edge of cup, punch force-displacementcurve and split-ring springback.