Research On High-strength-steel’s Springback Prediction Considering With Inelastic Recovery After Plastic Deformation

With the rapid development of the automobile industry, the country’s energyrequirements for cars continuous improvement,so the lightweight body has become ahot competition in the automotive industry. Lightweight body is the most importantparts of automotive lightweight, since the high-strength steels, magnesium alloy andother new materials applications in the car white body become more widespread,new material forming processes become a new research field, especially thespringback prediction and control. Solving the springback problem of high-strengthsteels in sheet metal has a great significance.This paper summarized the current research situation and development trend ofhigh strength steel springback among domestic and foreign scholars. Considering thenon-elastic recovery phenomenon of high strength steel after plastic forming,implement multiple loading and unloading cycle tensile test of dual-phase steel indifferent strength, comparative and analysis of stress-strain curve after loading andunloading deformation, proposed a concept of “hysteresis plastic” strain to defineand explain the mechanism of non-elastic recovery strain.Then, comparing the law of stess-strain curve between theoretical andexperimental stress-strain curves, fitting to experimental stress-strain curve andintroduce two-yield surface model to found a new elastic modulus model forspringback simulation.Finally, select the S beam benchmark of numisheet’93for springback simulatio,comparing the results of springback simulation among conventional elastic modulusmodel,YOSHIDA model and the new constitutive material model, verified theimpact of non-elastic recovery on springback simulation of high-strength steel.Comparing the results of springback simulation for front beam of a domestic vehiclebetween three constitutive material model and experimental results, verified thebetter simulation accuracy of new constitutive material model. In order to verify thestability of the new material constitutive model under the different circumstance ofmaterial strength and parts structure, compared the results of springback simulationof B-pillar for a domestic vehicle body.Studies turn out that the Hysteresis Plastic Strain is reversible and energyconsumption, and it is the most important reason of non-elastic recovery phenomenon. This paper achieved a better agreement of springback result betweensimulation and experiment by optimizing a new constitutive material model.