The Study On Mechanical Properties Of High Strength Steel Plate For Stamping Under Cyclic Loading

In the cyclic loading process of tension-compression or compression-tension,Metal materials will appear Bauschinger Effect,hardening phenomenon and softening phenomenon,its mechanical performance compared with uniaxial tension or compression will be changed.The stress-strain curve of plate under cyclic loading can be obtained through cyclic loading plate test,revealing the changing rule of the mechanical properties,testing the Bauschinger Effect,comparing with material constitutive model prediction results,verifying the accuracy of the constitutive model.The plate is easily buckling in the process of compression and the corresponding suppression device should be added on the both sides of the plate.But adding the device,the friction produced between the sheet and device.It is difficult to obtain accurate stress-strain relationship.In order to obtain accurate cyclic stress-strain curve,this paper designed a set of large plate strain cyclic loading experiment system.The system consists of sample,prevent instability of fixture,fatigue testing machine,clamping force and non-contact measurement system of strain gauge.Experiment system can exert different clamping force,carried on the sheet of large strain cyclic loading experiment,measured the change of the clamping force,calculated the friction influence on experimental results,through data processing,accessed the accurate stress-strain relationship.Through this experimental system,the tensile-compression cyclic loading experiment and the compression-tensile cyclic loading experiment of B170P1,B210P1 and DP590 were done.With the method of strain control,the different deformation conditions and strain values cyclic stress-strain curves were obtained.Experiment system obtained the size of the clamping force in the process of the experiment.Coulomb friction conditions are used to calculate the friction influence on the experimental results.Through the cyclic data processing,the accurate stress-strain curve were obtained.This paper analyzed the changing rule of Bauschinger parameter,Bauschinger Stress Parameter,Bauschinger Energy Parameter and plastic modulus.under different loading branch,different strain values.The results showed that three kinds of plank existed Bauschinger Effect or the reverse loading yield stress increased.The pre-tension deformation of three kinds of planks existed hardening phenomenon in a compression stage,tensile stage appeared a softening phenomenon,the compression deformation showed cyclic hardening phenomenon.The results showed loading branches,the deformation and tissue composition etc will have an effect on board the mechanical properties of cyclic loading.