On Springback Prediction In Stamping Of AHSS BIW Components Utilizing Advanced Material Models

Transcription

1 On Springback Prediction In Stamping Of AHSS BIW Components Utilizing Advanced Material Models Ming F. Shi and Alex A. Konieczny United States Steel Corporation

2 Introduction Origin of Springback AHSS Springback Effect of Material Models on the Springback Prediction Examples of using Advanced Material Models in the Springback Prediction Accuracy Improvement Introduction of a Novel Large Deformation Tension and Compression Test Examples of Tension and Compression Data and Determined Advanced Material Model Parameters

3 Origin of Springback Material elastic recovery after forming Coupled with mechanical multiplying effects Stress Strain Elastic Recovery Mechanical multiplying

4 True stress, MPa Elastic Recovery, Cont d AL HSLA34 DP78 DP98 DP True strain, %

5 True Stress (MPa) True Stress (MPa) True Stress (MPa) True Stress (MPa) Greater Bauschinger Effect for AHSS DDQ True Plastic Strain HSLA True Plastic Strain DP True Plastic Strain 12 DP True Plastic Strain

6 True Stress (MPa) More Elastic Recovery for AHSS? DP78 Tension and Compression Test Data Linear Elastic Unloading Total True Strain

7 Springback of AHSS

8 Springback of AHSS

9 Under-predicted Springback using the Isotropic Hardening Model Measurement Prediction DP98 DP mm

10 Hardening Models Initial Yield Surface Stress 2 Stress 1 Kinematic Hardening Isotropic Hardening Isotropic/Kinematic Hardening

11 Yoshida Combined Isotropic/Kinematic Hardening Material Model Based on two surfaces model f f ( σ α) Y S β ( B R) F( σ ) f α α β * o α * * β o P m 2 3) bd p p (2 3) ad α p a B R Y C, [( β]; β Yoshida Model with Original Hardening Law: R m( Rsat R ) p Yoshida Model with modified hardening law N N K( e p Ke R ) N N a B R Y B Y K( e p) Ke

12 True Stress (MPa) Yoshida Model vs. Isotropic Hardening Model 1 DP78 Tension and Compression 5-5 Experiment Yoshida Model True Plastic Strain Isotropic hardening

13 Example 1: Springback Prediction Improvement using an Advanced Material Model Measured Springback Isotropic Hardening Model Yoshida Model

14 Example 2: DP6 Red: Isotropic Blue: Yoshida Black: Scan

15 Challenges in Determining Material Model Parameters 7 constitutive parameters in Yoshida Model 9 constitutive parameters in modified Yoshida Model Large deformation tension and compression test is required. Multiple loading cycles are required. Optimization algorithm is required to determine the parameters

16 Introduction of a Novel Tension-Compression Test Large deformation tension-compression Anti-Buckling in the width direction Anti-Buckling in the thickness direction Friction measurement

17 Tension-Compression Test

18 Tension-Compression Test, Cont d

19 Total Force, N Friction Force, N Tension-Compression Test, Cont d DP98-L4 +5% Total Force Friction Force Time, sec

20 True Stress, MPa Example of Tension-Compression Test Data Full Cycle DP98-5-L2 +/-5% True Plastic Strain

21 True Stress, MPa Example of Tension-Compression Test Data Strain Memory Cycle 98-5-L3+ 5% US# True Plastic Strain

22 Yoshida Model Parameters for DP78 Modied Yoshida Model Y (MPa) B (MPa) C m b (MPa) h K (MPa) N e Original Yoshida Model Y (MPa) B (MPa) C Rsat (MPa) m b (MPa) h

23 True Stress (MPa) Predicted and Tested Data from a Full Cycle Tension and Compression Test for DP True Plastic Strain Experiment Original Modified

24 True Stress (MPa) Predicted and Tested Data from a Strain Memory Tension and Compression Test for DP78 1 Experiment 5 Original Modified True Plastic Strain

25 On Springback Prediction In Stamping AHSS Thank you for your attention