1 / 28

Thermally-Enhanced Forming of Mg Sheets Midterm Report, Dec. 5, 2008 - May 31, 2009

Thermally-Enhanced Forming of Mg Sheets Midterm Report, Dec. 5, 2008 - May 31, 2009. Robert H. Wagoner R. Wagoner, LLC 144 Valley Run Place Powell OH 43065. One-Year Project Goals (from Research Agreement, signed December 5, 2008).

rgertrude
Download Presentation

Thermally-Enhanced Forming of Mg Sheets Midterm Report, Dec. 5, 2008 - May 31, 2009

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Thermally-Enhanced Forming of Mg SheetsMidterm Report, Dec. 5, 2008 - May 31, 2009 Robert H. WagonerR. Wagoner, LLC144 Valley Run PlacePowell OH 43065

  2. One-Year Project Goals(from Research Agreement, signed December 5, 2008) Task “1.Formulate a simple, approximate, constitutive equation based on simple testing temperature at a range of temperatures, rates and strains that is suitable for implementation in commercial sheet-forming softward (LS-Dyna, PamStamp, etc.). ” Status:First fitting completed. (For Posco AZ31B material provided.) To be improved. Task “2.Develop a thermo-mechanical FE model of a simplified sample part to be specified by Posco.” Status: The simplified model has been constructed in Abaqus and preliminary testing has been done. Will perform simulations using Abaqus for comparison with Posco simulation using LS-Dyna or PamStamp. Will refine thermal model. Task “3.Using the constitutive equation of Goal 2 and the FE model of Goal 3, identify optimal thermally-assisted forming strategies for the sample part.” Status: Not started yet.

  3. Summary Task I. Constitutive Equation – Measurement, fitting -A. Tensile testing – AUSTEM Mg AZ31B -B. Screening of material (use 118-5) -C. Tensile testing Posco Mg AZ31B -D. Fitting to 3 laws: H, V, H&V -E. Verify const. eq. using FEA simulation (tensile to broken) Task II. Postech/Posco Formability Test Simulation -A. Put in ABAQUS model -B. Modify B.C. for convergence -C. Preliminary simulation using Posco/Postech constitutive eq* * K. Oh and et al., “Development of New Formability Test for Sheet Materials using Axiomatic Design”, submitted to J. Mater. Proc. Tech..

  4. Summary of Properties of Mg sheets material used

  5. Tensile Tests Results:AUSTEM vs. Posco

  6. Tensile Tests of Mg AZ31B at 150oC & 200oC

  7. Tensile Tests of Mg AZ31B at 250oC & 300oC

  8. Tensile Tests Results of Posco Mg AZ31B Sheets

  9. Tensile Test of Mg AZ31B at 10-1/s & 10-2.5/s

  10. Tensile Test of Mg AZ31B at 10-4/s

  11. Constitutive Equation Framework = 3 choices Hollomon: Voce: H / V: Three versions: # Parameters (h(T) w/1 parameter) 1) Hollomon: 4 2) Voce: 5 3) H / V: 8

  12. Fitting Procedure Least squares fit to 4, 5, or 8 parameters, using tensile data from 0.02 – Software: SigmaPlot Starting parameters were varied in this order: K1, K2 = 50, 100, …, 1000 n = 0.05, 0.06, …, 0.5 m = 0.05, 0.06, …, 0.2 B = 0.01, 0.05,…, 0.5 C = 5, 10, …, 200 = 0.1, 0.2, …,1 = 0.1, 0.2, …,1 Least squares fit => K1, n, m, K2, B, C, , (smallest standard dev.)

  13. Choice of Temperature Function h(T) “T-1” “T-2” “T-exp”

  14. Least-Squares Fits (Current Best Eq.)

  15. Fitting of Tensile Test at 150oC & 200oC

  16. Fitting of Tensile Test at 250oC & 300oC

  17. Test of Best-Fit Constitutive Equations Tensile test simulations: • FEM model, using ABAQUS software • Uniform temperature distribution • Solid element: C3D8R • Material property: Voce Law – (T-2)

  18. Tensile test of Mg AZ31B – Voce (T-2)

  19. Tensile test of Mg AZ31B – Voce (T-2)

  20. PosTech / Posco Formability Test Simulation

  21. Simulation of Stamping Process • ABAQUS/Standard • Material: 340BH* • Thickness = 0.738 mm • * • Contact: • Friction coefficient: 0.15* • The z-coordinates of the nodes in • blankholder which were not 0 were • changed to 0. * K. Oh and et al., “Development of New Formability Test for Sheet Materials using Axiomatic Design”, submitted to J. Mater. Proc. Tech..

  22. Comparison: Current Results and Oh paper*, Fig. 14 D D C A A C B Oh paper* Fig. 14(c) B Current results Minor strain distribution Holding force = 300kN Drawing depth = 60 mm * K. Oh and et al., “Development of New Formability Test for Sheet Materials using Axiomatic Design”, submitted to J. Mater. Proc. Tech..

  23. Comparison: Current Results and Oh paper*, Fig. 14 B B C C A A Oh paper* Fig. 14(c) D D Current results Minor strain distribution Holding force = 300kN Drawing depth = 60 mm * K. Oh and et al., “Development of New Formability Test for Sheet Materials using Axiomatic Design”, submitted to J. Mater. Proc. Tech..

  24. Comparison: Current Results and Oh paper*, Fig. 9 D D A A C C B B To be compared with Fig. 9 (a)* To be compared with Fig. 9 (a)* Thickness distribution Holding force = 100kN Drawing depth = 30 mm Thickness distribution Holding force = 300kN Drawing depth = 30 mm * K. Oh and et al., “Development of New Formability Test for Sheet Materials using Axiomatic Design”, submitted to J. Mater. Proc. Tech..

  25. Comparison: Current Results and Oh paper*, Fig. 9 D A C B To be compared with Fig. 9 (c)* Thickness distribution Holding force = 500kN Drawing depth = 30 mm * K. Oh and et al., “Development of New Formability Test for Sheet Materials using Axiomatic Design”, submitted to J. Mater. Proc. Tech..

  26. Note Need original Oh data* for Figure 9 and possibly other draw depths + variables for comparison with current results. * K. Oh and et al., “Development of New Formability Test for Sheet Materials using Axiomatic Design”, submitted to J. Mater. Proc. Tech..

  27. Simulation of Stamping Process * K. Oh and et al., “Development of New Formability Test for Sheet Materials using Axiomatic Design”, submitted to J. Mater. Proc. Tech..

  28. Conclusion • Tensile tests of Posco Mg AZ31B has been carried out, 150oC - 300oC, • 10-1/s - 10-4/s. • A preliminary constitutive model reproduces measured tensile data with • Reasonable accuracy (<s> = 7 MPa) • Further refinement of constitutive model is needed to reproduce • large-strain tensile response. • The Oh formability test has been implemented and tested using Abaqus • (material: 340BH) • Additional data from Oh simulations are requested to make additional • Verification. * K. Oh and et al., “Development of New Formability Test for Sheet Materials using Axiomatic Design”, submitted to J. Mater. Proc. Tech..

More Related