Plasticity and Fracture Prediction of Metal Sheets
Under Nonlinear Loading
Yuanli Bai ([email protected])
Assistant Professor, Dept. of Mech., and Aero. Engr.,
Lab of Solid and Structure Mechanics
University of Central Florida, Orlando, FL, 32816
October 28, 2016
1
Proposed project for SMF roadmap conference at UNH
mailto:[email protected]
Outline
• Background on nonlinear loading in sheet metal forming
• Proposed testing and modeling research
• Timeline and proposed deliverables
Background: Examples of nonlinear loading conditions in sheet metal forming
• (a) Strain reversal in a punching process
• (b) An example of two step forming
• (c) Edge crack of AHSS metal sheets
• (d) Forming to crash simulation in car bodies
(a)
(b)
(c) (d)
Proposed testing efforts under monotonic and multiaxial loadings
Uniaxial
Tension
Speckle painting is used for DIC measurement.
Notch
Tension
Punch Test Pure
Shear
Uniaxial / Biaxial / Plane Strain Compression
Through-Thickness Compression
4
All tests can be
done in one
universal testing
machine.
Proposed testing efforts under nonlinear loading
Reduced Size Dogbone Specimen with Anti-buckling Device
Opened Window
for DIC
5
Rolling Direction
for Second Step
Two-stage Uniaxial Tension
with Orientation Change
An example of test matrix for Mg AZ31B-H24 conducted at UCF
Loading Type Orientations Repeated Total Tests
Uniaxial Tension 5 3 15
Uniaxial Tension (1mm) 3 3 9
Notch Tension 5 3 15
Uniaxial Compression 5 3 15
Biaxial Compression 5 3 15
Plane Strain Compression 5 3 15
Through-Thickness Compression 1 3 3
Pure Shear 5 3 15
Punch 1 3 3
Reverse Loading 3 3 9
Two-Stage Uniaxial Tension 56
170
6 *Jia, Y., Bai, Y, “Experimental Study of the Mechanical Properties in AZ31B-H24 Magnesium Alloy Sheets under Various Loading Conditions”, International Journal of Fracture, January 2016, 197(1): 25-48.
Proposed modeling efforts under nonlinear loading
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Isotropic
Hardening
Kinematic
Hardening
Cross
Hardening
Loading Condition
Dependency
Anisotropic
Yield Criterion
A Fully Modularized Framework
Combined Different Types of Hardening
General Framework for Multiple Materials
User-friendly Application
Non-aftereffect on Model Calibration
Easy to be Implemented into FEA
Anisotropic eMMC fracture model for metal sheets
* Jia, Y., Bai, Y., “Ductile fracture prediction for metal sheets using all-strain-based modified Mohr-Coulomb model”, International Journal of Mechanical
Sciences, 2016, 115: 516–531.
Comparison between tested and simulated strain histories for magnesium
AZ31B-H24 sheets (a), and TRIP780 steel sheets (b), in the space of
anisotropic equivalent plastic strain versus strain angle Φ.
(a) (b)
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Timeline, cost and proposed deliverables
• (a) It should be a long term project (3-5 years)
• (b) Experimental, analytical and numerical studies are involved.
• (c) The object is come up with one accurate and reliable modeling and prediction methodology for industrial application.
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