validation of plasticity models
TRANSCRIPT
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McMat 2005, June 2005, Baton Rouge
Validation of a multi-physics codePlasticity models & Taylor Impact
Biswajit BanerjeeUniversity of Utah
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Outline
The UINTAH multi-physics code Verification & Validation Materials & Models Taylor Impact Test Validation Metrics Results Conclusions
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The UINTAH code
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Verification
Comparisons with exact solutions Rate of convergence of the truncation
error (theory vs. code) Manufactured test problems Monitoring of conserved parameters Preservation of symmetry Comparisons with existing codes
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Validation
Comparisons with experimentsLevel 1: Experiments to validate individual
component physicsLevel 2: Experiments to validate combinations
of componentsLevel 3: Experiments to validate the complete
simulation
Need experiments designed to validate large codes.
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Goals
Determine plasticity model best suited for fire-steel interaction
Strain rates - 0.001/s to 108/sTemperatures - 230 K - 800 K
Validate Plasticity ModelsTaylor Impact TestsFlyer-Plate Impact Tests
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Materials & Models
Materials OFHC Copper (Annealed) 6061-T6 Aluminum Alloy 4340 Steel Alloy
Yield Stress Models: Johnson-Cook (JC) Steinberg-Cochran-Guinan-Lund (SCG) Zerilli-Armstrong (ZA) Mechanical Threshold Stress (MTS) Preston-Tonks-Wallace (PTW)
Shear Modulus/Melting Temp. Models: Nadal-Le Poac Follansbee-Kocks Steinberg-Cochran-Guinan
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OFHC-Copper - strain rate
JC vs MTS JC vs PTW
JC vs SCG JC vs ZA
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OFHC-Copper - temperature
JC vs MTS JC vs PTW
JC vs SCG JC vs ZA
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OFHC-Copper - moduli/melting
Shear Modulus
Melt Temp.
Equation of State
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Taylor Impact Test
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Experiments - OFHC Copper
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Experiments - 6061-T6 Al
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Experiments - 4340 Steel
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Validation Metrics
Eyeball-norm Final Length Elastic Length (green) Final vertical length
(red+green) Mushroom Diameter Diameter at 0.2 L (x) Final area Final volume Centroid (1st moment) Moment of Inertia Time of impact
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Final Profiles: OFHC Copper
210 m/s, 295K 188 m/s, 718K 181 m/s, 1235K
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Error Metrics: OFHC Copper
188 m/s, 718K
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Time Metrics: OFHC Copper
188 m/s, 718K
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Range of States: OFHC Copper
188 m/s, 718K
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Final Profiles: 6061-T6 Al
194 m/s, 635K 354 m/s, 655K373 m/s, 294K
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Error Metrics: 6061-T6 Al
194 m/s, 635K
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Final Profiles: 4340 Steel
160 m/s,1285K312 m/s, 725K308 m/s, 295K
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Error Metrics: 4340 Steel
312 m/s, 725K
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Conclusions
Thermal softening is inadequate in the physically based models
Johnson-Cook is the best bet among the models investigated
More high temperature data are needed in the high rate regime
A temperature sensitive length scale may be needed to prevent spurious mesh sensitivity