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McMat 2005, June 2005, Baton Rouge
Validation of a multi-physics codePlasticity models & Taylor Impact
Biswajit BanerjeeUniversity of Utah
Outline
The UINTAH multi-physics code Verification & Validation Materials & Models Taylor Impact Test Validation Metrics Results Conclusions
The UINTAH code
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
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.
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
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
OFHC-Copper - strain rate
JC vs MTS JC vs PTW
JC vs SCG JC vs ZA
OFHC-Copper - temperature
JC vs MTS JC vs PTW
JC vs SCG JC vs ZA
OFHC-Copper - moduli/melting
Shear Modulus
Melt Temp.
Equation of State
Taylor Impact Test
Experiments - OFHC Copper
Experiments - 6061-T6 Al
Experiments - 4340 Steel
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
Final Profiles: OFHC Copper
210 m/s, 295K 188 m/s, 718K 181 m/s, 1235K
Error Metrics: OFHC Copper
188 m/s, 718K
Time Metrics: OFHC Copper
188 m/s, 718K
Range of States: OFHC Copper
188 m/s, 718K
Final Profiles: 6061-T6 Al
194 m/s, 635K 354 m/s, 655K373 m/s, 294K
Error Metrics: 6061-T6 Al
194 m/s, 635K
Final Profiles: 4340 Steel
160 m/s,1285K312 m/s, 725K308 m/s, 295K
Error Metrics: 4340 Steel
312 m/s, 725K
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