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