Material Point Method Simulations of Fragmenting Cylinders

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Material Point Method Simulations of Fragmenting
Cylinders

• Biswajit Banerjee
• Department of Mechanical Engineering
• University of Utah
• 17th ASCE Engineering Mechanics Conference, 2004

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Outline

• Scenario
• Material Point Method (MPM)
• Approach
• Validation
• Simulations of fragmentation

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Scenario
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What happens to the container ?
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Simulation Requirements

• Fire-container interaction
• Large deformations
• Strain-rate/temperature dependence
• Failure due to void growth/shear bands

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The Material Point Method (MPM)(Sulsky et
al.,1994)
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Why MPM ?
Advantages
Disadvantages

• Tightly-coupled fluid-structure interaction.
• No mesh entanglement.
• Convenient contact framework.
• Mesh generation trivial.
• Easily parallelized.
• No tensile instabilities.

• First-order accuracy.
• High particle density for tension dominated
  problems.
• Computationally more expensive than FEM.

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Stress update

• Hypoelastic-plastic material
• Corotational formulation (Maudlin
  Schiferl,1996)
• Semi-implicit (Nemat-Nasser Chung, 1992)
• Stress tensor split into isotropic/deviatoric
• Radial return plasticity
• State dependent elastic moduli, melting
  temperature

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Plasticity modeling

• Isotropic stress using Mie-Gruneisen Equation of
  State.
• Deviatoric stress
• Flow stress Johnson-Cook, Mechanical Threshold
  Stress, Steinberg-Cochran-Guinan
• Yield function von Mises, Gurson-Tvergaard-Needl
  eman, Rousselier
• Temperature rise due to plastic dissipation
• Associated flow rule

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Damage/Failure modeling

• Damage models
• Void nucleation/growth (strain-based)
• Porosity evolution (strain-based)
• Scalar damage evolution Johnson-Cook/Hancock-MacK
  enzie
• Failure
• Melt temperature exceeded
• Modified TEPLA model (Addessio and Johnson, 1988)
• Drucker stability postulate
• Loss of hyperbolicity (Acoustic tensor)

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Fracture Simulation

• Particle mass is removed.
• Particle stress is set to zero.
• Particle converted into a new material that
  interacts with the rest of the body via contact.

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Validation Plasticity Models
635 K 194 m/s
718 K 188 m/s
JC
MTS
SCG
JC
MTS
SCG
655 K 354 m/s
727 K 211 m/s
6061-T6 Aluminum
EFC Copper
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Validation Mesh dependence
1,200,000 cells
151,000 cells
18,900 cells
OFHC Copper 298 K 177 m/s MTS
11,500 cells
735,000 cells
91,800 cells
6061-T6 Al 655 K 354 m/s JC
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Validation Penetration/Failure
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Validation Penetration/Failure
160,000 cells
1,280,000 cells
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Validation Erosion Algorithm
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Validation Impact
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Validation Impact Results
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Validation 2D Fragmentation
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Validation 2D Fragmentation
JC (steel), ViscoScram (PBX 9501)
MTS (steel), ViscoScram (PBX 9501)
Gurson-Tvergaard-Needleman yield, Drucker
stability, Acoustic tensor, Gaussian porosity,
fragments match Grady equation, gases with
ICE-CFD code.
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Simulations 3D Fragmentation
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Simulation Container in Fire
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Questions ?