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Material Point Method Simulations of Fragmenting Cylinders

Explore simulations of fragmenting cylinders using the Material Point Method (MPM) for fluid-structure interaction without mesh entanglement. Learn about stress update, plasticity modeling, damage/failure modeling, fracture simulation, and validation processes with different materials and cell counts.

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Material Point Method Simulations of Fragmenting Cylinders

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  1. Material Point Method Simulations of Fragmenting Cylinders Biswajit Banerjee Department of Mechanical Engineering University of Utah 17th ASCE Engineering Mechanics Conference, 2004

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

  3. Scenario

  4. What happens to the container ?

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

  6. The Material Point Method (MPM)(Sulsky et al.,1994)

  7. 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. Why MPM ? Advantages Disadvantages

  8. 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

  9. 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-Needleman, Rousselier • Temperature rise due to plastic dissipation • Associated flow rule

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

  11. 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.

  12. 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

  13. Validation: Mesh dependence 18,900 cells 151,000 cells 1,200,000 cells OFHC Copper 298 K 177 m/s MTS 11,500 cells 91,800 cells 735,000 cells 6061-T6 Al 655 K 354 m/s JC

  14. Validation: Penetration/Failure

  15. Validation: Penetration/Failure 160,000 cells 1,280,000 cells

  16. Validation: Erosion Algorithm

  17. Validation: Impact

  18. Validation: Impact Results

  19. Validation: 2D Fragmentation

  20. 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.

  21. Simulations: 3D Fragmentation

  22. Simulation: Container in Fire

  23. Questions ?

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