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Material Point Method Simulations of Fragmenting Cylinders

Material Point Method Simulations of Fragmenting Cylinders. Biswajit Banerjee Department of Mechanical Engineering University of Utah 17th ASCE Engineering Mechanics Conference, 2004. Outline. Scenario Material Point Method (MPM) Approach Validation Simulations of fragmentation.

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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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