Debris Field Kinetics during the Dynamic Fragmentation of Polyphase Natural Ceramic Blocks: Ejecta Measurements and Damage Modes

• Author(s) / Creator(s)

  • Hogan, James
  • Schneider, Markus
  • Rogers, Robert
  • Spray, John
  • Vincent, Gregory

• The dynamic fragmentation of coarse and fine grained granitoid blocks during impact has been examined for energies of 1.9 kJ to 3.0 kJ and 2.7 kJ to 6.8 kJ, respectively. A particle tracking algorithm was developed to measure ejecta size and velocity at the rear of the target for a horizontal railgun arrangement. Fragments for the finer-grained material are smaller than the coarser-grained specimens as a result of enhanced comminution of fractured surfaces and increased intergranular fracture. Length scales > 6 mm contain > 80 % of the total mass and kinetic energy. Median ejection velocities increase for increasing impact energy (range from 5 m/s to 10 m/s for both materials). These are low in comparison to incoming projectile velocity (250 m/s to 500 m/s) and indicate that the bulk of incoming energy is dissipated into forms other than kinetic energy transfer (e.g., heat and comminution). Approximately 25 % of the mass and 80 % of the kinetic energy is contained in velocities > 20 m/s. The total conversion of impact energy to ejecta kinetic energy is estimated as approximately 3 % for the coarser material and 4 % for the finer grained material. The % conversion to momentum is higher, increasing from 7 % to 11 % for the coarser grained material and 21 % to 30 % for the finer grained material. This highlights the importance of momentum transfer during impact testing at low speeds into blocks.

• Date created

  2013

• Subjects / Keywords

  • Brittle materials
  • Particle tracking velocimetry
  • Ejecta measurements
  • Dynamic fragmentation
  • Planetary materials
  • Brittle fracture
  • Railguns

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/R3RB6WG2D

• License

  © 2013 Hogan, J., Spray, J., Rogers, R., Vincent, G., & Schneider, M. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.