Dynamic Compressive Responses and Flow Behavior of Damaged Ceramics Under High Confinement
Final rept. 1 Jul 2002-30 Jun 2005
ARIZONA UNIV TUCSON
Pagination or Media Count:
We developed a novel dynamic loadingreloading experimental technique modified from a split Hopkinson pressure bar SHPB to determine the dynamic properties and to record the damagefailure modes in the ceramic specimen, in which a ceramic specimen was loaded by two consecutive stress pulses. The first pulse determines the dynamic response of the intact ceramic material and then crushes the specimen to a desired damage level. The second pulse then determines the dynamic compressive constitutive behavior of the damaged but still interlocked ceramic specimen. The first pulses were slightly varied to control the damage levels in the ceramic specimen while the second pulse was maintained identical. The damage modes in a hot-pressed silicon carbide SiC-N specimen have been correlated to its dynamic compressive response at high strain rates. The results show that the compressive strengths of damaged ceramics depend on a critical level of damage, below which the specimen retains its load-bearing capacity and only axial cracks are observed in the specimen. When the specimen is critically damaged, axial cracks and isolated pulverized regions are observed. When the specimen id damaged beyond the critical level, the ceramic specimen is crushed into cracked particles with pulverized comminuted materials along the particle boundaries, which displays a granular flow behavior in its stress-strain curve.
- Inorganic Chemistry
- Ceramics, Refractories and Glass