Tests for Determining Failure Criteria of Ceramics under Ballistic Impact

摘要

A three-year Balanced Technology Initiative (BTI) program to develop tests fordetermining the failure criteria of ceramics under ballistic impact is described. The phenomenology of the penetration of a confined ceramic block by a long rod penetrator was established by examining the fracture damage in targets after ballistic testing. The material properties that govern the penetration resistance of ceramics were deduced. Two plate impact tests-the high-strain-rate pressure/shear test and the symmetric pressure/shear test-were then developed to measure the granulation and granular flow properties of candidate armor ceramics at strain rates and pressures representative of those at the tip of an advancing penetrator. In the development of the tests, a laser-Doppler velocimeter was applied for the first time to measure the transverse motion of the target plate. The tests were applied to aluminum nitride, boron carbide, and Coors AD-85 and AD-995 aluminas; and the resultant behaviors were compared. Two one-dimensional computational models, one based on a continuum Mohr-Coulomb description of the flow of granulated ceramic and the other (developed in a companion BTI project) based on the frictional sliding of blocks, were applied to interpret the symmetric pressure/shear tests, which revealed the near-penetrator failure behavior. The observations and data were used as input for two-dimensional penetration simulations using the block-sliding model. Ceramic armor, Mescall Zone, Balanced Technology Initiative, Long rod penetrator, Pressure-shear tests.