Accession Number:

ADA371689

Title:

A Granular Flow Model for Developing Smart Armor Ceramics

Descriptive Note:

Final technical rept. 29 Aug 94-31 Dec 97

Corporate Author:

SRI INTERNATIONAL MENLO PARK CA

Report Date:

1998-01-31

Pagination or Media Count:

102.0

Abstract:

SRI International modeled the comminution and flow of ceramic under conditions like those in ceramic armor at the nose of an advancing penetrator. We delivered a model, FRAGBED2, that models fracture, comminution, compaction, and fragment flow, and can be implemented in hydrocodes. Fragment motion is treated by analogy with atomic dislocation theory. Compaction occurs by the outflow of dislocation holes. The rate of comminution is zero below a threshold stress and saturates above a saturation stress, and varies smoothly in between. We tested FRAGBED2 by comparing results from three types of experiments spherical cavity expansion tests, thick-walled cylinder collapse tests, and ballistic tests. In the cavity expansion tests, an explosion in a spherical cavity machined in a block of ceramic produced a distribution of fragment sizes as a function of distance. From the distribution, we obtained parameters for calibrating the comminution model. The thick-walled cylinder test was modified by introducing a taper that allowed a complete range of strains to be produced. Extensive shear banding was observed in recovered specimens, which FRAGBED2 was not able to model in 2-D plane strain. However, FRAGBED2 did a good job of matching the ballistic test results.

Subject Categories:

  • Ceramics, Refractories and Glass
  • Armor

Distribution Statement:

APPROVED FOR PUBLIC RELEASE