Accession Number : ADA191182

Title :   Fragmentation and Plugging Failure of Projectile/Target System.

Descriptive Note : Final rept. 15 Sep 85-30 Sep 86,

Corporate Author : LEHIGH UNIV BETHLEHEM PA INST OF FRACTURE AND SOLID MECHANICS

Personal Author(s) : Sih, G C ; Lee, Y D

PDF Url : ADA191182

Report Date : Mar 1987

Pagination or Media Count : 129

Abstract : The energy density theory is applied to analyze the progressive damage of a projectile/target system with emphasis placed on failure by fragmentation and/or fracture. Presented is a finite element code that accounts for the exchange of surface and volume energy density in each element. Such an interaction being neglected in the conventional theories of continuum mechanics plays a major role in the damage process where energy is transferred from the projectile to the target during impact. The dynamically loaded elements are not only highly stressed but they also undergo high gradients of strain whose history is no longer preassumed as in the classical approach. The distribution of each time increment is determined analytically. This enables a realistic prediction of the damage states and provides a consistent means of analyzing projectile/target failure. Results are obtained for a projectile made of tungsten impacting a target plate made of 4340 steel at a velocity of 1,200 m/sec. Appropriate time increments are chosen such that a sequence of damage states can be exhibited leading up to the final fracture of the target plate by plugging whose thickness is approximately one-half of that of the target plate. As thermal/mechanical interaction effects are inherently coupled in the energy density theory, heat dissipation and temperature change are automatically embedded in the solution. Information such as the latent heat used to alter the material microstructure can be found in a straightforward manner for estimating the location and size of the so-called adiabatic shear band that occurs during plugging, a topic that will be left for future investigation.

Descriptors :   *CONTINUUM MECHANICS, *FRAGMENTATION, *PLUGGING, *PROJECTILES, *TARGETS, ADIABATIC CONDITIONS, CODING, DAMAGE, DENSITY, ENERGY, EQUATIONS OF STATE, EXCHANGE, FAILURE, FINITE ELEMENT ANALYSIS, FRACTURE(MECHANICS), HEAT LOSS, INTERACTIONS, LATENT HEAT, MATERIALS, MECHANICAL PROPERTIES, MICROSTRUCTURE, SEQUENCES(MATHEMATICS), SHEAR PROPERTIES, SURFACES, TEMPERATURE, THEORY, THERMAL PROPERTIES, THICKNESS, TIME INTERVALS, VOLUME

Subject Categories : Ballistics

Distribution Statement : APPROVED FOR PUBLIC RELEASE