Shaped Charge Jet Stability and Penetration Calculations.
Final rept. Jun 76-Aug 77,
DYNA EAST CORP WYNNEWOOD PA
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This present study focuses on two important aspects of shaped charge mechanics, jet breakup and broken jet penetration. The jet breakup problem is studied from a stability approach. A one-dimensional stability theory for stretching plastic jets is presented. This theory yields a stability criterion which depends on the stress-strain curve of the material. It also gives a critical disturbance wavelength disturbances of this wavelength grow faster than all others. In addition, the theory shows that the disturbance growth rate increases with decreasing jet stretching rate and increases with increasing flow stress to density ratio. Comparison with two-dimensional finite difference calculations indicates the general theoretical trends are correct. The second study examines the problem of broken jet penetration by using two-dimensional calculations to observe the effects of sequential projectile impact on the bottom of a hole in a target. Past experiments show decrease in penetration caused by the increase in gap between projectiles. Calculations of lead projectiles upon lead targets do not show the interference phenomenon which is expected to account for the decrease in penetration. Calculations of copper projectiles at typical shaped charge jet velocities impacting upon steel targets, however, do show the expected interference phenomenon. Author
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