Temperature
Composite Plate Sample
Electrical Timers
Recorder
Vacuum Test Chamber
Fire Switch
Vacuum Gauge
Gun
(5/8 in. bore)
Sand
Vacuum
Pump
Coldroom
Gun Room
Chronograph
Screens
a. Schematic of ballistic test facility.
b. Assembly of the ballistic test gun system.
Figure 2. CRREL ballistic test facility and gun system.
pairs on both sides of the target. The output from
of the first chronograph screen, it starts the count-
the chronograph screen starts and stops a timer
ing clock. When it passes the next one, the signal
with 107 second accuracy.
from it stops the counting, thus displaying the time
of travel on the time counter. By measuring the
All tests were performed using 12.7-mm-
distance between the two light screens, the pro-
(0.5-in.-) diam. hardened steel sphere projectiles.
jectile velocity is calculated.
The projectile is first located in the gun with a suit-
No attempt was made to capture the fragments
able sabot (a winged plastic receptacle) to guide
the sphere through the gun barrel without any
from the impact on the unidirectional composite.
appreciable loss of firing pressure of the explosive
The focus of the unidirectional composite impact
powder. The amount of gun powder necessary to
test was to identify the gross damage pattern de-
veloped on the composite. The fragments from the
propel the projectile at the desired velocity was
quasi-isotropic composites were collected on the
first determined by trial runs. These trials estab-
adhesive coated papers that lined the interior of
lished the relation between the quantity of gun
powder and the projectile velocity. The actual vel-
the target chamber on both the impact and exit
ocities of the projectile before impacting the tar-
sides. Figure 3 shows one typical perforated plate
get and after exiting from the target were also
of unidirectional Gr/Ep, and Figure 4 shows
measured by a set of light-activated chronograph
a carefully cut section through the 30-ply quasi-
screens. When the projectile crosses the light path
isotropic Gr/Ep.
3
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