Transparent Armor Multi Hit Testing

1
Transparent Armor Multi Hit Testing (ref STANAG
4569 Annex C Appendix 2
With transparent armor the weakest point of the
panel will generally be at the perimeter of the
component. In this case the aim point should be
chosen close to the border between the MAIN AREA
and the EXCLUDED ZONE reserved for STRUCTURALLY
WEAK AREA testing.
Shot 1 The first projectile (1) is fired at an
aim point which is 10mm from an EXCLUDED ZONE
(EZ), and 55mm from the adjacent EZ (fig A.) The
actual impact should be within a /- 10mm zone of
this aim point. The EZ is defined as the zone
25mm wide at the perimeter of the target panel
excluding any gasket material or at the inner
perimeter of the armor frame protecting the
perimeter of the transparent armor panel in the
vehicle system. The armor frame must be
described in the purchase documentation to be
considered in the determination of the width of
the EZ.
2
Transparent Armor Multi Hit Testing (ref STANAG
4569 Annex C Appendix 2
Shot 2 The possible positions for the second
shot (2) are then determined by tracing
concentric circles of R25mm and 45mm on the
target at (1). The aim point for shot (2) shall
be 10mm from EZ1 (see fig B).
3
Transparent Armor Multi Hit Testing (ref STANAG
4569 Annex C Appendix 2
Shot 3 Two concentric circles centered on the
midpoint between shots (1) and (2), of radial
distance 100mm and 120mm can be traced on the
target. From the midpoint, an angle of /- 60
degrees is traced in the directions perpendicular
to shot (1) and (2). The zone formed by the
concentric circles and the angles is the allowed
area for shot (3). The aim point for shot (3)
is to be 110mm from the midpoint of shots (1)
and (2) and 10mm from EZ2 (see fig C). Shot
4 The fourth shot shall be aimed in the zone
formed by concentric circles of R25mm and R45mm
from the impact point of shot (3), but not
closer to the midpoint of shots (1) and (2)
than 100mm. The aim point shall be 35mm form shot
(3) and 10mm from EZ2 (see fig D).
4
Transparent Armor Multi Hit Testing (ref STANAG
4569 Annex C Appendix 2
5
Transparent Armor Multi Hit Testing (ref STANAG
4569 Annex C Appendix 2
The witness system shall consist of a nominal
0.5mm /- 0.05mm (.020) aluminum sheet of alloy
2024 T3 or T4. It shall be placed at a standoff
distance of 150mm (/- 10mm) behind and parallel
to the back surface of the target at the aim
point. The witness plate should extend over a
sufficient area (equal to or larger than the
target size) such that all significant projectile
or target debris can be deflected. The level of
damage on the aluminum witness plate is the
criterion for the evaluation of success or
failure of a target panel. After each ballistic
impact, the witness plate shall be visually
inspected for damage and evidence of penetration
by the projectile or target materials. A Complete
Penetration (CP) is recorded when light is
observed to pass through the damage in the
witness plate. A Partial Penetration is recorded
when no light is visible through the damage if
present. In addition, during testing all
ballistic impacts should be marked on all
components of the target and witness plate.
Numbers should be sequential and account for all
serials fired including any preliminary test
rounds or non-fair impacts, etc. More than one
four shot group may be fired at a target panel if
it is judged that there is no damage caused by
the different shot groups which would affect the
outcome of a shot group. Before a transparent
armor recipe is deemed acceptable for production,
12 PP shots (three 4-shot groups) must be made
and the armor panels and the corresponding
witness plates must be submitted to the
Government for examination. If a CP shot is
recorded a new 12 shot sequence must be tested
and all results submitted to the Government
before production is commenced.