JOURNAL DE PHYSIQUE IV
Colloque C8, supplkment au Journal de Physique III, Volume 4, septembre 1994
Analytical modelling of composite panels subjected to impact loading
C. Navarro, J. Rodriguez* and R. CortCs*
Department of Engineering, Carlos 111 University,
Avda. de Butarque 15, Legangs, 28911 Madrid, Spain * Department of Materials Science, Polytechnic University of Madrid, E.T.S.J. de Caminos, Canales y
Puertos, Ciudad Universitaria sln, 28040 Madrid, Spain
To illustrate the model prediction capability, the problem of
a 9mm Parabellum projectile impacting
against a 34 layer polyethylene
fibre composite with an elastomeric matrix is analyzed. The composite is
fabricated by DSM and its commercial name is Dyneema UD66. Following
the manufacturer's information
the fibre density is 970 kg/&, the areal density of a ply is about 0.166 kg/&, and the number of fibres per
centimetre is 5.9. In Table 1
the results of the predictions are compared with some manufacturer's data [6],
for the impact problem on a composite of areal
density of 5 kg/m2 at two projectile velocities below the
ballistic limit. Predictions are made at each velocity for two
different impacts, case A corresponding to a
projectile radius of 4.5 mm (standard
radius of the projectile), and case B for a radius of 6.0 mm (typical
value of the radius of the considered projectile after impacting a composite target).
It was also analyzed the problem of a 7.62*51 Ball projectile at 820 m/s
impacting 150 plies of a
Dyneema UD66 composite 25 mm thick. Experimentally the projectile is defeated
by the composite armour.
In applying the engineering model it was necessary to assume a maximum breaking stress corresponding
to a strain in the composite about 6.46 %, which greatly exceeds the maximum static strain that this material
can support although dynamic tests carried out using a Hopkinson Bar device lead to values of the critical strain close to
5 %.
