This work intended to study the effect of the surface scratch depths with
scratch depths of 272, 416 and 573 μm on the drop weight (impulse) impact
energy of glass fiber mats reinforced unsaturated polyester composites with 25
Vol.% fiber volume content. Moreover, the fracture behavior of the abovementioned
composites was also investigated for each case. The results showed
that the impact energy of scratched composites was enhanced by adding the
scratch on the compression side for different scratch depths compared to that of
the virgin specimen. Moreover, effect of increasing scratch depth has slightly
effect on the total impact energy and time duration contact of the composites.
The fracture behavior showed that by adding the scratch to the compression
side of the composites for different scratch depths, the crack deflection and
delamination propagate along the weak preferable path (scratch path) and so
the area of the crack increases and this dissipates most of the impact energy
and so the impact energy is improved. Moreover, on the back face matrix
cracks and fiber splitting are the main failure mode and the perforation is
accompanied by a pyramid-shaped back face failure.