Perforation of Layered Composite Plates byImpactors of Different Nose Shapes

Abstract

Conical and hemispherical nose-shaped cylindrical impactors have been used in drop weightimpact experiments on 3.1 mm CSM-polyester laminated plates. Based on experimental results,various failure mechanisms and energy absorbed in different failure modes are identified and calculated.It is found that the damage area beyond a certain value of impact energy does not increase. Theperforation geometry is the same as that of the impactor irrespective of increased crack length, andcomplete rotation of petals takes place at impactors radius. It is also observed that the crack lengthincreases with decrease in contact area. But, when the nose is sharp (5 mm hemispherical nose), thereis no extended crack beyond perforated region. Blunt nosed (truncated conical impactor with 10 mmnose dia) impactors cause more number of petals/cracks than 10 mm hemispherical nosed impactorand less than 5 mm hemispherical nosed impactor. The petals formed by a cylindrical impactor with40 mm hemispherical nose are unequal in size, whereas in the case of conical impactors, these areequal. At lower energies, blunt nosed impactors cause more delamination than the hemisphericalones, and at higher energy, it is the reverse. It is found that there exist many visible concentriccircular ring hinge mechanisms at the top surface of plates.