Low Velocity Transverse Impact Behavior of 8-ply, Graphite-Epoxy Laminates

Abstract

This work discusses the behavior of 8-ply, quasi-isotropic, graphite epoxy laminates subjected to low velocity transverse impact loading. Large deflection theory of plates was used to predict the load-deflection characteristics during the impact event. The im pact model considered that the indentation, flexural and shear stiffnesses could be represented by 3-equivalent springs in series. The analysis of static and dynamic impact loading test-data concluded that the mem brane parameter, β, used in flexural stiffness relation was proportional to the square of the coefficient of restitution, e, of the impactor. Use of β = 0.443 e2 was made in load- deflection relations to consider the drop in plate stiffness due to delamination. The results of impact tests up to impact velocity 5.3 m/sec. were found in close agreement of the predictions.