Characterization of Interlaminar Shear Strength of a Unidirectional Carbon/Epoxy Laminated Composite : Effect of Deformation Rate

Abstract

The interlaminar shear strength (ILSS) of a unidirectional carbon/epoxy (T700/2521) laminated composite under impact loading is determined using the conventional split Hopkinson pressure bar. Double-notch shear (DNS) specimens with lateral constraint from a supporting jig are used in the static and impact interlaminar compressive shear tests. Short-beam shear specimens are also used under static 3-point bending. Finite element analyses are performed to determine the shear stress and normal stress distributions on the expected failure plane in the DNS specimen using the MSC/NASTRAN package. The effects of deformation rate at failure on the ILSS and failure mode are investigated. It is observed that the ILSS is independent of the deformation rate at failure up to nearly 1.5m/s. The validity of the test results is confirmed by microscopic examinations of both static and impact failure surfaces for the DNS specimens.