Unidirectional Composite Compression Strengths Obtained by Testing Cross-Ply Laminates

Abstract

The strength and stiffness of a unidirectional AS4/3501-6 carbon/epoxy composite material system was experimentally determined using tabbed and untabbed cross-ply specimens tested in established shear- and end-loaded compression test fixtures. Four different analysis techniques were used to predict the unidirectional lamina strength from the measured cross-ply specimen strength. The compressive strength and failure mode of the cross-ply laminates showed a desirable immunity to fabrication techniques, testing conditions, and fixture type. Several special aspects of using cross-ply laminates, including isolating the 0° laminae, free-edge effects, and stress concentrations induced by end tabs, are discussed. The effects of these topics on the cross-ply laminates used in the present study are compared to conventional unidirectional specimens.