A LONGITUDINAL COMPRESSION TEST FOR COMPOSITES USING A SANDWICH SPECIMEN

This paper describes a novel miniature sandwich specimen developed to measure composite compression strength. The specimen is composed of composite skins on either side of a resin matrix core. Specimen instability and interlaminar stresses in the free-edge region under axial loading are major considerations in the design of this sandwich specimen. The material systems investigated were unidirectional carbon fiber-reinforced epoxy and PEEK, and S2-glass-reinforced epoxy. All specimens were tested in an IITRI test fixture in accordance with ASTM standards. The sandwich specimens produced higher longitudinal compressive strengths than conventional composite coupons for all the material systems evaluated. Failure occurred in the specimen gage section without any indication of specimen buckling.