Scaling effects in notched composites

A program of scaled tests on unnotched and open-hole tension and compression specimens is summarized. Quasi-isotropic IM7/8552 carbon-fiber epoxy specimens have been tested using two different scaling techniques: sub-laminate-level ([45/90/ - 45/0]ns) and ply-level scaling ([45n/90 n/ - 45n/0n]s), independently varying the thickness and in-plane dimensions. Significant scaling effects are shown, with both strength and failure mechanisms changing with specimen size and the thickness scaling method having a particularly important effect. Failure mechanisms and scaling behavior are compared between tension and compression and models presented that predict the observed size effects from fundamental material parameters without any fitting factors.