Failure mechanisms of composite plates with a circular hole under remote static biaxial planar compressive loading

An experimental investigation carried out for the analysis of failure mechanisms in fibrous laminated composite plates containing stress raisers, in the form of circular cutouts, under static biaxial planar compressive loading (i.e. compression in the two inplane orthogonal directions) is presented. A specially designed biaxial loading frame was used in the testing of the composite specimens. A series of biaxial tests were carried out with 48 ply graphite/epoxy composites of varying fiber orientation. The stacking sequences resulted in quasi-isotropic, generally orthotropic and shear dominated laminates. In all cases, the hole diameter to plate width aspect ratio remained in a range suitable for infinite plate assumptions. Fiber microbuckling, fiber kink banding and fiber/matrix debonding are identified as the dominant failure mechanisms.