The results of an experimental investigation into the compressive behavior of T300-5208 graphite/epoxy plates measuring 12.70 cm by 25.40 cm and containing circular cutouts ranging to 3.81 cm are reported. Two thicknesses, 24 ply and 48 ply were chosen to differentiate between stability failures due to buckling and strength failures due to the presence of the cutout.

The critical load of the 24 ply panels was found to be independent of hole size with bifurcation occurring in the two halfwave mode longitudinally and one halfwave laterally in the quasi-isotropic panels. For the orthotropic 24 ply panels, bifurcation began in the one halfwave shape in each direction but changed to the two halfwave shape before failure. Consistent post-buckling strength was exhibited by both laminate configurations.

The 48 ply specimens displayed decreasing ultimate load with increasing hole diameter to approximately 50% of the no-hole panel ultimate for a diameter-to-width ratio of 0.30. The 48 ply orthotropic panels displayed a strength/stability threshold between cutout diameters of 0.3175 cm and 0.635 cm. Panels with cutout diameters below 0.3175 cm displayed buckling before failure and those with cutouts larger than 0.635 cm experienced material failure around the hole before panel collapse. The 48 ply quasi-isotropic panels showed no sign of such a threshold with failure due to the hole occurring for all hole sizes.