An experimental study of scaling effects in notched quasi-isotropic carbon/epoxy laminates under compressive loads

The size effects in centre-notched quasi-isotropic carbon/epoxy laminates under compression were investigated. The in-plane dimensions of the baseline specimen were scaled up by a factor of up to 14. The centre-notched specimens were compared to open-hole specimens of the same dimensions. It was found that compressive strength of the small centre-notched specimen is similar to that of the open-hole specimen. However, as the in-plane dimensions increase, the centre notches are weaker than the open holes, and start to follow a Linear Elastic Fracture Mechanics (LEFM) scaling line. These trends were well captured by a Composite Compressive Strength Modeller (CCSM) using the fracture toughness measured in the current study. Fibre micro-buckling was confirmed to be the dominant failure mechanism under compression. The failure mechanisms under compression were also compared against those under tension. Matrix splitting under compression was observed through X-ray Computed Tomography but was less extensive than under tensile loading.