Effect of fracture toughness properties on the crushing of flat composite plates

The aim of the work presented in this paper is to correlate the sustained crushing stress (SSCS) of glass fibre reinforced plastic (GRP) composite plates to their Mode-I and Mode-II fracture toughness properties. The GRPs, manufactured from multiaxial warp knit non-crimp fabrics (NCF) and thermosetting resins were crushed in a plate crush rig. Mode-I and Mode-II testing were by the double-cantilever beam method (DCB) 4-point end notch flexure method (4-ENF), respectively; in addition, the interlaminar shear strengths (ILSS) of the laminates were also measured to compare with previous results. The results showed that there is a relationship between the SSCS and the Mode-I and Mode-II fracture toughness properties. Furthermore, the Mode-I crack initiation properties have also been shown to proportionately affect the specific peak stress at which the crushing of a composite plate initiates.