Interlaminar tensile strength of different angle-ply CFRP composites

Abstract Due to high specific strength and modulus requirements, demand for the use of polymer-based composites in structural applications has been increasing more than ever. On the other hand, their interlaminar properties are known to be relatively weak. Such structures are prone to interlaminar failures including delaminations under static or impact loads. Interlaminar tensile strength (ILTS) is one of the interlaminar properties which gives an indication of delamination onset in through the thickness loading for composite structures, while fracture toughness is another property which gives information about the propagation of delamination. Conventionally ILTS value which is experimentally obtained specifically for 0˚//0˚ interface according to ASTM International D 6415/D 6415 M (2013) is used in design and analysis even for interfaces with different ply orientation. In this paper, our objective is to investigate the effect of ply orientation on the ILTS for CFRP. For this purpose, curved beam strength (CBS) experiments are conducted on CFRP 0˚//0˚, and 45˚//-45˚ interfaces. It is found that for CFRP laminates 0˚//0˚ ILTS is significantly higher than the other orientation.