Analysis of mechanical behavior of multi-functional CFRP under bending and DCB Mode-I fracture

Biomimicry has been a source of inspiration for scientists in a quest for development. Natural materials are multifunctional to some extent. Similarly, in pursuit of multiple functionalities, a carbon fibre reinforced epoxy composite (ref specimen) and carbon fibre reinforced epoxy composite enhanced by functionalised interlayer technology (FIT) touted as an electrically conductive specimen (ec specimen) are compared based on their tensile, flexural and GIC Mode-I fracture properties. Tensile, flexural and DCB mode-I fracture tests were performed according to test standards ASTM D3039, ASTM D790, and ASTM D5528 respectively. Comparison of these two distinct specimens showed similar tensile stress values, 13.24 % increase in tensile strain and 15.17 % decrease of elastic modulus for ec specimen. Flexural stress increases by 6.43%, flexural strain suffered a decline of 41.60% and flexural modulus increased by 32.76% for ec specimen. For Mode-I fracture tests, ec specimens absorbed more energy before the crack jump corresponding to the first unloading. However, both ref and ec specimens showed similar permanent deformation after the second unloading. Energy release rate (ERR) of ec specimens was lower when compared with ref specimens. On comparison, modulus values for ec specimen showed an increase, as the delamination front progressed beyond 60 mm.