Mixed-mode I/II Interlaminar Fracture of CF/PEI Composite Material

Failures in composite materials occur mainly due to interlaminar fracture, also called delamination, between laminates. This indicates that characterizing interlaminar fracture toughness is the most effective factor in the fracture of composite materials. This study reports investigation on mixed-mode interlaminar fracture behaviour in woven carbon fibre/polyetherimide (CF/PEI) thermoplastic composite material based on experimental and numerical analyses. Experiments were conducted using the special test loading device. By varying the loading angle, from 0 to 90, pure mode-I, pure mode-II and a wide range of mixed-mode data were obtained experimentally. Using the finite-element results, geometrical factors were applied to the specimen. Based on experimentally measured critical loads, mixed-mode interlaminar fracture toughness for the composite under consideration determined. The fracture surfaces were examined by scanning electron microscopy to gain insight into the failure responses.