Effects of carbon nanotubes on open-hole carbon fiber reinforced polymer composites

Properties and damage evolution of open-hole carbon fiber-reinforced composite laminates without/with MWCNTs during tensile damage were monitored by a complementary technology combining acoustic emission, digital image correlation and finite elements analysis. Meanwhile, the AE signals can be post-processed by fuzzy C-Means. It was concluded that adding amount of MWCNTs can reduce the stress concentration, improve the strength and fracture interface stiffness of laminate specimens and prevent the evolution of micro-cracks. The AE signals are concentrated in three areas: 23-74 kHz (matrix cracking), 82-120 kHz (fiber pull-out and delamination), 120-190 kHz (fiber breakage), respectively. An enhancement of properties of materials is obtained correspondingly due to the addition of MWCNTs into matrix. The number and amplitude of AE signals corresponding to matrix cracking produced by the specimen without MWCNTs are much larger than that of the specimen with MWCNTs, indicating that the damage degree of matrix cracking for the specimen without MWCNTs is more serious. The properties and damage evolution of composites can be studied from experimental research and numerical simulation, respectively.