Materials Today: Proceedings | 2019
Damage monitoring of different concentration carbon nanotube/epoxy glass fiber reinforced composites under quasi-static incremental loadings
Abstract
Abstract Multiwall carbon nanotubes (MWCNTs) reinforced polymer composites have been manufactured using the vacuum-assisted resin infusion method, aiming to enhance the composite with an additional functionality, i.e., the ability to measure strain/damage by in-situ recording the surface electrical resistance of the coupon. Coupons with different MWCNTs concentration as nano-reinforcement agent as well as with different measuring lengths have been tested in the present work. The coupons were subjected to incremental mechanical loading - unloading loops, inducing known level of damage, till fracture. It has been proved that the low concentration of MWCNTs (0.5 wt.%) does not essentially decrease the quasi-static mechanical properties of the composite and gives the best results in terms of sensing ability and sensitivity analysis among the materials tested. The gauge factor of this material for converting electrical resistance change to axial strain was determined to be approximately equal to 0.16, for the whole range of the loads induced, till fracture. Excessive concentration of the nano-reinforcement (3.0 wt.%) gives satisfactory sensing results up till the 40 % of fracture stress. Concerning the measuring length for the determination of the electrical resistance of the coupon, it was concluded that it should not exceed 50 mm in order to obtain the optimum sensing performance.