Damage Detection in Epoxy Embedded Carbon Nanotubes Using Electrical Resistance and Acoustic Emission

AbstractAn experimental study was conducted to detect the onset of damage in epoxy embedded carbon nanotubes (CNTs) using a novel combination of in situ electrical resistance and acoustic emission measurements. A simple fabrication process was employed to fabricate epoxy embedded CNTs, and experiments were conducted under quasi-static tensile loading conditions. In situ electrical measurements were made using a high-resolution four circumferential ring probe measurement system. Acoustic emissions were captured simultaneously using sensors mounted within the gauge length area. Both electrical and acoustic responses were later correlated with stress–strain response. The experimental data show that electrical resistance increases monotonically with axial deformation until about maximum tensile stress and later decreases remarkably before failure. Although acoustic counts are less in number at the initial stages of tensile loading, later the count increases significantly after a specimen reaches peak tensile stress owing to the generation and propagation of microcracks from agglomerated CNTs.