Health Monitoring of Composite Structures Using Carbon Nanotube and Acoustic Sensors

Abstract

Matrix-dominated damage initiation has a major impact on fiber composite performance and durability. Detection of the onset and evolution of this damage has wide practical implications for the life prediction of composite structures. The formation of a percolating network of carbon nanotube sensors in the polymer matrix at low nanotube volume fraction is minimally invasive and does not require complicated sensing equipment. In order to evaluate the damage accumulation in the cross-ply laminates using the carbon nanotube networks formed in the polymer matrix, incremental cyclic loading accompanied by real-time measurement of electrical property changes and microscopic edge replication has been conducted. In addition, simultaneous acoustic characterization was conducted using both the SMART Layer and carbon nanotube-based sensing approaches. The carbon nanotube monitoring system was able to detect both microcracks and localized damage/delamination in composite structures with very high sensitivity. The piezoelectric sensor based SMART Layer technique could complement and leverage the carbon nanotube system with accurate damage location and size.