Locally Patterned Carbon Nanotubes for In Situ Sensing Of Deformation and Damage in Composite Materials

Erik ThostensonCarbon nanotubes (CNT) possesses many properties that deem the material to be multi-functional and capable of being used for various applications. Carbon nanotubes can improve the overall strength, modulus, fatigue life, and thermal properties of polymers and composites. Percolating conductive networks of carbon nanotubes are capable of detecting deformation and damage in materials. Nanotube composites possess strain-dependent electrical properties that enable carbon nanotube deposited ink sensors to be used in health monitoring systems. Screen printing is a scalable way to incorporate carbon nanotube-based inks into composites for patterned sensors. This research focuses on formulating carbon nanotube inks for creating patterned sensors and evaluating their sensing response in composites. The properties of the ink are first characterized and used to produce the patterned sensors. The addition of cellulose, PolyoxTM, and polyvinylpyrrolidone (PVP) provide the desired rheology to enhance print quality onto glass fibers. Concentration and performance evaluations permit the creation of tailorable inks depending on different precursor solutions and application. To understand the performance of the carbon nanotube sensors composites are mechanically tested under quasi-static and cyclic loading conditions. Acoustic emission and edge replication is used to confirm the ability of the nanotube printed sensors to be used in structural health monitoring systems and monitor crack, strain, and permanent deformation in composite materials.Mechanical Engineerin