Project title: Integrated Research and Education on the Electro-Mechanical Behavior of Multifunctional Structural Coatings
Source of support: National Science Foundation, CAREER
Multifunctional coatings are materials intentionally encoded with multiple engineering functionalities. In particular, carbon nanotube’s (CNT) unique material properties have motivated engineers to use them as nano-scale building blocks for fabricating strain sensitive coatings that also possess improved mechanical properties/robustness (Fig. 1). Such material-based sensors offers tremendous advantages compared to conventional, discrete, electronic or mechanical-based transducers, since every location of the film or coating is sensitive to external stimuli. The ability to map the two- or three-dimensional electromechanical properties of these multifunctional materials can lead to innovations in spatial sensing for applications such as structural health monitoring.
Despite this, CNT-based coatings' electromechanical response to applied loads remains poorly understood. Future innovations require the derivation of experimentally validated models and theory that describe their electromechanical behavior. As a step towards this goal, the research objective of this project is to derive and validate the fundamental electromechanical behavior of CNT-polymer thin films. This study began with the derivation of a two-dimensional percolation-based computational model that is physically representative of the CNT-polymer thin film's nano- and micro-structure. Variations of these numerical models were used to explore how changes at the nano- and/or micro-scale affect the electromechanical response at the meso-scale. The initial focus was centered on the strain sensing properties of the CNT-based thin films (Fig. 2) and how strain sensitivity and its nominal electrical properties changed when parameters, such as CNT length, density, geometric shape, and intrinsic gage factor, were varied.