Computational Micromechanics Model to Study the Effective Macroscale Piezoresistivity of Carbon Nanotube-Polymer Nanocomposites for Strain and Damage Sensing

The formation/disruption of the electron hopping pathways is considered to be one of the dominant mechanisms affecting macroscale effective piezoresistive response of carbon nanotube (CNT)-polymer nanocomposites. In this study, a computational micromechanics model is developed using finite element techniques to capture the effect of electron hopping induced conductive pathways at the nanoscale which contribute to the macroscale piezoresistive response of the CNT-polymer nanocomposites. In addition, damage is allowed to evolve at the CNT-polymer interface through electromechanical cohesive zones resulting in disruption of electron hopping pathways in the direction of applied strain. The impact of the electron hopping mechanism and nanoscale interfacial damage evolution on the effective piezoresistive response is studied through the macroscale effective material properties and gauge factors evaluated using micromechanics techniques based on electrostatic energy equivalence. It is observed that the interfacial damage at the nanoscale results in lower gauge factors as compared to the perfectly bonded interface.