Computational micromechanics analysis of electron hopping and interfacial damage induced piezoresistive response in carbon nanotube-polymer nanocomposites subjected to cyclic loading conditions

The current computational multiscale micromechanics based exploration of sensing capabilities in carbon nanotube (CNT)-polymer nanocomposites focuses on the macroscale piezoresistive response when the nanocomposite is subjected to cyclic loading conditions. It has been shown that electron hopping at the nanoscale is the primary mechanism behind the observed macroscale piezoresistivity for such nanocomposites. A continuum description of the non-continuum electron hopping effect used in the current work enables the use of multiscale continuum micromechanics based approaches to study nanocomposite piezoresistivity. The focus of the current work is on the interfacial separation/damage initiation, evolution and accumulation when subjected to cyclic loading. Interfacial separation/damage is allowed at the nanoscale CNT-polymer interface using electromechanical cohesive zones. The mechanical response of the CNT-polymer interface is obtained in terms of normal/tangential traction-separation behavior from atomistic scale Molecular Dynamics based models reported in the literature. The coupled electrostatic response is based on evolving interfacial resistance through the electron hopping induced current density across the separated interface. It is observed that the effective macroscale piezoresistive response obtained from the current modeling framework captures interfacial separation/damage state and shows sensitivity to damage accumulation over several cycles of applied strains.