Investigation of piezo-resistivity in CNT nano-composites under damage

Abstract

The piezoresistivity of carbon nanotube (CNT) reinforced nanocomposites is modeled using a multiscale damage modeling technique. Two phenomena of piezoresistivity are studied, the inherent piezoresistivity of the CNTs and the electrical tunneling effect. The damage model is developed under the framework of continuum damage mechanics (CDM) with a physical damage evolution equation inspired by Molecular Dynamics (MD) simulations. This damage model is applied to a nanocomposite unit cells with randomly dispersed CNTs. Orders of magnitude change in piezoresistivity is observed as the nanocomposite changes from non-damaged state to damaged state. This study provides insights into the prevailing mechanisms associated with piezoresistivity in the damaged and undamaged state of the CNT reinforced nanocomposites at the sub micro scale.

Atomistically derived cohesive behavior of interphases in carbon fiber reinforced CNT nanocomposites

“…Interphase elements that are defined by the constitutive behavior represented in Equation 4 can be developed using user material subroutines and commercial finite element solvers. A significant advantage of this approach is that the cohesive law can be incorporated within any multiscale framework for computational nanocomposite analysis, including the one developed by the authors [21,22]. Such a framework can be used to study damage initiation and propagation at the interface, fiber debonding, fiber pullout, matrix cracks in the polymer and the interaction of matrix damage with the interphase damage which lead to rapid structural failure.…”

“…This methodology was used to simulate damage caused by successive bond breakages using a combination of high strain rate and low temperature MD simulations and was compared to quasi-continuum (QC) simulations showing excellent correlation [20]. Thus, a computationally efficient numerical approximation to physics-based damage initiation phenomenon (QC-equivalent) in nanoparticle-embedded epoxy polymers was generated and implemented within a fully stochastic microscale damage framework [21,22]. The damage initiation model is integrated in this work for the characterization of the fiber/matrix interphase in the three-constituent system.…”