Fracture energy of CNT/epoxy nanocomposites with progressive interphase debonding, cavitation, and plastic deformation of nanovoids

Abstract

The characteristics of the debonding process zone involving macroscale, microscale, and nanoscale mechanisms along CNT interface influence the fracture behavior of nanocomposites and their structural integrity. In current article, a multi-scale and multi-mechanism modeling approach with a cylindrical RVE comprising CNT, interphase, and matrix is developed to assess such damage progression and energy dissipation occurring at the nanoscale. The model considers the dominant damaging phenomena emerging in CNT/epoxy nanocomposites, that is, CNT debonding with an interphase zone around nanoparticles, cavitation, and plastic deformation of nanovoids. Enhancement of fracture toughness with the weight fraction of CNT is investigated with a qualitative variation of geometric and mechanical properties of the interphase, cavitation, and plastic yielding adopting strain energy release rate procedures. The fracture energy is shown to be critically influenced by the stiffness ratio of interphase to the matrix, interphase thickness, and hardening exponent. The model is validated using experimental and analytical data. © 2022 John Wiley & Sons Ltd.