Modeling of CNTs and CNT–Matrix Interfaces in Continuum-Based Simulations for Composite Design

Abstract

Abstract A series of molecular dynamic (MD), finite element (FE) and ab initio simulations are carried out to establishsuitable modeling schemes for the continuum-based analysis of aluminum matrix nanocomposites reinforced with carbonnanotubes (CNTs). From a comparison of the MD with FE models and inferences based on bond structures and electrondistributions, we propose that the effective thickness of a CNT wall for its continuum representation should be related to thegraphitic inter-planar spacing of 3.4 A. We also show that shell element representation of a CNT structure in the FE modelsproperly simulated the carbon-carbon covalent bonding and long-range interactions in terms of the load-displacement behaviors.Estimation of the effective interfacial elastic properties by ab initio simulations showed that the in-plane interfacial bond strengthis negligibly weaker than the normal counterpart due to the nature of the weak secondary bonding at the CNT-Al interface.Therefore, we suggest that a third-phase solid element representation of the CNT-Al interface in nanocomposites is not physicallymeaningful and that spring or bar element representation of the weak interfacial bonding would be more appropriate as in the casesof polymer matrix counterparts. The possibility of treating the interface as a simply contacted phase boundary is also discussed.Key wordscarbon nanotube, molecular dynamic simulation; ab initio simulation; nanocomposite.