Nonlinear Multiscale Homogenization of Carbon Nanotube Reinforced Composites With Interfacial Slippage

Abstract

A nonlinear hierarchical multiscale approach is proposed in this work, for the characterization of the mechanical and damping properties of carbon nanotube reinforced composites (CNT-RCs) considering slippage at CNT/polymer interface. The proposed numerical strategy encompasses various length scales, from nano to micro to macro. Individual CNTs are modeled at the nanoscale as space frame structures using the modified Molecular Structural Mechanics (mMSM) approach. Then the mMSM model is projected to an equivalent continuum beam element (EBE) which is subsequently used as the basic building block for the construction of full length straight CNTs at the microscale, embedded in a polymer matrix. The interfacial load transfer mechanism between the lateral surface of the CNT and the surrounding polymer is modeled with a nonlinear bond-slip friction-type model. This scheme provides with the finite element model of a Representative Volume Element (RVE) at the microscale in which a nonlinear homogenization scheme is implemented in order to compute effective material properties for the macrocontinuum. A Hill's anisotropic plasticity model is fitted onto the results of finite element analysis of the microstructured RVE model, so that anisotropic stiffness and energy dissipation mechanism, due to the directionality of the CNTs, can be captured by the equivalent macro model. Sensitivity analysis is performed with respect to various weight fractions (wf) of CNTs and interfacial shear strength (ISS) values. Global mechanical and damping properties for the homogenized models are assessed and compared with direct calculations on detailed fine scale models.

Effect of waviness and orientation of carbon nanotubes on random apparent material properties and RVE size of CNT reinforced composites

“…Tserpes et al [17] proposed a multiscale finite element based RVE model for CNT-RCs integrating nanomechanics and continuum mechanics. In Savvas and Papadopoulos [18] a nonlinear multiscale computational homogenization was proposed for the characterization of the mechanical and damping properties of CNT-RCs considering slippage at CNT/polymer interface. The effect of random CNT waviness and orientation on the mechanical and physical properties of CNT-RCs has not been adequately addressed so far.…”

Multiscale analysis of nano-composites using surrogate models

“…As described in [142] the detailed MSM model of a CNT structure can be associated to an equivalent beam element model. To this purpose, the detailed MSM model is subjected to tensional axial force ( ), bending force ( ) perpendicular to its longitudinal axis and torsion (T), as shown in Figure 2.…”

“…To this purpose, the detailed MSM model is subjected to tensional axial force ( ), bending force ( ) perpendicular to its longitudinal axis and torsion (T), as shown in Figure 2. As demonstrated in [142], the above described methodology allows for accurate and efficient simulation of long CNTs as a series of EBEs, with significantly lower degrees of freedom compared to the corresponding detailed MSM model.…”

Study of the mechanical properties of interfaces in nanocomposites with molecular simulations

“…Even though some footsteps have been made, in the epoxy nanocomposites and especially in these with graphenic fillers, 26 a rigorous quantitative understanding of interfacial failure between the graphene layer and epoxy from a molecular point of view has not been introduced or even proposed, although some first attempts in mesoscale have been made. 43,44 Especially the mechanism which promotes this slippage phenomenon and its dependence of molecular parameters has not been studied.…”