Multiscale modeling of regularly staggered carbon fibers embedded in nano-reinforced composites
Abstract
This article deals with the multiscale modeling of stress transfer characteristics of nano-reinforced polymer composite reinforced with regularly staggered carbon fibers. The distinctive feature of construction of nano-reinforced composite is such that the microscale carbon fibers are packed in hexagonal array in the carbon nanotube reinforced polymer matrix (CNRP). We considered three different cases of CNRP, in which carbon nanotubes (CNTs) are: (i) aligned along the direction of carbon fiber, (ii) aligned radially to the axis of carbon fiber, and (iii) randomly dispersed. Accordingly, multiscale models were developed. First, molecular dynamics (MD) simulations and then Mori-Tanaka technique were used to estimate the effective elastic properties of CNRP. Second, a micromechanical three-phase shear lag model was developed considering the staggering effect of microscale fibers and the application of radial loads on the cylindrical representative volume element (RVE).
Summary
This paper provides theoretical foundations for understanding hierarchical composite reinforcement - combining carbon nanotubes (nanoscale) with carbon fibers (microscale) in a polymer matrix. Key insights for composite filament development:
- Hierarchical Reinforcement Concept: Using two scales of reinforcement:
- Microscale: Carbon fibers (the primary structural reinforcement)
- Nanoscale: Carbon nanotubes (CNTs) dispersed in the polymer matrix between fibers
- CNT Orientation Effects: Three configurations studied:
- CNTs aligned parallel to carbon fibers
- CNTs aligned radially (perpendicular) to carbon fibers
- CNTs randomly dispersed
- Best Performance: Randomly dispersed CNTs around the microscale fibers showed significantly improved stress transfer characteristics
- Mechanism: The nano-reinforced polymer matrix (CNRP) improves the interface between carbon fibers and the base polymer, enhancing load transfer
This is relevant for understanding why some high-performance commercial composite filaments include both carbon fiber and carbon nanotube additives. It suggests that future DIY composite filament formulations could benefit from multi-scale reinforcement strategies.