  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) of
nano-reinforced composite. Our results reveal that the stress transfer
characteristics of the nano-reinforced composite are significantly improved by
controlling the CNT morphology, particularly, when they are randomly dispersed
around the microscale fiber. The results from the developed shear lag model
were also validated with the finite element shear lag simulations and found to
be in good agreement.
