  Carbon nanotube (CNT) reinforced metal matrix composites have been the focus
of researchers due to their high load-bearing capacity. Among single and
multi-wall carbon nanotubes (MWCNT), the latter is preferred by manufacturers
and engineers for making composites due to their economic feasibility of
synthesizing. However, the effect of layer numbers along with other parameters
of the reinforcing MWCNT must be understood before its industrial application.
In this article, we developed a novel theoretical approach for predicting the
variation of strength and stiffness of MWCNT reinforced iron composites
(MWCNT-Fe) with the layer number of reinforcing MWCNT and validated the
prediction with a series of Molecular dynamics (MD) simulation. Our analysis
revealed that for every addition of two extra layers, the strength and
stiffness of the composite increase 9.8% and 7.2% respectively up to eight
layered MWCNT and then becomes saturated. We also employed MD simulations for
investigating the effect of grain boundary on the failure mechanism of CNT
reinforced iron composites in contrast to previous studies. Our investigations
revealed that instead of the matrix-fiber interface, the failure was initiated
from the grain boundary and merges with the interface. The results in this
study will not only help engineers and manufacturers choose optimal layered
MWCNT for synthesizing composite for a specific application but also provide
scientists a new method to model composites for predicting desired properties.
