Multi-scale modeling of hierarchical hybrid graphene quantum dot - epoxy/carbon fiber composite

Graphene Quantum dots (GQDs) have emerged as a promising nanofiller for the design and development of the next generation of polymer matrix composites for aerospace, defense, and energy applications. Integrated computational materials engineering (ICME)-based multiscale frameworks can be used to design the next generation of high-performance composites. In this research, effects of GQDs on the epoxy matrix are investigated using molecular dynamics (MD) simulations at the nanoscale. Further, the hierarchical hybrid composite model of GQD – Epoxy/carbon fiber is investigated using micromechanics to predict the mechanical properties. At the nanoscale, density, cure shrinkage, free volume, Young's modulus, shear modulus, bulk modulus, yield strength, glass transition temperature, and coefficient of thermal expansion are predicted as a function of GQD mass fraction. At higher length scales, the GQD dispersion in the epoxy matrix and elastic moduli in transverse and axial directions are investigated using micromechanics. Results of this study indicate that the GQDs improve the mechanical and thermal performance of epoxy; GQDs improve the transverse modulus of the composite; and GQDs reduce the thermal shrinkage of the epoxy by 29%, which is critical for industrial large-scale composite processing. Current work is the first to report the effects of nano-scale GQD and edge functionalization on large-scale carbon fiber epoxy composites through an ICME-based multi-scale approach.