The effect of MWCNTs with different diameters on the interface properties of Ti/CFRP fiber metal laminates

Abstract

Fiber-metal laminates (FMLs) consist of alternating thin layers of metal and fiber-polymer composite and are characterized by a relatively weak interface. In this paper, to address the needed improvement in the strength of the metal-resin interface, we apply molecular dynamics (MD) simulations in the design of an interface model of titanium-polyimide (Ti/PI) in which multi-walled carbon nanotubes (MWCNTs) of diameters ranging from 2 nm to 20 nm are added to PI resin to enhance the interface mechanical properties of the obtained Ti/carbon fiber-reinforced polyimide (Ti/CFRP) FMLs. As a result, these mechanical properties can be significantly improved by adding MWCNTs of different diameters to a polymer matrix. The van der Waals energy and the total energy of the system linearly increased with increasing diameter of the MWCNTs. Furthermore, the interfacial interaction energy decreased with increasing MWCNT diameter to a minimum, then increased and finally stabilized, which implied that the improvement of the interface properties followed the same trend. Notably, at an average MWCNT diameter of 8 nm, the interface fracture energy as an indication of interface mechanical performance is increased by nearly 180% compared to the material without MWCNTs.