Strengthening of composite T-joints using 1D and 2D carbon nanoparticles

An experimental study is presented into the strengthening of composite T-shaped joints using carbon nanoparticles. The structural properties of carbon fibre reinforced epoxy composite T-joints containing a small weight fraction (1%) of carbon nanotubes (CNTs), carbon nanofibers (CNFs) or graphene nanoplatelets (GNPs) within the polymer matrix phase is studied. Experimental testing reveals that the strengthening effect depends on the nanoparticle type, with CNFs being the most effective at increasing the failure initiation load (~68%), ultimate failure load (46%) and absorbed energy capacity (~200%) of the T-joint. Improvements to the structural properties are also gained with the use of CNTs, although there is little or no gain with GNPs. The improvements to the T-joint properties correlate with the increases to the interlaminar fracture toughness properties of the carbon fibre reinforced composite laminates containing the nanoparticles. The strengthening and toughening mechanisms induced by the nanoparticles are described.