Investigation of FRP Lap Splice Using Epoxy Containing Carbon Nanotubes

Abstract

In many situations, it is necessary to splice multiple layers of fiber-reinforced polymer (FRP) composite laminates. The relatively low bond and shear strength of FRP layers usually necessitates long lap splices. In this paper, the authors demonstrate how lap splices shorter than those used in standard FRP design today can be made viable by incorporating carbon nanotubes in the epoxy resin. Experimental and numerical investigations are conducted to evaluate the significance of using multiwalled carbon nanotubes (MWCNTs) on FRP lap splice. Double lap shear joints of carbon-fiber-reinforced polymer (CFRP) were fabricated and tested with various amounts of functionalized MWCNTs (0.5, 1.0, and 1.5%). Experiments show that the shear stress-strain response of the CFRP lap splice can be engineered with the appropriate amount of MWCNTs to increase the bond strength by 50% and/or the failure strain by 300%. The numerical modeling shows that the shear-slip at the interface governs the bond strength and ductility of the lap joints.