Analysis of Interfacial Shear Strength of Fiber/Epoxy Composites by Microdroplet-Bond Test

Abstract

Interfacial shear strength between epoxy and carbon fiber was analyzed utilizing the mi- crodroplet-bond specimens adhered onto single carbon fiber. The shear stress distributions along the fiber/matrix interface were calculated by finite element analyses using such models as droplet, sphere and cylindrical pull-out. (1) The interfacial shear stress analysis showed that larger stress concentration arose along the fiber/matrix interface for the microdroplet-bond specimen than for the cylindrical one. (2) Microdroplet-bond specimens showed high interfacial strength, which was caused by various effects of the geometry and size of microdroplet as well as stress concentration in the region contacting with the micro-vise tip. (3) Analysis of the octahedral shear stress in the micro-droplet specimens indicated that the average τ_ over the embedded length was suitable to the evaluation of interfacial shear strength.