Quasi-Disk Type Microbond Pull-Out Test for Evaluating Fiber/Matrix Adhesion in Composites

Abstract

Adhesion strength between epoxy resin and carbon fiber was analyzed using various microbond types adhered onto a single carbon fiber. Experimental pull-out tests were performed for a quasi-disk type, a hemispherical type and a droplet type microbond specimen. The quasi-disk type microbond specimen showed high regression coefficient and low standard deviation in the measurement of interfacial shear strength data as compared with the droplet and hemispherical ones. Average value of interfacial shear strength for quasi-disk type was about 55% as large as those for the other types. Finite element analysis showed that the stress distributions along the interface in the quasi-disk type specimen did not have such drastic stress concentrations susceptible to variations in the specimen geometry as revealed in the cases of droplet and hemispherical types. The experimental data were different according to the kinds of loading device such as the microvise-tip and the pin-holed plate. The use of a pin-holed steel section was useful for testing the quasi-disk type microbond specimens to give low scattering in the measurement of strength data.