MICROMECHANICS PREDICTION OF THE TRANSVERSE TENSILE-STRENGTH OF CARBON FIBER EPOXY COMPOSITES - THE INFLUENCE OF THE MATRIX AND INTERFACE/

Currently, there is great interest in understanding and improving the bond between the fibers and matrix in high performance composite mater ials. In many recently developed systems, fiber surface treatments hav e been developed to improve poor bonding. These treatments are often e valuated by measuring their effect on a composite property sensitive t o the interfacial bond strength, typically the composite shear strengt h. This paper presents an evaluation of the influence of the matrix an d interface properties on the transverse tensile strength. These effec ts were quantified by comparing transverse flexural experimental data with results from a finite element micromechanics model. The results i ndicate that the transverse tensile strength is significantly more dep endent upon sizing than is the shear strength. Finally, the transverse flexure test appears to provide an additional and complementary test for evaluating interface bond characteristics.