Notched Kevlar fabric/epoxy monolayers

Abstract

The notched and unnotched response of a Kevlar 49 plain weave fabric/epoxy monolayer is examined. The unnotched material stiffens under tensile loads. In shear it is initially linear elastic; after yielding it deforms in a manner akin to work hardening materials. A method of modelling such a fabric reinforced monolayer for the purpose of a shear-lag analysis is described. This technique is used to analyse a 1-in-wide monolayer with varying numbers of initially cut yarns. Calculated strengths and load-notch opening displacement relations are in reasonable agreement with those measured experimentally. Predicted matrix and fibre stress concentrations are quite localised with nonlinear material response limited to the notch-tip region. Accordingly, a fully linear elastic analysis is shown to give a good estimate of yarn stress concentration factors. © 1982.