FIBER WALK-OUT DURING SMALL-AMPLITUDE OSCILLATORY SMEAR OF CONTINUOUS-FIBER COMPOSITES

In this paper we present an experimental study of a recently discovere d phenomenon, referred to as ''fibre walk-out' which can occur during small-amplitude oscillatory shear of continuous fibre-reinforced compo sites between parallel plates. Tests are carried out on a model compos ite consisting of straight, rigid fibres of Nylon in a viscous, Newton ian matrix of golden syrup, and the influence of various experimental parameters such as the duration of oscillation, strain, sample orienta tion and frequency on the Extent of walk-out is investigated. We also present a theoretical study of the flow of a laminated composite when it experiences small-amplitude oscillation between parallel plates. Th e laminate is assumed to consist of an arbitrary number of alternating resin-rich layers and plies. Velocity profiles are determined for a t hree-layer resin/ply/resin laminate in which the fibres in the ply are inclined at different angles to the direction of oscillation, and a c omparison is made between the along-fibre velocity and the extent of w alk-out observed in the experiments. (C) 1998 Elsevier Science Ltd. Al l rights reserved.