DESIGNING FIBRE SHAPE TO IMPROVE OUT-OF-PLANE PERFORMANCE IN COMPOSITES

摘要

Composite materials are increasingly used for primary load bearing components in aerospace applications. Their poor through thickness properties are a major concern for their wider use. Existing approaches to improving these properties have a number of key limitations. A new approach, based upon fibres of novel cross-section, is currently being evaluated. The fibres used in advanced continuous fibre reinforced plastics either have, or are considered to have, a circular cross section. Whilst it has been pointed out that fibre shape is a variable in the effective bonding between matrix and fibre, little work has been done to actively manipulate the shape and exploit potential benefits. Correct selection of the fibre shape could allow extensive load transfer by mechanical interlocking of the fibres and matrix as well as by interfacial bonding over a larger surface area. Pre-impregnated epoxy tape was produced using shaped fibres. The tape was laid up into test coupons for fracture toughness tests (Mode I - 0°/0°, 0°/45° and 0°/90° interfaces). Similar tape was made with circular glass fibres and identical test coupons laid up for comparison. The Mode I fracture toughness testing indicates that shaped fibre composite can provide >20% improvement over circular fibres.