The influence of size effects and dynamic loading on the fracture toughness of commercial GRP materials

The influence of specimen thickness and the effect of dynamic rates of test ing on fracture toughness behaviour of laboratory-prepared and commercial g lass-reinforced plastic materials have been investigated. The four material s, from different sources, gave similar fracture toughness data. The result s show that the fracture toughness increases with specimen size, for specim ens with nominal thicknesses in the range 10 to 25 mm; this is thought to b e associated with the length of fibres in the testpiece ligament. Dynamic t ests produced higher fracture toughness values than those obtained statical ly. This was believed to be due to a change in fracture mode from fibre fra cture to fibre pull-out. Crown Copyright (C) 2000 Published by Elsevier Sci ence Ltd. All rights reserved.