FRACTURE-MECHANICAL CHARACTERIZATION OF FIBER-REINFORCED PLASTICS IN THE INTRALAMINAR CRACK OPENING MODE (MODE-I) AND IN THE SHEAR MODE (MODE-II)

Two novel techniques and evaluation procedures for the fracture mechan ical characterization of fibre reinforced plastics (FRPs) in the intra laminar mode I (crack opening mode) and mode II (shear mode) based on the fracture energy concept are presented. The splitting (mode I) as w ell as the punch-through shear (mode II) test are experimentally simpl e; the loading device and the sample geometries are small and well sui ted for measurements at cryogenic temperatures on both unirradiated an d irradiated samples. The test results are load versus displacement cu rves, from which the strain-softening behaviour of the FRPs can be eva luated employing finite element calculations (FEM). All material param eters necessary for the FE calculations of the fracture behaviour can be taken directly from the strain-softening diagram and represent char acteristic intrinsic material parameters (fracture parameters), Result s obtained on a two-dimensionally glass fibre reinforced epoxy laminat e are presented. (C) 1998 Elsevier Science Ltd. All rights reserved.