Double cantilever beam Mode-I testing for vacuum infused reparis of GFRP

摘要

This study presents the feasibility of the vacuum asissted resin infusion(VARI) process for strengthening and repair of glass/vinyl estr composites.Te process has attracted considerablej finterest in teh marine sector as a route to the manufacture of new structures such as boat hulls but has not been discussedas route to repair damaged parts where adhesion is required between a repair preform and the original material.In this work,the adheison that may be obtained between an infusion resin and a composite substrate is interpreted using a fracture mechanics approach involving double cantilever beam (DCB)Mode-I fracture toughnesstests.It is shown that once adequate adhesion is established from a comparison of particular pretreatments,both Mode-I critical strain energy release rate values and crack resistance curves are icnreased by teh itnroduction of ultra-thin polyestr veils to goughen the impregnation resin at the critical bonding area of the repair condiguration.Post-failure examination of the fracture surfaces show that the failue locus is transferred from the itnerface to the reinforced resin bondline.This exploits the high strain-to-failure characteristics of the thermoplastic veil materials.The strong crack resistance observed is attributed to the ply bridging mechanism of the thermoplastic fibres that defom plastically in the wake of the crack.Two different data reduction methods are adopted for the current study,namely the compliance calibration (CC) and the modified beam theory (MBT) and a relationship is derived from teh variation of their parameters n and DELTA in order to analyse and compare the fracture energy values obtained.