EFFECTS OF CHANGING SEAWATER TEMPERATURE ON MECHANICAL PROPERTIES OF GRP COMPOSITES

摘要

Glass fi bres were used to fabricate epoxy and unsaturated polyester laminated composites, which were thenrnimmersed in seawater. The specimens were immediately transferred from one seawater bath to another one atrna different temperature to induce thermal shock, with concurrent hydrothermal ageing. Thermal shocks of tworntypes, up-cycle (lower to higher temperature immersion) and down-cycle (higher to lower temperature immersion)rnwere applied and their repetition induced thermal fatigue. The aged samples were subjected to 3-point short beamrnshear tests. The tests were performed at room temperature with 2 mm/min and 50 mm/min crosshead speeds.rnThe weakening effects were sensitive to loading rate. The effect of fi bre volume fraction was also investigated.rnThe maximum interlaminar shear strength fell by 35% in glass/epoxy composites (in 55 and 65 weight% fi bres)rnand by 33% in glass/polyester composites (in 60 weight% fi bres) as a result of the most severe conditioningrncycles. It was also observed that the reduction in shear strength in general was less at high crosshead speeds.rnThis may have been linked to a reduction in matrix ductility.