Mechanical Behaviour of FRP Composites at Low Temperature

Abstract

Experimental studies have been carried out to understand the mechanical behavior of glass/epoxy composite laminates at cryogenic conditions and at different loading rates. This study uses 3-point flexural test to qualitatively assess and compare such behavior for 50 weight percentage of E-glass fibers reinforced epoxy composites during cryogenic and ambient conditions. The specimens were tested at 2 mm/min, 50 mm/min, 100 mm/min, 200 mm/min and 500 mm/min crosshead speeds to evaluate the sensitivity of mechanical response during loading at these conditions. The mechanical performances of the laminated specimens at cryogenic conditions were compared with room temperature property by using SEM photographs. Phenomenological behavior of these materials may be attributed by polymer stress relaxation, cryogenic matrix hardening, matrix cracking, resin/fiber debonding and misfit strain due to differential thermal coefficient of the constituent phases and also by enhanced mechanical keying factor by compressive residual stresses at cryogenic temperatures