Damage accumulation in hybrid woven fabric composites.

Abstract

Damage accumulation in glass fibre woven reinforced epoxy laminates manufactured from two different fabrics have been investigated under three different loading conditions. One of the woven fabrics was non-hybrid glass using E-glass fibre yams in both warp and weft (fill) directions, the second fabric was a hybrid woven fabric using E-glass fibre yams in the warp direction and R-glass fibre yams in the weft direction. Destructive tests such as interlaminar shear, flexural and uniaxial tension tests were carried out on two different categories. In the first category four different fibre volume fractions of nonhybrid E-glass woven fabric reinforced epoxy resin laminates have been investigated. In the second category hybrid and non-hybrid woven fabric reinforced epoxy resin laminates for similar fibre volume fractions have been investigated. Acoustic Emission (AE) and Scanning Electron Microscopy (SEM) were employed as nondestructive tools to predict and characterise the damage events in the composites. All laminates were fabricated using the wet hand lay-up process to laminate the fabric layers prior to curing. Epoxy resin (L20-SL set) was the sole matrix used for all composites. Test results showed higher mechanical performance for the hybrid composites and improvements in mechanical properties for higher fibre volume fraction in the non-hybrid composites. DMTA tests were carried out on the laminates of the categories mentioned above, the test results indicated the effect of fibre surface treatment concentration on the performance of mechanical properties of woven composites. DMTA data has been used to correlate the results of ILSS, flexural and tensile tests. A model was developed in this study based on the damage event sequential process of glass woven fabric reinforced epoxy resin composites. The model is an experimental analysis model, supported by DMTA, AE, SEM and visual examination of specimen fracture surface.