Damage behaviors in cross-ply cloth CFRP laminates cured at different temperatures

Abstract

Damage behaviors in cross-ply, [0/904]s cloth Carbon Fiber Reinforced Plastic (CFRP) laminates with different curing temperatures have been observed as a function of applied stress. Coupons manufactured by Vacuum-assisted Resin Transfer Molding (VaRTM) method with resin cured at room temperature and at 80-degree Celsius (post-curing temperature) were monotonically and cyclically loaded. Residual properties which are Young’s modulus etc. together with damage accumulation, have been recorded as a function of applied stress. DCB tests have been performed for matrix fractography purpose in this study. Significant differences can be observed in the mechanical properties, damage initiation, and progression in the laminates when the post-curing procedure is implemented. For room temperature cured laminates, matrix cracks initiated arbitrarily on the edge of the coupon with the influence of voids and other internal structures in the cloth laminates such as wefts, etc. without completely propagating in the thickness nor the width direction of the laminates. However, for post-cured laminates, cracks started at the edges and propagated through the thickness and width direction of the laminates. Matrix fractography results show that laminates cured at room temperature exhibit more plastic deformation which showed fewer brittle properties compared to laminates cured at higher temperatures as the matrix behaved in a more brittle fashion, which enhanced the tensile microcracking.

Keywords

• damage behavior
• curing temperature
• cross-ply
• woven laminates
• epoxy resin
• matrix cracks