Interlaminar Fracture Response of Glass Fibre/Epoxy Laminates Toughened with Glass Fibre Veils

Abstract

This study investigates the influence of glass fibre veil interlayers on the Mode I interlaminar fracture behaviour of glass fibre-reinforced epoxy laminates. Laminates with a stacking sequence of [0]₈ were manufactured using a vacuum-assisted resin infusion process. A 30 g/m² glass fibre veil is inserted at the mid-plane to evaluate the toughening efficiency of the veils. Mode-I interlaminar fracture properties are determined through double cantilever beam (DCB) tests in accordance with ASTM D5528. The fracture initiation (GI,C) and propagation (GI,R) energies are calculated using Modified Beam Theory (MBT). The load–displacement responses revealed stable crack growth for both laminate configurations, while veil-toughened laminates exhibit higher fracture resistance during crack initiation and propagation under mode-I loading. The incorporation of the glass fibre veils leads to ∼44% increase in fracture initiation energy and a ∼22% increase in propagation fracture energy compared to the untoughened baseline laminates. Rising R-curve behaviour is observed in untoughened and toughened laminates, indicating the activation of intrinsic and extrinsic toughening mechanisms under mode-I loading conditions. The digital images captured from the specimens demonstrate that fibre bridging fracture mechanisms are established in both laminate systems. In addition, crack migration toward neighbouring lamina is observed from both laminates. The study concludes that crack deviation is more closely associated with fibre waviness induced by stitching patterns in non-crimp fibre fabric preforms rather than differences in interfacial material properties. Overall, the results demonstrate that glass fibre veils offer an effective and easy-to-apply strategy for improving the interlaminar fracture resistance of glass fibre-reinforced epoxy laminates.

Keywords

• Composite laminates
• Delamination
• Interlaminar toughening
• Mode-I interlaminar fracture

Ethical Statement

Ethics committee approval was not required for this study because of there was no study on animals or humans.

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