The present work is focused on improving mode I and mode II delamination resistance of glass/epoxy composite laminates (50 wt.% of glass fibers) with milled glass fibers, added in various amounts (2.5, 5, 7.5 and 10% of the epoxy weight). Including fillers in the interlayer enhances the delamination resistance by providing a bridging effect, therefore demanding additional energy to initiate the crack in the interlaminar domain, which results in turn in enhanced fracture toughness. The maximal increase of mode I and mode II fracture toughness and of flexural strength was obtained by the addition of 5% milled glass fiber. The mechanism observed suggests that crack propagation is stabilized even leading to its arrest/deflection, as a considerable amount of milled glass fiber filler was oriented transverse to the crack path. In contrast, at higher filler loading, tendency towards stress concentration grows due to local agglomeration and improper dispersion of excess fillers in inter/intralaminar resin channel, causing poor adhesion to the matrix, which leads to reduction in fracture toughness, strength and strain to failure. Fractured surfaces analyzed using scanning electron microscopy (SEM) revealed a number of mechanisms, such as crack deflection, individual debonding and filler/matrix interlocking, all contributing in various ways to improve fracture toughness.

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This research work investigates the low-velocity impact induced damage behavior and its influence on the residual flexural response of glass/epoxy composites improved with milled glass fillers. The low-velocity impact damage employing varying impact velocities (3 m/s, 3.5 m/s, and 4 m/s) was induced on baseline and filler loaded samples with different fiber orientations. The residual performance and their damage modes were characterized using post impact flexural (FAI) test and acoustic emission (AE) monitoring. In all fiber orientations, the filler modified glass/epoxy samples showed improved impact strength and stiffness properties. A substantial improvement in impact damage tolerance, especially for samples impacted at 3.5 m/s and 4 m/s was observed. The presence of filler at the interlaminar zone contributed to improved energy dissipation through filler debonding and pull-out. This further contributed in arresting the crack growth, showing reduced damaged area. The inclusion of milled fibers on glass/epoxy laminates enhanced the impact toughness and residual flexural behavior.

In this research work, the low-velocity impact behavior and post impact performance of carbon/epoxy laminates modified with milled glass fibers was investigated. Unidirectional (UD) and Cross-ply (CP) carbon/epoxy laminates were incorporated with milled glass fibers by 5 wt % of epoxy. Low-velocity impact test was performed at impact velocity of 3, 3.5, 4, 4.5, and 5 m/s, respectively and the results were correlated with the baseline samples without filler. The filler loaded samples exhibited higher peak force, lesser deformation, and lower damage degree than the baseline samples. The milled glass fibers in the interlaminar zone restricts the delamination crack propagation resulting in reduced impact damage area and also promotes additional energy dissipation mechanism including filler debonding/pullout. Furthermore, the CP filler-loaded samples show higher residual loadbearing capacity for impact velocities 3, 3.5, and 4 m/s, respectively. Although the unidirectional filler-loaded samples showed better load bearing capacity for impact velocities beyond 4 m/s. POLYM. COMPOS., 40:2441-2451, 2019

This work focuses on investigating the effect of interface fibre orientation with milled glass fillers on mode-II fracture toughness of [0°7/θ°//θ°/0°7] glass/epoxy laminates. The result reveals that the loading of 5 wt-% milled glass fillers in the epoxy matrix enhanced the interlaminar fracture toughness. Significantly, the filler-loaded samples improved the fracture toughness by 232% (3.32 times) in 0°/0° and 184% (2.84 times) in ±45° interface fibre orientation compared to the baseline samples. In addition, the interlaminar shear strength increased was increased by 82% in 0°/0° interface and 76% in ±45° interface fibre orientation. Finally, field emission scanning electron microscopic (FESEM) was used to study the fracture surfaces of different fibre orientations.