Effect of viscoelastic behaviour of glass laminates on their energy absorption subjected to high velocity impact

• This study correlated the viscoelastic behaviour of the polymer composites with energy absorption during ballistic impact.
• E-glass/phenolic composites absorb more energy than E-glass/epoxy composites due to better storage modulus and loss modulus.
• Absorbed energy is highly influenced by laminate thickness as well as projectile velocity.
• High speed video camera, environmental SEM and stereo microscope were used to explain the various damage modes of composites.

In the present work, a comparative study is carried out on the energy absorption ability of phenolic and epoxy matrices reinforced with glass fibres. E-glass/phenolic and E-glass/epoxy laminates having different thickness (5 mm, 10 mm, 15 mm, 20 mm & 25 mm) were fabricated and subjected to ballistic impact against 7.62 × 39 mm mild steel core projectile. Dynamic Mechanical Analysis (DMA) of E-glass/phenolic and E-glass/epoxy laminates was also carried out. It was observed that, E-glass/phenolic laminates which have shown higher storage and loss modulus were found to show higher energy absorption than E-glass/epoxy laminates which have shown lower storage and loss modulus. This is observed to be because of ease of delamination and transverse stretching of fibres in E-glass/phenolic laminates as the matrix at the interface is allowing easy sliding. However this effect is found to be significant only when the laminate thickness to projectile diameter ratio (t/d) is more than two. Mechanisms influencing the observed trend in results are analyzed in the present paper with the help of DMA and high speed video imaging during impact. Failure analysis of laminates was studied by using microscopy techniques.

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