Abstract
The quasi-static penetration properties of hybrid laminates were experimentally investigated. Aramid fabrics, carbon fabrics, and short hemp fibres were applied as the reinforcements of hybrid and non-hybrid composite laminates with polyurethane–polyurea (PUR/PUA) matrix. The laminates were made by hand, in a mould. They were cured at room temperature for 24 h. Hybrid laminates consisted of aramid and carbon layers in two different configurations, i.e., aramid at the innermost layers and outermost layers. Aramid/PUR/PUA and carbon/PUR/PUA composites were fabricated for comparison purposes. Laminates were also prepared via an analogue sequence of laying the reinforcement layers with the addition of 5% by weight of hemp fibres in the PUR/PUA matrix. Quasi-static penetration tests (QSPT) were conducted using a tensile testing machine with a surface-hardened, hemispherical, steel punch (9 mm diameter tip), reflecting the geometry of the Parabellum projectile. A quasi-static puncture test was carried out until the laminate was perforated. The ratio between the support span (Ds) and the punch diameter (Dp) was SPR = Ds/Dp = 5.0. The results showed the influences of laminate hybridisation on the values of absorbed energy, punch shear strength, and damage mechanism in the QSPT test. The addition of hemp fibres to aramid laminates resulted in a positive hybridisation effect. The order of layers of aramid and carbon fabrics in hybrid laminates influenced the results obtained in the QSPT test.
Highlights
Polymer composites are of interest to researchers and engineers due to their potential applications in the automotive, aircraft, and defence industries
The results showed the influences of laminate hybridisation on the values of absorbed energy, punch shear strength, and damage mechanism in the Quasi-Static Penetration Tests (QSPT) test
7 present these curves for laminates and hybrid laminates based on an elastic matrix
Summary
Polymer composites are of interest to researchers and engineers due to their potential applications in the automotive, aircraft, and defence industries. This has been shown by numerous scientific papers in which the results of quasi-static penetration and ballistic tests of polymer composites are presented [1,2]. Composite materials of the first type (a) are usually based on carbon fibre reinforced polymers. These materials are very effective in deforming or fragmenting a projectile, but they have limited ability to absorb the kinetic energy of the projectile. Composites of the second type (b) are characterised by the ability to absorb most of the kinetic energy carried by the projectile
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