Towards balancing in-plane mechanical properties and impact damage tolerance of composite laminates using quasi-UD woven fabrics with hybrid warp yarns

Abstract

An experimental study is conducted with the aim of balancing in-plane mechanical properties and impact damage tolerance in composite woven laminates using a quasi-unidirectional (quasi-UD) woven fabric (i.e. low crimp architecture) and yarn-level fibre hybridisation. In this work, composite laminates are manufactured with and without yarn-level hybridisation and yarn crimp. By combining high-strength fibres (i.e. S-glass) and high-elongation fibres (i.e. polypropylene, PP) with commingling and core-wrapping processes, hybrid S-glass/PP yarns are produced. A quasi-UD fabric is then produced with unbalanced warp and weft yarns (i.e. 5H satin with high linear density hybrid S-glass/PP warp and low linear density S-glass weft yarns), and subsequently laminates are manufactured using vacuum-assisted resin infusion. In addition, hybrid S-glass/PP yarns are used to manufacture non-crimp (i.e. without weft yarns) and 5H satin fabric (i.e. with balanced S-glass/PP warp and weft yarns) laminates. For comparison, S-glass yarns are used to manufacture non-crimp cross-ply laminates (i.e. without yarn-level hybridisation and without weft yarns). For all the laminates, the in-plane mechanical properties are measured by using tensile and compressive tests, and the low velocity impact response is investigated using drop-weight impact tests with different energy levels (i.e. 15, 25, 35 and 50 J). Furthermore, the impact damage tolerance is characterised by measuring residual compressive strengths with compression-after-impact tests. The damaged specimens are investigated using scanning electron microscopy to identify inter- and intra-laminar failure mechanisms. The results indicate that the quasi-UD woven fabric composites with low crimp and yarn-level hybridisation can be successfully used to introduce conducive fibre architecture and microstructures to balance in-plane mechanical properties and impact damage tolerance.