Influence of Fibre Stacking Sequence on Impact Resistance and Residual Strength in Flax/Basalt Hybrid Laminates

Abstract

This study investigates the effects of different fibre stacking configurations on the low-velocity impact (LVI) resistance and compression after impact (CAI) behaviour of hybrid laminates reinforced with flax and basalt fibres. Five types of laminates with different stacking sequences were manufactured using twill weave basalt and flax fibre fabrics, resulting in laminates with 15 layers each. The configurations included symmetric, asymmetric, and sandwich-type laminates with varying the distribution of flax and basalt fibre layers. The laminates were subjected to drop-weight impact tests at energy levels of 30 J, 45 J, and 60 J to evaluate their impact resistance. Post-impact, CAI tests were conducted according to ASTM standards to assess the residual compressive strength. Furthermore, both quantitative and qualitative analysis of results were conducted to investigate the effect of variations in stacking sequences. The experimental results showed that the placement of flax fibre layers significantly influences both the impact performance and residual strength of the hybrid laminates. The results revealed that the symmetric laminate having an alternating arrangement of flax and basalt fibres through its thickness, exhibited superior impact resistance and the highest residual compressive strength across all energy levels. Furthermore, different types of damage mechanisms were also observed depending on the variation in stacking sequences and impact energies, which include the damage the permanent indentation, matrix cracking, fibre pull-out, and delamination. At lower impact energies, all laminates primarily exhibited surface indentations and matrix cracking without perforation.