The effect of stacking sequence on the impact and post-impact behavior of woven/knit fabric glass/epoxy hybrid composites

In this study, the effect of stacking sequence on the impact behavior of sequentially stacked woven/knit fabric glass/epoxy hybrid composites was investigated. 2D (double layer) fabric was used as a woven fabric and rib and milano fabrics were used as knitted fabrics. Woven and knit fabric layers were sequentially stacked in six different variations to fabricate eight ply woven/knit fabric hybrid composites. The composite laminates were processed by hand lay-up technique using 3 mm thick spacers and cured under pressure of 8 MPa for 100 min. at 100 °C, followed by cooling at room temperature under same pressure. The impact and post-impact (CAI) behavior of hybrid composites at various impact energies were investigated. FEA results were compared with experimental results. Results show that specimens having outer layer of woven fabric exhibited better impact properties than that of the specimens having outer layer of knitted fabric. The worst performance in terms of impact resistance was observed in knit/knit composites. FEA analysis was in a good agreement with the experimental results.