Izboljšanje mehanskih lastnosti Kevlarjevih kompozitov z optimiziranimi parametri šivanja

The study explores the development of stitched reinforced composites using Kevlar woven fabric as the primary reinforcement. The influence of stitching parameters, stitch type, needle type and stitches per cm (SPC) on the mechanical performance of the composites was systematically investigated. Kevlar fabric was stitched using different needle types and SPC values before being mechanically tested for tensile strength, delamination resistance and impact performance. The results demonstrate that composites stitched with a ballpoint needle using a chain stitch at 3.94 SPC exhibited the highest mechanical strength, with tensile strength increasing from 145 MPa (unstitched) to 191.5 MPa (lock stitch) and 240 MPa (chain stitch). Impact resistance improved from 98 kJ/m² (unstitched) to 133 kJ/m² (ballpoint needle, lock stitch), with chain-stitched composites showing even better performance due to the greater load distribution of the sewing thread and reduced fabric damage. Conversely, lock-stitched composites provided superior delamination resistance due to enhanced interlayer gripping. These findings highlight the potential of the developed composite for advanced protective applications, including bulletproof vests and aerospace structures requiring superior impact resistance and structural integrity.