Mechanical properties of biaxial weft-knitted and cross-ply thermoplastic composites

Abstract

Within the scope of experiments, two kinds of biaxial weft-knitted (BWK) fabrics with aramid (AR) and polyamide (PA) 66 stitch fibers were used as reinforcement systems to fabricate thermoplastic composites with PA66 resin yarn. Then, the final composite became BWK with AR stitch yarn and cross-ply. The mechanical properties of composites were investigated by conducting tensile and three-point bending impact tests on specimens. In all specimens, PA66 was commingled with AR yarn. AR was used as reinforcement. In preliminary studies, AR unidirectional composites with AR/PA66 commingled fibers and with various twisting angles were produced and appropriate twisting angle was found out by conducting tensile test on specimens. Due to the random multiple cracks that changed the fracture behavior of BWK composites with AR stitch, the tensile properties of the BWK composites with AR stitch became lower compared with the cross-ply. However, the three-point bending impact properties of the BWK composites with AR stitch fiber were higher compared with the cross-ply.