Off-axis tearing properties of the biaxial warp-knitted fabrics

This study presents an experimental and analytical investigation of the tearing properties of the biaxial warp-knitted fabrics with different off-axis angles. Firstly, the off-axis tensile tests, central tearing tests, single edge notch tearing tests, and trapezoidal tearing tests were carried out at seven off-axis angles. The strength, failure mode, and failure mechanism of the specimens under each test condition were studied. The results show that in the off-axis tensile tests, the lowest values of the tensile strength of the biaxial warp-knitted fabrics appear at the off-axis angles of 15° and 75° rather than the conventional 45°. Under the coupling effect of tensile strength and shearing strength, the yarn layers peeling occurs instead of yarn fracture, which is a unique failure mode of biaxial warp-knitted fabrics. The yarns of the biaxial warp-knitted fabrics can fully deform to balance the load due to the warp-knitting method, which improves the tearing strength and makes the failure brittle.