Experimental investigation of the tensile and bending behavior of multi-axial warp-knitted fabric composites

An experimental study was carried out on the tensile and bending behavior of multi-axial warp-knitted fabric composites. Five specimens reinforced with multi-axial warp-knitted fabric/epoxy were manufactured by a vacuum-assisted resin transfer molding method. Quasi-static tensile and three-point bending tests were carried out in a number of orientations relative to the stitching direction: quadriaxial, triaxial, biaxial (±45° and 0/90°) and unidirectional. The results of the tests revealed that the quadriaxial and biaxial (±45°) samples showed quasi-isotropic behavior, whereas the other laminates showed anisotropic behavior. The influence of fiber volume fraction and the orientation distribution of the constituent material on the tensile and bending behavior were also analyzed. The relationships between the stress and strain and the tensile and bending behavior of different multi-axial warp-knitted fabric composite were obtained by polynomial fitting.