Multi-axial fabrics are fibrous structures in which yarns are incorporated in various directions within the structure. Multi axial warp knitting fabrics are extensively used in production of composites. This is due to their high strength/weight ratio in comparison to metallic materials. These composites have extensive applications in industries, military, aerospace, automotive, renewable energy, shelters, and sport equipment. The aim of this research is to investigate the tensile behavior of multi-axial needle punched Fibrous structure. Samples were prepared by placing the incorporated yarns in 0, +45, -45, and 90 degrees using a suitable frame. Layers of nonwoven webs were needled on both sides of prepared networks. The effect of various factors such as punch density, needle penetration depth, and the direction of yarns on average maximum tensile under uni-axial testing condition were investigated. The experimental results demonstrated that insignificant difference in average maximum strength of samples at various angles exists. Thus it was concluded that the mean strength values of the samples in all directions is also different. Statistically it was found that except for punch densities of 40 and 120 punch per square cm, the amount of needling imparted to the samples does not affect the average maximum strength of samples. Additionally it was observed that needle penetration depth has considerable effect on fabric strength. It was also found that fabric strength is influenced by needling method. Results indicated that due to combined effect of needle penetration depth and punch density. The strength of multi-axial needle punched fabrics is reduced. Keywords : Tensile strength, Multi-axial warp fabrics, needling, punch density, needle penetration depth.
