Multi-axial fabrics are a type of technical textiles that have gained increasing importance due to their high mechanical properties, good flexibility and high production speed compared to conventional weaving in various fields. In the production of multi-axial warp knitted fabric (MWKF), first layering is needed and then the layers are connected to each other. One subset of multi-axial fabrics is stitched multi-axial fabrics. Which in the case of threading and layering in common with MWKF and difference only in the sewing part. These fabrics alone do not perform well against bending and impact. In recent years, the use of composite materials in structures has received much attention. The sandwich panel consists of a number of faces and a core. The main purpose of this study was to investigate the effect of factors such as foam injection into the core, different geometries, sewing parameters and type of multi-axial fabric on bending, impact and post-impact bending behavior of multi-axial warp knitted structures. For this purpose, first the multi-axial warp knitted fabric was made of glass threads and then structures with rectangular cross-section, right triangle and equilateral triangle were produced by Lock stitch sewing machine and special sewing technique. To produce the composite structure and create the desired geometry, first, wooden molds appropriate to the structure were placed in the cells of the structure and impregnated with resin by hand-layup process. Then half of the structures were filled by injecting polyurethane foam into the empty space of the structure cells and foamless and foamed structures subjected to three-point bending test, impact test and three-point post-impact bending test. The results generally showed that the type of cross-section and injection of foam into the core have a significant effect on improving the bending properties and impacts of the structure. Structures with equilateral triangles have a difference of 29.5% compared to rectangular structures and 57% compared to right triangle structures at the maximum tolerable force and more. The results also showed that the injection of foam into the structure greatly increases the maximum 127 tolerable bending force and the amount of energy absorbed. While sewing parameters such as stitch density and type of multi-axial fabric do not have a significant effect on bending and impact properties.