This study provides an evaluation of performance of the flat-knitted spacer reinforced composites filled with polyurethane foam. Multi-cellular knitted spacer fabrics (MKSF) are 3D structures consisting of two knitted facings which are joined by multiple fabric layers with different geometries. However, there are some drawbacks which limit their application in load bearing due to highly-looped configurations. This paper aims to investigate the role of foam on the bending and compressive behavior of the composites reinforced with MKSFs. 3D knitted spacer fabrics were manufactured on an electronic flat knitting machine with three cross-sectional shapes using Glass/ polyester yarns. The 3D knitted fabrics were then impregnated with epoxy resin by vacuum injection process and the prepared composite structures were filled with polyurethane foam and subjected to three-point bending and compression loading. The results revealed the cross-sectional shape and foam filling have a significant effect on the bending and compressive properties. The results also demonstrated that the parameter cross-sectional shape does not affect the flexural stiffness but has a significant effect on the core shear modulus. Also, the foam-filled composite structures represented better performance due to increasing the core resistance against the shear forces. The results also showed the foam improved vividly the energy absorption proportional to type of core cross-sectional shape
