Weft knitting technology has a wide variety of applications such as tissue structures due to their capability in designing and production of 3D fabrics with complicate structural shapes. This issue eventually results in specific improvements regarding the production of knitted structures suitable for reinforced composite manufacturing. In this study, a new generation of textiles called as 3D weft-knitted spacer fabrics is considered to be used as composite reinforcement in cooperation with epoxy resin via the vacuum bag resin transfer molding method. The final 3D advance composite structures consist of two independent outer layers which are bonded together by numerous connecting fabric layers. Some advantages of these composite samples are high specific stiffness, the higher ratio of strength to weight, desirable sound absorbency due to their structural porosity, higher resistance to impact loadings, good thermal insulation, and improved strength to the delamination effects. Since now, limited reports regarding the mechanical behavior of 3D weft-knitted spacer fabrics reinforced thermoplastic composites are available among them, analytical studies on their flexural strength are still remained uncompleted. In this study, it is aimed to investigate the flexural properties of these 3D advance composites analytically through the simulating procedure using finite element method. The modeled unit-cell of weft knitted fabric reinforced composite because of the curved–threads in cross model, is considered to be representative volume element of composite samples containing both the fiber-rich and resin-rich areas. As the first step, the unit cell knitted fabric was graphically simulated in the CATIA software environment and then fed to the ABAGUS software for further analytical studies. Through this investigation, to model the properties of the yarn by using the calculation average tension volume method, two distinct states of isotropic and anisotropic behaviors were taken into account. During simulation, the meso-scale structure of the unit cells was examined initially in order to obtain their elastic properties. Then, the achieved elastic properties obtained was extended to macro-scaled composite structure using the homogenization technique for analyzing the flexural performance of the whole structure. According to the software outcome, it was indicated that there is a good correlation between the experimental results and numerical simulation regarding anisotropic behaviors of the composite samples. Keyword: composite,weft knitted spacer fabric, bending properties, numerical simulation.
