Interference‐free assemblable representative volume elements of three‐dimensional braided composites for effective elastic properties prediction

Abstract According to the four‐step braiding process, the length of corner braiding side yarn is twice that of surface side braiding yarn in theory, and the interior braiding yarns are equivalent to straight lines to construct three representative volume elements (RVEs) topology models of 3D braided composites. Based on the assumption that three RVEs have the same braiding yarns cross section area, non‐interference RVE geometric models are established, and the effective elastic properties of 3D braided composites are calculated by cross‐scale finite element method. The effectiveness of the model is verified by comparison with experimental data, and the influence of braiding angle and fiber volume fraction on the effective elastic properties is predicted. In addition, it is found that the orientation straightening of braiding yarns during the tension process is one of the important factors affecting the direction modulus under small deformation. Highlights Meso‐scale models without interference can be assembled like building blocks. The tensile modulus of interior RVEs is higher than that of other RVEs. The orientation straightening of side yarns reduces the modulus during tensiletesting.