A Multiscale Architecture-Tailoring Approach for Quasi-Isotropic Design of Three-Dimensional Multi-Axial Woven Composites

Three-dimensional woven composites exhibit excellent through-thickness reinforcement, delamination resistance, and damage tolerance, making them promising candidates for lightweight load-bearing structures in aerospace and rail transportation applications. However, conventional three-dimensional orthogonal woven composites generally exhibit pronounced in-plane orthotropy due to the nonuniform spatial distribution of warp and weft yarns, resulting in considerable differences in stiffness and load-bearing capacity among different directions and thereby limiting their engineering applications under complex multidirectional loading conditions. In this study, a quasi-isotropic design method for three-dimensional multi-axial woven composites based on multiscale architecture tailoring is proposed. First, a multiscale analysis framework encompassing microscale yarn modeling, mesoscale woven architecture modeling, and macroscale effective property prediction is established. The predictive capability of the framework is validated against quasi-static tensile tests of three-dimensional orthogonal woven composites, demonstrating that the developed models can effectively capture the anisotropic mechanical response of three-dimensional woven composites. On this basis, an orientation-dependent elastic property prediction method is developed using fourth-order compliance tensor transformation, and two quantitative indices, namely the stiffness symmetry deviation and isotropy consistency, are introduced to evaluate the in-plane quasi-isotropic behavior of three-dimensional multi-axial woven composites. The designed material is further applied to the cab skin panel of a rail vehicle for numerical deformation assessment, and the predicted maximum displacement satisfies the adopted deformation limit under the considered loading condition. The results demonstrate that the proposed method enables cross-scale tailoring from yarn architecture parameters to macroscale structural performance, providing an effective approach for the design of three-dimensional multi-axial woven composites subjected to complex load-bearing requirements.