Uniaxial variable-stiffness layup configuration for carbon fiber-reinforced polymer laminates to improve bending performance

Curved fiber tows offer a promising alternative to classical constant stiffness composites in terms of design and performance. However, the analysis of such structures is more challenging because the fiber orientation and the resulting stiffness properties vary continuously over the laminate. In this study, a uniaxial variable-stiffness layup configuration is proposed, in which “uniaxial” means that the fiber orientation and the resulting stiffness distribution vary only along a single in-plane coordinate direction, namely the x -axis, rather than over the general two-dimensional x – y domain. This design incorporates a specific strategy for planning the curved trajectories of the fiber tows. For the bending analysis of the resulting uniaxial variable-stiffness laminates, a finite strip formulation is adapted to account for the spatially varying stiffness coefficients. Furthermore, a response-surface proxy model based on the radial basis function is constructed to establish the relationship between design variables and laminate center deflection. Comparison with experimental results demonstrates that the designed uniaxial variable-stiffness laminates effectively facilitate load transfer, mitigating stress concentration and delaying damage initiation.