Multi-scale variable stiffness design optimization of continuous fiber-reinforced composite with multi-point shape preserving constraints and integrated design-manufacturing

Perforated fiber-reinforced composites are widely employed in aerospace and new energy power equipment. The functional holes play a crucial role in achieving an overall lightweight design, high stiffness, and effective deformation control, which are essential for maintaining geometric accuracy. This study addresses the local warping deformation control problem in the multi-scale lightweight design of fiber-reinforced composite structures with holes. Based on the Normal Distribution Fiber Optimization (NDFO) discrete material interpolation scheme, the paper proposes a multi-point shape preserving concurrent multi-scale variable stiffness design optimization method for fiber-reinforced composites. This approach achieves structural lightweight while suppressing warping deformation around holes. By introducing the Artificial Weak Elements (AWE) and multi-point shape preserving, quantitative measure and constraint local warping deformation near structural holes are achieved. Analytical sensitivity for both macro-scale topology and micro-scale fiber orientation variables relative to the objective function, and multi-point shape preserving constraints are derived. Furthermore, by employing the first-order shear deformation theory and a multi-scale continuous filtering strategy for discrete fiber angles, the effectiveness and engineering applicability of the proposed method are demonstrated through both numerical simulations and experimental validation, offering a novel approach for achieving lightweight design and deformation control in composite materials.