Effect of Fiber Paths and Structural Parameters on the Buckling Resistance of Nonlinear Variable Stiffness Composites

ABSTRACT The buckling resistance is a fundamental design criterion for thin‐walled composite structures in aerospace applications. This resistance can be enhanced through variable stiffness (VS) design, achieved by automatic fiber placement (AFP) along curved paths. While VS composites exhibit improved mechanical properties, their buckling behavior is significantly influenced by structural parameters. In this investigation, a nonlinear fiber path incorporating additional control points is proposed to expand the design space of VS composite cylinders. Finite element analysis (FEA) was employed to evaluate the buckling resistance across various structural configurations. Subsequently, the effects of both the fiber path and structural parameters on buckling behavior were analyzed. The results demonstrate that nonlinear design can increase buckling loads compared to linear VS composites at equivalent structural parameters. Furthermore, the critical buckling loads of VS plates show a negative correlation with the aspect ratio, and the buckling modes exhibit geometric dependence within the aspect ratio range of 1–2.5. The buckling modes of VS cylinders are significantly influenced by the length‐to‐diameter (L/D) ratio, which ranges from 0.1 to 1. However, the structural enhancement ratio approaches negligible values when the L/D ratio exceeds 1. This nonlinear fiber path design shows significant potential for aerospace applications, enabling thin‐walled composites with superior mechanical properties.