Free Vibration of Composite Orthogrid and Hierarchical Stiffened Cylinders

Composite stiffened cylinders are critical lightweight structural components in aerospace and automotive applications, prized for their exceptional load-carrying capacity, efficiency, and design flexibility. However, existing research has an insufficient understanding of the dynamic characteristics of orthogrid and hierarchical stiffened cylinders, particularly the lack of systematic studies on the influence of parameters, which limits the further application of the cylinder. Given this, based on the discrete stiffener theory and the first-order shear deformation theory, a dynamic characteristics prediction model and a finite element analysis model of the composite orthogrid and hierarchical stiffened cylinders are established in this work. The dynamic characteristics of the composite orthogrid and hierarchical stiffened cylinders are explored. The influence and mechanism of the cylinder geometric parameters on its dynamic characteristics are elucidated, and the accuracy of the model is verified through a free vibration test. Results show that, compared to the orthogrid stiffened cylinder, the fundamental frequency decreases by 4.27% for T-CHOSC and 9.23% for F-CHOSC, with model prediction errors below 4.05%. Parametric sensitivity analysis reveals that rib thickness is the dominant factor, while skin thickness shows peak sensitivity for the second mode, enabling targeted modal suppression. Among configurations, F-CHOSC exhibits the highest overall sensitivity, offering superior tunability. The research results provide a theoretical and engineering basis for the dynamic optimization design of complex stiffened shell cylinders.