Exploring natural frequencies and vibration patterns in composite concentric plates inspired by tree annual rings

Bio-inspired composite structures have attracted considerable attention because of their potential to provide lightweight and high-performance structural solutions. However, despite extensive studies on the vibration behaviour of conventional laminated composite plates, the influence of tree growth-ring-inspired concentric architectures on the modal characteristics of composite plates has remained largely unexplored. Therefore, this study investigated the free vibration characteristics of bio-inspired concentric composite plates inspired by the annual-ring growth pattern of tree stems. A finite element model was developed in ANSYS APDL, in which concentric graphite fibre rings were bonded with an epoxy matrix to form multilayer composite plates. Modal analyses were performed to determine the first five natural frequencies and their corresponding mode shapes. The vibration characteristics of the proposed bio-inspired composite plates were also compared with those of conventional laminated composite plates. The results demonstrated that increasing structural stiffness through appropriate annular-ring configurations and fully clamped boundary conditions significantly improved the natural frequencies. Furthermore, the bio-inspired concentric architecture exhibited favourable vibration performance compared with conventional laminate configurations, demonstrating its potential as an efficient lightweight structural design for advanced engineering applications.