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This article provides an in-depth exploration of the current state of research in microwave-absorbing composite materials, juxtaposing the status quo of coating type and structurally reinforced resin-based composites, with a particular emphasis on the latter's structural and performance superiority. It succinctly elucidates the mechanisms of electromagnetic shielding, as well as the conditions and underlying principles that govern the absorption of microwaves by composite materials. The review continues by dissecting the strategies for enhancing the microwave-absorption capabilities of resin-based composites, including the classification of absorbents, absorbent selection, and an overview of structural design innovations in microwave-absorbing materials. Structural wave-absorbing composites are manufactured by combining different types of resin matrices, absorbers, reinforcing fibers and construction methods. The interactions between these components are scrutinized to reveal how each contributes to the overall performance of the composite. We spotlight the unique construction methods and the intricate relationship between structure and performance in structurally reinforced composites, offering insights into the optimization strategies for composite-material absorption characteristics. Concluding with a forward-looking perspective, the article contemplates the burgeoning potential and future applications of fiber-reinforced resin-based microwave-absorbing composites, setting the stage for a new era in material science and technology. [ABSTRACT FROM AUTHOR]

The concept of pier-supported submerged floating tunnel (PSFT) is feasible if the water depth is within 100 m. In this study, semi-analytical solutions are proposed for determining the seismic responses of a tunnel tube in a PSFT subjected to vertical excitation. The tunnel tube consisting of tube segments and flexible joints is simplified as beam components connected through bending springs. The supporting system comprising bearings and piers is regarded as a series of discrete Kelvin elements. Seismic action is considered as the inertia force and hydrodynamic pressure is calculated by the Morison equation. The tunnel tube displacement is derived by the modal superposition method. On this basis, the semi-analytical solutions of the displacement and bending moment of the tunnel tube are deduced using the Runge–Kutta method. The finite element method is employed to examine the validity of the proposed solutions. Furthermore, the effects of the fluid, flexible joints, and damping ratio are discussed. The results show that the Froude–Klylov force can significantly reduce the response amplitude, and the hydrodynamic mass force can alter the response frequency under real seismic input motion. Flexible joints can adjust the bending moment distribution in the tunnel tube. With the adoption of flexible joints, the hogging moments at the bearings considerably decrease. The change in damping ratio also have substantial effects on the structural seismic response. [ABSTRACT FROM AUTHOR]