Prediction and experiment on the free vibration behavior of carbon-fiber-reinforced cylindrical foldcore sandwich structure

Abstract

Abstract Free vibration behaviors of advanced carbon-fiber-reinforced cylindrical foldcore sandwich structures (CFSSs) are investigated through theoretical, numerical and experimental methods. The governing equations of motion are developed by adopting the first-order shear deformation theory. To obtain the eigenfrequencies, the equivalent shear moduli of carbon-fiber-reinforced cylindrical foldcore are derived by an energy approach for the first time. The representative specimens of CFSSs are fabricated through a pre-folding prepregs and hot-press molding method. Numerical simulation validated by modal tests is carried out to examine the accuracy of the theoretical solution. When the number of circumferential cells is more than 30, the error of the theoretical results with respect to the numerical ones can be well controlled within 10%, which is considerably acceptable for engineering designs. The influences of the layup sequences and geometrical parameters of CFSSs on the structural vibration performance are thoroughly investigated, which maybe provide some significant references for researchers on the practical engineering application and design of advanced carbon-fiber-reinforced cylindrical shells. Compared with other traditional carbon-fiber-reinforced sandwich cylinders under condition of nearly same size and mass, CFSSs always possess higher fundamental frequency, indicating that CFSSs are much stiffer and could be designed even lighter in aerospace applications.