Experimental and numerical investigation of vibration characteristics of X-frame CFRP sandwich plates

The vibration performance of the X-frame carbon fiber reinforced polymer (CFRP) sandwich plates was studied by experiments and simulations in this paper. The research focused on the influences of foam filling, relative density (RD) and designed parameters of the core on the modal characteristic and surface mean quadratic velocity of the plates. Firstly, the vibration modals and mean quadratic velocity of X-frame sandwich plates with or without foam-filled were measured in vacuum as well as underwater through experiments. Then, numerical simulation analysis was carried out, and the results by numerical simulation analysis were highly consistent with the experimental results. Finally, the vibration performance of X-frame sandwich plates with different parameters was researched by the validated numerical simulation analysis. The results of experiments indicated that filling low-density foam into the core could increase the natural frequencies slightly and reduce the mean quadratic velocity at the natural frequencies of the plates. The low-density foam played a role in peak shaving. Improving the relative density of the core increased the natural frequencies significantly and reduced the overall mean quadratic velocity of the plates. The influence of parameter variations on vibration performance was discussed based on the favorable agreement observed between the results by experiment and simulation. The simulation results showed that the 45° X-frame sandwich plate had the smallest surface mean quadratic velocity compared with the other three designed angles including 40°, 55°, and 70° when the relative density of the core was same.