Numerical Investigation of Broad Mid-Frequency Flexural Bandgap in Composite Sandwich Structures with Periodic Hollow-Shaped Core Geometry

Objective: Periodic structures have been widely investigated in the past decade because of its potential for noise and vibration reduction. However, there is limited research applying the concept of periodic structures to composite sandwich structures. This paper proposes two lightweight types of periodic hollow-shaped cores in composite sandwich structures, which are simple geometries and able to generate wide flexural bandgap in mid-frequency range for broaden applications. Methodology: Floquet theory and wave finite element method are used to compute the bandgap behavior. The frequency response function (FRF) of the proposed structures is performed to demonstrate the performance of vibration attenuation by using the finite element simulation. Results and Conclusions: The FRF shows that the low vibration transmissibility is observed within a certain frequency range, which is consistent with the predicted flexural bandgap. The effect of face–core delamination on the FRF is also examined. Our findings indicate that the proposed structures have higher performance of vibration attenuation than the pristine conventional sandwich structures, even when the proposed structures exhibit face–core delamination. Last, our study demonstrates that despite the simplicity of the core design, it is capable of achieving comparable bandgap behavior to more complex geometries.