Constrained vibration of butterfly-shaped honeycomb sandwich panels under base motion

Periodic base motion at the edges of panels can induce significant vibrations, impacting stability, safety, and stealth performance. This study examines the vibration characteristics of butterfly-shaped auxetic honeycomb sandwich panels (BF-HSP) under base motion. Through experiments and 3D FE modeling (3D-FEM), the accuracy of the 2D equivalent plate model (2D-EPM), based on the variational asymptotic method, is validated in free modal analysis. Further analysis using 3D-FEM and 2D-EPM evaluates the constrained modes and local responses of BF-HSP under periodic base motions. Compared to 3D-FEM simulations, the equivalent model enhances computational efficiency, requiring only 1.04% of the computation time, while maintaining high accuracy in predicting constrained vibration characteristics, with a maximum error under 10%. Compared to arc-shaped and re-entrant honeycomb sandwich panels (AR-HSP and RE-HSP), the proposed BF-HSP excel in suppressing low-frequency resonance and reducing resonance amplitude by up to 6.1%. Local field analysis reveals that the butterfly-shaped core of BF-HSP effectively mitigates dynamic stress concentration, especially along the inclined core struts, resulting in a 4.1% reduction in local dynamic stress compared to AR-HSPs and a 32.4% reduction compared to RE-HSPs. This study offers a highly efficient and reliable solution for the design of auxetic honeycomb sandwich panels, enhancing vibration damping performance and structural stability while mitigating the adverse effects of vibration resonance.