Vibration and damping characteristics of auxetic honeycomb sandwich panels with polyurea-metal laminate face sheets

All-metal sandwich panels of auxetic honeycomb are usually ultralight and robust but have poor vibration damping. The in-plane auxetic honeycomb sandwich panels (AHSPs) with polyurea-metal laminate (PML) were presented, and its vibration and damping characteristics were studied. The damping characteristic analysis model of the auxetic honeycomb sandwich structure of the PML panel was created by ABAQUS and the model was verified. The frequency/time response curve, natural frequency, mode shapes, and damping loss factor were simulated by the finite element (FE) method, which was then compared with the sandwich plate without a polyurea layer. To investigate potential enhancement processes and examine vibration-damping characteristics, a finite element-modal strain energy (FE-MSE) integrated approach was put forward, taking into account the natural frequency and damping behavior of polyurea. The damping of the PML panel significantly increased due to the viscoelastic energy consumption of the polyurea layer. By reasonably adjusting the thickness and distribution of the polyurea layer, the passive damping ability of sandwich panels can be further enhanced. The frequency and damping loss factor of the AHSPs were able to be successfully improved by raising the thickness of the polyurea layer. The symmetric PML-A laminate was better than the asymmetric structure in vibration reduction, and the damping loss factor can grow from 29% to 40%, with a thickness ratio of $\frac{3}{3}$.