Effectively reduce transient vibration of 2D wing with bi-stable metamaterial

Unsteady time-varying flow during flight may causes transient vibrations of wings, limiting aircraft safety and requiring effective suppression methods. Nonlinear acoustic metamaterials have recently attracted extensive attention owing to their superior capability for low-frequency and broadband vibration suppression. However, most existing nonlinear metamaterials consist of mono-stable nonlinear resonators, whose transient vibration reduction capability requires significant improvement. This paper proposes a 2D metamaterial wing model consisting of bi-stable nonlinear resonators. Based on CFD simulation, we establish an equivalent model surrounded by a fluid-like medium and systematically investigate its transient dynamics and energy dissipation. Results indicate that the bi-stable metamaterial can quickly dissipate the transient vibrations of the wing with an efficiency much higher than the linear and mono-stable nonlinear counterparts. An energy dissipation rate of over 75% is achievable with an added mass ratio of 4%-8%, while the energy dissipation rate of the linear counterpart is below 60%. The subharmonic nonlinear beatings and subharmonic resonance capture, such as 1:2 or 2:3 resonances between multiple modes, are essential mechanisms for the improvement. The reduction is robust to varying amplitudes and the distance between the two stable states. These findings provide new ways to reduce the fluid-structure interaction transient vibrations of structures.