用壁板颤振理论解决某系列飞机的方向舵蒙皮裂纹故障

高速飞行器部件多采用轻质薄壁加筋结构，当飞行器长时间跨音速或低超音速飞行时，这种薄壁结构在非定常气动载荷的作用下会表现出强非线性的流固耦合特征，其中激波运动、边界层效应、流动分离等流场非线性与几何大变形等结构非线性相互耦合作用会使壁板产生失稳行为，引起结构疲劳或损毁。该文基于CFD/CSD耦合数值模拟技术，预测和判别壁板在跨音速气流中随马赫数变化过程中响应形态，发现在跨音速区内会出现明显的单模态颤振形式。随马赫数的增大，其形态演化次序为稳态收敛、第一模态极限环振荡、屈曲、稳态收敛、跨音速颤振、非共振型极限环振荡、共振型极限环振荡、高频周期振荡、高频非周期振荡、第一模态极限环振荡到稳态收敛的过程。当壁板厚度增加、来流密度减小，演化形态会发生变化。同时，当考虑非定常加速效应和粘性效应后，会出现一定的延迟和阻尼效应，对高频非周期振荡起到抑制作用，这对于降低结构的疲劳损伤有积极效果。

Historical development of air craft flutter

The lightweight thin-walled stiffened structure composed of skeletons and skins is mostly applied in the wings and bodies of high-speed flight vehicles. When the vehicles are flying at transonic or low-supersonic speed for a long time, this thin-walled structure will show strong nonlinear fluid-solid coupling characteristics under unsteady aerodynamic loads. Among them, the nonlinear interaction between fluid nonlinearity such as shock-wave movement, boundary layer effect, flow separation and geometric large deformation will cause the unstable behavior of the panel, thusly result in structural fatigue or damage. Based on CFD/CSD coupling method, this paper predicts and discriminates the response of the panel in the transonic domain with Mach number. It is found that single-mode flutter occurs in the transonic regime, and there will be the convergence, first-mode LCO, buckling, transonic flutter, non-resonant LCO, resonant LCO, high-frequency periodic oscillation, high-frequency non-periodic oscillation, and so on for the shape evolvements with the Mach number. The evolution pattern changes when the thickness of the panel increases, and the incoming flow density decreases. Furthermore, there will be a delay and damping effect, which can suppress the high-frequency non-periodic oscillation when considering the unsteady acceleration and viscous effects. It has a positive effect on reducing the fatigue damage of the structure.