大展弦比复合材料机翼的非线性颤振分析

 大展弦比机翼在气动力作用下产生较大变形,颤振速度和颤振频率随之发生明显变化,线性理论难以获得比较合理的解答。综合考虑了结构几何非线性、气动非线性和材料各向异性对机翼运动状态的影响,将复合材料机翼建模为非线性薄壁单闭室截面梁,建立机翼的运动方程,并使用小扰动分析的方法得到机翼在平衡位置附近的振动方程。采用Theodorsen非定常气动理论构建气动模型,获得机翼在平衡位置附近的非线性颤振方程,并利用v-g法判定机翼颤振稳定性。通过算例演示了一些非线性颤振的特点,讨论了铺层角、展弦比、机翼线密度等参数对颤振速度的影响,并与线性理论得到的结果进行对比。

Study of Nonlinear Flutter of High-aspect-ratio Composite Wing

High-aspect-ratio wing undergoes large deflections under aerodynamic force, and these large deflections can noticeably change the wing's flutter speed and frequency. Linear analysis methods usually yield unreasonable results for this problem. Dynamic equations are built up with composite wing being modeled as thin-wall box beam, and geometric nonlinearity, aerodynamic nonlinearity as well as stiffness coupling are simultaneously involved in it. Vibration equations are deduced through perturbing the dynamic equations at wing's equilibrium position. Flutter equations are obtained by using Theodorsen's unsteady aerodynamic theory, then flutter stabilities at various wind speeds are determined by the v-g method. Several examples show the distinguished differences between results from nonlinear flutter analysis and one from linear flutter analysis. Variations of flutter speed with wing parameters, such as ply angle, aspect ratio and mass per unit length, are also discussed.