机身刚度对双体飞机颤振的影响规律分析

针对某双体飞机颤振特性复杂的问题,本文采用片条理论修正后的偶极子网格方法,建立了双体飞机非定常气动力模型,同时基于地面振动试验建立了不同机身刚度双体飞机等效梁模型。通过有限元方法,分析了机身刚度对双体飞机结构动力学的影响,同时通过求解耦合得到的频域方程,探究了机身刚度对双体飞机颤振的影响规律。研究结果表明,机身截面垂向刚度对机身一阶垂直对称弯曲模态、机身一阶垂直反对称弯曲模态与平尾滚转模态频率影响较大。机身截面垂向刚度降低到原设计刚度67%时,机身反对称弯曲模态对平尾扭转效应增强,机身一阶垂直反对称弯曲模态、平尾滚转模态与平尾一阶垂直反对称弯曲模态耦合,双体飞机在269.34 m/s时发生颤振,颤振频率为37.2 Hz。

Analysis of the influence of fuselage stiffness on flutter of twin-fuselage aircraft

The flutter characteristics of a twin-fuselage aircraft are studied.An unsteady aerodynamic model is established by using the double lattice method(DLM)and stipe modified double lattice method.Characteristics of structural dynamic was found using ground vibration test(GVT),based on which equivalent beam models with different fuselage stiffness was established.The influence of fuselage stiffness on structural dynamics is found by finite element method(FEM).The influence of fuselage stiffness on the flutter of twinfuselage aircraft was investigated by solving the coupled frequency domain equation.The results show that the Zdirection stiffness of the fuselage cross-section has a great influence on fuselage 1st vertical symmetric bending mode,fuselage 1st vertical anti-symmetric bending mode and horizontal rolling mode.When the Z-direction stiffness of fuselage section reduced to the 67%of the original design,the torsion effect of the fuselage 1st vertical anti-symmetric bending mode on the horizontal tail enhanced,the twin-fuselage aircraft flutters at 269.34 m/s and flutter frequency is 37.2 Hz.