机体连接处局部刚度对轻型飞机起落架摆振稳定性的影响研究

The influence of the fuselage joint local stiffness on landing gear shimmy stabilization of the light aircraft

针对前起落架与飞机机体连接处局部刚度对起落架系统摆振稳定性影响的问题,以前起落架为研究对象,建立了考虑起落架与机体连接处局部刚度影响的起落架摆振分析模型,并采用复特征值优化法对摆振稳定性进行了计算与分析。最后,针对某轻型飞机前起落架,分析了机体连接处局部刚度对起落架系统摆振稳定性的影响,并通过物理试验验证了理论计算的正确性。研究表明:起落架与机体连接处局部刚度对起落架摆振稳定性影响比较明显;连接处局部刚度越小,系统所需临界阻尼越大,系统越不稳定;反之亦然;连接处局部刚度越小,系统摆振频率越小,反之亦然。在防摆设计时,应考虑起落架与机体连接处局部刚度与起落架侧向刚度之间的匹配关系。

Considering the local stiffness effect at the joint place between the nose landing gear and the fuselage, an analytical model was built. Then, the stability of landing gear system was analyzed by adopting complex eigenvalue optimization. At last, the developed method was employed to analyze the stability of a landing gear system of a light aircraft. Moreover, a corresponding experimental was implemented and its results verified the proposed method. It is also demonstrated that the local stiffness showed an obvious effect on the shimmy stability of the landing gear. It showed that the higher of the joint stiffness, the higher of the critical damping, the lower of the landing gear shimmy stability, and vice versa. Meanwhile, the lower the joint stiffness, the lower the shimmy frequency, and vice versa. The local stiffness at the joint place between the nose landing gear and the fuselage and the lateral stiffness of the land gear should be matched during the anti shimmy design.