全机模型模态局部化及频率曲线转向研究

On Mode Localization and Frequency Loci Veering of Aircraft Model

研究了某机简化模型线性振动的模态局部化现象，以及与此现象密切相关的频率曲线转向现象。运用近频摄动理论中的缩聚方法，深入探讨了局部化和曲线转向现象的发生机理和规律，提出了一个简单判据。计算实例验证了理论分析所得的结果．

Chinese aircraft cnginccrs arc becoming intcrcsted in some strange localized vibration phenomena that occur during ground vibration test and flutter test: mode localization and frequency loci veering.This paper goes deeper than was done in Ref.[1] and together they are believed to be the first papers in China on this subject.Ordinary perturbation method used in Ref.[1] fails when modes of nearly equal frequencics exist in the system. In this paper, the authors cope with such failure by replacing ordinary perturbation method with perturbation theory for nearly equal frequcncies. A model for an aircraft with 8 degresof fieedom is cstabhshed; tills model is carefully adjusted until it gives main results that agree with expcriTncntal data of the aircraft.When non-symmetry of the mass and stiffness in the external store of the model exists, Table 2 and Figs.2 and 3 can be consulted to find easily under what conditions do mode localization and frequency loci veering occur. The results obtained are valuable in the analysis of some non--symmetry effects for aircraft design.