Abstract: The finite element model of structural dynamics of fuselage frame of unmanned helicopter was established and the natural frequencies and mode shapes of its first 6 orders were obtained. Compared with modal test, the maximum error of calculation was less than 3 %. It shows that the finite element model is correct and accurately reflects the structural dynamics character of the fuselage frame of unmanned helicopter. The computational natural frequencies of frame avoided the natural frequencies of main rotor, tail blade and engine and can meet the request of dynamic of unmanned helicopter. The dynamic analysis method based on finite element analyses, which combines verification test and modal modification, can effectively guarantee the accuracy of the fuselage frame of unmanned helicopter. And it also provides the refrence for finite element dynamic modeling about other structure??of unmanned helicopter.

Key words: vibration and wave, unmanned helicopter, frame, structural dynamics, finite element modeling, modal testing

摘要： 建立某无人直升机机身框架的动力学有限元模型，计算得到前六阶固有频率和振型，与模态试验结果相比较，误差小于3 %，验证了有限元模型的正确性，表明该有限元模型能准确地反映该无人直升机框架的结构动力学特性。有限元计算的机身框架固有频率值避开了旋翼、尾桨、发动机主通过频率值，满足动力学设计要求。这种有限元计算、试验验证以及模型修改相结合的动力学分析方法，能保证框架固有特性计算的精确，也为无人直升机其它结构的动力学建模提供借鉴。

关键词: 振动与波, 无人直升机, 框架, 动力学, 有限元建模, 模态试验