The finite element model of a dual-rotor system was established by Timoshenko beam element. The dual-rotor system is a coaxial rotor whose supporting structure is similar to that of an aero-engine rotor system. The inner rotor is supported by three bearings, which makes it a redundantly supported rotor. The outer rotor connects the inner rotor by an intershaft bearing. The spectrum characteristics of the dual-rotor system under unbalanced excitation and misalignment excitation were analysed in order to study the influence of coupling misalignment of the inner rotor on the spectral characteristics of the rotor system. The results indicate that the vibration caused by the misaligned coupling of the inner rotor will be transmitted to the outer rotor through the intershaft bearing. Multiple harmonic frequency components, mainly 1x and 2x, will be excited by the coupling misalignment. The amplitudes of all harmonic frequencies increase with the misalignment in both the inner and outer rotors. The vibration level of the outer rotor affected by the misalignment is lower than that of the inner rotor because it is far from the misaligned coupling. Harmonic resonance occurs when any harmonic frequencies of the misalignment response coincide with a natural frequency of the system. In order to verify the theoretical model, experiments are performed on a test rig. Both the experimental and simulation results are in good accordance with each other.

中文翻译：

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耦合不对准的同轴双转子系统的频谱分析

Timoshenko梁单元建立了双转子系统的有限元模型。双转子系统是同轴转子，其支撑结构类似于航空发动机转子系统的支撑结构。内转子由三个轴承支撑，这使其成为冗余支撑的转子。外转子通过轴间轴承连接内转子。为了研究内转子耦合不对准对转子系统频谱特性的影响，分析了双转子系统在不平衡激励和失准激励下的频谱特性。结果表明，由内转子未对准引起的振动将通过轴间轴承传递到外转子。多个谐波频率分量，主要是1x和2 x会因耦合失准而激发。所有谐波频率的幅度都随着内转子和外转子中的未对准而增加。受未对准影响的外转子的振动水平低于内转子的振动水平，因为它离未对准的联轴器很远。当失准响应的任何谐波频率与系统的固有频率一致时，就会发生谐波谐振。为了验证理论模型，在试验台上进行了实验。实验结果和仿真结果都很好地吻合。