Dynamic Characteristics And Response Of Vibration Localization In Rotating Blade

Blade, which is the core of the gas turbine, undergoing serious working conditions like high temperature, high pressure, high speed and variety of load cases, has been focus for a long time. In recent years, the application of new materials has improved the strength of the blade, now blade fracture simply caused by overload can be hardly seen in actual use. According to statistics, the fatigue failure of engine blade is one of the most common type of failure mode, about 80% of the entire blade failure. The high cycle fatigue caused by excitation and self-excitation is considered to be one of the main factor of blade fatigue. In addition, maldistribution of vibration energies makes the position of damage varied.This article will focus on the rotating blades and study its vibration characteristics in the field of structural vibration localization comprehensive analysis. The content can be summarized as the following aspects:First of all, this paper made a comprehensive review on the blade vibration related research status domestic and abroad and analyzed the current modelling method of rotating blade and the calculation method of dynamic response. Then a 8 nodes three-dimensional isoparametric element is established, and the method of calculating its modal and response is studied. Specific the vibration localization concept, and points out that not only mistuning would cause vibrational energy localization to some blades of the system, the influence of external excitation will also cause vibration energy localization on a single blade.Blisk structure dynamic characteristics are analysed, the random mistuning, shaft bending effects on dynamic characteristics of the blisk. Diagram of modal distribution, modal separation are introduced to describe their effect.Modal analysis was carried out to the blade, and mapped the Campbell diagram of the rotor blades. Then several kinds of external excitation may cause local vibration are analyzed:blade/casing contact, aerodynamic excitation and foundation excitation. Mathematical models of these external excitations are set up, respectively. Different analysis method is carried out for different load cases. The dynamic response of the blade under these loadings are studied. Curve interpolation, curve fitting and Fourier series expansion method are introduced for waveform analysis, spectral analysis and harmonic response analysis.Programming dynamic analysis software of the rotating blade, realized the automation of all the work done in this article.