Bearings Failure of Gear Drive Unit Caused by Gear Resonance

Ognjanović, Milosav; Ristić, Miloš; Vasin, Sanja

doi:10.1007/978-94-007-6558-0_30

Cited by 1 publication

(1 citation statement)

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“…The mass of the rotating parts on the auxiliary branch (gears 2 and 3 with other parts that rotate around the spin) is 0.9 kg. By calculating the stiffness of the teeth in the mesh together with reduced equivalent masses, according to DIN3990, natural (resonant) frequency of this gear pair is 3,333 Hz with the similar approach as in papers [5,6,7]. This calculation shows that the first pair operates in supercritical mesh frequency range with almost 5 times larger mesh frequency regarding the natural frequency.…”

Section: Gear Mesh Resonance Frequenciesmentioning

confidence: 73%

Dynamic stability of high speed turboshaft engine with reducer

Kolarević

Micković

Crnojević³

et al. 2018

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. The dynamic behavior of machines which rotate at extreme high speeds is crucial for stable and long operation. In design process some dynamics calculation must be taken into account to avoid potential operation near resonance areas. This paper considers dynamic analysis of the high speed reducer, designed together with the turbo-shaft engine. Resonances can occur when frequency of rotation and teeth mesh frequency are close to gear pair in mesh natural frequency, to the shafts natural frequencies and to the other parts natural frequencies. Problems can be avoided by translating resonant areas to higher or lower level of frequency by changing some design parameters, mass, stiffness and by variation of the stiffness of bearing supports. The paper presents the approaches to natural frequencies identification for the example of high speed reducer design. Some examples of design solutions, especially for elastic bearing supports and their experimental testing are also presented. IntroductionHigh speed machines like turbo-jet and turbo-shaft engines operate with high frequencies of rotation which pass through some resonant areas. Operation in resonant areas can at least reduce operating life of the parts but it usually leads to failure of the entire system. Therefore, it is crucial to avoid these areas in permanent operation, 15 to 20 % before and after the resonant frequency value. Operating regimes should be below them. In high speed machines, it can be complicated to achieve this, so their operation can be achieved at frequencies above resonant values which must be achieved by fast run across during start up process. The calculations and experimental testing for predicting these areas are a very important and unavoidable phase in design process of such structures.The case study in this paper is a high speed reducer for turbo-shaft engine that operates at extreme speeds of revolution. Gas generator provides power of 230 kW by generating the gas (combustion products) at high temperature and pressure. This operating fluid drives the free turbine which is installed after the gas generator, Figure 1. The free turbine is on the input shaft of the reducer and it provides mechanical power on the output of system. The reducer has a task to transform the torque and the speed from 40,000 rpm to 6,000 rpm and it is designed for helicopter application.It consists of three identical auxiliary branches which divide the power from the input gear and deliver the power to single output gear. Basically, it has only two different gear pairs. This type is used in order to achieve the least possible dimensions and weight.

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Section: Gear Mesh Resonance Frequenciesmentioning

confidence: 73%