• 대한기계학회논문집A
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• 제32권11호
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• pp.905-910
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• 2008

Vibration analysis is widely used in machinery diagnosis and the wavelet transform has also been implemented in many applications in the condition monitoring of machinery. In contrast to previous applications, this paper examines whether acoustic signal can be used effectively along vibration signal to detect the various local fault, in local fault of gearboxes using the wavelet transform. Moreover, envelop analysis is well known as useful tool for the detection of rolling element bearing fault. In this paper, a acoustic emission (AE) sensor is employed to detect gearbox damage by installing them around bearing housing at driven-end side. Signal processing is conducted by wavelet transform and enveloping to detect her fault all at once gearbox using AE signal.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.116-123
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• 1999

A case of the axle gear box which was one of tile power transmission components of high speed train was supported by the bearings installed in axle and the reaction arm connected in bogie frame. Structural analyses of this case were executed for investigation the application of aluminum for weight reduction. The evaluations of the material strength, the thermal strength and deformation, and the stability of natural vibration were carried out according to computer simulation. It was found out that the steel case was safe from the structural failure. For the aluminum case, there was no worry about the vibration resonance and the static failure, but some efforts to reduce tile deformation of the bearing mounting part.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.178.2-178.2
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• 2010

The wind turbine gearbox is important rotating part to transmit torque from turbine blade to generator. Generally, gear shaft which rotates causes vibration by influence of stiffness and mass with gear shaft. Root cause of this vibration source is well known to gear transmission error that is decided from gear tooth property. Transmission error excites a gear, and makes excitation force that is vibrated shaft. This vibration of shaft is transmitted to gearbox housing through gearbox bearing. If the resonance about which the natural frequency of the gearbox accords with shaft exciting frequency occurs, a wind turbine can lead to failure. The gearbox for wind turbine should be considered influence of vibration as well as the fatigue life and its performance by such reason. The cause to vibration should be closely examined to reduce influence of such vibration. In this paper, the cause of the vibration which occurs by a gearbox is closely examined and the method which can reduce the vibration which occurred is shown. It is compared with vibration test outcome of a 3MW gearbox for verification of the method shown by this paper.

• Tribology and Lubricants
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• 제11권5호
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• pp.136-143
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• 1995

The effect of additive chemistry on the serface fatigue of gears was investigated using the FZG gear tester and fluids based on an API GL-5 grade oil. Surface fatigue lives were determined as a function of load and additive chemistry. At 1.52 GPa, the removal of the primary extreme pressure additive (EP) from the fully formulated gear oil decreased the fatigue life of gears slightly (4%), however, the removal of the primary antiwear additive (AW) decreased the fatigue life of gears significantly (83%). At 1.86 GPa, the removal of the EP additive from the fully formulated gear oil decresed the gear fatigue life 27%, however, the removal of the primary AW additive decreased the fatigue life of gears significantly (75%). Micropitting was the dominant surface morphology in the dedendum of gears tested With two oils at load stage: one using the complete additive package, and a second where the EP additive has been removed. However, spalling is the primary failure mode of gears tested without an AW additive independent of whether an EP agent was present. Surface analysis of pinion gears showed the formation of a mixed phosphate/phosphite-oxide layer on the surface of gears tested with fluids containing an AW. Formation of this layer seems to be key to long fatigue life.

• 항공우주시스템공학회지
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• 제14권6호
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• pp.58-67
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• 2020

In this study, finite element fatigue analysis combined with a fatigue correlation factor is proposed to predict the bending fatigue life of a gear in an electro-mechanical aircraft actuator. First, stress-life curves are obtained for the gear material via a round bar fatigue test. Subsequently, stochastic stress-life (P-S-N) curves are derived for 50% and 1% failure probabilities, separately. The curves are applied to the fatigue analysis model of a single gear tooth, and the effect of the fatigue correction factor is analyzed. The analytical P-S-N curves reflecting the fatigue correction factor matched the experimental data. This shows that the analytical fatigue life is reliable and that the analysis technique is effective.

• Tribology and Lubricants
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• 제26권1호
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• pp.61-67
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• 2010

The purpose of this paper is to study and analyze the failure examples on tribological characteristics of an automotive steering system. In this failure study, the grease leakage may stick leaked grease, dust, and wear particles between pinion and rack gears in mechanical steering system. In the case of seal failures such as a rod seal, o-ring and oil seals, the gear box and oil pump do not operate properly due to lack of oils. This means that oil pump does not supply a working fluid and produce a normal oil pressure of the steering system. This leads to leak a working fluid from the seals and produce a wear between pinion and rack gears. Especially, the leaked oil is usually mixed with internal wear particles and foreign dust/fine sands. Thus no leakage of working oils is very important design concepts, which is strongly related to the sealing components and smoothly operating of the mechanical friction parts of power steering system.

• 한국신뢰성학회지:신뢰성응용연구
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• 제11권4호
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• pp.331-342
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• 2011

The transmission of tracked vehicles performs complex functions as steering, shifting, braking, etc. and the system level life time has been a key influenced by the number of sub-parts like as gear assembly, torque converter, clutches, bearings and so on. In particular, the mechanical type steering system in tracked vehicle has impact shock torques in steering shift and those kind of shock torques can effect on the durability of many sub-parts in power train system. The field failure modes of gear assembly, steering assembly and the bearings of output shaft appear as a very complex phenomenon. In this study, the actual failure, which may occur in field, of the transmission was investigated comprehensively and that the endurance test on the resulting output shaft bearing failure analysis and life assessment was performed. Life time test method used in this study, developed for the purpose of the internal usage, and under these testing techniques the impact of the each bearing damage, which used in tracked vehicle transmission left / right outputs of different structures, was analyzed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1069-1074
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• 2008

Tool condition monitoring (TCM) is crucial for improvement of productivity in manufacturing process. However, TCM techniques have not been applied to monitor tool failure in an industrial gear shaving application. Therefore, this work studied a statistical TCM method for monitoring gear shaving tool condition. The method modeled the shaving process using beta probability distribution in order to extract the effective features. Modeling includes rectifying for converting a bi-modal distribution into a unimodal distribution, estimating parameters of beta probability distribution based on method of moments. The usefulness of features obtained from the proposed method was evaluated and discussed.

• 한국소음진동공학회논문집
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• 제24권5호
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• pp.407-413
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• 2014

The diesel engine and reduction gear combination is one of the common propulsion system in a naval vessel. Since the diesel engine has torsional vibration caused by reciprocating motion of the mass and gas pressure force of the cylinder, high cycle torsional fatigue can be occurred. Therefore, ROK navy restricts the maximum stress of the propulsion shaft according to MIL G 17859D. In this paper, the root cause for the failure of the diesel engine and reduction gear connecting shaft occurred in typical naval vessel is investigated based on the measured bending and torsional moment according to MIL G 17859D procedure.

• 한국정밀공학회지
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• 제13권3호
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• pp.123-131
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• 1996

This paper presents the development of an algorithm for the reliability and life of a hypoid gear axle system (located in the last section of power train) in heavy vehicles. The algorithm is developed about expecting the reliability and service-life for applied loads on each component in the system using the Weibull's probabilistic distribution and the extended Palmgren's model. The probabilistic method is used to results. Also this model is involved in predicting the failure which is related to the number of load cycles with the approaching load. Then the precious evaluation of the reliability and life in the axle system can be effectively carried out. Thus the general procedures of a reliability and life design, including the mathematical formulation and numerical examples, are illustrated for a hypoid gear axle system.