• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.497-501
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• 2008

To improve occupants' safety in an emergency, crashworthy design is necessary to rotorcraft design and development. To improve crashworthiness capability, most of the crash energy should be absorbed by rotorcraft and the energy transmitted to the occupants should be minimized. To absorb the crash energy efficiently, the individual energy attenuation provided by landing gear, structure, fuel tank and seats should be considered totally. Especially, landing gear has the important role for crashworthy design because landing gear absorbs relatively large energy for the crash landing. In addition, military specifications require failure of landing gear shall not increase danger to any occupants by penetration of the airframe. To meet the specification requirements, failure mechanism should be prepared so that landing gear is collapsed safely and doesn't penetrate the airframe. In this study, design of failure mechanism which is necessary for the rotorcraft landing gear was performed and the results were presented.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.469-474
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• 2008

The reason for crashworthy landing gear is to contribute to the overall aircraft design goals in the event of a crash. One of crashworthy landing gear design approaches is inclusion of structural fuse. Structural fuse is used to control the mode of failure of landing gear. If structural fuse doesn't work at desired condition, other unexpected accidents can occur. In this paper, failure probability is calculated for landing gear structural fuse and improvement measure is introduced to improve failure probability of structural fuse.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.722-727
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• 2004

The gear that is used in various mechanical components occurs easily damages due to the repeated torque and the high oil temperature. The main failure mode of the gear is the surface deterioration with the tooth surface fatigue. Therefore, the life evaluation and the failure analysis of the gear were very important since it may cause fatal damage of entire gear box system. In this paper, the failure mechanism and the life of the gear were evaluated using the durability analysis simulator such as MSC.FATIGUE. Moreover, the reliability analysis model of the spur gear with the accelerated life testing technique was proposed.

• Advances in Computational Design
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• 제8권3호
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• pp.255-271
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• 2023

The gear drive of a combat aircraft engine is responsible for power transmission to the different accessories necessary for the engine's operation. Incorrect power transmission can occur due to the presence of failure modes in the gears like bending fatigue, pitting, adhesive wear, scuffing, abrasive wear and polished wear etc. Fault diagnosis of the gear drive is necessary to get an early indication of failure of the gears. The present research is to develop an algorithm using different vibration signal processing techniques on industrial vibration acquisition systems to establish gear fault diagnosis architecture. The signal processing techniques have been used to extract various feature vectors in the development of the fault diagnosis architecture. An open-source dataset of other gear fault conditions is used to validate the developed architecture. The results is a basis for development of artificial intelligence based expert systems for gear fault diagnosis of a combat aircraft engine.

• Tribology and Lubricants
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• 제24권6호
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• pp.285-290
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• 2008

The purpose of this paper is to present the case study of tribological failure analysis on the gear damages, oil leakage, and sealant sealing in a manual transmission of front engine and front wheel drive vehicle. The manual transmission is to change the speed range and direction of the engines depending on the driving conditions by friction driving forces with input and output gear system. The material property and surface roughness of the gears are strongly related to the gear noise and micro-vibration, oil leakage and wear, which may decrease the real contact area of the gear and the strength of the oil film thickness between the driving gear and driven one. The O-ring damage of speedometer driven gear and bad sealant sealing of oil pan may produce oil leakage through the contact surfaces, which cause the oil shortage and seizure on the sliding surfaces of the transaxle gears. In the failure case study, the proper repair working and good lubrication are very important for the long life of the transaxle without any tribological failures and oil leakage.

• 드라이브 ㆍ 컨트롤
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• 제14권1호
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• pp.1-7
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• 2017

The power train of a concrete truck mixer reducer includes differential planetary gears to get a large reduction ratio for operating the mixer drum in a compact structure. These differential planetary gears are a very important part of the mixer reducer where strength problems are the main concern. Gear bending stress, gear compressive stress and scoring failure are the main concerns. Many failures in differential planetary gears are due to the insufficient gear strength and resonance problems caused by major excitation forces such as gear mating failure in the transmission. In the present study, where the excitation frequencies are the gear tooth passing frequencies of the mating gears, a Campbell diagram is used to calculate differential planetary gear critical speeds. Mode shapes and natural frequencies of the differential planetary gears are calculated by CATIA V5. These are used to predict gear resonance failures by comparing the working speed range with the critical speeds due to the gear transmission errors of the differential planetary gears.

• Tribology and Lubricants
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• 제39권5호
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• pp.173-182
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• 2023

The composite planetary gear reducer, a power transmission component of armored vehicles, operates at a high torque and is used in severe environments such as mountain, gravel or unpaved roads. Therefore, they must be designed and manufactured to have high durability. To design such a planetary gear reducer, there are numerous specifications to validate, such as selecting the module and the number of teeth of each gear satisfied the requirements, and calculating gear specifications and durability strength. Because planetary gears constitute a combination of several gears, there are many restrictions and interferences in selecting the number of teeth and addendum modification coefficients, and designing the tooth shape. Developing an auto design program is necessary to design various planetary gears more conveniently and quickly. In this study, a planetary gear reducer design software, widely used in various machines and armored vehicles, was developed. This design software can automatically select the number of teeth and modules of the gears, calculate specifications and quickly evaluate its fatigue durability strength and scoring failure according to the planetary gear reducer design theory.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.136-141
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• 2004

The gear in various mechanical components easily occurs at damages by the external torque. The main failure modes of the gear are surface pitting with the tooth surface and breakage with tooth root by caused fatigue. Therefore, the gear is very important role in the reliability research since it may cause fatal damage of entire system such as the gear box in automobile transmission. In this study, the failure mode of the gear was analyzed and accelerated durability analysis was employed for the life estimation of spur gears. In the case of assumed load spectrums, the reliability of spur gears was evaluated by inverse power law-Weibull accelerated life test model with cumulative damage exposure.

• 대한기계학회논문집
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• 제11권6호
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• pp.1014-1025
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• 1987

본 연구에서는 기계요소중에서도 그 성능에 미치는 인자의 수가 많고 또 그 영향이 복잡하고 난해하며 아직도 경험적 요소가 수많이 남아있으면서도 공업적으로 매우 중요한 동력전달용 치차장치를 예로 들어 그 설계, 제작, 손상 및 트러블슈팅을 하기 위한 엑스퍼트시스템을 개발하려고 한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.147-152
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• 2000

The ASF(Automatic Sheets Feeders) part of the printer has many bosses supporting gear-trains. Steel-pin bosses are substituted for plastic mold bosses because of advantages such as cost reduction, convenience of manufacturing and accuracy in dimension, but they have a weak point such as fatigue fracture due to low material strength, which causes a serious problem in the reliability of product. To prevent the fatigue fracture of bosses, we should exactly estimate the life to failure of the various shapes of bosses. We take the linear FEM analysis and the statistical method in this paper to figure out the life to failure of bosses. The maximum stress and life to failure of bosses can be easily estimated by this method. This paper specifies how to figure out the life to failure of bosses.