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김도식(Do-Sik Kim),김형의(Hyoung-Eui Kim),윤성한(Sung-Han Yoon),강이석(E-Sok Kang) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.3
본 논문은 교정가속수명시험법을 이용하여 액슬구동축의 피로수명을 예측하는 법을 제안한다. 교정가속 수명시험법은 수명예측, 시험시간 절감, 신뢰성 정량화시에 매우 효과적이다. 피로시험은 두 개의 고 부하 수준과 한 개의 저 부하 수준에서 수행되고, 외삽법을 사용하여 사용수준에서의 수명시간을 예측하게 된다. 본 논문에서는 수행시험 결과로부터 획득한 수명시간, 가속지수, 형상모수, 척도모수등과 같은 주요 신뢰성 인자들을 보여주고 있다. 액슬구동축의 수명예측은 부하스펙트럼 데이터와 시험데이터와의 비교 연구를 수행하여 검증하였다. 교정가속수명시험법을 사용한 수명예측법은 짧은 시간내에 수명을 예측하는데 매우 효과적인 방법임을 확인하였다. In this paper, a method to predict the fatigue life of an axle drive shaft by the calibrated accelerated life test (CALT) method is proposed. The CALT method is very effective for predicting lifetimes, significantly reducing test time, and quantifying reliability. The fatigue test is performed by considering two high stress and one low stress levels, and the lifetime at the normal stress level is predicted by extrapolation. In addition, in this study, the major reliability parameters such as the lifetime, accelerated power index, shape parameter, and scale parameter are determined by conducting various experiments. The lifetime prediction of the axle drive shaft is verified by comparing the experimental results with load spectrum data. The results confirm that the CALT method is effective for lifetime prediction and requires a short test time.
김형의(Hyoung-Eui KIM) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
It has been passed eight years since Reliability Assessment Centers of 18 fields including machinery and electronic field were established in 2000 to enhance the reliability of components and materials which are foundation of domestic industry. When Reliability Assessment Centers were established in 2000, many questions and issues have been headed. Those questions and issues were how reliability and quality are different, how the reliability measurement can be expressed, how the reliability requirements can be made, how the reliability of components can be tested and evaluated and etc. Currently it is the state that the controversy and improvement methods about reliability qualification, no failure test and one failure acceptance test were issued. This paper investigates the problems toward test and evaluation methods to certificate R-Mark and presents the direction of Korean Reliability Certification System.
김형의(Hyoung-Eui Kim),장무성(Mu-Seong Chang) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
In these days, most components are designed to operate without a failure for a long time. Accelerated testing can be used to assess or demonstrate reliability of components in a short time. In the case of one stress factor, Arrhenius model or Inverse Power Law (IPL) model is commonly selected for an accelerated model according to stress types. However, there are more than three stress factors in the industrial fields. In this study, we will explain the accelerated models that can apply to the case with three stress factors. The models are general log-linear model and IPL model using calibrated accelerated life testing. We shall compare the two models with a numerical example.
김도식(Do-Sik KIM),이승훈(Seung-Hun Lee),유영철(Yung-chul Yoo),김형의(Hyoung-Eui Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
In this study, we are to analyze the life and the main failure mode of ball screw that are usually applied to the Machine tools. Ball screw have complicated failure cause since they are organized as a complex of various elements. Therefore, in this paper, we analyzed the main failure mode of ball screw, and then performed life test and performance test according to the international standards. On the basis of these processes, we estimated a shape parameter that is the main factor for the calculation of test time for the reliability of ball screw by analyzing life distribution data.
가속 스트레스의 교호작용을 고려한 가속계수 모델에 대한 연구
김형의(Hyoung-Eui Kim),강보식(Bo-Sik Kang),조유희(You-Hee Cho) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
An accelerated life test(ALT) is a test method that forces components to fail more quickly than they would under use condition by applying higher overstresses. When 2 or more accelerating stresses are involved in ALT, the interaction effect may occur. The life data obtained are extrapolated using a life-stress relationship to estimate the life distribution at a use condition. We use the general log-linear relationship to model the dependence of life of the Weibull distribution on stress. Therefore, this study suggests the acceleration factor model between the lives at use condition and accelerated condition by using pneumatic cylinder life data considering an interaction effect.
김형의(Hyoung Eui Kim),이기천(Gi Chun Lee),김재훈(Jae Hoon Kim) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.7
압력용기, 유압호스 조립체, 어큐뮤레이터, 유압실린더, 유압밸브, 파이프 등의 제품들의 시험은 일반적으로 ISO와 SAE에서 정의되는 충격압력 조건들로 작동되고 있다. 충격압력 시험 장비는 높은 압력, 정확한 제어 시스템, 장기간 사용할 수 있는 수명을 가지는 것이 요구되며, 언급된 사항들은 유압 시스템에서 보다 높은 압력이 발생되어지는 충격압력 발생기를 제작하는데 필요하다. 충격압력 시험기는 제어는 편리하지만 높은 가격인 서보밸브 제어 시스템이 적용되었다. 제어 시스템의 적용은 시험하는 제품들에 영향을 주는 압력의 파형을 생성한다. 본 연구는 유량과 압력, 압력의 상승속도를 고려한 충격압력 발생시스템 설계 및 제작 과정을 연구하는 것을 목적으로 한다. 이것은 또한 결과로써 시스템에서 초고압의 압력을 발생시키는 압력 파형을 얻을 수 있었다. Components such as pressure vessel, hydraulic hose assembly, accumulator, hydraulic cylinder, hydraulic valve, pipe, etc., are tested under the impulse-pressure conditions prescribed in ISO and SAE standards. The impulse pressure test machine needs to have a high pressure, a precise control system and a long life. It should satisfy the requirements for fabrication of the impulse tester to generate ultra high pressure in the hydraulic system. In the impulse tester, a servo-valve control system is adopted; although the control application is convenient, it is expensive owing to the cost of developing the system. The type of the control system determines the pressure wave, which affects the components that are tested. In this study, the manufacturing process and the intensifier system design related to the flow, pressure, and the increasing rate of pressure are investigated. The results indicate the ultra high pressure waves in the system.