• Title/Summary/Keyword: Accelerated Life Test

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Development of accelerated life test method for mechanical components using Weibull-IPL(Inverse Power Law) model (와이블-역승법을 이용한 기계류부품의 가속시험 방법 개발)

  • Lee, Geun-Ho;Kim, Hyoung-Eui;Kang, Bo-Sik
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.445-450
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    • 2003
  • This study was performed 10 develop the accelerated life test method using Weibull-IPL(Inverse Power Law) model for mechanical components. Weibull-IPL model is concerned with determining the assurance life with confidence level and the accelerated life test time From the relation of weibull distribution factors and confidence limit, the testing times on the no number of failure acceptance criteria arc determined. The mechanical components generally represent wear and fatigue characteristics as a failure mode. IPL based on the cumulative damage theory is applied effectively the mechanical components to reduce the testing time and to achieve the accelerating test conditions. As the actual application example, accelerated life test method of agricultural tractor transmission was described. Life distribution of agricultural tractor transmission was supposed to follow Weibull distribution and life test time was calculated under the conditions of average life (MTBF) 3,000 hours and 90% confidence level for one test sample. According to IPL, because test time call be shorten in case increase test load test time could be reduced by 482 hours when we put the load 1.1 times of rated load than 0.73 times of rated load that is equivalent load calculated by load spectrum of the agricultural tractor. This time, acceleration coefficient was 11.7.

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Weibull Step-Stress Type-I Model Predict the Lifetime of Device (소자의 수명 예측을 위한 Weibull Step-Stress Type-I Model)

  • 정재성;오영환
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.6
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    • pp.67-74
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    • 1995
  • This paper proposes the step-stress type-I censoring model for analyzing the data of accelerated life test and reducing the time of accelerated life test. In order to obtain the data of accelerated life test, the step-stress accelerated life test was run with voltage stress to CMOS Hex Buffer. The Weibull distribution, the Inverse-power-law model and Maximum likelihood method were used. The iterative procedure using modified-quasi-linearization method is applied to solve the nonlinear equation. The proposed Weibull step-stress type-I censoring model exactly estimases the life time of units, while reducting the time of accelerated life test and the equipments of test.

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Design and Analysis of Accelerated Life Tests (ALT) for Small Power Relays (소형 계전기에 대한 가속수명시험 설계 및 분석)

  • 권영일;유영철
    • Journal of Applied Reliability
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    • v.4 no.1
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    • pp.1-14
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    • 2004
  • Accelerated life test models and procedures are developed to assess the reliability of typical power relays. The main function of relays is to control high voltage circuits by operating low voltage circuits. The accelerated life test method and test equipments are developed using the relationship between stresses and life characteristics of the products. Using the developed accelerated life test method, the parameters of the ALT model and lifetime distribution are estimated and the reliability of the relays at use condition is assessed. The proposed accelerated life test method and procedure may be extended and applied to testing similar kinds of products to reduce test time and costs of the tests remarkably.

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An Accelerated Life Test of Booster Pump for Water Purifier (정수기용 부스터펌프의 가속수명시험)

  • Moon, Ji-Seob;Jeong, Seon-Yong;Kim, Myung-Soo
    • Journal of Applied Reliability
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    • v.11 no.3
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    • pp.281-291
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    • 2011
  • This paper presents an accelerated life test of booster pump for home water purifier. The failure analysis shows that decreased flux due to the plastic deformation of bypass spring adjusting pressure is the predominant failure mechanism. An accelerated life test is designed and implemented to estimate the lifetime of the booster pump. Temperature, water pressure and voltage are selected as accelerating variables through the technical review about failure mechanism. It is assumed that the lifetimes of booster pumps follow lognormal distribution and the combination model of temperature and non-thermal stresses holds. The life-stress relationship, acceleration factor, and $B_{10}$ life at design condition are estimated by analyzing the accelerated life test data.

An Analysis Method of Accelerated Life Test Data with a Change of Failure Mechanism (가변 고장메카니즘을 가진 가속수명시험 데이타 분석방법)

  • Won, Y.C.;Kong, M.B.
    • Journal of Korean Institute of Industrial Engineers
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    • v.20 no.1
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    • pp.39-51
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    • 1994
  • Almost all accelerated life tests assume that no basic failure mechanism changes within the test stresses. But accelerated life test, considering failure mechanism changes, is needed since failure mechanism changes when accelerating beyond the used stress. This paper studies the analysis when the failure mechanism changes within the test stresses. The piecewise linear regression, which the join point of two lines is estimated, is applied In particular, two accelerated life tests, with and without a change in failure mechanism are examined.

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No-Failure Accelerated Life Test of Flap Actuating System using Weibull Distribution (와이블 분포를 이용한 플랩구동장치의 무고장 가속수명시험)

  • Cho, Hyunjun;Lee, Inho;Kim, Sangbeom;Park, Sangjoon;Yang, Myungseok
    • Journal of Aerospace System Engineering
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    • v.10 no.1
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    • pp.51-58
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    • 2016
  • In this paper, we present some results on No-failure accelerated life test of aerial vehicle for reliability demonstration. The design of general accelerated life test consists of the three phases: 1) Estimating normal life test time of a single product from Weibull distribution model; 2) Determining the acceleration factor (AF) by utilizing the relation between the life of mechanical components and the applied torque; 3) Calculating the accelerated life test time, which comes from dividing the estimated normal life test time into AF. Then, we applied the calculated life test time to the real reliability test of the flap actuating system, while considering the requirement specification for mechanical components and operating environment of the actuation system. Real experimental processes and results are presented to validate the theory.

Study on Properties and Accelerated Life-time Test of Rubber O-ring by Temperature Stress

  • Shin, Young-Ju;Kang, Bong-Sung;Chung, Yu-Kyung;Choi, Kil-Yeong;Shin, Sei-Moon
    • Proceedings of the Korean Reliability Society Conference
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    • 2006.05a
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    • pp.48-54
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    • 2006
  • In this thesis, accelerated life test (ALT) method and procedure for rubber O-ring are applied to assure specified reliability of the products at guaranteeing the life of the products. Rubber O-ring is parts that keep intensity or make machine operation smoothly on attrition portion of machine and is used to prevent that oil is leaked. Usually. Rubber O-ring used NBR that is copolymer of acrylonitrile and butadiene. this are superior oil resistance, heat resistance, durability of abrasion, cold resistance, chemical resistance etc. The accelerated life test model for rubber O-ring are developed using the relationship between stresses and life characteristics of products. Using the accelerated life test method and the acceleration life test equipment which is developed, we performed life test, collected life data and analyzed the results of tests. The proposed accelerated life test method and procedure may be extended and applied to testing similar kinds of products to reduce test times and costs of the tests remarkably.

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Accelerated Life Test Using Structural Analysis of a Helicopter Accumulator (헬기용 축압기의 구조해석에 의한 가속 수명시험)

  • Lee, Geon-Hui;Hur, Jang-Wook
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.6
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    • pp.67-72
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    • 2020
  • Life tests are essential in reducing the catastrophic damage caused by the accidents of large machinery such as aircraft and ships. However, life tests are challenging to implement due to the high costs and time required to test the life of large machinery parts. Therefore, it is advantageous and convenient to apply accelerated life test techniques for key components to reduce costs and time. In fact, extensive research has already been conducted on these techniques. However, recently, there have been cases in which an experimental value was applied to the shape parameter of the Weibull distribution used in the reliability test, but the test time was not significantly reduced. Therefore, in this paper, the shape parameters are estimated from the probability density function of the Weibull distribution for the analysis of an accelerated life test for bladder accumulators, which are core components of military helicopters. The test time was derived based on the number of samples and confidence level by substituting it into the test time equation. Next, the accelerated life test time was calculated using the steady-state test time with an acceleration factor obtained from the Arrhenius model. The steady-state life test required approximately 15,000 H, whereas the accelerated life test time for one sample at 100 ℃ was 34% shorter than that of the steady-state life test.

An Accelerated Life Test Sampling Plan for Bulk Material (벌크재료 가속시험샘플링검사방식설계)

  • Kim Jong-Geol;Kim Dong-Cheol
    • Proceedings of the Safety Management and Science Conference
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    • 2006.04a
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    • pp.411-419
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    • 2006
  • This paper aims at designing an accelerated life test sampling plan for bulk material and showing its application for an arc-welded gas pipe. It is an integrated model of the accelerated life test procedure and bulk sampling procedure. The accelerated life tests were performed by the regulation, RSD 0005 of ATS at KITECH and bulk sampling was used for acceptance. Design parameters might be total sample size(segments and increments), stress level and so on. We focus on deciding the sample size by minimizing the asymptotic variance of test statistic as well as satisfying consumer's risk under Weibull life time distribution with primary information on shape parameter.

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A Study on the Reliability Evaluation of Shot Peened Aluminium Alloy Using Accelerated Life Test (가속수명시험을 이용한 쇼트피닝가공 알루미늄 합금의 신뢰성 평가에 관한 연구)

  • Nam, Ji-Hun;Kang, Min-Woo;Cheong, Seong-Kyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.12 s.255
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    • pp.1534-1542
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    • 2006
  • In this paper, the concept of accelerated life test, which is a popular research field nowadays, is applied to the shot peened material. To predict the efficient and exact room temperature fatigue characteristics from the high temperature fatigue data, the adequate accelerated model is investigated. Ono type rotary bending fatigue tester and high temperature chamber were used for the experiment. Room temperature fatigue lives were predicted by applying accelerated models and doing reliability evaluation. Room temperature fatigue tests were accomplished to check the effectiveness of predicted data and the adequate accelerated life test models were presented by considering errors. Experimental result using Arrhenius model, fatigue limit obtain almost 5.45% of error, inverse power law has about 1.36% of error, so we found that inverse power law is applied well to temperature-life relative of shot peened material.