• Title/Summary/Keyword: Accelerated Life Test

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A Durability Evaluation of Remanufactured Industrial Hydraulic Pump and Solenoid Valve (산업용 유압펌프 및 솔레노이드 밸브 재제조품의 내구성 평가)

  • Lee, Kyu-Chang;Park, Sang-Jin;Son, Woo-Hyun;Jeon, Chang-Su;Mok, Hak-Soo
    • Journal of the Korean Society of Industry Convergence
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    • v.24 no.5
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    • pp.537-546
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    • 2021
  • Remanufacturing is one of the most important resource recycling technology in response to resource depletion and environmental pollution. Domestic remanufacturing industry don't invigorate compared to other advanced countries because of low price and reliability of remanufactured product. In this study, remanufactured hydraulic pump and solenoid valve were evaluated durability by accelerated life test. In order that standard remanufacturing process was developed by core analysis and failure mode and effect analysis. And cores were remanufactured by standard remanufacturing process. For accelerated life test, the evaluation item and criteria were deduced by results of FMEA, reliability standards and enterprise interior criteria. To evaluate durability of remanufactured product, the remanufactured hydraulic pump and solenoid valve were evaluated performance after accelerated life test and the results were satisfied with criteria. This study showed that remanufactured products have a similar level of durability to new products by definition of remanufacturing.

Accelerated Life Evaluation of Propeller Shaft for Forklift Truck (지게차용 추진축의 가속 수명 평가)

  • Kim, Do-Sik;Sung, Baek-Ju
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.11
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    • pp.1221-1229
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    • 2014
  • This paper proposes an approach for predicting the fatigue life of a propeller shaft of a forklift truck by an accelerated life test method. The accelerated life test method adopted in this study is the calibrated accelerated life test, which is highly effective in the prediction of the lifetime and enables significant reduction of the test time as well as a quantification of reliability in the case of small sample sizes. First, the fatigue test was performed under two high stress levels, and then, it was performed by setting low stress levels in consideration of the available test time and extrapolation. Major reliability parameters such as the lifetime, accelerated power index, and shape parameter were obtained experimentally, and the experimentally predicted lifetime of the propeller shaft was verified through comparison with results of an analysis of load spectrum data under actual operating conditions.

Accelerated Life Test of Industrial Cleaner Motor (산업용 청소기 모터의 가속수명시험)

  • Eom, Hak-Yong;Lee, Gi-Chun;Chang, Mu-Seong;Park, Jong-Won;Lee, Yong-Bum
    • Journal of Applied Reliability
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    • v.18 no.3
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    • pp.193-200
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    • 2018
  • Purpose: In this study, the life of the motor is investigated by performing the accelerated life test with the brush wear of the industrial cleaner motor as the main failure mode. Methods: The accelerating stress factor of the accelerated life test is a voltage, which can increase the number of revolutions of the motor to accelerate the brush wear due to the friction between the brush and the commutator. Also, the accelerating stress level was determined after determining the maximum allowable level of the voltage through the preliminary test. Results: The motor failure time at each accelerating stress level was predicted by regression analysis with brush wear length as performance degradation data. The main failure mode, which is brush wear, of the motor was reproduced by this test. The shape parameter of the Weibull distribution was confirmed to be the same statistically at all accelerating stress levels by the likelihood ratio test. Conclusion: The life of the motor was investigated by performing the accelerated life test with the brush wear of the industrial cleaner motor as the main failure mode. Through the accelerating test method of the cleaner motor, various life expectancy and life expectancy of the acceleration factor are predicted.

New Accelerated Life Test Plans for Weibull and Lognormal Lifetime Distributions (와이블과 대수정규 수명분포를 따를 때 새로운 가속수명시험 계획의 개발)

  • Seo, Sun-Keun
    • Journal of Applied Reliability
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    • v.14 no.3
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    • pp.182-190
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    • 2014
  • This paper presents new practical accelerated life test plans with different censoring times at three levels of stress for Weibull and lognormal lifetime distributions, respectively. The proposed plans are compared with the corresponding two-level statistically optimal plans and three-level compromise and practical plans. Computational results indicate that new practical plans have been more precise and effective than the existing three-level plans under a constraint of total testing time. In addition, a procedure to determine useful ALT plans is illustrated with a numerical example.

Development of Optimal Accelerated Life Test Plans for Weibull Distribution Under Intermittent Inspection

  • Seo, Sun-Keun
    • Journal of Korean Society for Quality Management
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    • v.17 no.1
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    • pp.89-106
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    • 1989
  • For Weibull distributed lifetimes, this paper presents asymptotically optimal accelerated life test plans for practical applications under intermittent inspection and type-I censoring. Computational results show that the asymptotic variance of a low quantile at the design stress as optimal criterion is insensitive to the number of inspections at overstress levels. Sensitivity analyses indicate that optimal plans are robust enough to moderate departures of estimated failure probabilities at the design and high stresses as input parameters to plan accelerated life tests from their true values. Monte Carlo simulation for small sample study on optimal accelerated life test plans developed by the asymptotic maximum likelihood theory is conducted. Simulation results suggest that optimal plans are satisfactory for sample size in practice.

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DEVELOPMENT OF AN ACCELERATED LIFE TEST PROCEDURE FOR COOLING FAN MOTORS

  • Shin, W.G.;Lee, S.H.;Song, Y.S.
    • International Journal of Automotive Technology
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    • v.7 no.6
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    • pp.757-762
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    • 2006
  • Reliability of automotive parts has been one of the most interesting fields in the automotive industry. Especially, a small DC motor was issued because of the increasing adoption for passengers' safety and convenience. For several years, small DC motors have been studied and some problems of a life test method were found out. The field condition was not considered enough in the old life test method. It also needed a lot of test time. For precise life estimation and accelerated life test, new life test procedure was developed based on measured field condition. The vibration condition on vehicle and latent force on fan motor shaft were measured and correlated with each other. We converted the acceleration data into the load data and calculated the equivalent load from integrated value. We found the relationship which can be used for accelerated life test without changing the severity by using different loading factors.

Optimum multi-objective modified step-stress accelerated life test plan for the Burr type-XII distribution

  • Srivastava, P.W.;Mittal, N.
    • International Journal of Reliability and Applications
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    • v.15 no.1
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    • pp.23-50
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    • 2014
  • This paper deals with formulation of optimum multi-objective modified step-stress accelerated life test (ALT) plan for Burr type-XII distribution under type-I censoring. Since it is impractical to estimate only one objective parameter after conducting costly ALT tests; also, it is not desirable to assume instantaneous changes in stress levels because of limited capacity of test equipments and the presence of undesirable failure modes, therefore, an optimum multi-objective modified step-stress ALT plan has been designed. The optimal test plan consists in determining the optimum low stress level and optimal time at which stress starts linearly increasing from low stress by minimizing the weighted sum of the asymptotic variances of the maximum likelihood estimator of quantile lifetimes at design constant stress. The method developed has been illustrated using an example. Sensitivity analysis has been carried out. Comparative study has also been done to highlight the merits of the proposed model.

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Reliability Evaluation on PTC Heater Using Accelerated Life Test and Failure Analysis (고장 분석과 가속 수명시험을 통한 PTC 히터의 신뢰성 평가)

  • Choi, Hyoung-Seuk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.12
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    • pp.843-846
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    • 2015
  • In this paper, the failure mechanism of PTC heater were examined closely by failure analysis and based on it, accelerated life test were conducted. Finally, life distribution and acceleration model were established. The failure mechanism of PTC heater such as crack, increase of resistance due to heating were identified. Two acceleration factors such as temperature, humidity were chosen with two levels each and accelerated life test were done. Life distribution were identified as Weibull distribution with shape parameter 5.4 and Temperature-Humidity model was fitted as an acceleration model.

Life Prediction of High Pressure Hydraulic Hose Assemblies by the Impulse Test

  • KIM, Hyoung-Eui;LEE, Yong-Bum;Kwon, Young-Il
    • Corrosion Science and Technology
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    • v.3 no.5
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    • pp.209-215
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    • 2004
  • Flexible hydraulic hose assembly that consists of hose and joints is used widely on various construction heavy equipments, agricultural machines, motor vehicles, and industrial heavy machines that require flexibility on hydraulic pipelines. It is classified by the maximum usage pressure which is determined by the winding layers of coiling steel wire and the inner diameter of the hoses. In this paper, we designed and performed an accelerated life test for assessing the reliability of a flexible hydraulic hose assembly. In the proposed accelerated life test, typical impulse pressure testing method is applied with the half omega flexing operation to simulate the practical flexing motion of the hose assembly.

The Study of Accelerated Life Test for Micro Display Device (마이크로 디스플레이 디바이스의 가속수명시험에 관한 연구)

  • 차상목;윤성록;조여욱
    • Journal of Applied Reliability
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    • v.2 no.1
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    • pp.15-22
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    • 2002
  • This paper is concerned about an Accelerated Life Test for Micro Display Device which is being used in a Projection TV, in order to find a failure mode occurred in field in a short time, to identify a major factor to affect a life, and to estimate a mean life. For this purpose, we selected a temperature as a accelerated factor to perform a test and measured degradation of display device using visual inspection and chromaticity table. In the result of Accelerated Life Test, it is confirmed that failure mode is equal to the degradation of display device by vendor and the Temperature is a major factor to affect a failure. Besides, according as the display device is turned to green as degraded, it is identified that the change of the chromaticity value is one method to measure the degree of the degradation . So, we applied the optimal condition, which consider a cost and life to lower the Temperature which is a major factor acquired by the result of ALT, to PTV design

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