헬기용 축압기의 구조해석에 의한 가속 수명시험

이건희(Geon-Hui Lee),허장욱(Jang-Wook Hur) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.6

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.

Design of accelerated life test of the traction inverter in the High Speed Train(KTX-1) using acceleration effect of the applied voltage

S. K. Jung,H. Y. Maeng 한국도시철도학회 2014 IJAR Vol.2 No.3

This study intends to design an accelerated life test of the capacitor, a major component of the traction inverter in the KTX propulsion control system. Design of accelerated life tests is carried out according to the sequence of selection of failure mechanism, determination of accelerating stress and its range, determination of test conditions, determination and distribution of the number of samples. It is possible to estimate life at use temperature by using life-shortening effect of applied voltage and verify the life-shortening effect of applied voltage by performing accelerated life test. This accelerated life method can be applied to accelerated life tests of other products which are stressed by temperature and to which a certain voltage is irregularly applied.

A Study on the Accelerated Life Test for Evaluating the Reliability of Nickel-Cadmium Batteries

Kwon, Soo-Ho,Huh, Yang-Hyun,Lim, Tae-Jin The Korean Reliability Society 2000 International Journal of Reliability and Applicati Vol.1 No.1

Accelerated testing consists of a variety of test methods for shortening the life of products or hastening the degradation of their performance. This paper presents practical, modern statistical methods for evaluating the reliability of Nickel-Cadmium batteries at their design temperature of 2$0^{\circ}C$ by accelerated life test. Batteries have been life tested at three high temperature conditions, 50, 60, 7$0^{\circ}C$, respectively to yield failures quickly. The failures have been observed and judged by means of charge and discharge current integration. Analyses of life data from those conditions resulted in the Weibull distribution, which has been verified on the ground of the Kolmogorov-smirnov test and the pairwise t-test. Life data are modeled according to the Arrhenius life-temperature relationship. The mean life of tested batteries is assessed at about 590 cycles, and the activation energy of this chemical reaction is concluded to be 0.39eV as results. This study provides procedures for estimating the reliability of batteries in a short period, which has little been possible in domestic industries. The results can be applied in many fields such as proof testing, acceptance testing, and estimating assurance periods.

가속 스트레스의 교호작용을 고려한 가속계수 모델에 대한 연구

김형의(Hyoung Eui Kim),강보식(Bo Sik Kang),조유희(You Hee Cho) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.7

사용조건에서 수명시험을 수행할 경우 시험시간이 많이 소요되므로 사용조건보다 가혹한 스트레스 조건을 추가하여 가속수명시험을 수행하면 시험시간을 단축시킬 수 있다. 수명에 영향을 미치는 스트레스를 선정하여 각 스트레스의 사용조건과 가속조건에서 시험을 수행할 경우 가속 스트레스간에 교호작용이 존재할 수 있다. 그러나 기존의 연구에서는 2가지 이상의 가속 스트레스를 부과하여 가속수명시험을 수행할 경우 교호작용을 고려하지 않은 경우와 가속 수명에 대한 모델식을 제시한 연구들이 대부분이다. 본 논문에서는 기계류 부품의 수명에 영향을 미치는 가속 스트레스를 선정한 후 교호작용을 고려한 시험계획에 따라 가속수명시험을 수행한 자료를 이용하여 가속 계수와 가속 스트레스간의 관계식을 산출하는 방법을 제시하고자 한다. 또한 본 논문에서 제시한 교호작용을 고려한 가속시험방법과 가속 계수를 산출할 수 있는 모델식을 이용하여 복합적인 가속수명시험 수행시 쉽게 적용하고 결과를 산출할 수 있는 기초가 될 것으로 기대된다. An accelerated life test (ALT) is a test method that forces components to fail more quickly than they would under use conditions by applying higher overstresses. When two or more accelerating stresses are involved in an ALT, an interaction effect may occur. In previous studies, mostly ALTs without considering an interaction of accelerated stresses and accelerated life models were proposed. The life data obtained are extrapolated using a life-stress relationship to estimate the life distribution at use conditions. We use the general log-linear relationship to model the dependence of life in the Weibull distribution on stress. Therefore, this study suggests the acceleration factor model between the lives at use conditions and accelerated conditions by using mechanical component life data considering an interaction effect. Further, the accelerated life test method and acceleration factor model proposed in this paper will be the basis for adopting an accelerated life test with accelerated stress interactions.

ACCELERATED LIFE TESTING OF A MILD HYBRID POWERTRAIN USING ARRHENIUS EQUATION

Habib Kaymaz 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.5

Electrification of city buses, which play a major role in public transportation, is imperative for efficient use of limited resources and reducing adverse effects of fossil fuels on the environment. One of the vital processes in electrification projects in the automotive industry is testing. The main target of testing is to achieve a reliable and reproducible test that simulates real-world driving conditions to disclosure any weakness of the product at the early stage of the life cycle. Other side targets of testing are to achieve the main target with low cost and environmentally friendly testing. In this study, results of research and development in accelerated life test stand for a mild hybrid system is described. The realized test stand serves to product reliability by enabling life tests with in excess of its normal service parameters real-world driving conditions such as revolution, electrical power, high ambient temperature, cooling effect, and rest-bus CAN simulation. By using temperature as a stress factor for the mild hybrid powertrain under test, life test duration was shortened 4.65 times according to the Arrhenius equation. Thanks to the realized test stand, the mild hybrid life test was achieved by decreasing time and cost.

천정 거치형 디지털 사이니지 회전 시스템의 BLDC모터 가속수명시험에 관한 연구

김기홍,권순홍,권순구,박종민,김종순,정성원,최원식 한국산업융합학회 2018 한국산업융합학회 논문집 Vol.21 No.3

In a time when product development cycles are getting shorter and shorter, many companies are making efforts to develop products with high reliability in a short period of time, accelerated life test is widely used as a method to quickly evaluate reliability. Accelerated life test reduces the test life or the life of the product from the observed data by shortening the lifetime of the product or abruptly lowering the performance under the worse condition than the actual condition in order to shorten the test cost or the test time. In this paper, BL3640A-06P+RB35, DC12V model, which is used in the support device of an automatic rotation type digital signage, which display various information such as textures and images on a display screen in a public place or a commercial space, BLDC motors were subjected to a constant stress test and at the rotational speed of 1rpm, 180° rotation and reverse rotation under actual use conditions, the stress was imposed on the rotating speed of 2rpm and the weight of the actual installed product from 22.2kgf to 10kgf were installed. The lifetime of the actual use environment condition is 23,545 hours and the rotation speed is accelerated. The life time of the acceleration condition with the additional weight is 1,380 hours. The acceleration factor is calculated as 17.06, the one year guarantee test day is 235 days to 14 days, of the period from 470 days to 28 days, and the third year from 704 days to 42 days. The test date of the BLDC motor was tested on the shortened test date, and the rotational speed and the current value were measured. It is found that there is no defect even if it operates as the test date corresponding to the specified one year warranty period and the 3 year accelerated life test which is experimented. Using the statistical technique of the regression analysis the expected time for the motor to defect to #4 samples was 20 years.

공압 실린더의 수명시험과 온도 및 압력을 고려한 가속수명시험 결과 비교에 대한 연구

강보식(Bo-Sik Kang),조유희(You-Hee Cho) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

Pneumatic Cylinder is major machinery parts in automatic assembly line that is widely used in various industries. We perform a life test at a use condition and accelerated life test at a accelerated condition of temperature or pressure to predict the life of pneumatic cylinder. First, the lifetime and confidence interval for lifetime of pneumatic cylinder at a use condition are estimated using the life data acquired through life test. Second, the life data acquired through accelerated life test are extrapolated using Arrhenius or Inverse Power Law model and the lifetime at use condition is estimated. Finally, this study validate a accelerated life test result with 95% confidence interval for the life time at life test.

독립현가형 AWD 차량의 구동축 가속 수명 평가에 관한 연구

김도식(Do Sik Kim) 한국신뢰성학회 2011 신뢰성응용연구 Vol.11 No.4

This paper proposes an accelerated life evaluation of drive shaft. The life test of drive shaft for independent suspension type AWD vehicle should be performed by use of the least test sample because many number of samples can"t be used for the test because of its mass capacity and high price. We calculated the no failure test time by application of no failure test concept, and the already performed test data for drive shaft are applied for some kinds of reliability coefficients which are needed for calculation of life test time. And, for analysis of real driving condition of vehicle, the load spectrum is prepared using the needed road condition and vehicle data. The inverse power model is used for accelerated life test. The equivalent torque of load spectrum is achieved by use of Miner"s Rule, and then the final accelerating condition is determined by decision of the accelerated test torque. This paper shows that the accelerated life test results corresponds with the target life and the proposed life test method can be very well applied to no failure life test for mass capacity machinery components.

Evaluation Criteria of Reliability on Transmission Control Unit for Passenger Car

Choi, M.,Ryu, S.,Lim, J.H.,Jeong, H.S. The Korean Reliability Society 2010 International Journal of Reliability and Applicati Vol.11 No.1

There has been a recent upsurge in demand for the improvement of car reliability in the Northern American which is the primary market of South Korea automobile industry. It has been required that the warranty for transmission control unit for passenger cars directly related to passenger safety or security should be extended for 10 years and 160,000 km. In this paper, the test method for reliability and evaluation criteria is presented to evaluate the reliability on the automatic transmission controller. Reliability certification test can be roughly divided into two types: a quality test and life assessment test and a quality test can be subdivided into a basic performance test and environmental resistance test. There are 3 types of tests on the performance test for automatic transmission controller and environmental resistance test is composed of 14 items. Life test is performed with only the product passed this quality test. In this study, operation limit test at the high-temperatures, accelerated life test under specific temperature and accelerated life test for 2 or 3 stress levels are shown as a way for life test.

유니버설조인트 시험방식을 이용한 치과용 임플란트의 피로시험 및 가속수명시험에 관한 연구

도경훈(Gyeong Hun Do),이석진(Seok Jin Lee),김종미(Jong Mi Kim),김성민(Sung Min Kim) 한국신뢰성학회 2017 신뢰성응용연구 Vol.17 No.1

Purpose : This paper is a comparative analysis results of the fatigue test for dental implants and accelerated life test by using a static type loading device commonly used in Korea and a dynamic type loading device (universal-joint) recommended by FDA. Methods : Fatigue tests of dental implant is based on ISO 14801 and classified into static load test and dynamic load test. The tests were carried out on three test specimens by four load stress steps under each loading device. For analysis on failure mode such as crack, fracture and permanent deformation of test specimens, we used X-ray three-dimensional computed tomography on test specimens before and after the fatigue tests. The design of the accelerated life test was based on the analysis results of the fatigue life data obtained from the dynamic load test and the statistical analysis software (Minitab ver.15) was used to analyze the appropriate life distribution. Results : As a result of the fatigue tests and the accelerated life tests at same acceleration condition under each test method, the fatigue life under the dynamic type loading device (universal-joint) was shorter than when static type loading device was applied. Conclusion : This paper can be used as a reference when the universal-joint type loading device for implants fatigue test is applied as ISO 14801.