• 제목/요약/키워드: Degradation test

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압입법을 이용한 1Cr-1Mo-0.25V강의 열화도 평가에 관한 연구 (A study on the Evaluation of Material Degradation of 1Cr-1Mo-0.25V Steel using Ball Indentation Method)

  • 석창성;김정표;안하늘
    • 한국정밀공학회지
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    • 제18권4호
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    • pp.151-159
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    • 2001
  • As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. BI(Ball Indentation) test has a potential to replace conventional fracture tests like a uniaxial tensile test, fracture toughness test, hardness test and so on. In this paper, we would like to present the ageing evaluation technique by the BI method. The four classes of the thermally aged 1Cr-!mo-0.25V specimens were prepared using an artificially accelerated aging method. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed. The results of the BI tests were in good agreement with fracture characteristics by a standard fracture test method within 5%. The IDE(Indentation Deformation Energy) of a BI technique as a new parameter for evaluating a degradation was suggested and the new IDE parameter clearly depicts the degradation degree.

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압입법을 이용한 재료 열화의 평가에 관한 연구 (A Study on the Evaluation of Material Degradation using Ball Indentation Method)

  • 김정표;석창성;안하늘
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집A
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    • pp.171-176
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    • 2000
  • As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. BI(Ball Indentation) test has a potential to replace conventional fracture tests like a uniaxial tensile test, fracture toughness test, hardness test and so on. In this paper, we would like to present the aging evaluation technique by the BI method. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed. The results of the BI tests were in good agreement with fracture characteristics by a standard fracture test method. The IDE(Indentation Deformation Energy) of a BI technique as a new parameter for evaluating a degradation was suggested and the new IDE parameter clearly depicts the degradation degree.

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열화데이터를 이용한 자색 연막수류탄(KM18)의 저장수명 평가 (Storage Life Evaluation of a Violet Smoke Hand Grenade(KM18) using Degradation Data)

  • 장일호;홍석환;장현정;손영갑
    • 한국군사과학기술학회지
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    • 제15권2호
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    • pp.215-223
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    • 2012
  • A violet smoke hand grenade(KM18) is used to generate signals. The grenade is considered to fail when its smoke emission time is longer than the specified one so that its smoke concentration becomes lighter. Accelerated degradation test for the grenade was performed, and then failure in smoke emission time was reproduced from the test. Stress for the degradation test was selected as temperature/humidity from the pre-test results. Degraded data of emission time from the accelerated test were analyzed through applying a distibution-based degradation model. Then, Peck Model was applied to predict the storage life under field conditions. In addition, the predicted storage life was compared with that of ASRP(Ammunition Stockpile Reliability Program).

고분자전해질형 연료전지 가스확산층의 내구 성능 저하에 관한 실험적 분석 (Experimental Analysis of GDL Degradation in PEM Fuel Cell)

  • 하태훈;박재만;조준현;김한상;민경덕;이은숙;정지영;김도훈;진용원
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2009년도 추계학술대회 논문집
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    • pp.132-132
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    • 2009
  • To achieve the commercialization of PEM fuel cell, the durability problem must be solved. Recently, many researchers have focused on this durability problem and degradation studies about membrane and electrode have been reported. But durability characteristics of gas diffusion layer is not much reported yet. Durability of GDL is very important to maintain the performance of PEM fuel cell because the main function of GDL is a path of fuel and water and the GDL degradation causes the loss of the GDL function. In this study, the degradation of GDL, especially, the mechanical degradation process was investigated with the leaching test. The effect of water dissolution was observed through the test and the amount of GDL degradation was measured with various measurement methods such as weight measurement, static contact angle measurement, scanning electron microscope. After 2,000 hours test, the GDL showed structural damage and loss of hydrophobicity.

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열화성능에 의한 건설자재 수명평가에 관한 연구 (Assessment of Service Life of Building Materials Based on Performance Degradation)

  • 권영일
    • 한국신뢰성학회지:신뢰성응용연구
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    • 제6권4호
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    • pp.275-284
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    • 2006
  • A test method for assessing service life of building materials and components based on performance degradation data is developed. The performance of a building material degrades as time goes by and the failure of the material is often defined as the point at which the performance of the material reaches a pre-specified degraded level. A performance-based test method is developed and a numerical example is provided to illustrate the use of the developed test method.

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내구시험을 통한 베어링의 열화 특성과 그리스의 화학적 열화 특성 연관성 분석 (Correlation Analysis Between Chemical Degradation Characteristics of Grease and Degradation Characteristics of Bearing Through Durability Test)

  • 강보식;이충성;류경하
    • 한국산업융합학회 논문집
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    • 제25권6_3호
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    • pp.1239-1246
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    • 2022
  • This paper introduces the effect of grease on the degradation characteristics of bearings used as key components of packaging equipment and automation systems. Bearings parts are installed to fix and support the rotating body of the system, and performance degradation of the bearings has a great effect on the life of the system too. When bearings are used in various devices and systems, the grease is applied to reduce friction and improve fatigue life. Determining the type of lubricant (grease) is important because it has a great influence on the operating environment and lifespan and ensures long lifespan of systems and facilities. However, studies that simultaneously compared and analyzed the change in mechanical degradation characteristics and the comparison of chemical degradation characteristics according to grease types under actual operating conditions are insufficient. In this paper, three types of small harmonic drive, high-load reducer, and low-load reducer grease used in power transmission joint modules are experimentally selected and finally injected into ball bearings with a load (19,500N) to improve bearing durability. Degradation characteristics were tested by attaching to test equipment. At this time, after the durability test under the same load conditions, the mechanical degradation characteristics, that is temperature, vibration according to the three greases types. In addition, the chemical degradation characteristics of the corresponding grease was compared to present the results of mutual correlation analysis.

비파괴법에 의한 선박용 디젤엔진 배기밸브의 열화도 평가에 관한 기초적 연구 (Fundamental Study on Degradation Evaluation of Marine Diesel Engine Exhaust Valve by Nondestructive Test)

  • 심규현;김현수;남기우
    • 동력기계공학회지
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    • 제3권4호
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    • pp.51-56
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    • 1999
  • The ultrasonic method, which is well known as nondestructive test method, is widely used to evaluate the material damage due to degradation. However, this method is just used for measuring the crack size and the thickness loss of the tube. The purpose of this study is to investigate the applicability of the ultrasonic technique for the evaluation of marine diesel engine exhaust valve and to suggest the correlations between the ultrasonic characteristics and valve degradation. From the evaluation of the results obtained, the technique of using the ultrasonic property was founds to be a efficient method to evaluate the degree of marine diesel engine exhaust valve by nondestructive test.

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Basic Study of Degradation Test for Magnetic Contactors and Reliability Centered Maintenance

  • Ryu, Haeng-Soo;Han, Gyu-Hwan;Yoon, Nam-Sik
    • Journal of Electrical Engineering and Technology
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    • 제2권4호
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    • pp.441-444
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    • 2007
  • The mechanical endurance is the critical characteristic of Magnetic contactors (MCs), which are widely used in such industrial equipments as elevators, cranes, and factory control rooms in order to close and open the control circuit. Testing time, however, is so long in most cases that some method of reducing the testing period is required. Therefore, the degradation test by the detected vibration of MCs is developed to reduce the testing time in this work. The degradation test data are analyzed and the prediction model is provided. Also, the possibility of this technology for Reliability Centered Maintenance (RCM) will be shown. This will reduce the period of the product development and raise the reliability of the equipment in power distribution.

가속열화시험을 적용한 MEMS 진공패키지의 신뢰성 분석 및 개선 (Reliability Assessment and Improvement of MEMS Vacuum Package with Accelerated Degradation Test (ADT))

  • 최민석;김운배;정병길;좌성훈;송기무
    • 한국신뢰성학회지:신뢰성응용연구
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    • 제3권2호
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    • pp.103-116
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    • 2003
  • We carry out reliability tests and investigate the failure mechanisms. of the wafer level vacuum packaged MEMS gyroscope sensor using an accelerated degradation test. The accelerated degradation test (ADT) is used to evaluate reliability (and/or life) of the MEMS vacuum package and to select the accelerated test conditions, which reduce the reliability testing time. Using the failure distribution model and stress-life model, we are able to estimate the average life time of the vacuum package, which is well agreed with the measured data. After improving several package reliability issues such as prevention of gas diffusion through package, we carry out another set of accelerated tests at the chosen acceleration level. The results show that reliability of the vacuum packaged gyroscope has been greatly improved and can survive without degradation of performance, which is the Q-factor in gyroscope sensor, during environmental stress reliability tests.

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Solid State Drive(SSD)에 대한 가속열화시험 데이터 모델링 및 분석 (Modeling and Analysis of Accelerated Degradation Testing Data for a Solid State Drive (SSD))

  • 문병민;최영진;지유민;이용중;이근우;나한주;양중섭;배석주
    • 한국신뢰성학회지:신뢰성응용연구
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    • 제18권1호
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    • pp.33-39
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    • 2018
  • Purpose: Accelerated degradation tests can be effective in assessing product reliability when degradation leading to failure can be observed. This article proposes an accelerated degradation test model for highly reliable solid state drives (SSDs). Methods: We suggest a nonlinear mixed-effects (NLME) model to degradation data for SSDs. A Monte Carlo simulation is used to estimate lifetime distribution in accelerated degradation testing data. This simulation is performed by generating random samples from the assumed NLME model. Conclusion: We apply the proposed method to degradation data collected from SSDs. The derived power model is shown to be much better at fitting the degradation data than other existing models. Finally, the Monte Carlo simulation based on the NLME model provides reasonable results in lifetime estimation.