• Title/Summary/Keyword: 피로 신뢰성평가

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불규칙 하중하의 확률론적 피로 해석의 신뢰성 평가

  • 송삼홍;장두수
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1993.04b
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    • pp.365-369
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    • 1993
  • The reliability assessment of a simple porbabilistic fatigue analysis under random loading is proposed. Using the crack closure concept, the crack opening stress is assumed to be constant during random loading. The available loading history and test data are used for the comparison with the results of the reliability assessment of probabilistic fatigue analysis.

Evaluation of Statistical Fatigue Life of Hybrid Composite Joints in Low-Floor Bus (저상버스용 하이브리드 복합재 조인트부의 통계적 피로수명평가)

  • Jung, Dal-Woo;Choi, Nak-Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.11
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    • pp.1705-1713
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    • 2010
  • The reliable fatigue life for hybrid composite joint structures was estimated by a statistical method for evaluating fatigue life; the results of the fatigue test varied widely. Cyclic bending tests were performed on a cantilever beam with a hybrid composite joint, which was developed for the body of a low-floor bus. In order to estimate the fatigue life of the hybrid composite joint structure by comparing the data obtained during the fatigue tests, the most suitable probabilistic density function among the normal, lognormal, and Weibull distributions was selected. The probabilistic-stress-life (P-S-N) curves calculated by using the selected Weibull distribution was suggested for process of statistical fatigue life estimation and reliability design.

Development of the Condition Assessment Scheme of Aged Ships (노후선박의 Condition Assessment Scheme의 개발)

  • 박영일;백점기;이제명;고재용
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2004.04a
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    • pp.77-82
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    • 2004
  • This study presents reliability assessment of merchant ships with focus on hull girder ultimate limit state, taking into account the time-dependent effects of corrosion, fatigue cracking and local denting. Some considerations for establishing a reliability-based repair and maintenance scheme are also made so as to keep a ship's hull girder strength reliability at an acceptable level even later in life.

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Statistical Investigateion of Fatigue Life Predictioin of the Spot Welded Lap Joint(II) ; to verity reliabilty of fatigue strength estimatioin method (Spot 용접이음재의 피로수명 예측에 관한 확률적 검토(II) : 피로강도 평가법의 신뢰성 검증)

  • 손일선;배동호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.7
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    • pp.242-249
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    • 1999
  • Spot welding is very important and useful technology in fabrication of an automobile body structure. Because fatigue strength of the spot welding point is however considerably lower than parent metal due to stress concentration at the nugget edge, accurate stress analysis and fatigue stength evaluation of spot welded lap joint are very important to valuate the reliability and durability of automobile body structure and to establish a criterion of long life fatigue design. Many invetigators have studied so far onsystematic fatigue strength evaluation with various methods. It is however necessary to verify their reliability and abailability for practical application to fatigue design of spot welded structure, Thus,in this study, fatigue strength evaluation methods of spot welded lap joint. which are the maximum principal stress method. the fracture and availability with the Weibull probability distribution. From the results, it was found that reliability and availability withe the Weibull probaility distribution. From the results, it was found that reliability and availability of the suggest fatigue strength estimation methods methods were higher than $\Delta$P-$N_f$ relation. However, among them , reliability of the maximum pricipal stress method was the highest.

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Fatigue Strength Analysis and Reliability Analysis of D/H VLCC (D/H VLCC의 피로강도해석과 피로 신뢰성해석)

  • Yang, P.D.C.;Lee, J.S.;Yoon, J.H.;Seo, Y.S.
    • Journal of the Society of Naval Architects of Korea
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    • v.34 no.2
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    • pp.64-74
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    • 1997
  • The necessity and importance of fatigue failure to variable load has been appreciated as the structural design technique develops and use of high tensile steel is increasing. This is much more appreciated for a large ship such as VLCC. The rigorous fatigue analysis and safety assessment should be, hence, carried out at the design stage to avoid the possibility of fatigue failure and to achieve the design result having a sufficient structural safety to fatigue strength. This paper deals with an efficient spectral fatigue analysis of ship structures by introducing the concept of stress influence coefficient. In the process included are probabilistic loading analysis, evaluation of long-term distribution of stress range and estimation of fatigue life applying the spectral fatigue analysis. An integrated computer program has been developed in which reliability analysis to fatigue strength is also included and has been applied to D/H VLCC.

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Reliability Estimation of Steam Turbine Blade Using First Order Reliability Method (FORM을 이용한 증기 터빈블레이드의 신뢰성 평가)

  • 황진호;김철수;김정규
    • Proceedings of the Korean Reliability Society Conference
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    • 2002.06a
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    • pp.199-204
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    • 2002
  • 본 연구에서는 저압 증기 터빈블레이드의 안전성 확보를 위하여 작용응력 및 강도의 변동성을 고려한 확률론적 해석을 수행하였다. 정상상태에서 작용응력은 이론 및 유한요소해석에 의해서 얻을 수 있으며, 최대 von-Mises 응력은 215.4MPa이다. 회전굽힘 하중하에서의 피로한도는 응력비 R= -1에서 계단식 시험법을 이용하여 구하였으며, 이의 확률론적 특성에 가장 적합한 분포는 3 모수 와이블 분포이다. 그리고 신뢰성에 미치는 다양한 인자들의 영향은 영향계수(sensitivity factor)를 이용하여 정량적으로 평가하였다.

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Solder Alloy Types and Solder Joint Reliability Evaluation Techniques (솔더 합금 종류 및 솔더 조인트의 신뢰성 평가 기법)

  • You-Gwon Kim;Heon-Su Kim;Tae-Wan Kim;Hak-Sung Kim
    • Journal of the Microelectronics and Packaging Society
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    • v.30 no.1
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    • pp.17-29
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    • 2023
  • In this paper, a method for evaluating the reliability of solder joints is introduced, as they play a crucial role in packaging technology due to the miniaturization and high-performance requirements of electronic device. Firstly, properties of solder based on various alloy compositions and solder types are described, followed by an analysis of solder joint structures in different packages. Next, the influence of solder alloy composition and microstructure on the thermal and mechanical properties of solder is analyzed, and solder creep behavior is briefly introduced. Subsequently, analytical techniques considering creep models and fatigue models for reliability evaluation are presented, and various ways to improve the reliability of solder joints are discussed. This study is expected to provide valuable information for evaluating and enhancing the reliability of solder joints in the semiconductor packaging technology field.

A Reliable Group management for the Distributed Real-time Environment (분산 실시간 환경을 위한 신뢰성있는 그룹 관리 기법)

  • 남광현;홍영식
    • Proceedings of the Korean Information Science Society Conference
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    • 2001.10c
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    • pp.631-633
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    • 2001
  • 인터넷의 대중화로 컴퓨터 네트워크의 사용이 보편화 되었고, 그룹통신 기법이 화상회의 등 많은 응용분야에서 활용되고 있다. 분산 실시간 시스템에서 피를 통신의 신뢰성을 보장하는 일은 매우 중요하다. 또, 그룹 통신에서 효과적으로 그룹을 관리할 필요가 있고, 현재 실시간 환경에서의 그룹통신은 네트워크의 부하 때문에 생기는 패킷의 손실과 노드의 고장 같은 여러 가지 문제점들을 가지고 있다. 본 논문에서는 이러한 문제점들을 개선시켜 보고자 고장이 발생했을 때에도 그를 변경을 가능하게 하는 분산 실시간 환경을 위한 신뢰성 있는 그룹관리기법을 제안하고, 실시간 시뮬레이션을 통해 제안된 기법을 평가한다.

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The Development of Life Evaluation Program for LNG Storage Tank considering Fatigue and Durability (피로 및 내구성을 고려한 LNG 저장탱크의 수명평가 프로그램 개발)

  • Kim, Jung-Hoon;Kim, Young-Gu;Jo, Young-Do
    • Journal of the Korean Institute of Gas
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    • v.21 no.3
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    • pp.39-45
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    • 2017
  • The LNG storage tank as core facility of LNG industry is mainly composed of the inner tank of nikel 9% steel and the outer tank of prestressed concrete. To respond proactively increased risk of structure performance deterioration due to fatigue of the inner tank and durability reduction of the outer tank, life evaluation program for LNG storage tank is needed. In this study, life evaluation program for LNG storage tank was developed to assess fatigue of the inner tank and durability(carbonation and chloride attack) of the outer tank. By defining the main three scenarios in the inner tank, the fatigue life analysis is conducted from structural analysis and Miner's damage rule. Carbonation progress of the outer tank is predicted according to thickness of cover concrete by using carbon dioxide contents and data of penetration depth. To consider a variety of input conditions and a reliability in results of chloride attack, the evaluation of choride attack for the outer tank is constructed through Life-365 program of open source.

A study on performance evaluation of rod rubber bushing under static and fatigue loadings (토크 로드 부품의 정하중 및 피로하중하에서의 성능평가 연구)

  • 이순복;김완두
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.5
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    • pp.1320-1329
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    • 1990
  • A static performance tester for a torque rod assembly was developed to evaluate the three characteristics of the rod rubber bushing : radial spring characteristic, thrust spring characteristic, and rotational torque characteristic. Among the various schemes considered in the conceptual design stage, the final versatile type was determined to perform three different tests in one machine. The performance testing machine carried out radial spring test, thrust spring test, and torque test of the torque rod assembly. Static performance of the torque rod assembly was evaluated with the tester developed and fatigue strength of the assembly was also tested with the servo-hydraulic structural fatigue testing machine. The life of the component was found to be related with the rubber quality and adhesionability between the rubber and the steel rod. The optimum rubber hardness was experimentally found by changing the chemical compositions of rubber, and the adhesion was improved by optimizing the shape of the outer section of a the rubber, this study ensured the development of a reliable torque rod assembly.