• Title/Summary/Keyword: Reliability Design

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System Structure and Reliability Optimization of VVVF Urban Transit Brake System Through Cost Function Construction (비용함수를 이용한 VVVF 전동차 제동장치의 시스템 구조 및 신뢰도 최적화)

  • Kim, Se-Hoon;Kim, Hyun-Jung;Bae, Chul-Ho;Lee, Jung-Hwan;Lee, Ho-Yong;Suh, Myung-Won
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.3
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    • pp.63-71
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    • 2007
  • During the design phase of a product, reliability and design engineers are called upon to evaluate the reliability of the system, The question of how to meet target reliability for the system arises when estimated reliability or cost is inadequate. This then becomes a problem of reliability allocation and system structure design. This study proposes the optimization methodology to achieve target reliability with minimum cost through construction of the cost function of system. In cost function, total cost means the sum of initial cost, repair cost and maintenance cost. This study constructs optimization problem about system structure design and reliability allocation using cost function. This problem constructed is solved by Multi-island Genetic Algorithm(MIGA), and applies to urban transit brake system. Current brake system of the urban transit is series system. Series system is the simplest and perhaps one of the most common system, but it demands high reliability and maintenance cost because all components must be operating to ensure system operation. Thus this study makes a comparative study by applying k-out-of-n system to brake system. This methodology presented can be a great tool for aiding reliability and design engineers in their decision-makings.

Calibration of Current LRFD Formats for R.C. Structure Design (철근콘크리트구조물의 현행 LRFD 설계식 검정)

  • 김상효;배규웅;박흥석
    • Proceedings of the Korea Concrete Institute Conference
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    • 1990.10a
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    • pp.35-40
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    • 1990
  • Because of the inherent random nature of most manmade and environmental loadings and materials as well as the emperfect structural analysis, the reliability-based structural design has been recognized as a rational approach and the probability-based design criteria has been successfully developed for many standards. In order to do this it is necessary to establish target reliability levels, for which the reliability levels inherent in present design practice will be used as a rational guide. In this study the reliability levels implied in current practices, therefore, are investigated using the load and resistance models developed for domestic uses.

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Resilience Allocation for Resilient Engineered System Design (복원가능 시스템 설계를 위한 복원도 할당)

  • Youn, Byeng-D.;Hu, Chao;Wang, Pingfeng;Yoon, Joung-Taek
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.11
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    • pp.1082-1089
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    • 2011
  • Most engineered systems are designed with high levels of system redundancies to satisfy required reliability requirements under adverse events, resulting in high systems' LCCs (Life-Cycle Costs). Recent years have seen a surge of interest and tremendous advance in PHM (Prognostics and Health Management) methods that detect, diagnose, and predict the effects of adverse events. The PHM methods enable proactive maintenance decisions, giving rise to adaptive reliability. In this paper, we present a RAP (Resilience Allocation Problem) whose goal is to allocate reliability and PHM efficiency to components in an engineering context. The optimally allocated reliability and PHM efficiency levels serve as the design specifications for the system RBDO (Reliability-Based Design Optimization) and the system PHM design, which can be used to derive the detailed design of components and PHM units. The RAP is demonstrated using a simplified aircraft control actuator design problem resulting in a highly resilient actuator with optimally allocated reliability, PHM efficiency and redundancy for the given parameter settings.

A Framework to Automate Reliability-based Structural Optimization based on Visual Programming and OpenSees

  • Lin, Jia-Rui;Xiao, Jian;Zhang, Yi
    • International conference on construction engineering and project management
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    • 2020.12a
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    • pp.225-234
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    • 2020
  • Reliability-based structural optimization usually requires designers or engineers model different designs manually, which is considered very time consuming and all possibilities cannot be fully explored. Otherwise, a lot of time are needed for designers or engineers to learn mathematical modeling and programming skills. Therefore, a framework that integrates generative design, structural simulation and reliability theory is proposed. With the proposed framework, various designs are generated based on a set of rules and parameters defined based on visual programming, and their structural performance are simulated by OpenSees. Then, reliability of each design is evaluated based on the simulation results, and an optimal design can be found. The proposed framework and prototype are tested in the optimization of a steel frame structure, and results illustrate that generative design based on visual programming is user friendly and different design possibilities can be explored in an efficient way. It is also reported that structural reliability can be assessed in an automatic way by integrating Dynamo and OpenSees. This research contributes to the body of knowledge by providing a novel framework for automatic reliability evaluation and structural optimization.

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A Study on Optimum Reliability of P.S.C Box Girder Bridge (최적신뢰성에 의한 P.S.C Box Girder교의 연구)

  • Jung, Chul-Won;Yu, Han-Shin;Na, Ki-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.3 no.4
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    • pp.139-144
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    • 1999
  • Based on the recent developments of the reliability-based structural analysis and design as well as the extending knowledge on the probabiliistic characteristics of load and resistances, the probability based design criteria have been successfully developed for many standards. Since the probabilistic characteristics depend highly on the local load and resistances, it is recognized to develop the design criterion compatible with domestic requirements. The existing optimum design methods, which are generally based on the structural theory and certain engineering experience, do not realistically consider the uncertainties of load and resistances and the basic reliability concepts. This study is directed to propose a optimum design based Expected Total Cost Minimization on P.S.C Box Girder Bridge system which could possibly replace optimum design based traditional provisions of the current code, based on the Neldel-Mead Method reliability theory.

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Design of Reliability Qualification Test Based on Performance Distribution at the Earlier Stage (초기 단계의 성능분포를 활용한 신뢰성 인증시험의 설계)

  • Jeong, Hai-Sung
    • Journal of Applied Reliability
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    • v.12 no.3
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    • pp.131-138
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    • 2012
  • A design of reliability qualification test based on performance distribution is developed. In general, the performance of an item degrades as the time goes by and the failure of an item occurs when the performance degradation reaches the pre-determined critical level. This article considers the reliability qualification test based on a more tightened critical value at the earlier stage to reduce the evaluation testing time and cost. A numerical example is provided to illustrate how to use the developed reliability qualification test.

Design Optimization and Reliability Analysis of Jacket Support Structure for 5-MW Offshore Wind Turbine (해상풍력발전기 자켓 지지구조물의 최적설계 및 신뢰성해석)

  • Lee, Ji-Hyun;Kim, Soo-Young;Kim, Myung-Hyun;Shin, Sung-Chul;Lee, Yeon-Seung
    • Journal of Ocean Engineering and Technology
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    • v.28 no.3
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    • pp.218-226
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    • 2014
  • Since the support structure of an offshore wind turbine has to withstand severe environmental loads such as wind, wave, and seismic loads during its entire service life, the need for a robust and reliable design increases, along with the need for a cost effective design. In addition, a robust and reliable support structure contributes to the high availability of a wind turbine and low maintenance costs. From this point of view, this paper presents a design process that includes design optimization and reliability analysis. First, the jacket structure of the NREL 5-MW offshore wind turbine is optimized to minimize the weight and stresses, while satisfying the design requirements. Second, the reliability of the optimum design is evaluated and compared with that of the initial design. Although the present study results in a new optimum shape for a jacket support structure with reduced weight and increased reliability, the authors suggest that the optimum design has to be accompanied by a reliability analysis during the design process, as well as reliability based design optimization if needed.

INTERACTIVE SYSTEM DESIGN USING THE COMPLEMENTARITY OF AXIOMATIC DESIGN AND FAULT TREE ANALYSIS

  • Heo, Gyun-Young;Lee, Tae-Sik;Do, Sung-Hee
    • Nuclear Engineering and Technology
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    • v.39 no.1
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    • pp.51-62
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    • 2007
  • To efficiently design safety-critical systems such as nuclear power plants, with the requirement of high reliability, methodologies allowing for rigorous interactions between the synthesis and analysis processes have been proposed. This paper attempts to develop a reliability-centered design framework through an interactive process between Axiomatic Design (AD) and Fault Tree Analysis (FTA). Integrating AD and FTA into a single framework appears to be a viable solution, as they compliment each other with their unique advantages. AD provides a systematic synthesis tool while FTA is commonly used as a safety analysis tool. These methodologies build a design process that is less subjective, and they enable designers to develop insights that lead to solutions with improved reliability. Due to the nature of the two methodologies, the information involved in each process is complementary: a success tree versus a fault tree. Thus, at each step a system using AD is synthesized, and its reliability is then quantified using the FT derived from the AD synthesis process. The converted FT provides an opportunity to examine the completeness of the outcome from the synthesis process. This study presents an example of the design of a Containment Heat Removal System (CHRS). A case study illustrates the process of designing the CHRS with an interactive design framework focusing on the conversion of the AD process to FTA.

Integrating Machine Reliability and Preventive Maintenance Planning in Manufacturing Cell Design

  • Das, Kanchan;Lashkari, R.S.;Sengupta, S.
    • Industrial Engineering and Management Systems
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    • v.7 no.2
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    • pp.113-125
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    • 2008
  • This paper presents a model for designing cellular manufacturing systems (CMS) by integrating system cost, machine reliability, and preventive maintenance (PM) planning. In a CMS, a part is processed using alternative process routes, each consisting of a sequence of visits to machines. Thus, a level of 'system reliability' is associated with the machines along the process route assigned to a part type. Assuming machine reliabilities to follow the Weibull distribution, the model assigns the machines to cells, and selects, for each part type, a process route which maximizes the overall system reliability and minimizes the total costs of manufacturing operations, machine underutilization, and inter-cell material handling. The model also incorporates a reliability based PM plan and an algorithm to implement the plan. The algorithm determines effective PM intervals for the CMS machines based on a group maintenance policy and thus minimizes the maintenance costs subject to acceptable machine reliability thresholds. The model is a large mixed integer linear program, and is solved using LINGO. The results point out that integrating PM in the CMS design improves the overall system reliability markedly, and reduces the total costs significantly.

A Reliability Information Model Using IDEF1 (IDEF1을 이용한 신뢰성 정보 모델)

  • 장중순;안동근;김민성
    • Journal of Korean Society for Quality Management
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    • v.25 no.4
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    • pp.185-205
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    • 1997
  • Reliability management requires many activities such as conceptual design, detail design, reliability evaluation and analysis, life testing, and environmental screening, etc.. To perform these activities effectively, a lot of information are required : information for failure mechanism, failure modes, part characteristics, and environmental conditions, etc.. These information should be managed to be used effectively and accurately in reliability activities and feedback to product design and manufacturing. This study identified and characterized these information and classified them according to the reliability activities commonly adopted in many manufacturing industries. IDEF1 was used to define and characterize the flow and the relationship of these reliability information and model is proposed which represents the structure of reliability information systems. The proposed model can be used as a basis for developing reliability management softwares.

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