• 제목/요약/키워드: Reliability-based Design

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판 구조물의 감도해석 및 신뢰성해석 (Sensitivity and Reliability Analysis of Elate)

  • 김지호;양영순
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 1991년도 가을 학술발표회 논문집
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    • pp.57-62
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    • 1991
  • For the purpose of developing the method for efficiently calculating the design sensitivity and the reliability for the complicated structure such as ship structure, the probabilistic finite element method is introduced to formulate the deterministic design sensitivity analysis method and incorporated with the second moment reliability methods such as MVFOSM, AFOSM and SORM. Also, the probabilistic design sensitivity analysis needed in the reliability-based design is performed. The reliability analysis is carried out for the initial yielding failure, in which the derivative derived in the deterministic desin sensitivity is used. The present PFEM-based reliability method shows good agreement with Monte Carlo method in terms with the variance of response and the associated probability of failure even at the first or first few iteration steps. The probabilistic design sensitivity analysis evaluates explicitly the contribution of each random variable to probability of failure. Further, the reliability index variation can be easily predicted by the variation of the mean and the variance of the random variables.

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Reliability-Based Design Optimization of a Superconducting Magnetic Energy Storage System (SMES) Utilizing Reliability Index Approach

  • Jeung, Gi-Woo;Kim, Dong-Wook;Sung, Young-Hwa;Kim, Heung-Geun;Kim, Dong-Hun
    • Journal of Magnetics
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    • 제17권1호
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    • pp.46-50
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    • 2012
  • A reliability-based optimization method for electromagnetic design is presented to take uncertainties of design parameters into account. The method can provide an optimal design satisfying a specified confidence level in the presence of uncertain parameters. To achieve the goal, the reliability index approach based on the firstorder reliability method is adopted to deal with probabilistic constraint functions and a double-loop optimization algorithm is implemented to obtain an optimum. The proposed method is applied to the TEAM Workshop Problem 22 and its accuracy and efficiency is verified with reference of Monte Carlo simulation results.

신뢰성을 고려한 유연 날개 형상 최적 설계에 대한 연구 (STUDY OF RELIABILITY BASED FLEXIBLE WING SHAPE DESIGN OPTIMIZATION)

  • 김수환;권장혁
    • 한국전산유체공학회지
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    • 제11권1호
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    • pp.21-28
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    • 2006
  • Reliability Based Design Optimization(RBDO) is one of the optimization methods that minimize the product failure due to small changes of operating conditions or process errors. It searches the optimum that satisfies the safety margin of each constraint, and it gives stable and reliable designs. However, RBDO requires many times oj computational efforts compared with the conventional deterministic optimization(DO) to evaluate the probability of failure about each constraint, therefore it is hard to apply directly to large-scaled problems such as a flexible wing shape design optimization. For the efficient reliability analysis, the approximate reliability analysis method with the two-point approximation(TPA) is proposed In this study, the lift-to-drag ratio maximization designs are performed with 3-dimensional Navier-Stokes analysis and NASTRAN structural analysis, and the optimization results about the deterministic, FORM and SORM are compared.

보수적 근사모델을 적용한 신뢰성 기반 강건 최적설계 방법 (Study of Reliability-Based Robust Design Optimization Using Conservative Approximate Meta-Models)

  • 심형민;송창용;이종수;최하영
    • 한국해양공학회지
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    • 제26권6호
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    • pp.80-85
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    • 2012
  • The methods of robust design optimization (RDO) and reliability-based robust design optimization (RBRDO) were implemented in the present study. RBRDO is an integrated method that accounts for the design robustness of an objective function and for the reliability of constraints. The objective function in RBRDO is expressed in terms of the mean and standard deviation of an original objective function. Thus, a multi-objective formulation is employed. The regressive approximate models are generated via the moving least squares method (MLSM) and constraint-feasible moving least squares method (CF-MLSM), which make it possible to realize the feasibility regardless of the multimodality/nonlinearity of the constraint function during the approximate optimization processes. The regression model based RBRDO is newly devised and its numerical characteristics are explored using the design of an actively controlled ten bar truss structure.

근사신뢰도기법을 이용한 효율적인 공력 형상 설계에 관한 연구 (Study of the Efficient Aerodynamic Shape Design Optimization Using the Approximate Reliability Method)

  • 김수환;권장혁
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2004년도 추계 학술대회논문집
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    • pp.187-191
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    • 2004
  • The conventional reliability based design optimization(RBDO) methods require high computational cost compared with the deterministic design optimization(DO) methods. To overcome the computational inefficiency of RBDO, single loop methods have been proposed. These need less function calls than that of RBDO but much more than that of DO. In this study, the approximate reliability method is proposed that the computational requirement is nearly the same as DO and the reliability accuracy is good compared with that of RBDO. Using this method, the 3-D viscous aerodynamic shape design optimization with uncertainty is performed very efficiently.

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Reliability-based design of prestressed concrete girders in integral Abutment Bridges for thermal effects

  • Kim, WooSeok;Laman, Jeffrey A.;Park, Jong Yil
    • Structural Engineering and Mechanics
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    • 제50권3호
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    • pp.305-322
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    • 2014
  • Reliability-based design limit states and associated partial load factors provide a consistent level of design safety across bridge types and members. However, limit states in the current AASHTO LRFD have not been developed explicitly for the situation encountered by integral abutment bridges (IABs) that have unique boundary conditions and loads with inherent uncertainties. Therefore, new reliability-based limit states for IABs considering the variability of the abutment support conditions and thermal loading must be developed to achieve IAB designs that achieve the same safety level as other bridge designs. Prestressed concrete girder bridges are considered in this study and are subjected to concrete time-dependent effects (creep and shrinkage), backfill pressure, temperature fluctuation and temperature gradient. Based on the previously established database for bridge loads and resistances, reliability analyses are performed. The IAB limit states proposed herein are intended to supplement current AASHTO LRFD limit states as specified in AASHTO LRFD Table 3.4.1-1.

역해석법에 의한 피복재의 부분안전계수 산정 (Evaluation of Partial Safety Factors of Armor Units by Inverse-Reliability Analysis)

  • 이철응;박동헌
    • 산업기술연구
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    • 제28권B호
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    • pp.149-156
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    • 2008
  • A reliability model of Level II AFDA is developed to analyze the stability of armor units on the sloped coastal structures. Additionally, the partial safety factors of random variables related to armor units can be straightforwardly evaluated by applying the inverse-reliability method in which influence coefficients and uncertainties of random variables, and target probability of failure are combined directly. In particular, a design equation for armor units is derived in terms of the same criteria as deterministic design method in order to apply the reliability-based design method of Level I without some understanding to the reliability analysis. Finally, it is confirmed that several results redesigned by the reliability-based design method of Level I have satisfactorily agreement with results of CEM as well as those of Level II AFDA.

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일차근사신뢰도법을 이용한 초전도 자기에너지 저장장치 권선 최적설계 (Optimization of SMES Windings Utilizing the First-Order Reliability Method)

  • 김동욱;정상식;성영화;김동훈
    • 전기학회논문지
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    • 제60권7호
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    • pp.1354-1359
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    • 2011
  • This paper presents a novel methodology for improving the reliability of electromagnetic devices and machines based on the reliability-based design optimization method. To achieve this, the method includes reliability analysis and optimization process taking into account uncertainties of design variables. One of the first-order reliability analysis techniques, called reliability index approach, is adopted to evaluate the reliability of performance functions with respect to probabilistic design variables. The proposed method has been successfully applied to designing a superconducting magnetic energy storage system. For verifying the efficiency and accuracy of the method, the results are compared with those of conventional optimization methods.

Cracking in reinforced concrete flexural members - A reliability model

  • Rao, K. Balaji;Rao, T.V.S.R. Appa
    • Structural Engineering and Mechanics
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    • 제7권3호
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    • pp.303-318
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    • 1999
  • Cracking of reinforced concrete flexural members is a highly random phenomenon. In this paper reliability models are presented to determine the probabilities of failure of flexural members against the limit states of first crack and maximum crackwidth. The models proposed take into account the mechanism of cracking. Based on the reliability models discussed, Eqs. (8) and (9) useful in the reliability-based design of flexural members are presented.

교량기초의 신뢰성 설계규준에 관한 연구 (A Study on Reliability Based Design Criteria for Bridge Foundation)

  • 손용우;정철원
    • 전산구조공학
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    • 제6권1호
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    • pp.77-89
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    • 1993
  • Current Bridge foundation design is based on Working Stress Design(WSD), but Load Factor Based on Optimum Reliability(LFBOR) design method is more rational than the WSD. For this reason, this study proposes a reliability based design criteria for the bridge foundation, which is most common type of bridge foundation(Shallow, Pile and Caission), and also proposes the theoretical basis of nominal safety factors of stability analysis by introducing the reliability theory. The limit state equations of stability analysis of bridge foundation and the uncertainty measuring algorithms of each equation are also derived by Cornell's MFOSM(Mean First Order 2nd Moment Methods)using the stability analysis fourmula Highway Bridge Design Codes.

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