• Structural Engineering and Mechanics
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• 제59권6호
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• pp.1095-1120
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• 2016

This paper investigates the change of structural characteristics of steel cable-stayed bridges after cable failure. Cables, considered as the intermediate supports of cable-stayed bridges, can break or fail for several reasons, such as fire, direct vehicle clash accident, extreme weather conditions, and fatigue of cable or anchorage. Also, the replacement of cables can cause temporary disconnection. Because of the structural characteristics with various geometric nonlinearities of cable-stayed bridges, cable failure may cause significant change to the structural state and ultimate behavior. Until now, the characteristics of structural behavior after cable failure have rarely been studied. In this study, rational cable failure analysis is suggested to trace the new equilibrium with structural configuration after the cable failure. Also, the sequence of ultimate analysis for the structure that suffers cable failure is suggested, to study the change of ultimate behavior and load carrying capacity under specific live load conditions. Using these analysis methods, the statical behavior after individual cable failure is studied based on the change of structural configuration, and distribution of internal forces. Also, the change of the ultimate behavior and load carrying capacity under specific live load conditions is investigated, using the proposed analysis method. According to the study, significant change of the statical behavior and ultimate capacity occurs although just one cable fails.

• International Journal of Reliability and Applications
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• 제12권1호
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• pp.49-60
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• 2011

The geometric process (GP) has been widely used for modeling failure and repair time sequences of repairable systems. The GP is mathematically tractable but restrictive in reliability applications since it actually assumes that the mean function of inter-failure times sequence asymptotically decreases to zero; and the mean function of successive repair times sequence asymptotically increases to infinity. This is generally unrealistic from an engineering perspective. This paper presents three extended GP models for modeling reliability deterioration and improvement (or growth) process. The extensions maintain the advantage of mathematical tractability of GP model. Their usefulness and appropriateness are illustrated with three real-world examples.

• Steel and Composite Structures
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• 제38권3호
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• pp.305-317
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• 2021

The mechanical behavior of the outer square inner circular concrete-filled dual steel tubular (SCCFT) stub columns under axial compression is investigated by means of experimental research, numerical analysis and theoretical investigation. Parameters such as diameter ratio, concrete strength and steel ratio were discussed to identify their influence on the mechanical properties of SCCFT short columns on the basis of the experimental investigation of seven SCCFT short columns. By establishing a finite element model, nonlinear analysis was performed to discuss the longitudinal and transverse stress of the dual steel tubes. The longitudinal stress characteristics of the core and sandwich concrete were also analyzed. Furthermore, the failure sequence was illustrated and the reasonable cross-section composition of SCCFT stub column was proposed. A formula to predict the axial load capacity of SCCFT stub column was advanced and verified by the results from experiment and the finite element.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.1-4
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• 2002

With the wide application of fiber-reinforced composite material in aero-structures and mechanical parts, the design of composite joint have become a very important research area because they are often the weakest areas in composite structures. In this paper, the failure area index method to predict the strength of the mechanically fastened composite joint which has the same stacking sequence was suggested and evaluated. By the suggested failure area index method, the strength of the mechanically fastened composite joint could be predicted within 6.03%.

• Structural Engineering and Mechanics
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• 제4권5호
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• pp.485-496
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• 1996

This paper describes a numerical and experimental study on the stability and failure behaviour of rectangular symmetric laminated composite plates. The plates are simply supported along the unloaded edges and clamped along the loaded ends, and they are subjected to uniaxial in-plane compression. The finite element method was employed for the theoretical study. The study examines the effect of the plate's stacking sequence and aspect ratio on the stability and failure response of rectangular symmetric laminated carbon fibre reinforced plastics composite plates. The study also includes the effect of the unloaded edge support conditions on the postbuckling response and failure of the plates. Extensive experimental investigation were also carried out to supplement the finite element study. A comprehensive comparison between theory and experimental data are presented and discussed in this contribution.

• 한국CDE학회논문집
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• 제18권4호
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• pp.250-257
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• 2013

This paper introduces a failure analysis procedure that underpins real-time fault prognosis. In the previous study, we developed a systematic eventization procedure which makes it possible to reduce the original data size into a manageable one in the form of event logs and eventually to extract failure patterns efficiently from the reduced data. Failure patterns are then extracted in the form of event sequences by sequence-mining algorithms, (e.g. FP-Tree algorithm). Extracted patterns are stored in a failure pattern library, and eventually, we use the stored failure pattern information to predict potential failures. The two practical case studies (marine diesel engine and SIRIUS-II car engine) provide empirical support for the performance of the proposed failure analysis procedure. This procedure can be easily extended for wide application fields of failure analysis such as vehicle and machine diagnostics. Furthermore, it can be applied to human health monitoring & prognosis, so that human body signals could be efficiently analyzed.

• Korean Chemical Engineering Research
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• 제43권5호
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• pp.571-578
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• 2005

불연속 화학공정은 소비자 수요에 탄력성 있게 대처할 수 있는 장점이 있는 반면에 그 특유의 동특성 때문에 복잡하고, 계획된 조업 시간과 실제 조업 시간 사이에서 외란(disruption) 또는 불확실 변수(uncertainty)에 의한 차이가 자주 발생하는 단점이 있다. 이에, 본 논문에서는 예측 생산계획(predictive scheduling)에 의해 결정된 생산계획에서 미래에 발생하는 공정 변수 값의 변화를 실시간으로 예측 생산계획을 수정, 제시하여 주는 생산 계획 시스템인 동적 생산계획(reactive scheduling) 기법을 개발하였다. 불확실 인자를 고려한 동적 생산계획에서, 본 논문에서는 장치 이상(equipment failure)이 발생하였을 때 공정 운전조건의 변화를 실시간으로 반영하여, 예측 생산계획(predictive scheduling) 모델에 의하여 제시된 전체 생산 계획을 최대한 유지하고 공정 변수의 변화를 실시간으로 반영하기 위하여 right shift rescheduling과 total regeneration 기법을 사용하였다. 또한, 불확실 인자의 발생 전후의 predictive scheduling과 reactive scheduling 간의 변화 정도를 측정하는 수단인 schedule stability 위하여, 본 논문에서는 수정된 sequence deviation과 percentage change in makespan을 사용하여 제안된 동적 생산계획의 안정성을 측정하였다. 본 논문에서 제안한 동적 생산계획 시스템은 기존에 제시되었던 경험 법칙에 의한 결과값에 비해 좋은 결과를 보여주었다.

• Smart Structures and Systems
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• 제33권3호
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• pp.177-188
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• 2024

The fatigue-induced sequential failure of a structure having structural redundancy requires system-level analysis to account for stress redistribution. System reliability-based design optimization (SRBDO) for preventing fatigue-initiated structural failure is numerically costly owing to the inclusion of probabilistic constraints. This study incorporates the Branch-and-Bound method employing system reliability Bounds (termed the B³ method), a failure-path structural system reliability analysis approach, with a metaheuristic optimization algorithm, namely grey wolf optimization (GWO), to obtain the optimal design of structures under fatigue-induced system failure. To further improve the efficiency of this new optimization framework, an additional bounding rule is proposed in the context of SRBDO against fatigue using the B³ method. To demonstrate the proposed method, it is applied to complex problems, a multilayer Daniels system and a three-dimensional tripod jacket structure. The system failure probability of the optimal design is confirmed to be below the target threshold and verified using Monte Carlo simulation. At earlier stages of the optimization, a smaller number of limit-state function evaluation is required, which increases the efficiency. In addition, the proposed method can allocate limited materials throughout the structure optimally so that the optimally-designed structure has a relatively large number of failure paths with similar failure probability.

• 품질경영학회지
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• 제46권2호
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• pp.311-326
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• 2018

Purpose: Using international specifications, this study classified international standards and automobile manufacturers' test items based on the kind of test used and determined the test order for ISO 16750. Methods: The effects of international standards' environmental factors were examined, based on the major impacts of the product and the results of product failure. Automobile manufacturers' test items were compared with the test item in the ISO 16750. A generic algorithm was then used to determine the test sequence for ISO 16750. Results: International standards and automobile manufacturers' common test items were classified. The test sequence of ISO 16750 was determined for five cases. Conclusion: Although mechanical and environmental tests share many common features, there are differences in the details of the tests. There is a common sequence of tests, but weights are allocated tests differently.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.714-718
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• 2009

3D reconstruction of a human face from an image sequence remains an important problem in computer vision. We propose a method, based on a factorization algorithm, that reconstructs a 3D face model from short image sequences exhibiting rotational motion. Factorization algorithms can recover structure and motion simultaneously from one image sequence, but they usually require that all feature points be well tracked. Under rotational motion, however, feature tracking often fails due to occlusion and frame out of features. Additionally, the paucity of images may make feature tracking more difficult or decrease reconstruction accuracy. The proposed 3D reconstruction approach can handle short image sequences exhibiting rotational motion wherein feature points are likely to be missing. We implement the proposal as a reconstruction method; it employs image sequence division and a feature tracking method that uses Active Appearance Models to avoid the failure of feature tracking. Experiments conducted on an image sequence of a human face demonstrate the effectiveness of the proposed method.