ALBERT

Notes: In ASME Sec. III ‘design by analysis’ approach, stresses are generally calculated by finite element method and compared to corresponding stress limits after categorizing those components. However, in order to obtain optimum results, time consuming and expensive manipulations are required owing to its mesh size dependency and complicate stress categorization. In this paper, a newapproach based on structural stress is proposed to resolve the issues and applied to a heat exchanger motor operated valve. At first, the technical bases and specific features of structural stress approach are briefly discussed. Secondly a series of finite element analyses are carried out to show the limitations of current ASME approaches and to get basic data for the proposed approach. Finally, astructural stress concentration factor of motor operated valve is determined after comparison of local stresses and structural stresses, and utilized for fatigue life evaluation. Since the results show a promising applicability, it seems that the structural stress based approach can be utilized for fatigue life evaluation of components with complex geometries

Notes: During the last two decades, the interests of large scale seamless analysis have been increased with respect to lifetime extension and management of infra-structure. And then, a seamless analysis of complex geometry is one of greatly interesting topic. However, there are still gaps between the industrial applications and fundamental academic studies owing to time consuming the modeling and analyzing process. To resolve these problems, the integrity evaluation procedure from knowledge-based information system (KIS) to ADVENTRUE has been proposed for the application of auto mesh generation and large scale analysis. The virtual plant which is used for the master of KIS, provides the 3D information of entities for mesh generation. And then, the ADVENTURE makes a domain decomposed mesh and analyzes it using hierarchical domain decomposition method.Considering the good applicability in both efficiency and exactness point of views, it is anticipated that the proposed study on large scale analysis can be used as a promising integrity evaluation method of infra-structures

Notes: The heavy load carrying facility, such as ladle crane, is operating under severe working environment. It usually carries melted iron to the furnace, and thus, the accident due to crane failure may cause detrimental damage to the entire steel making factory. While the ladle crane is designed for 20 years of safe operation in a steel making company, several critical cracks due to fatigue loadinghave been reported during the maintenance process. In order to prevent fatal failure due to crack growth, ladle crane has been periodically inspected and maintained. However, the inspection and maintenance including repair and replacement cause the whole manufacturing line to stop, it is critical to set the appropriate inspection interval and replacement criteria. For this reason, the importance ofplant maintenance (PM) has been highly raised to provide efficient plant operation. Recently, a number of engineering methodologies, such as fitness for service guidelines (FFS) and plant lifecycle management (PLM) system, have been applied to improve the plant operation efficiency. Also, a network-based business operation system, which is called ERP (Enterprise Resource Planning), has been introduced in the field of plant maintenance. However, there hasn’t been any attempt to connect engineering methodologies to the ERP PM(Plant Maintenance) system. In this paper, an engineering methodology which provides life time evaluation under fatigue loading has been implemented to the web-based ERP PM system along with real-time fatigue monitoring system. In order to monitor the real time loading, a web-based fatigue monitoring system for ladlecrane has been developed and installed inside the ladle crane. For the estimation of fatigue life, 3-dimensional finite element (FE) analyses were conducted for actual transients. Finally, the fatigue life time estimation program is developed by integrating FE analysis results and real-time monitoring data. For the direct calculation of remained fatigue life, an artificial neural network (ANN) algorithmhas been applied. The proposed system is expected to play a great role in determining appropriate inspection and maintenance schedule which has become critical issue for the efficient plant maintenance

Notes: Major nuclear components have been designed by conservative codes to preventunanticipated fatigue failure. However, more realistic and effective assessment is necessary in proofof continued operation beyond the design life. In the present paper, three-dimensional stress andfatigue evaluation is carried out for pressurizer employing complex full geometry itself instead ofconventional discrete subcomponents. For this purpose, temperature and mechanical stress transferGreen’s functions are derived from finite element analyses and applied to critical locations ofpressurizer. In accordance with comparison of resulting stresses obtained from the Green’s functionand detailed finite element analysis, suitability of the specific Green’s function is investigated. Finally,prototype of fatigue life assessment results is provided along with relevant ongoing activities

Notes: In this paper, the applicability of local approach is examined for SA515 Gr.60 nuclearsteel through a series of finite element analyses incorporating modified GTN and Rousselier modelsas well as fracture toughness tests. To achieve the goal, fracture toughness test data of standardcompact tension (CT) specimens are used for calibration of micro-mechanical parameters. Then,from finite element analyses employing the calibrated parameters, fracture resistance (J-R) curvesof CT specimens with different crack length to width ratio, with different thickness andwith/without 20% side-grooves are predicted. Finally, suitability of the numerically estimated J-Rcurves was verified by comparison with the corresponding experimental J-R curves

Notes: The purpose of this paper is to investigate fluid characteristics and flat panel displaybehaviours on contact-free flat panel display handler nozzles. Since air force distributions streamingbottom surface of a flat panel display highly dependent on operating as well as design conditions andconfiguration of contact-free handler nozzle, influences of various parameters such as flow rate,supply air pressure, floating height are examined through a series of computational fluid dynamicsanalyses. Moreover, dynamic finite element analyses of the flat panel display are carried out to assurethat an oscillation effect caused by disturbances is not significant. Key findings from the bothcomputational fluid dynamics and structural integrity analysis results are presented and discussed,which can be figured out an optimized operating condition of contact-free handler nozzles

Notes: In general, the fatigue life of major nuclear components has been evaluated based on designcodes conservatively. However, sometimes, more exact fatigue life evaluation is required forcontinued operation beyond the endorsed life. The purpose of this paper is to carry out 3-D stress andfatigue analyses reflecting full geometry as well as actual operating data. The actual operating dataacquired through a monitoring system were filtered and assessed. Then, temperature and stresstransfer Green’s functions were developed and applied to critical locations of reactor pressure vessel.The finite element analyses results for representative design transients were verified throughcomparison to reference solution and showed that the conservatism of current 2-D evaluation.Therefore, it is anticipated that the proposed scheme adopting Green’s function and real operatinghistories can be utilized for remaining life time evaluation of major components

Notes: Fracture toughness data from the cleavage resistance test of structural steels often show alarge scatter. Geometry dependency as well as the scatter makes it difficult to evaluate appropriatefracture integrity of cracked components. To address these restrictions, several stochastic modelshave been proposed by Beremin group, Mudry and other researchers while each of them employsspecific estimation scheme and micro-mechanical parameters. The purpose of this paper is toinvestigate applicability of the Weibull stress model in transition temperature regime and to quantifyconstraint effect among different-sized CT and PCVN specimens. The constituting parameters m andσu are determined at three temperatures by maximum likelihood estimate (MLE) technique in use ofFE analysis results and experimental data of PCVN specimens. Also, failure probabilities of PCVNand CT specimens are calculated from the Weibull parameters, which are used for derivation of aprototype of toughness scale diagram. The diagram provides a technical basis to resolvetransferability issue in the same material under different temperatures and constraint conditions

Notes: The objective of this paper is to investigate failure characteristics of SA508 carbon steelin ductile-brittle transition temperature region. To achieve this goal, a series of finite elementanalyses as well as fracture toughness tests are performed for pre-cracked V-notch specimens. Anassessment of failure probabilities is, then, carried out employing Weibull stress models withdifferent rank probability options. Finally, a prototype of toughness scale diagram is derivedthrough comparison of estimated fracture toughness data with those for compact tension specimens.The present results can be utilized to found a basis of realistic integrity evaluation on major nuclearcomponents containing defect

Notes: In the ASME Code Section III ‘design by analysis’ approach, stresses are determined bynumerical method and compared with corresponding stress limits. This approach provides severalstress criteria for fatigue life assessment and procedures for categorizing the representative stresscomponents. Since the stress criteria were derived from two-dimensional basis, however, it mayinappropriate to delineate structural components with complex geometry. In this paper, detailedtransient analyses are performed for modular pressurizer with an asymmetric geometry, whichincludes perforated parts to mount various piping and equipments. Also, the applicability of aneffective elastic modulus to consider the perforation and the appropriateness of stress linearizationmethod using stress classification line are assessed. Then, the cumulative usage factor as well as stressintensities at critical locations of the pressurizer are calculated and compared with correspondingallowable design stress limits. The key findings of this work can be used to make regulatory guides forevaluation and confirmation of structural intensity of components with asymmetric perforated parts