Integrity Assessment of Cracked Piping Components: Experimental, Analytical and Numerical Studies

2005 ◽  
Author(s):  
J. Chattopadhyay ◽  
T. V. Pavankumar ◽  
A. K. S. Tomar ◽  
B. K. Dutta ◽  
H. S. Kushwaha
Keyword(s):  
Power Plants ◽  
Research Centre ◽  
Experimental Investigations ◽  
Integrity Test ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Pipe Elbow ◽  
Numerical Studies ◽  
Point Bend ◽  
Considerable Work

Integrity assessment of piping components is very essential for safe and reliable operation of power plants. Over the last several decades, considerable work has been done throughout the world to develop a methodology for integrity assessment of pipes and elbows, appropriate for the material involved. However, there is scope of further development/improvement of issues, particularly for pipe bends, that are important for accurate integrity assessment of piping. Considering this aspect, a comprehensive Component Integrity Test Program was initiated in 1998 at Bhabha Atomic Research Centre (BARC), India. In this program, both theoretical and experimental investigations were undertaken to address various issues related to the integrity assessment of pipes and elbows. Under the experimental investigations, fracture mechanics tests have been conducted on pipes and elbows of 200–400 mm nominal bore (NB) diameter with various crack configurations and sizes under different loading conditions. Tests on small tensile and three point bend specimens, machined from the tested pipes, have also been done to evaluate the actual stress-strain and fracture resistance properties of pipe/elbow material. The load-deflection curve and crack initiation loads predicted by non-linear finite element analysis matched well with the experimental results. The theoretical collapse moments of throughwall circumferentially cracked elbows, predicted by the recently developed equations, are found to be closer to the test data compared to the other existing equations. The role of stress triaxialities ahead of crack tip is also shown in the transferability of J-Resistance curve from specimen to the component.

Load Bearing Capacity of Through Wall Cracked Elbows: Comparison of Test Results With Calculation

2004 ◽  
Author(s):  
J. Chattopadhyay ◽  
B. K. Dutta ◽  
H. S. Kushwaha
Keyword(s):  
Power Plants ◽  
Limit Load ◽  
Research Centre ◽  
Test Results ◽  
Element Analysis ◽  
Bhabha Atomic Research Centre ◽  
Integrity Assessment ◽  
Theoretical Predictions ◽  
Fracture Tests ◽  
Set Up

Integrity assessment of piping components with postulated cracks is very important for safe and reliable operation of power plants. Pipe bends or elbows are one of the very important piping components in any power plant. The existing equations of limit load of elbows have various shortcomings. Additionally, the test data on elbows are not so abundant in the literature. Against this backdrop, a comprehensive experimental and analytical program has been undertaken at Reactor Safety Division (RSD) of Bhabha Atomic Research Centre (BARC) to carry out fracture tests on through wall cracked elbows and also to propose new limit load formulas of through wall cracked elbow. The present paper describes the elbow test specimens, test set-up, test results, brief description of elastic-plastic finite element analysis, newly proposed collapse moment equations for through wall circumferentially cracked elbows and the comparison of test results with theoretical predictions.

Development of Analysis Method for Impact and Splash Behavior of Water-Filled Tank

2017 ◽  
Author(s):  
Hidekazu Takazawa ◽  
Kazuma Hirosaka ◽  
Katsumasa Miyazaki ◽  
Norihide Tohyama ◽  
Naomi Matsumoto
Keyword(s):  
Structural Damage ◽  
Power Plants ◽  
Impact Test ◽  
Velocity Ratio ◽  
Research Centre ◽  
Test Results ◽  
Analysis Method ◽  
Cylindrical Tank ◽  
Element Analysis ◽  
The Impact

A new Japanese nuclear regulation requirement prepares estimating the possible damage to plant structures due to acts of terrorism, such as intentional aircraft impact. Aircraft impact needs to be considered in existing nuclear power plants. The structural damage and fuel splash behavior after aircraft impact into plant structures can be estimated using finite element analysis (FEA). FEA needs validated experimental data to determine the reliability of results. In this study, an analysis method was validated using a simple model such as a cylindrical tank. Numerical simulations were conducted to estimate the impact and splash behavior for a water-filled cylindrical tank. The simulated results were compared with the test results of the VTT Technical Research Centre of Finland. Simulations were carried out using a multipurpose FEA code LS-DYNA®. The cylindrical tank was modeled using a shell element, and filled water was modeled using a smoothed particle hydrodynamics (SPH) element. First, two analysis models were used to estimate the effect of the number of SPH elements. One was generated with about 300,000 SPH elements. The other was generated with 37,000 SPH elements. The cylindrical tank ruptured in the longitudinal direction after impact into a rigid wall, and the filled water splashed. Few differences emerged in the simulated results using different numbers of SPH elements. The impact test of the VTT was simulated with an arbitrary Lagrangian-Eulerian (ALE) element to consider the air drag. The analytical splash pattern and history of splash velocity ratio agreed well with the impact test results.

Development of Stress Intensity Factors for Surface Cracks With Large Aspect Ratio in Plates

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Yinsheng Li ◽  
Kunio Hasegawa ◽  
Genshichiro Katsumata ◽  
Kazuya Osakabe ◽  
Hiroshi Okada
Keyword(s):  
Stress Intensity ◽  
Aspect Ratio ◽  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Crack Depth ◽  
Surface Cracks ◽  
Large Aspect Ratio ◽  
Element Analysis ◽  
Integrity Assessment

A number of surface cracks with large aspect ratio have been detected in components of nuclear power plants (NPPs) in recent years. The depths of these cracks are even larger than the half of crack lengths. When a crack is detected during in-service inspections, methods provided in ASME Boiler and Pressure Vessel Code Section XI or JSME Rules on fitness-for-service for NPPs can be used to assess the structural integrity of cracked components. The solution of the stress intensity factor (SIF) is very important in the structural integrity assessment. However, in the current codes, the solutions of the SIF are provided for semi-elliptical surface cracks with a limitation of a/ℓ ≤ 0.5, where a is the crack depth, and ℓ is the crack length. In this study, the solutions of the SIF were calculated using finite element analysis (FEA) with quadratic hexahedron elements for semi-elliptical surface cracks with large aspect ratio in plates. The crack dimensions were focused on the range of a/ℓ = 0.5–4.0 and a/t = 0.0–0.8, where t is the wall thickness. Solutions were provided at both the deepest and the surface points of the surface cracks. Furthermore, some of solutions were compared with the available existing results as well as with solutions obtained using FEA with quadratic tetrahedral elements and the virtual crack closure-integral method (VCCM). Finally, it was concluded that the solutions proposed in this paper are applicable in engineering applications.

Validation of Constraint Based Methodology in Structural Integrity – VOCALIST: Experimental Programme

2002 ◽  
Author(s):  
Richard Bass ◽  
Ulrich Eisele ◽  
Elisabeth Keim ◽  
Heikki Keinanen ◽  
Ste´phane Marie ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Experimental Investigations ◽  
Integrity Assessment ◽  
Experimental Programme ◽  
Safety Margins ◽  
Materials Used ◽  
Shallow Crack

The aim of VOCALIST (Validation of Constraint-Based Assessment Methodology in Structural Integrity) is to develop and validate innovative procedures for assessing the level of, and possible changes to, constraint-related safety margins in ageing pressure boundary components [1]. An iterative process of experiment and analysis will address this overall objective. The experimental investigations within VOCALIST are performed on three different materials representing the as new state of materials used for components of nuclear power plants as well as a state representing an in service degraded state of RPV materials. Within the experimental programme fracture mechanics specimens with different constraint situations are tested in order to quantify the influence of the constraint on the specimens failure behaviour as a basis for the advanced components integrity assessment. The investigations are performed on small laboratory specimens as well as on biaxially loaded cruciform specimens and large piping components. Within this contribution the experimental programme of VOCALIST is introduced. The investigated materials are characterized in terms of their mechanical properties. Special consideration is given to results of fracture mechanics specimens highlighting the constraint effect via the shallow crack effect and its contribution to a shift of the master curve.

EC FP7 Structural Performance of MULTI-METAL Component: Project Overview

2013 ◽  
Author(s):  
Paivi Karjalainen-Roikonen ◽  
Elisabeth Keim ◽  
Philippe Gilles ◽  
Sébastien Blasset
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Good Practice ◽  
Research Centre ◽  
Resistance Testing ◽  
Joint Research ◽  
Text Book ◽  
Integrity Assessment ◽  
Dissimilar Metal

The purpose of this paper is to introduce a new EUROATOM project focusing on the structural integrity assessment of dissimilar metal weld. The project started in February 2012 and will last 3 years. The project is coordinated by VTT with 10 partner organizations from Europe: Technical Research Centre of Finland, Finland (VTT) - Coordinator AREVA NP, France and Germany (ANP) Commissariat à l’Énergie Atomique et aux energies alternatives, France (CEA) Joint Research Centre of the European Commission, Belgium (JRC) EdF-Energy, United Kingdom (BE) Bay Zoltán Foundation for Applied Research, Hungary (BZF) Electricité de France, France (EDF) TECNATOM, Spain (TEC) Jožef Stefan Institute, Slovenia (JSI) Studsvik Nuclear AB, Sweden (STU). Within MULTIMETAL, the main objectives are: - Develop a codification for fracture resistance testing in multi-metal specimens. - Develop harmonized procedures for dissimilar metal welds integrity assessment. The underlying aim of the project is to provide recommendations for a good practice approach for the integrity assessment (especially testing) of dissimilar metal welds as part of overall integrity analyses including leak-before-break (LBB) procedures. The project will promote the development of a common understanding for structural integrity assessment of dissimilar metal welds (DMWs) in existing and future nuclear power plants (NPPs) in EU member states. It will provide the technical basis for the development of harmonized European codification for multi-metal components, which is currently non-existing. A trainee program will be finally developed and text book as well as learning materials will be issued. The project will interact with the European Network of Excellence NULIFE and NUGENIA.

EFFICIENT COST MANAGEMENT AS AN IMPORTANT FACTOR OF INCREASING THE COMPETITIVENESS OF THE ECONOMIC SUBJECT

2020 ◽  
Keyword(s):  
Management System ◽  
Structural Model ◽  
Driving Forces ◽  
Cost Management ◽  
Management Accounting ◽  
Practical Significance ◽  
Research Centre ◽  
Experimental Investigations ◽  
Sources Of Information ◽  
Interactive Approach

The research is actual, has a theoretical and applied nature. Theoretical developments at cost management branch of economic organization were illustrated by practical examples. In the work the follow methods are used: abstract-logical, methods of induction and deduction, system and situate approaches, methods of comparative analysis, analysis of breakeven, monographic analysis. The follow sources of information were used: literature, the results of the experimental investigations, carried out in Verkh-nevolzhsky Federal Agrarian Research Centre, observations, carried out at an agricultural organization. Theoretical structural model of cost management was created in a functional way, relationship between elements were designated in it, as well as driving forces of its realization were determined. Such terms as “cost management ” and «management accounting» were specified. The paradigm of a relation to cost process was described. Approaches to realization of cost management system of organization on the basis offlexibility principle were developed. The most important of them are: application of applied programs packages and special program means for computer, organization of feedback, account of functional relationship of cost with production results, cost accounting on elements, places of origin, carriers and centers of responsibility, as well as interactive approach. Some examples which show possibilities of using some instruments of cost management and management accounting for generation of management solutions were described. These instruments are: analysis and planning on the basis of standards of constant and variable costs and flexible cost management in interrelations to other subsystems in management system of organization (in this case it is with technology management. The work is of theoretical and practical significance.

scholarly journals Experimental and Numerical Studies on the Structural Performance of a Double Composite Wall

2021 ◽  
Vol 11 (2) ◽  
pp. 506
Author(s):  
Sun-Jin Han ◽  
Inwook Heo ◽  
Jae-Hyun Kim ◽  
Kang Su Kim ◽  
Young-Hun Oh
Keyword(s):  
Shear Strength ◽  
Precast Concrete ◽  
Structural Performance ◽  
Behavioral Characteristics ◽  
Element Analysis ◽  
Numerical Studies ◽  
Shear Performance ◽  
Flexural Analysis ◽  
Composite Wall ◽  
Current Code

In this study, experiments and numerical analyses were carried out to examine the flexural and shear performance of a double composite wall (DCW) manufactured using a precast concrete (PC) method. One flexural specimen and three shear specimens were fabricated, and the effect of the bolts used for the assembly of the PC panels on the shear strength of the DCW was investigated. The failure mode, flexural and shear behavior, and composite behavior of the PC panel and cast-in-place (CIP) concrete were analyzed in detail, and the behavioral characteristics of the DCW were clearly identified by comparing the results of tests with those obtained from a non-linear flexural analysis and finite element analysis. Based on the test and analysis results, this study proposed a practical equation for reasonably estimating the shear strength of a DCW section composed of PC, CIP concrete, and bolts utilizing the current code equations.

scholarly journals Mechanical Integrity Assessment of Two-Side Etched Type Printed Circuit Heat Exchanger with Additional Elliptical Channel

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4711
Author(s):  
Armanto P. Simanjuntak ◽  
Jae-Young Lee
Keyword(s):  
Heat Exchanger ◽  
Stress Intensity ◽  
Maximum Stress ◽  
High Stress ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Printed Circuit ◽  
Mechanical Integrity ◽  
Finite Element Analysis Simulation ◽  
Maximum Stress Intensity

Printed circuit heat exchangers (PCHEs) are often subject to high pressure and temperature difference between the hot and cold channels which may cause a mechanical integrity problem. A conventional plate heat exchanger where the channel geometries are semi-circular and etched at one side of the stacked plate is a common design in the market. However, the sharp edge tip channel may cause high stress intensity. Double-faced type PCHE appears with the promising ability to reduce the stress intensity and stress concentration factor. Finite element analysis simulation has been conducted to observe the mechanical integrity of double-etched printed circuit heat exchanger design. The application of an additional ellipse upper channel helps the stress intensity decrease in the proposed PCHE channel. Five different cases were simulated in this study. The simulation shows that the stress intensity was reduced up to 24% with the increase in additional elliptical channel radius. Besides that, the horizontal offset channels configuration was also investigated in this study. Simulation results show that the maximum stress intensity of 2.5 mm offset configuration is 9% lower compared to the maximum stress intensity of 0 mm offset. This work proposed an additional elliptical upper channel with a 2.5 mm offset configuration as an optimum design.

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