Validation of Constraint Based Methodology in Structural Integrity: VOCALIST — Analytical Programme

2003 ◽  
Author(s):  
Elisabeth Keim ◽  
Michael Ludwig ◽  
Richard Bass ◽  
Wallace McAfee ◽  
Sean Yin ◽  
...  
Keyword(s):  
Large Scale ◽  
Structural Integrity ◽  
Structural Features ◽  
Experimental Program ◽  
Safety Margins ◽  
Standard Specimens ◽  
First Results ◽  
Materials Used ◽  
Constraint Effects ◽  
Large Scale Tests

The aim of the European Community (EC) project 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-based safety margins in ageing nuclear pressure boundary components. An iterative process of experiment and analysis will address this overall objective. The analytical investigations within VOCALIST cover all three ferritic materials used in the experimental program. Two of the three materials are investigated in the ductile to brittle transition regime and the third material will be tested in the ductile regime. The main effort is to predict the results of the large-scale tests in terms of constraint effects. All participants use constraint based methods, which as a first step are calibrated to the behaviour of standard specimens and then applied to the structural features and (or) large scale tests of each material. In this contribution the progress since last year of the analytical program of VOCALIST will be reported. The analyses of the specimens and components under investigation are highlighted with respect to modelling aspects and the first results are presented.

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

2002 ◽  
Author(s):  
Elisabeth Keim ◽  
Richard Bass ◽  
Wallace McAfee ◽  
Surender Bhandari ◽  
Philippe Gilles ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Large Scale ◽  
Structural Integrity ◽  
Weibull Model ◽  
Experimental Program ◽  
Structural Behaviour ◽  
Local Approach ◽  
Safety Margins ◽  
Materials Used ◽  
Large Scale Tests

The aim of the EC project 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-based safety margins in ageing nuclear pressure boundary components. An iterative process of experiment and analysis will address this overall objective. The analytical investigations within VOCALIST cover all three ferritic materials used in the experimental program. Two of the three materials are investigated in the brittle to transition regime and the third material will be tested in the ductile regime. The main effort is to predict the results of the large-scale tests in terms of constraint effects. All participants use constraint based methods, which are in a first step calibrated to the behaviour of well-known specimens and then applied to the features or the large scale tests of each material. ORNL has developed a very promising method for the prediction of cleavage fracture using the local approach based on a three-parameter Weibull model. This model has been successfully used to predict the biaxial effects on fracture toughness during the HSST program. It could be further developed and used to predict the structural behaviour of a component containing a shallow flaw and loaded biaxially by using the results of standard fracture toughness specimen with deep notches and loaded uniaxially. In this contribution the first steps of the analytical program of VOCALIST are introduced. The specimens and components under investigation are highlighted with respect to modelling aspects and the first results are presented.

Application of a Weibull Stress Model to Predict the Failure of Surface and Embedded Cracks in Large Scale Beams Made of Clad and Unclad RPV Steel

2004 ◽  
Author(s):  
Shengjun Yin ◽  
Richard Bass ◽  
Paul Williams ◽  
Michael Ludwig ◽  
Elisabeth Keim
Keyword(s):  
Crack Front ◽  
Large Scale ◽  
Local Approach ◽  
Rpv Steel ◽  
Failure Scenario ◽  
Constraint Effects ◽  
The One ◽  
Stress Models ◽  
Large Scale Tests ◽  
Weibull Stress

Within the European Network NESC, the project NESC IV deals with constraint effects of cracks in large scale beam specimens, loaded by uni- or biaxial bending moments and containing surface or embedded cracks. The specimens are fabricated from original US RPV material, being cladded or cladding is removed. All large scale tests have been conducted at ORNL outside the NESC IV project. The outcome and the analyses of these uncladded and cladded beams containing the surface or embedded cracks are shown. By means of the finite element method, local approach methods and the Weibull stress models the specimens are analysed at the test temperatures and the probability of failure is calculated, taking into account constraint effects. For the case of the embedded cracks it turned out that the failure moment of the uncladded beam is 5% lower than the one of the cladded beam. Both crack fronts of the embedded crack are supposed to fail at the same failure moment. The results of the analysis of the cladded beam showed that the upper crack front nearer to the surface fails prior to the lower crack front, which is located deeper in the specimen (the failure moment is 5% lower). The numerical results agree very well with the experiments. The experimental failure moments could be well predicted and the failure scenario (which crack front fails first) could be determined. A theoretical shift in the transition temperature T0 due to constraint effects could be defined for both crack fronts.

Targeting Problems of Composite Failure

2009 ◽  
Vol 417-418 ◽  
pp. 37-40 ◽  
Author(s):  
Peter W.R. Beaumont
Keyword(s):  
Life Expectancy ◽  
Stress Corrosion Cracking ◽  
Large Scale ◽  
Structural Integrity ◽  
Engineering Structures ◽  
Composite Failure ◽  
Long Life ◽  
Catastrophic Fracture ◽  
Materials Used ◽  
Integrity Analysis

Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Fitness considerations for long-life implementation of aerospace composites include understanding phenomena such as fatigue, creep and stress corrosion cracking that affect reliability, life expectancy, and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined; furthermore, SI takes into account service duty.

Structural Integrity Assessment of Doel 3 and Tihange 2 RPVs Linear Elastic and Elastic-Plastic X-FEM Calculations Performed for Large Scale Tests

2016 ◽  
Author(s):  
Valéry Lacroix ◽  
Pierre Dulieu
Keyword(s):  
Large Scale ◽  
Structural Integrity ◽  
Load Capacity ◽  
Pressure Vessels ◽  
Integrity Assessment ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Nuclear Control ◽  
Large Scale Tests ◽  
Reactor Pressure

In the framework of the hydrogen flakes issue concerning the reactor pressure vessels of the two Belgian NPP’s Doel 3 and Tihange 2, the Federal Agency of Nuclear Control required to perform tests on large scale specimens taken from a block representative of the pressure vessels with the double objective of validating the structural integrity approach and of verifying the load capacity of the specimens affected by flakes. The large scale tests were led on many kinds of specimens: 4 points bending specimens, CT specimens and tensile specimens containing hydrogen flakes or flawed with EDM notches. All of these tests have been simulated using extend finite element method (XFEM). The paper describes the linear elastic and elastic-plastic fracture mechanics calculations performed in the frame of these large scale tests using XFEM and presents the comparison between simulations and experiments. A focus is done on the XFEM capabilities to model 3D complex shaped flaws like hydrogen flakes.

European Project ATLAS+: Status of the WP1 Relative to the Experimental Program on Pipes and Specimens

2020 ◽  
Author(s):  
Dominique Moinereau ◽  
Tomas Nicak ◽  
Anna Dahl
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Large Scale ◽  
Structural Integrity ◽  
Assessment Tools ◽  
Ductile Material ◽  
Experimental Program ◽  
Small Scale ◽  
Integrity Assessment ◽  
European Project

Abstract The 4-year European project ATLAS+ (Advanced Structural Integrity Assessment Tools for Safe long Term Operation) was launched in June 2017. One of its objectives is to study the transferability of ductile material properties from small scale specimens to large scale components and validate some advanced tools for structural integrity assessment. The study of properties transferability is based on a wide experimental program — within the framework of work-package 1 (WP 1) — which includes a full set of fracture experiments conducted on conventional fracture specimens and on large scale components (mainly pipes). Three materials are considered in the program: a low-alloy ferritic steel 15NiCuMoNb5 (WB36) typical from feedwater line in German PWR, an aged austenitic stainless steel weld typical (narrow gap) from EPR and a typical VVER austenitic stainless steel dissimilar weld (DMW). Several European organizations are involved in the experimental work: EDF, CEA, Framatome, ARMINES, KIWA, Framatome GmbH, VTT, BZN, MTA-EK, and CIEMAT.

scholarly journals Structural integrity of engineering composite materials: a cracking good yarn

2016 ◽  
Vol 374 (2071) ◽  
pp. 20160057 ◽  
Author(s):  
Peter W. R. Beaumont ◽  
Costas Soutis
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Large Scale ◽  
Structural Integrity ◽  
High Efficiency ◽  
Human Life ◽  
Engineering Structures ◽  
Catastrophic Fracture ◽  
Materials Used ◽  
Integrity Analysis

Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Where human life depends upon engineering ingenuity, the burden of testing to prove a ‘fracture safe design’ is immense. Fitness considerations for long-life implementation of large composite structures include understanding phenomena such as impact, fatigue, creep and stress corrosion cracking that affect reliability, life expectancy and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined, and takes service duty into account. However, there are conflicting aims in the complete design process of designing simultaneously for high efficiency and safety assurance throughout an economically viable lifetime with an acceptable level of risk. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.

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.

Large-Scale Model Investigation for Monopile Decommissioning of Offshore Wind Turbines: Overpressure and Vibratory Pile

2021 ◽  
Author(s):  
Nils Hinzmann ◽  
Patrick Lehn ◽  
Jörg Gattermann
Keyword(s):  
Large Scale ◽  
Planning Process ◽  
Complete Removal ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbines ◽  
Large Scale Model ◽  
First Results ◽  
Set Up ◽  
Large Scale Tests

Abstract As of now, only a small number of offshore foundations, related to offshore wind energy, were decommissioned in Europe. With a diameter up to nine meter, an embedment of about 40 meter and a set up effect over 25 years, the necessary force to pull the pile out of the seabed can be assumed, if at all determinable, to be enormous. The piles that were decommissioned were cut beneath the mud line, which leaves approximately one third of the foundation permanently in the seabed. Different methods and techniques for a complete removal of offshore pile foundation are currently investigated within the project DeCoMP. Vibratory extraction aims for a reduction of the pile skin friction by creating a layer of less density between the pile shaft and pending soil. During the design and planning process for vibratory installation or extraction a drivability prediction is a key element. In order to identify and characterize soil parameter for the numerical simulation of a drivability prediction, large-scale tests are performed by the Institute of Geomechanics and Geotechnics of the Technische Universität Braunschweig (IGG-TUBS) [1]. In this paper first results of pilot tests with two vibrators are presented and key elements such as crane uplift, frequency and acceleration displayed.

Materials for the history of the gospel-Baptist movement in Ukraine

1996 ◽  
pp. 4-15
Author(s):  
S. Golovaschenko ◽  
Petro Kosuha
Keyword(s):  
Large Scale ◽  
Religious Studies ◽  
Theological Seminary ◽  
National Academy Of Sciences ◽  
Evangelical Christians ◽  
Evangelical Christian ◽  
First Results ◽  
History Of ◽  
Fruitful Cooperation ◽  
Academy Of Sciences

The report is based on the first results of the study "The History of the Evangelical Christians-Baptists in Ukraine", carried out in 1994-1996 by the joint efforts of the Department of Religious Studies at the Institute of Philosophy of the National Academy of Sciences of Ukraine and the Odessa Theological Seminary of Evangelical Christian Baptists. A large-scale description and research of archival sources on the history of evangelical movements in our country gave the first experience of fruitful cooperation between secular and church researchers.

Accelerated Discovery of High-Refractive-Index Polyimides via First-Principles Molecular Modeling, Virtual High-Throughput Screening, and Data Mining

2019 ◽  
Author(s):  
Mohammad Atif Faiz Afzal ◽  
Mojtaba Haghighatlari ◽  
Sai Prasad Ganesh ◽  
Chong Cheng ◽  
Johannes Hachmann
Keyword(s):  
Data Mining ◽  
Refractive Index ◽  
High Throughput ◽  
First Principles ◽  
High Throughput Screening ◽  
Large Scale ◽  
Computational Study ◽  
High Refractive Index ◽  
Structural Features ◽  
Learning Program

<div>We present a high-throughput computational study to identify novel polyimides (PIs) with exceptional refractive index (RI) values for use as optic or optoelectronic materials. Our study utilizes an RI prediction protocol based on a combination of first-principles and data modeling developed in previous work, which we employ on a large-scale PI candidate library generated with the ChemLG code. We deploy the virtual screening software ChemHTPS to automate the assessment of this extensive pool of PI structures in order to determine the performance potential of each candidate. This rapid and efficient approach yields a number of highly promising leads compounds. Using the data mining and machine learning program package ChemML, we analyze the top candidates with respect to prevalent structural features and feature combinations that distinguish them from less promising ones. In particular, we explore the utility of various strategies that introduce highly polarizable moieties into the PI backbone to increase its RI yield. The derived insights provide a foundation for rational and targeted design that goes beyond traditional trial-and-error searches.</div>

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