bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further Improvements to ASME Section XI Code Case N-806 in a Proposed Second Revision
Authors: McGill Robert O. , Antaki George A. , Moenssens Mark A. , Scarth Douglas A. 
Published: November 2019

Abstract
ASME Section XI Code Case N-806, for evaluation of metal loss in Class 2 and 3 metallic piping buried in a backfilled trench, was first published in 2012. This Code Case has been prepared by the ASME Section XI Task Group on Evaluation Procedures for Degraded Buried Pipe. The Code Case addresses the nuclear industry need for evaluation procedures and acceptance criteria for the disposition of metal loss that is discovered during the inspection of metallic piping buried in a back-filled trench. In a second revision of the Code Case, several changes are proposed. First, guidance is provided for analytical evaluation of greater detail including finite element analysis methods. A new nonmandatory appendix is included to provide procedures for the evaluation of soil and surcharge loads using finite element analysis. Next, a second new nonmandatory appendix is provided giving detailed guidance on the evaluation of seismic loads. Finally, the need to evaluate the fatigue life of buried piping subjected to cyclic surface loading is now included and a design factor applied to the modulus of soil reaction is introduced. This paper presents details of the proposed changes to Code Case N-806-1 and their technical basis where applicable.
Large-Scale Parallel Thermal Elastic-Plastic Welding Simulation Using Balancing Domain Decomposition Method
Authors: Yusa Yasunori , Murakami Yuma , Okada Hiroshi 
Published: November 2019

Abstract
From the mechanical point of view, welding processes can be modeled as a coupling problem between heat conduction and thermal elastic–plastic problems. Such a welding mechanics problem generally requires a large amount of computational time due to its nonlinearity as well as a lot of time steps with a moving heat source. To overcome this difficulty, we are developing a large-scale welding simulator based on the domain decomposition method, which is one of parallel finite element methods. In the present paper, the methodology of the domain decomposition method that is applied to welding analysis is presented, followed by the algorithm. Then, a bead-on-plate problem, which is a popular benchmark problem in the field of computational welding mechanics, was analyzed by the simulator. The bead-on-plate problem was successfully analyzed within very small numbers of iteration steps of the Newton–Raphson and conjugate gradient methods.
Temperature Profile and its Effect on Hardness Numbers of a Mild Steel Butt Weld
Authors: Ma Qin 
Published: November 2019

Abstract
Fusion welding of steel joints is common through history of industrial applications. Among those, Shielded Metal Arc Welding (SMAW) and Gas Tungsten Arc Welding (GTAW) are most common. Fusion welding process comprises of rapid heating and cooling cycles. Each cycle produces a non-uniform and transient temperature distribution and causes rapid thermal expansion followed by thermal contraction. Thus plastic deformation and thermal residual stresses can be induced in a welded joint when it cools down gradually to room temperature. In this study, temperature profiles of a hand-weld mild steel butt weld are analyzed by means of the finite element method (FEM) through ANSYS Mechanical APDL The moving heat source is simulated using the Gaussian distribution heat source model. A parametric study was then performed to evaluate the importance of certain key process parameters that affect the quality of a weldment. The effects of temperature profile on hardness numbers inside and away from the heat affected zone (HAZ) are discussed. It was found that the residual stress results obtained from the simulation agree with the distribution of hardness numbers tested on the weldment sample.
Forensic Estimation of Uplift of an Anchored Tank During the 2011 Earthquake Off the Pacific Coast of Tohoku
Authors: Yoshida Yuichi , Taniguchi Tomoyo , Nakashima Teruhiro , Hatayama Ken 
Published: November 2019

Abstract
The reconnaissance just after the 2011 earthquake off the Pacific coast of Tohoku reported the pulling out of anchor bolts of an upright cylindrical tank. Regarding the tank as an unanchored tank and employing the accelerogram recorded at 2 km off the tank, uplift of the unanchored tank during the 2011 earthquake off the Pacific coast of Tohoku was forensically examined. The time history of the uplift displacement of the tank computed by the explicit finite element analysis reveals that the unanchored tank uplifts during the earthquake and its uplift displacement is more than the length of the pulling out of the anchor bolts found by the reconnaissance. This implicitly corroborates applicability of the explicit finite element analysis to analyzing the tank rocking behavior. In addition to that, the uplift displacement of the unanchored tank was estimated by some calculation methods available to date and compared with that computed by the explicit finite element analysis. Comparison reveals that the calculation methods used herein may likely overestimate the uplift displacement of the unanchored tank and need to improve their calculation accuracy.
A Method to Estimate Cross-Sectional Stress Distributions on Reinforced Nozzle Corners Under Internal Pressure
Authors: Oh Chang-Sik , Song Tae-Kwang , Lee Sang-Min 
Published: November 2019

Abstract
Stress distribution through the nozzle corner cross-section may be required to calculate stress intensity factor (SIF) for a nozzle corner crack in accordance with ASME Section XI Nonmandatory Appendix G. This paper proposes a simple method to predict nozzle corner cross-section stress distributions on reinforced nozzle corners of pressure vessels under internal pressure. This method includes simplified equations for predicting stresses on the inner surfaces of the nozzle corner region. These equations are expressed in terms of stress concentration factor (SCF) and geometric variables. Approximate SCF solutions for the reinforced nozzle corners are also proposed. Stress distributions using the proposed method are compared with finite element (FE) analysis results of nozzle-vessel intersections of various geometric dimensions, and agreements are quite good within postulated crack depths. Furthermore, SIFs calculated from the estimated stress distributions in accordance with ASME Section XI Nonmandatory Appendix G are compared with those from the FE results, showing good agreement.
The Effects of Crack Growth History on Fracture Toughness
Authors: Probert M. A. , Coules H. E. , Truman C. E. , Hofmann M. 
Published: November 2019

Abstract
The introduction of cracks into loaded versus unloaded components has a significant effect on the apparent fracture toughness within finite element modelling. The history effects of crack introduction can be beneficial to defect assessment procedures that do not consider prior plasticity specifically from crack introduction. It is assumed that as strain energy is released due to plastic deformation during crack formation a reduction in the energy available for crack propagation under fracture conditions is experienced. This can be characterized by the formation of a plastic wake behind the crack tip and leads to significant increases in load at critical J and other crack growth parameters for modelling situations. However experimental evidence validating this apparent fracture toughness increase are needed. A beneficial increase in apparent fracture toughness can prolong the life of components that might be taken out of service prematurely if history effects are not considered.
This paper discusses a series of experimental and modelling approaches that have been taken to assess the magnitude of the benefit in increase of apparent fracture toughness by the manipulation of crack introduction history effects. An initial parametric study of material properties on the effect of introducing cracks into loaded and unloaded components indicates that most benefit be derived from high hardness, high yield materials such as Aluminum 7000 series alloys. Further work has been carried out with experimental C(T) specimens of Aluminum Alloy 7475 T7351. Cracks were introduced by fatigue into the samples. One set of specimens was fatigued with a low mean load and the other with a high mean load, this was achieved by keeping a consistent ΔKI between specimens and changing the load ratio one set of specimens. Fracture test results indicate that the influence of prior plasticity on fracture initiation is much subtler in experimental trials than in the finite element model. Crack growth resistance curves and neutron diffraction results measuring the residual stress created ahead of the crack tip by this method are be discussed and contrasted with the parametric study and finite element modelling of the two different crack introduction scenarios.
Sliding Response of Unanchored Steel Storage Tanks Subjected to Seismic Loading
Authors: Kalemi Bledar , Farhan Muhammad , Corritore Daniele 
Published: November 2019

Abstract
Steel storage tanks are critical components of an industrial installation due to their high seismic vulnerability and containment of hazardous materials. Failure of a which, may lead to loss of containment (LOC) triggering domino effects such as explosion, environmental pollution, loss of functionality and disruption of business. Past earthquakes have demonstrated different type of failure modes in steel storage tanks. Although there are plenty of studies related to different failure modes like elephant foot buckling or tank uplifting, there are very few efforts on the sliding behavior of tank. Large displacements caused by the tank sliding can lead to pipe detachment and release of hazardous material which might cause damage propagation. Consequently, this damage state is very important for the Quantitative Seismic Risk Assessment of industrial plants.
In order to enumerate the sliding displacement of unanchored steel storage tanks, a simplified numerical model realized with OpenSees platform is proposed. The friction model used in OpenSees is calibrated with the results obtained from ABAQUS FE model. Sliding response of tanks with different D/H ratio is analyzed using the simplified model. Fragility curves for the tank sliding damage state are analytically evaluated for different D/H ratio of the tank using the “cloud method”. Finally, a parametric study is conducted in order to comprehend the influence of different parameters on the sliding behavior such as friction coefficient, tank filling level and the influence of the vertical component of ground motions.
The Effects of Non-Proportional Biaxial Loading Paths on Ductile Fracture Initiation: A Void Growth Analysis
Authors: Jin Zhaoyu , Wang Xin 
Published: November 2019

Abstract
The effects of non-proportional biaxial loading paths on ductile fracture initiation toughness are studied in this paper. To this end, the growth of a cylindrical void (hole) located in front of a mode I plane strain crack has been studied using large deformation finite element analysis (FEA). A specific microstructural feature of a steel alloy was thoroughly studied by having a single void positioned at a fixed distance from the crack tip and void that was equal to 10 times the diameter of the void. In particular, the non-proportional biaxial loading path effects on the crack tip blunting, void-growth, ligament reduction and near-tip stress fields are investigated computationally. Under small-scale yielding conditions, one proportional loading and two non-proportional loading paths are applied to the modified boundary layer (MBL) model. It is observed that the non-proportional load paths have a marked effect on the void growth, crack tip blunting and their interaction. By applying the criteria for the coalescence of the crack tip and void, the ductile fracture initiation toughness is estimated. It is shown that the ductile fracture toughness is dependent on loading paths, and the T-stress ratios. Results from this study are of relevance to ductile fracture assessment of components or pressure vessels that operate under non-proportional biaxial loading conditions.
Effect of Pre-Weld Heat Treatment on Microstructure and Creep Strength of ICHAZ in Grade 91 Steel
Authors: Wang Yiyu , Zhang Wei , Feng Zhili 
Published: November 2019

Abstract
In this work, Grade 91 base metal was normalized with two different cooling conditions, water quenching and air cooling. The intercritical welding thermal cycle simulated by using the Gleeble system was applied to the heat-treated base metals to reproduce the intercritical heat-affected zone (ICHAZ). Microstructure, including precipitate and tempered martensite, of the base metal and ICHAZ was carefully characterized with advanced microscopy techniques. Creep strength of the simulated ICHAZs was evaluated at a high creep temperature of 650 °C with a stress of 100 MPa. A correlation between the microstructure and creep behavior of the ICHAZ is built to understand creep rupture mechanisms in the ICHAZ. The results show that more coarse carbides precipitated along the prior austenite grain boundaries after tempering in the water-quenched base metal. These carbides cannot be fully dissolved by the intercritical welding thermal cycle. The simulated ICHAZ generated from the water-quenched base metal underwent a higher grain recovery and growth during the typical post-weld heat treatment at 760 °C. Both simulated ICHAZs from two pre-weld heat treated base metals exhibit an extremely low creep resistance with a typical ductile fracture during creep testing. The faster grain growth and precipitate coarsening in the ICHAZ, simulated from the water-quenched base metal, made it even worse.
Pitch and Pattern Effects on Streamwise Fluidelastic Instability in Tube Arrays
Authors: Hassan Marwan , Weaver David 
Published: November 2019

Abstract
Fluidelastic instability (FEI) is well known to be a critical flow-induced vibration concern for the integrity of the tubes in nuclear steam generators. Traditionally, this has been assumed to occur in the direction transverse to the direction of flow but the tube failures at San Onofre Nuclear Generating Station (SONGS) in Los Angeles proved that this assumption is not generally valid. A simple tube-in-channel theoretical model was previously developed to predict streamwise as well as transverse FEI in a parallel triangular tube array. This predicted that this array geometry was particularly sensitive to streamwise FEI for high mass-damping parameters and small pitch ratios, the conditions in which the SONGS failures occurred. The advantage of this simple modelling approach is that no new empirical data are required for parametric studies of the effects of tube pattern and pitch ratio on FEI. The tube-in-channel model has been extended to in-line square, normal triangular and rotated square tube arrays and the stability of these geometric patterns are analyzed for the effects of varying pitch ratio and the mass-damping parameter. The results are compared with the available experimental data and conclusions are drawn regarding the relative vulnerability of these different tube array geometries to streamwise FEI.
A Development of the Technical Basis for the New Code Case “Mitigation of PWSCC and CISCC in ASME Section III Components by the Advanced Surface Stress Improvement Technology”
Authors: Cho S. W. , Yi W. G. , Mohr N. , Amanov A. , Stover C. , Tatman J. , Vasudevan V. , Kim Y. S. , Pyun Y. S. , Naralasetty H. , Kim K. T. 
Published: November 2019

Abstract
It is necessary for nuclear power plant operation and spent fuel canisters to provide a sound technical basis for the safety and security of long-term operation and storage respectively. A new code case for mitigation of Primary Water Stress Corrosion Cracking (PWSCC) and Chloride Induced Stress Corrosion Cracking (CISCC) in Section III components by using an advanced surface stress improvement technology (ASSIT) is being developed by Task Group ASSIT which is one of the task groups under the ASME (The American Society of Mechanical Engineers). The necessary technical reports supporting this code case are being developed as part of joint research projects conducted by Doosan Heavy Industries and Construction (DOOSAN), Electric Power Research Institute (EPRI) and Sun Moon University (SMU). A well-known approach to prevent PWSCC and CISCC are to be performed using materials resistant to PWSCC and CISCC. The objective is to eliminate residual tensile stresses, or to induce compressive residual stress using ASSIT methods such as laser peening, water jet/cavitation peening, ultrasonic peening and ultrasonic nanocrystal surface modification (UNSM). Performance and measurement criteria for mitigation of PWSCC by ASSIT will be established based on the magnitude of surface stress and depth of compressive residual stress, sustainability, inspectability and lack of adverse effects. Additionally, for mitigation of CISCC by ASSIT, the evaluation of chloride induced corrosion pitting, the depth and density of corrosion pits and stress corrosion crack initiation and growth under chloride salt chemistry conditions are also being examined. This paper explains the approach, and progress of testing and analysis. The results and details from testing and analysis will be presented in a future PVP paper upon completion.
RCC-M Code: Recent Evolutions and Perspectives
Authors: Triay Manuela , Meister Eric , Lefever Benoît , Puybouffat Sylvain , Quéré Julien , Chantelat Emmanuel , Muller David , Cadith Julien , Marie Stéphane , de Mathan Nicolas 
Published: November 2019

Abstract
This paper covers the general approach followed by AFCEN, the French Society for Design, Construction and In-Service Inspection Rules for Nuclear Island Components in updating the nuclear code RCC-M, from the technical and organizational points of view. The main evolutions introduced in recent editions of RCC-M code are presented and commented on, with a focus on the 2018 edition of the code, which marks the end of the 3-year program carried out to demonstrate the conformity with European essential safety requirements for pressure equipment and French requirements for nuclear pressure equipment.
In addition, the main on-going activities are presented, as well as the future activities of the RCC-M subcommittee, in the frame of the 4-year editorial program that has been launched in 2019, in line with the AFCEN 4-year strategic plan. They encompass all fields covered by the code: design and analysis rules, material procurement, fabrication and nondestructive testing. The paper highlights how the industrial experience is integrated into the RCC-M code, and also how the new projects needs are taken into account.
Study on Added Mass Coefficient and Coupling Effect of Concentric Tube Bundles
Authors: Zhang Zhenshu , Guo Kai , Zhang Tianbao , Tan Wei 
Published: November 2019

Abstract
The added mass coefficient is an important parameter when calculating the flow induced vibration (FIV) in heat exchangers. The calculation method of the added mass coefficient for tube bundles in triangular and square arrays had been presented in relevant standards which like GB/T 151. Presently, concentric arrays of tube bundles are applied extensively in the heat exchangers at nuclear power plants. However, the method for calculating the added mass coefficient of tube bundles in concentric arrays has not been given in these standards. In this paper, in order to calculate the added mass coefficient of a central flexible tube surrounded by rigid tubes in concentric arrays, the fluid-structure interaction models of tube bundles has been established by ANSYS CFX. The influence of the circumferential and radial distance of the tube bundles on the added mass coefficient has been studied by calculating the natural frequency. The results are expected to provide the calculation reference for added mass coefficient of the tube bundles in concentric arrays. The coupling vibration of tube bundles in concentric arrays has been studied by the other model which is made up of all the flexible tubes, and the coupling vibration of the tube bundles is simulated by the rigid wall motion of ANSYS CFX. According to simulation results, there exists a band of amplitude peaks in the coupling vibration of the tube bundles. It is shown that as the circumferential and radial distance increases, the band of amplitude peaks becomes narrow.
Ratcheting Behaviour of 3D Printed and Conventionally Produced SS316L Material
Authors: Halama Radim , Pagáč Marek , Paška Zbyněk , Pavlíček Pavel , Chen Xu 
Published: November 2019

Abstract
This paper shows some differences in stress-strain behavior of conventional and 3D print SS316L. First, the influence of strain rate on the monotonic curve has been investigated. Specimens produced by Selective Laser Melting technology were not so sensitive to the strain rate. Viscoplasticity has to be taken into account for cyclic loading modelling in the case of conventionally produced SS316L but not for the 3D printed material.
A set of low-cycle fatigue tests was performed on specimens from both used production technologies. Uniaxial ratcheting tests were realized under constant amplitude of stress and varying mean stress. Experimental results show a good ratcheting endurance of SS316L produced by the Selective Laser Melting technology. Biaxial ratcheting tests were realized for 3D print SS316L only. Applied Digital Image Correlation technique makes possible to get more ratcheting curves from each ratcheting test.
European Project ATLAS+: Status of the WP1 Relative to the Experimental Program on Pipes and Specimens
Authors: Le Delliou Patrick , Moinereau Dominique , Bourgeois Myriam , Szavai Szabolcs 
Published: November 2019

Abstract
The 4-year European project ATLAS+ project was launched in June 2017. Its main objective is to develop advanced structural assessment tools to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems.
The transferability of ductile material properties from small scale fracture mechanics specimens to large scale components is one of the topics of the project. A large experimental work is conducted in support to development and validation of advanced tools for structural integrity assessment within the framework of the work-package 1 (WP 1): Design and execution of simulation oriented experiments to validate models at different scales.
The experimental work is based on a full set of fracture mechanics experiments conducted on specimens and large scale components (several pipes and one mock-up), including a full materials characterization. Three materials are considered:
• a ferritic steel 15NiCuMoNb5 (WB 36)
• an aged austenitic stainless steel weld
• a VVER dissimilar metal weld (DMW)
This paper presents the WP 1, the experimental programme and summarizes the first results. A companion paper [1] presents in more details the experimental programme on the ferritic steel.