bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plastic Collapse and Shakedown Analysis of PCHE Core with Channel Misalignment
Authors: Chen Xuanye , Shi Qianyu , Zhang Mingbao , Wang Fei , Liu Peng 
Published: November 2024

Abstract
Printed circuit heat exchanger (PCHE) has gained lots of attention from the academic and engineering fields for their high heat transfer efficiency with a surface-to-volume ratio up to 2500 m2/m3. Meanwhile, the diffusion bonding technique makes the PCHE suitable for high pressure and high temperature conditions. For some applications with high viscosity fluids, such as molten salt, liquid sodium, and liquid lead-bismuth alloys, large cross-section flow channels are often required to meet pressure loss requirements. And for that, two etching plates are often stacked with semi-circular channels face-to-face to get a larger cross-section flow channel, however, this may lead to channel misalignment in the diffusion bonding process due to the stacking accuracy and non-uniform temperature distribution. The channel misalignments will reduce the pressure boundary thickness of PCHE core and improve geometry discontinuity. Therefore, in this paper, a typical circular channel PCHE core with different misalignments is modeled to study its effect on plastic collapse and shakedown failure mode. Elastic-plastic stress analysis and shakedown analysis based on cyclic loadings are conducted considering pressure and temperature field. The results from this study can provide a reference for the design and manufacture of PCHE core in high viscosity fluid applications.
Some Challenges Regarding Qualification of Additive Manufacturing Components for a Nuclear Use – NUCOBAM Project
Authors: Bourgeois Myriam , Petesch Cecile , Verlet Romain , Misler Roxane 
Published: November 2024

Abstract
In the last decade, additive manufacturing (AM) technology has progressed significantly, and thus found its way into a number of industries. AM is particularly interesting for manufacturing components with complex geometries, which if produced via conventional manufacturing methods involve significantly more manufacturing steps and longer lead times for a limited number of pieces. The nuclear industry is no exception and has developed roadmaps that outline key steps that can potentially allow the usage of AM to produce nuclear reactor components. In this context, standardization can appear as a straightforward way to accelerate the qualification of these processes for a nuclear use. It is the overall goal of the project NUCOBAM (Nuclear Components based on Additive Manufacturing) to address the technical challenges associated with the production of reactor components via AM. The finality of the project is to develop a methodology for qualifying components produced via AM that complies with nuclear codes and standards. The AM method and alloy in scope of the project are Laser Powder Bed Fusion (L-PBF) and the stainless steel 316L. This paper presents the NUCOBAM project in more detail, including the challenges it reveals regarding standardization and the perspectives of qualification methodology.
Low Cycle Fatigue of Alloy 690 in the PWR Environment
Authors: Jayaram Kushal Gowda , Huret Joseph , Quibel Jonathan , Chitty Walter-John , Henaff Gilbert 
Published: November 2024

Abstract
Environmentally Assisted Fatigue (EAF) is one of the concerns for the extended operation of nuclear power plants. Over time, certain components experience thermal cycling while being exposed to the chemically active environment of Pressurized Water Reactors (PWRs). While many components in the primary loop are constructed from stainless steel, some critical parts are made from Alloy 690, a nickel-based alloy. Compared to the extensive research on EAF in stainless steels, only a limited focus has been placed so far on Alloy 690.
This study aims to assess the impact of the PWR environment on the fatigue life of Alloy 690. Low cycle fatigue tests were conducted in two different environments, namely air and PWR environments, at different strain amplitudes and strain rates. To investigate the mechanisms of EAF in Alloy 690, fracture surfaces were analyzed. In particular, fatigue crack growth rates as a function of crack depth were derived from striation spacing measurements. Additionally, microstructural changes, as influenced by Dynamic Strain Aging, in the air were examined using Transmission Electron Microscopy (TEM) on the specimens from interrupted tests at different stages of the fatigue life. A twofold ratio was expected according to the design rules, but the results indicate that there is minimal or almost no influence of the environment on the fatigue life of Alloy 690 in PWR conditions when compared to its behavior in an air environment. This observation is consistent with the crack growth rates, which demonstrate a constant growth in both the environments.
Design Margins of Fatigue Life of Carbon Steel Elbows and Tees Subjected to Reversing Dynamic Loads
Authors: Azuma Kisaburo , Fujiwara Keita , Kai Satoru , Otani Akihito , Furuya Osamu 
Published: November 2024

Abstract
Fatigue damage is a type of cumulative damage observed in piping systems. The fatigue damage is caused by various reversing dynamic loads including seismic loads. When the reversing dynamic loads produce plastic strain in each cycle, the loading cycles cause severe damage in the component, and thus the number of cycles to failure is relatively low. This type of failure due to the severe reversing load is called low-cycle fatigue. Past research revealed that some uncertainty is generally inevitable in predicting the number of cycles to low-cycle fatigue. Hence, it is of great importance to understand the mechanism of low-cycle fatigue and to ensure an ample margin in fatigue life evaluation in piping systems.
In this study, a series of shaking-table tests was carried out to study the mechanism of low-cycle fatigue and the design margin of pipe fittings. Three types of specimens were chosen as typical pipe fittings: elbows, equal tees, and reducing tees. All the specimens are made of JIS G3456 STPT370 seamless carbon steel pipe, equivalent to ASTM A106 Grade A. The response amplitudes of acceleration of each specimen were measured under the sinusoidal excitation of uniform frequency. We investigated the relation between input and output accelerations of the observed data, and then discussed the margin of pipe fittings based on the seismic design of nuclear piping systems.
Improved Analysis of Miniature Impact Toughness Tests
Authors: Arffman Pentti 
Published: November 2024

Abstract
A series of miniature impact tests was conducted. The analysis of instrumented impact curves was studied, and explicit procedures were sought to increase the consistency and reproducibility of results, as well as a decrease human influence on the analysis. These procedures are suggested for future considerations.
In order to smoothen noise and oscillations in the force-displacement curve, low-pass filtering of data is considered the most promising alternative. The method results in the most consistent elastic slopes and forces at onset of general yielding Fgy. A suitable cutoff frequency can be found by spectral analysis of the signal since it varies between test setups, but a phase shift in the resulting data needs to be addressed.
In the analysis, different characteristic points are identified on the force-displacement curve. When determining these points, the curve is sectioned into parts. Fitting Hooke’s line in the elastic region follows previously suggested methods. A polynomial of varying degree is fitted to the region following the elastic limit. Points of discontinuity reveal unstable fracture initiation and arrest locations, and a model consisting of linear and exponential terms is fitted to data beyond arrest. Once finalized, the points of interest in the instrumented impact curve are determined in accordance with ASTM and ISO standard guidance by searching the intersections of the fitted curves. Identification of the characteristic points in a consistent manner increases the confidence on material assessment from the data.
Proposed New Guidance for the Design of Fillet Welded Patches
Authors: Kummari Seetha Ramudu , Macejko Brian , Bifano Michael F. P. , Jones J. Ryan 
Published: November 2024

Abstract
Fillet welded lap patches may be applied to pressure vessels and piping that have suffered local wall thinning due to corrosion, erosion, and other damage mechanisms in the oil and gas, and petrochemical industries. This type of repair is considered temporary until there is an opportunity for permanent repair or replacement. The guidance provided in ASME PCC-2 Article 212 is widely used to design the fillet welded patches. The article provides a design procedure for determination of required thickness of the repair patches considering the bending stress due to eccentricity (thickness offset). However, ASME PCC-2 guidance results in significantly higher thickness for the fillet welded patches for most pressure vessels and piping applications, especially when the required thickness of the vessel shell is close to its nominal thickness. In this paper, conservatism associated with ASME PCC-2 guidance is discussed and an alternative, simplified, and less conservative procedure is proposed based on results from a parametric study of different design parameters using ASME Section VIII Division 2 Design By Analysis methodologies. Both two-dimensional (2D), and three-dimensional (3D) elastic-plastic finite element simulations were performed by varying lap patch-to-vessel shell thickness ratio, lap patch angle and length, etc. The differences between the trends from the 2D and 3D simulations is discussed along with a discussion of how the proposed methodology compares with the current ASME PCC-2 guidance.
Multi-Scale Failure Analysis Model for Cryogenic Pressure Vessel Under Combined Thermal Stress and Mechanical Stress
Authors: Cao Zhuangzhuang , Fu Bingjie , Bai Jiangkun , Wang Guoying , Zheng Jinyang , Shi Jianfeng 
Published: November 2024

Abstract
Cryogenic pressure vessels are promising types of containers, garnering significant attention due to their high energy storage density and low evaporative losses. These vessels are engineered with an outer shell, an insulation layer, and an inner vessel which is the fiber fully overwrapped metal liner. The core structural part, the fiber fully overwrapped metal liner, is designed to direct contact with cryogenic fluids, subjecting it to complex thermo-mechanical loads. Consequently, a comprehensive understanding of the thermodynamic responses of the vessels under cryogenic conditions is imperative to ensure their operational safety and reliability. Current analyses of the thermo-mechanical coupling in the liners primarily focus on the macroscopic thermal stresses caused by the mismatch in thermal expansion coefficients between the metal liner and the fiber wound layer, as well as the thermal stress between different fiber wound layers. However, the microscopic thermal stress caused by the difference in thermal expansion coefficients between the fiber and the matrix is not negligible. Therefore, this paper established a multi-scale model based on representative volume elements and conducts a thermo-mechanical coupled analysis of the fiber fully overwrapped metal liner. It predicts the distribution of thermal stresses within the fiber and matrix at various temperatures, as well as the failure pressure of the vessels.
Alternating Stress and Stress Linearization Analysis of Pipe Under High-Frequency Ultrasonics Cleaning Devices
Authors: Eslaminejad Ashkan , Crompton Andrew 
Published: November 2024

Abstract
This research explores ultrasonic vibration waveforms for cleaning nuclear power plant piping, aiming to improve flow dynamics and reduce radiation exposure. Various products using wide-frequency ultrasonic vibrations effectively remove particles from pipe interiors. Guided by American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants, this study monitors pipe vibrations, considering fatigue stress endurance limits and low-frequency bending mode stresses. Leveraging computational tools, particularly finite element analysis, enables precise assessments of piping responses to dynamic loads induced by ultrasonic transducers. Using linearization techniques, our analyses extract both bending and membrane stresses. External applications of ultrasonic transducers can induce high-frequency shell modes, leading to non-linear stress distributions within the pipe’s thickness. This paper advocates for utilizing linearized stress intensity derived from finite element linear dynamics analysis tools as a more conservative estimate of allowable alternating peak stress values, addressing the limitations of relying solely on bending stresses. Our research underscores the efficacy of linearized peak stress in evaluating stress-induced fatigue in high-frequency ultrasonic cleaning applications, contributing to optimizing maintenance practices and ensuring the structural integrity of piping systems in nuclear power plants.
Total Rotational Capacity of Threaded Connections in Pipe-Fitting Assemblies
Authors: Rusnak Cameron R. , Elfass Sherif A. , Rivas Allen J. 
Published: November 2024

Abstract
Fire suppression piping systems play a crucial role in minimizing the impact of unwanted fires. These systems primarily consist of welded or threaded connections at the pipe/fittings interface. Previous research conducted on threaded connections used the rotation at the pipe-fitting interface (about the face of the fitting) in order to calculate their rotational capacity, generating moment versus rotation response curves. While these methods are applicable in calculating the interface-rotational-capacity, the contribution of the fitting rotational capacity (bending of the fitting itself) has not been thoroughly explored.
Recent research conducted by the University of Nevada, Reno (UNR) has sought to address these gaps. The research team at UNR undertook a comprehensive experimental program involving threaded cast iron pipe-fitting assemblies to gain a deeper understanding of their total rotational capacity. This research has led to the development of a new procedure for calculating the total rotational capacity of threaded fittings.
Under UNR’s experimental program, 126 full-scale fitting assemblies were tested. The experiments included three fitting types (elbow, tee, and tee reducers), five (5) fitting sizes (1, 1.5, 2, 3, and 4 inches), and three configurations. All assemblies were filled with water and experiments were conducted at an internal operating water pressure of 140 ±5 psi.
UNR’s procedure goes beyond the conventional method by considering not only the rotation at the pipe-fitting interface (interface-rotational-capacity) but also the bending experienced by the fitting itself. This paper discusses the newly developed approach for evaluating the total-rotational-capacity of threaded assemblies. Given that this approach utilizes geometry to calculate total rotation, its applicability extends to both elastic and elastic-plastic regions providing there is no plastic hinging occurring in the pipe segment between the fitting and the sensor measuring the change in hypotenuse.
The Impact of FEA Modeling Techniques for Level 3 Dent Engineering Critical Assessment: Shell Vs. Solid Elements
Authors: Brust Alex , Xu Luyao , Kemp David 
Published: November 2024

Abstract
Engineering Critical Assessments (ECA) is crucial to evaluating the fitness for service of pipeline dents to comply with regulatory standards such as US CFR 49 part 192.712(c) and Canada CSA Z662 clause 10.10.4. For dents requiring a level 3 assessment, finite element analysis (FEA) is often employed to evaluate complex dent features categorized from in-line inspection (ILI) or direct examination of the pipeline. Various analysis techniques and element types exist within FEA for performing level 3 dent assessments. The appropriate analysis technique and corresponding element types (i.e., shell or solid elements) are often chosen by balancing the dent ECA’s complexity with computational accuracy and time. Shell elements are more computationally efficient than solid elements, however, the through-thickness stress distribution is more accurately captured with solid elements.
If computational time is of little concern, then solid elements are typically employed to obtain an accurate representation of the stress/strain distributions in and around the dent feature for further engineering assessment once FEA is completed. However, the nature of dent ECA rarely affords an assessment schedule with such a flexible time constraints. For instance, when the dent interacts with other complex deformation features such as metal loss, solid elements account for the local metal loss feature to achieve the most accurate results. As such, this study will compare the differences in using shell vs. solid elements for a dent ECA for plain dents using the same idealized indenter. Variations in the stress/strain results along with overall differences in the calculated remaining life of the feature will be assessed as a function of the solver time. The goal of the study is to provide guidance on how and to what extent the element type can affect the overall conclusions of two different element types of dent ECA.
Analytical and Numerical Solutions for the Elastoplastic Buckling Analysis of Shells of Revolution
Authors: Belone Gwladys , Le Grognec Philippe , Assaf Samir , Rohart Philippe 
Published: November 2024

Abstract
The buckling phenomenon is one of the main failure modes encountered in pressure vessels, due to the thin (shell-like) geometry of the structures involved and the predominant compressive stresses frequently observed under standard loads such as external pressure. This paper aims at presenting an analytical and numerical elastoplastic buckling analysis of classical shells of revolution usually encountered in pressure vessels. The purpose is first to provide new efficient (exact or approximate) closed-form solutions for the critical buckling loads of most usual components of pressure vessels under external pressure. Then, a finite element software is developed, which is dedicated to the buckling and post-buckling analysis of such shells, including arc-length and branch-switching methods. The analytical solutions and the numerical model are first validated thanks to finite element computations performed on a commercial software (Abaqus). Then, the numerical tool may provide reference bifurcation results so as to validate further analytical solutions in the idealized case of perfect shells. Finally, this home-made program will enable one to introduce easily both imperfections and (Bloch-)periodic boundary conditions in the model, for achieving parametric analyses of the imperfection sensitivity of the buckling problems in hand in a very efficient way.
Stress Relaxation Cracking (SRC) Susceptibility Comparison in UNS S34709 and UNS S34751 Stainless Steel Welds for Petrochemical Piping Applications
Authors: Pickle Tim , Fuenmayor Jean , Penso Jorge , Yu Zhenzhen 
Published: November 2024

Abstract
UNS S34751 and UNS S34709 austenitic stainless-steel alloys contain thermomechanical properties required for use in chemical processing pipe applications with 900–1200°F (482–665°C) operating temperatures. UNS S34751 alloy has demonstrated improved sensitization resistance compared to UNS S34709, a precursor for polythionic acid stress corrosion cracking (PA-SCC), due to lower carbon (C) content (0.01 wt.%) and higher niobium-to-carbon (Nb/C) ratio with lower overall niobium content. The addition of nitrogen (N) in UNS S34751 alloy provides similar thermomechanical properties compared to UNS 34709. Additionally, stress relaxation cracking (SRC) susceptibility in UNS 34709 welds has been documented thoroughly in literature and industry, which poses a problem for long term service life, while UNS S34751 welds have potential for improved SRC resistance without the need for post weld heat treatment (PWHT). In this paper, a literature review of S34751 is explored, and testing matrix of experimental SRC tests using a Gleeble 3500® thermomechanical simulator is developed for S34751 gas tungsten arc welded (GTAW) pipe samples in comparison to S34709 welds. Additionally, initial thermodynamic and kinetic CALPHAD calculations have been completed to analyze potential detrimental phases in S34751 in comparison to S34709, e.g., z-phase. SRC testing has been mostly completed in S34709 welds made with W34710 (E347-16) and S16880 (E16.8.2-15) weld filler, respectively, and SRC comparisons to S34751 are in progress. Current results show higher resistance to SRC in S34751 HAZ and FZ than S34709 FZ and W34710 FZ at 800°C. In the following year, a full comparative analysis between S34709 and S34751 HAZ and FZ, in addition to welds with alternative filler S16880, is planned, including SRC testing at 600–750°C temperatures, metallurgical characterization of intergranular and intragranular precipitates, and additional thermodynamic analyses to complement microstructural observations. Final conclusions on SRC susceptibility comparisons between S34751 and S34709 welds, including alternative fillers, will be made.
Pressure-Testing and Overpressure Protection Requirements for Section VIII Division 1 and Division 2 Pressure Vessels
Authors: Oland C. Barry , Lower Mark D. 
Published: November 2024

Abstract
Standards for boilers and pressure vessels are published in the Boiler and Pressure Vessels Code (BPVC) by the American Society of Mechanical Engineers (ASME). The intent of the design and fabrication rules specified in Section VIII, Division 1 and Division 2 of the ASME BPVC is to ensure safe and satisfactory performance for pressure vessels during their useful service lives. Design, pressure-testing, and pressure relief stress limits specified in Division 1 and Division 2 are consistent with the principles of limit state design theory, in which materials are assumed to have the minimum yield strength and exhibit an elastic-perfectly plastic stress-strain relationship with no strain hardening. These stress limits also provide a minimum design margin against plastic collapse (ductile rupture) equal to or greater than 1.5, where plastic collapse is the load at which overall structural instability occurs and excessive plastic deformation begins. Allowable stresses based on perfect plasticity and the principles of limit state design theory are considered by ASME to be a floor below which a pressure vessel constructed from any sufficiently ductile material will be safe. The actual yield strength and strain-hardening properties of materials permitted for pressure vessel construction give them an increased margin above this floor.