bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tensile Strain Characteristics of Small-Scale Fracture Toughness Test Specimens Under Loading
Authors: Park Dong-Yeob , Liang Jie , Gianetto James A. , Sakimoto Takahiro , Tajika Hisakazu , Igi Satoshi 
Published: November 2024

Abstract
Pipelines are susceptible to significant longitudinal deformation in areas affected by ground movements, including slope movement, frost heave, thaw settlement and/or erosion. The assessment of tensile strain capacity in girth-welded pipes with circumferential cracks, therefore, is of utmost importance when designing pipelines exposed to these geohazards. However, variations in strain calculation and measurement methods can lead to design inaccuracies due to the uneven strain distribution resulting from the inhomogeneous material properties in the weldment region of the pipe containing a crack. This study examines strain characteristics of small-scale single-edge notched tension (SENT) and single-edge notched bend (SENB) specimens under loading, compared to published data from intermediate-scale curved-wide plate test (CWPT) and full-scale (FS) pipe tests from the same pipe material and nominally identical girth welds. The findings in this study reveal that the stress distribution and responses of the SENT specimens closely resemble those of the CWPT and FS tests, exhibiting asymmetrical strains and asymptotic remote strains. It is important to emphasize that the fracture toughness of pipe/weld materials is influenced by the level of constraint at the crack tip. As a result, SENT tests are being used to evaluate the fracture toughness, due to the similarity in constraint between SENT specimens and FS pipes, rather than strain characteristics. The objective of this study is to enhance the understanding and characterization of strain behavior for a girth-welded pipeline.
Research and Development of Three-Dimensional Isolation System for Sodium Cooled Fast Reactor: Part 7 Development Summary of Three-Dimensional Isolation System
Authors: Watakabe Tomoyoshi , Yamamoto Tomohiko , Okamura Shigeki , Miyazaki Masashi , Miyagawa Takayuki , Uchita Masato , Hirayama Tomoyuki , Somaki Takahiro , Yukawa Masaki , Fukasawa Tsuyoshi , Fujita Satoshi 
Published: November 2024

Abstract
A sodium-cooled fast reactor (SFR) has been developed as one option for energy de-carbonization in 2050 in Japan. The SFR is operated under a high temperature and a low-pressure condition compared with existing light water reactors (LWRs). The mechanical components and piping in the SFR are consequently designed as thin-walled structures from the perspective of the elevated temperature design. In addition, seismic design earthquake level is to be severe more and more by regulatory requirements based on past earthquake disaster experiences. To secure the seismic safety of the thin-walled mechanical components and piping under a severe design earthquake level, employing a three-dimensional (3D) seismic isolation system has been planned in the SFR. The development results of the 3D isolation system have been reported in previous papers so far. Its update is reported in Part 7 to Part 9.
The proposed isolation system consists of a rubber bearing for reducing horizontal seismic load, disc spring units for reducing vertical seismic load, oil dampers for horizontal and vertical damping components, and a support function for assembling each isolation element. Part 7 describes the overview of the R&D, the test plan of the isolation system in the assembled state of each element, and the performance of individual isolation elements. In part 8, the performance of the isolation device that each element was assembled into was investigated through loading tests. Part 9 reports analytical studies by an analysis model validated based on the insight of the test results.
Research on Effects of Surface Finishing and Mean Stress on Fatigue Lives of Notched Specimens - Mean Stress Effect for Notched Specimens of Low Alloy Steel
Authors: Nomura Yuichiro , Takagoshi Daiki , Asada Seiji , Sugeta Atsushi , Kitamura Yoshihide 
Published: November 2024

Abstract
The DFC and DFC2 subcommittees in the Japan Welding Engineering Society developed a new fatigue analysis method with support from the Japanese utilities. This fatigue analysis method had several modifications made and has been incorporated into the JSME Environmental Fatigue Evaluation Method 2022 Edition (JSME S NF1). Also, research on effects of surface finishing and mean stress on fatigue lives of notched specimens have been conducted by DFC3 and DFC4. In this paper, the test plan and overview of the outcomes of the DFC3 and DFC4 are introduced.
In this series of research, effects of surface finishing on fatigue strength and relation between a fatigue strength reduction factor and mean stress correction have been investigated using notched specimens, of which materials are carbon steel (CS:JIS STPT370) and low alloy steel (LAS:JIS SQV2A). The applicability of the Ksf (factor for the effect of surface finishing) equation of the JSME S NF1 to notched specimens has been investigated and confirmed based on the experimental results. The results of the tests for the effects of surface are presented in PVP2024(Ref.[11]).
The order of consideration of the fatigue strength reduction factor and mean stress correction may not need to be considered if the Smith-Watson-Topper (SWT) approach can be applied to mean stress correction. Hence, the applicability of the SWT approach with stress concentration and mean stress have been investigated and confirmed based on the experimental results.
Finally, we evaluated the simultaneous effects of stress concentration due to notching and mean stress on fatigue life was discussed on LAS by comparing the smooth and notched specimens. The shape of the notched specimen affects stress concentration factors (Kt). Additionally, elastic-plastic finite element analysis (FEA) was conducted to confirm the behavior of the notch bottom when stress concentration due to the notch and mean stress act simultaneously. The applicability of the SWT approach was also confirmed using FEA results.
In the fatigue test of the notched specimen, it was confirmed that the effect of the with or without of the mean stress on the fatigue life was small, which was consistent with the results of the analysis. In this evaluation, four methods were evaluated as SWT approach. The Cases 1 to 3 is evaluated by setting the stress and strain values of the notched bottom obtained by FEA, and the Case 4 is simply evaluated by multiplying the nominal stress by the stress concentration factor.
It is confirmed that the SWT approach is on the conservative for design base. Therefore, the application of the SWT approach to the design is judged to be appropriate.
On the Possibility of Extending the Crack Length Criterion in the Master Curve Methodology
Authors: Sánchez Marcos , Cicero Sergio , Obermeier Florian , Serrano Marta , Chiu Yu-Lung , Altstadt Eberhard 
Published: November 2024

Abstract
The master curve methodology is a well-known approach utilized to characterize the ductile-to-brittle transition region of ferritic-pearlitic steels. This methodology was initially standardized in ASTM E1921 in 1997 and has undergone continuous evolution and improvement since its origin. However, the validity criterion for the crack aspect ratio (0.45 ≤ a0/W ≤ 0.55) has remained unchanged since its inception. It is worth noting that this criterion was originally established in accordance with standard ASTM E399, which characterizes fracture conditions under linear-elastic plane strain conditions, apparently for historical precedents rather than any scientific rationale. Furthermore, ASTM E1820, which is employed to characterize the fracture behavior of metallic materials in elastic-plastic conditions, permits a maximum crack length-to-width ratio of 0.70. In this context, and considering that ASTM E1921 measures KJc (elastic-plastic) values of the fracture toughness, our research seeks to empirically demonstrate that the crack length-to-width criteria established in ASTM E1921 can be increased up to 0.60, at the very least, without compromising the accuracy of the reference temperature calculations. Such a correction would offer significant advantages, especially when dealing with mini-C(T) specimens. Their tiny dimensions may result in the discarding of numerous specimens that could otherwise be effectively employed for reference temperature calculations.
Hydrogen Embrittlement Susceptibility and Fracture Toughness Measurements of Welded X65M Pipeline Steels
Authors: Moser Newell , Buck Zachary , Derimow Nicholas , Martin May L. , Lauria Damian , Lucon Enrico , Bradley Peter , Connolly Matthew 
Published: November 2024

Abstract
Hydrogen is known to deteriorate the mechanical performance of steels (i.e., hydrogen embrittlement). The welding processes involved in the manufacturing and joining of steel pipelines locally modifies the microstructure of the steel, further complicating the situation. NIST has evaluated three steel pipes from industrial contacts to assess the susceptibility of seam welds to hydrogen embrittlement; these three pipes are made from API 5L X65M steel. The three steels were characterized in terms of microstructure, Charpy experiments (performed in air), and fracture toughness via single-edge notched bend specimens (performed in pressurized hydrogen). When testing in air, there was an apparent reduction in toughness for welded regions relative to the baseline steel. In hydrogen, a significant reduction in toughness was observed, however, the welded regions were the toughest. Microstructural differences in the welded region, namely grain size and the presence of phases like bainite, likely have the largest influence on these toughness differences.
Aging Investigations of Metal Seals Used in Containers for Interim Storage of Spent Fuel
Authors: Jaunich Matthias , Goral Milan , Sagradov Ilja , Wolff Dietmar , Völzke Holger 
Published: November 2024

Abstract
For bolted casks for used fuel and high-level waste the sealing system has an important impact of ensuring safe enclosure of the inventory. The used metal seals show some changes over time which have been addressed for nearly 15 years in running experiments at BAM. The observed changes are temperature dependent and therefore it is expected that tests at higher temperature allow for an acceleration of the effects and ideally the proposal of an ageing model covering the expected time of use. Nevertheless, questions concerning the influence of the experimental approach on the results and effects taking place at the initial days of ageing remain. To address these a new project was launched to give a better understanding of the seal behavior.
A Novel Optimization Method to Improve Assembly Concentricity of Aero-Engine Rotor With Bolted Flange Joints Using Genetic Algorithms
Authors: Zhu Linbo , Yu Xiaobo , Bouzid Abdel-Hakim , Zhang Hanwen , Liu Junbing , Hong Jun 
Published: November 2024

Abstract
The assembly concentricity of the aero-engine rotor is a crucial parameter for assessing the overall assembly quality. It significantly influences vibration characteristics, particularly during high-speed rotation. Aero-engine rotors commonly utilize bolted flange joints as the fundamental method of connection. However, it is very difficult to accurately control the concentricity in practice due to the influences of geometric errors, assembly angles, et al. This paper presents a novel method to optimize the assembly concentricity of multi-stage aero-engine rotors using a genetic algorithm, which considers the amount of concentricity of each rotor. The objective of the optimization is to minimize the concentricity. The assembly angles of the bolted flange joints rotors are considered as the design variables. A prediction model for the concentricity of multi-stage rotors related to the assembly angles is proposed by using the homogeneous coordinate transformation theory. The concentricity of the final assembly is minimized by controlling the assembly angle of each rotor and the best assembly angles of different rotors can be obtained. The developed approach is validated by experimental tests on a multi-stage rotor. This study can provide guidance and enhance the dynamic performance of bolted joints for aero-engine rotors.
Investigation of Hydrogen Embrittlement in 304 Austenitic Stainless Steel Through Acoustic Emission Monitoring and Deep Learning
Authors: Hua Zhengli , Shen Xi , Sun Chen , Xu Meng , Li Xing , Yu Wentao 
Published: November 2024

Abstract
In this academic investigation, we employed Acoustic Emission (AE) monitoring and a Convolutional Neural Network (CNN) to scrutinize hydrogen-induced crack behavior in hydrogen-precharged 304 austenitic stainless steel during tensile stress. This study’s pivotal findings reveal that AE monitoring adeptly captures sound wave signal alterations induced by material stress, especially during the critical phase of crack initiation, from the late stage of strengthening to the necking stage. Additionally, industrial-grade Computed Tomography (CT) scans corroborated the presence of a singular principal crack during these phases, aligning with the crack type identified through unsupervised clustering analysis of Short-Time Fourier Transform (STFT)-processed AE signals using the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm. The developed CNN model, demonstrating a 98.32% accuracy rate in validation, effectively discriminated between the signals corresponding to distinct stages of material damage. This research underlines the efficacy and practicality of integrating AE monitoring with deep learning for hydrogen induced damage detection in materials.
Lift-Off Simulation and Revision of the Fluid-Driven MFL Pipeline Inspection Robot Under Obstacle Excitation
Authors: Chen Minghao , Shi Xinna , Pang Tong , Zhang Xiaoying , Zhang Hang 
Published: November 2024

Abstract
The use of fluid-driven Magnetic Flux Leakage (MFL) pipeline inspection robot to maintain oil and gas pipelines is an essential method of ensuring safe operation. The internal excitations of the pipe, such as girth weld and depressions, cause the vibration response of the robot and the variation of the Liftoff value of the sensors. In this study, the Lift-off value of the detection probe and the vibration response of a multi-sealing disc pipeline inspection robot passing through a girth weld under different design parameters are investigated by co-simulation. Considering the coupling between the fluid and robot, the fluid-structure interactions simulation model of MSC/ADAMS and MATLAB/SIMULINK is established. Simplify the modeling of probe detection arm and study the change trend of Lift-off value under excitation. The results show that the change of sealing disc interval and running speed has a significant influence on the dynamic response. The extreme value of vertical acceleration increases with the increase of the interval, but the increase of sealing disc interval has little influence on the change of tendency and the extreme value of axial acceleration. As the running speed increases, the extreme value of the vertical acceleration decreases significantly, and the degree of reciprocating oscillation in the time history curve decreases significantly. The extreme value and the range of variation of the Lift-off value at different locations are determined through result analysis and show a weakening trend at different speeds. The presented analysis is beneficial for structural fatigue analysis and Lift-off correction.
Auxetic Domes Under External Pressure
Authors: Blachut Jan , Sala Dariusz 
Published: November 2024

Abstract
In view of ongoing interest in novel materials exhibiting Negative Poisson Ratio (NPR), the current study examines its influence on buckling strength of externally pressurised torispherical pressure vessel closures. Failure pressures are computed for a fixed value of Poisson’s ratio, υ = −0.9. Shells made from two layers are investigated, i.e., the outer metallic skin is supported on inside by an auxetic layer. Both metallic and auxetic layers are assumed to be isotropic, and exhibit elastic, perfectly plastic behaviour with the following material properties: E = 207.0 GPa, the yield point of 414.0 MPa for both primary and auxetic layers. A reference hemisphere of diameter, D, wall thickness, to, and the ratio, D/to = 500 is adopted in computations. In all of them the shells are clamped at the equatorial plane. Axisymmetric collapse as well as asymmetric bifurcation buckling pressures are taken into account. Also, the weight of torispheres, WT, equals the weight of the reference hemisphere, WH.
Three full envelopes of admissible configurations illustrating the role of auxetic reinforcement on a like-for-like basis have been developed. They include domes with: (i) steel only, (ii) 50% steel and 50% auxetic, and (iii) 25% steel and 75% auxetic. The shape of admissible configurations for the cases (i, ii, iii), remain comparable. But the size of (ii) and (iii) are 84%, 1.08% of steel-only envelope.
For the case (iii), the results for the ratio of volume enclosed by torisphere, VT, to volume enclosed by hemisphere, VH, being VT/VH = 0.85 indicate that the inclusion of auxetic layer leads to 30% gain in failure pressures above auxetic-free, and weight equivalent, configuration of the dome. Within the same magnitude of the ratio, VT/VH = 0.85, calculations also identified the weakest head. As a result, the ratio of the best to the worst performing geometries was 4.80. The contents of the auxetic layer, i.e., its wall thickness was different for both the best and the worst geometries.
Digital Twin Development for Additive Manufacturing
Authors: Park Youngho , Love Allen , Behseresht Saeed , Valdez Pastrana Omar , Sakai James 
Published: November 2024

Abstract
Additive manufacturing (AM) is considered as a transformative manufacturing technology due to its ability to create complex structures and reduce material waste. However, the AM technology also introduces many challenges such as poor surface quality and structural integrity. To address these issues, a novel approach known as a digital twin (DT) has emerged. A digital twin is a digital representation of a physical object or system that enables real-time monitoring and control of their behavior. This study introduces a hybrid physical-virtual digital twin environment that combines a sensing-driven DT with a process simulation-driven DT. Specifically, we propose a hybrid digital twin environment (HDTE) customized for a fused deposition modeling (FDM) 3D printer. The HDTE is implemented into a 3D development platform. The present DT environment integrates external sensors to collect real-time data on temperature and location of the extruder on a 3D printer. It also includes a virtual AM process simulation using a commercial finite element software to predict temperature distribution and mechanical behavior during 3D printing. Position and temperature assessment experiments confirm the DT’s ability to replicate component positions under static and dynamic conditions as well as temperature variation within the 3D printer. Comparative analysis between the simulation and experimental data shows excellent agreement and further validate the DT’s capabilities. The present DT holds the potential for a significant advancement in 3D printing technology by offering real-time insights, predictive capabilities, and improved process control.
Reliability and Efficiency Improvements Using Long Term Vibration Monitoring Data
Authors: Wally Gernot , McKee Campbell , Sharpe Peter 
Published: November 2024

Abstract
Vibration is one of the most common root causes for fatigue failures on process equipment and structural vibration concerns can cause loss of production and limitations in plant operation. Current guidelines [1] usually recommend a measurement campaign to quantify the vibration-induced integrity threat which is mostly performed using a short-term assessment approach. Due to the required setup and logistics, this approach generally tries to assess the worst-case scenarios which then ultimately can lead to very conservative decisions regarding production limitations, inspections or even mitigation efforts.
Because vibration concerns are usually only discovered relatively late in the design or in the operating stage of a plant, normally, no provisions have been made to allow for a thorough assessment of these risks. Therefore, methods have been developed to use the data collected by an intrinsically safe, long term monitoring system to quantify the stress induced fatigue performance of process equipment which can then be correlated to the actual operating regime and environmental conditions. These methods use state-of-the-art acquisition systems coupled with advanced data analysis such as numerical analysis or machine learning algorithms to quantify the vibration-related integrity threat not only for the recorded monitoring period but also allow an extrapolation into past and future process scenarios. This ultimately will lead to higher production rates, lower integrity risks, elimination of unneeded mitigations, or more cost-effective use of specialist resources.
Based on four case studies, it will be shown how long-term vibration and stress data can be used to help with the increase of production, life extension decisions, root cause analysis, failure mode and effect analysis, definition of inspection campaigns, or temporary dispensation while having nominally unacceptable vibration present.
In general monitoring systems are well established but this paper will show innovative ways of how the monitoring data can be combined with advanced data processing, numerical analysis techniques or updated communication protocols to improve production efficiency, reduce the overall integrity risk, and possibly, extend the life of process equipment when it comes to vibration-induced fatigue concerns.
Damage Assessment of Liquid Nitrogen Filling on Type III Cylinder in Cryo-Compressed Hydrogen Storage Cylinder
Authors: Ge Zhoutian , Hu Peiyu , Qi Liangliang , Wang Guoying , Bai Jiangkun , Shi Jianfeng 
Published: November 2024

Abstract
Cryo-compressed hydrogen storage is a novel on-board hydrogen storage technique. It possesses a higher hydrogen storage density and prolonged dormancy periods. Cryo-compressed hydrogen storage cylinder is the primary component for on-board hydrogen storage, where the inner cylinder with carbon fiber fully wrapped aluminum liner (Type III structure) is directly contacted with hydrogen. However, the extremely low temperature and high pressure conditions can potentially lead to damage and failure of the fiber-wrapped layer in inner cylinder. In current literature, existing research did not clearly define the variation in pressure-bearing capacity of the inner Type III cylinder after low-temperature treatment, nor the distribution and evolution of internal damage in the fiber-wrapped layer after low-temperature treatment. In this study, a inner Type III cylinder of cryo-compressed hydrogen storage cylinder with a volume of 55L and a nominal working pressure of 35MPa was prepared. After subjecting to a 16-hour liquid nitrogen treatment, a significant increase in defect density in the body of cylinder, and new delamination and matrix cracking in both heads were observed through industrial CT detection. Finally, the residual pressure-bearing capacity of inner Type III cylinder after liquid nitrogen treatment was examined through hydrostatic burst test. This study examined the influence of low temperatures on the inner Type III cylinder of cryo-compressed hydrogen storage cylinders, and also provided a guidance for the failure analysis of cylinder at low temperature conditions.