bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevalence and antimicrobial susceptibility profile of uropathogens in dogs and cats with signs of urinary tract infection
Authors: López‐Córdova J. , Machuca P. , Araya‐Contreras T. , Briceño‐Montero C. , Pérez‐Tobar S. , Faúndez Comte P. , Castillo‐Ruiz M. , Bittner M.
Published: November 2024

Objectives

To determine the prevalence of uropathogens in dogs and cats with signs of urinary tract infection and to characterise their antimicrobial susceptibility.

Materials and Methods

Urine samples from canine and feline patients with clinical signs of urinary tract infection were collected between September 2015 and December 2019 in Santiago, Chile. Bacterial identification and bacterial susceptibility profile was performed through biochemical and antimicrobial susceptibility tests.

Results

Four hundred sixty‐six samples from dogs (37.7%) and 152 from cats (26.1%) showed bacterial growth. Positive samples were mainly from females (dogs: 52.8%; cats: 48.0%), with the highest infection rates in senior dogs (57.7%) and adult cats (45.4%). A single organism caused the infection in 78.2% of the cases, whereas the remaining 21.8% corresponded to a mixed infection. The most prevalent isolated pathogen in dogs and cats was Escherichia coli (42.6% and 49.7%, respectively). Staphylococcus spp. (15.6% and 14.6%), Enterococcus spp. (8.6% and 15.2%) and Proteus spp. (9.7% and 6.4%) were also commonly isolated. A total of 52.4% of Escherichia coli isolates were resistant to amoxicillin, 44.3% to amoxicillin/clavulanic acid, 40.0% to cephradine and 25.3% to ciprofloxacin. Regarding the other three uropathogens commonly isolated in this study, all of them showed a percentage of resistance to the antimicrobials analysed. In addition, 24.6% of multidrug resistance was detected in the E. coli isolates. Penicillin, cephalosporins and fluoroquinolones showed the lowest susceptibility levels.

Clinical Significance

The observed high rates of resistance to commonly prescribed antimicrobials raise concerns for public health.
Apocrine adenocarcinoma arising from mature cystic teratoma in the anterior mediastinum: A case report
Authors: Ueda Takuya , Takamochi Kazuya , Yoshimoto Taichiro , Ichikawa Tomohiro , Matsunaga Takeshi , Hayashi Takuo , Suzuki Kenji
Published: November 2024

Primary mediastinal apocrine adenocarcinoma is extremely rare, with only one case reported to date. Here, we report a surgical case of primary mediastinal apocrine adenocarcinoma. An anterior mediastinal cystic tumor with calcification was identified on chest computed tomography scan in a 51‐year‐old female patient undergoing maintenance hemodialysis. The tumor was 19 mm in size, did not invade the adjacent organs or show distant metastases, and was surgically removed. Microscopic examination revealed that the tumor cells exhibited cribriform or solid proliferation patterns with thick fibrous capsules. The tumor cells had an abundant eosinophilic cytoplasm, and decapitation secretion was noted. Immunohistochemistry revealed positivity for GCDFP‐15 and androgen receptors, with Ki‐67 positivity at 10%. The cyst wall exhibited extensive fibrosis and keratinized material, with bone and bronchial glands identified at the cyst periphery; the tumor cells were contiguous with those structures. The patient was diagnosed with apocrine adenocarcinoma arising from a mature cystic teratoma. The patient has maintained a recurrence‐free status without adjuvant therapy for 6 years after surgery. This case presents a small primary mediastinal apocrine adenocarcinoma that achieved remarkable long‐term survival.
Making sense of the economics of abortion in the United States
Authors: Weitz Tracy A.
Published: November 2024

In 2023 the editors of Perspectives on Sexual and Reproductive Health issued a special call for papers related to the economics of abortion. Ten of those submissions are included in this volume and address critical issues including: (1) the role Medicaid continues to play in abortion access and how changes in state Medicaid coverage of abortion have expanded and restricted abortion care use; (2) how low‐income individuals without insurance coverage for abortion utilize resources from abortion funds and through crowdsourcing platforms; (3) how the price of medication abortion has decreased with the availability of telemedicine medication abortion and how providers of that service are making efforts to reduce those prices even further; and (4) how legally restricting abortion access has significant economic implications for state economies and the US society as a whole. In this introduction, I review the general scope of prior research on the economics of abortion in the US as it relates to stigma‐induced silences, abortion seekers, abortion providers, and abortion assistance organizations. I then highlight the new contributions made by the articles contained in this special issue.
Multi-Task Learning for Intention and Trajectory Prediction in Human-Robot Collaborative Disassembly Tasks
Authors: Zhang Xinyao , Tian Sibo , Liang Xiao , Zheng Minghui , Behdad Sara
Published: November 2024

Human-robot collaboration (HRC) has become an integral element of many manufacturing and service industries. A fundamental requirement for safe HRC is understanding and predicting human trajectories and intentions, especially when humans and robots operate nearby. Although existing research emphasizes predicting human motions or intentions, a key challenge is predicting both human trajectories and intentions simultaneously. This paper addresses this gap by developing a multi-task learning (MTL) framework consisting of a Bi-LSTM-based encoder-decoder architecture that obtains the motion data from both human and robot trajectories as inputs and performs two main tasks simultaneously: human trajectory prediction and human intention prediction. The first task predicts human trajectories, focusing on reconstructing the motion sequences, while the second task tests two main approaches for intention prediction: supervised learning, specifically a Support Vector Machine (SVM), to predict human intention based on the latent representation, and, an unsupervised learning method, the Hidden Markov Model (HMM), that decodes the latent features for human intention prediction. Four encoder designs are evaluated for feature extraction, including interaction-attention, interaction-pooling, interaction-Seq2Seq, and Seq2Seq. The framework is validated through a case study of a desktop disassembly task with robots operating at different speeds. The results include evaluating different encoder designs, analyzing the impact of incorporating robot motion into the encoder, and detailed visualizations. The findings show that our proposed framework can accurately predict human trajectories and intentions.
CFD Model of Gravity-Induced Slurry Flow
Authors: Broz William R. , Chialvo Sebastian , Das Sandipan K. , Gray Amy
Published: November 2024

Corrosion damage was observed on piping that had been infiltrated by sand during extended on-site storage prior to installation. It was suspected that the required post-hydrotest flushing operation failed to clear the sand, ultimately contributing to the observed piping damage. To analyze the efficacy of the flushing procedure, a computational fluid dynamics (CFD) model was developed for a water-sand slurry. The model treated this multiphase flow utilizing a transient, three-dimensional Eulerian approach, including a granular submodel to simulate movement of the sand. The CFD model was validated against a previous study that considered a similar flow problem, achieving good agreement with experimental data. Analysis of the sand-infiltration incident then followed, with parameters such as flow velocity, initial sand volume fraction, pipe length, and duration of flushing varied to determine their effects on the flushing process. The CFD model revealed that, even for a pipe length about half that for a typical hydrostatic test segment, residual sand was likely to remain in the pipe at the conclusion of the flushing procedure. In contrast, a higher-velocity (2 m/s) remedial flush performed after weld repairs were completed was successful in removing remaining sand from the piping.
Effect of Specimen Rotation on Crack Size Estimation in J-R Curve Testing Using Compact Tension Specimen
Authors: Kim Kuk-Cheol , Song Jeon-Young , Ma Young-Wha
Published: November 2024

In order to verify the structural integrity of power generation facilities, many fracture toughness tests are being performed on high-toughness materials, and efforts are being made to obtain reliable J-R curve. In particular, in the case of nuclear piping system to which Leak Before Break (LBB) design is applied, high-toughness materials are used, and fracture toughness testing is also required to be conducted until sufficiently long crack extension is possible. However, when performing a J-R curve testing of a high-toughness material using a compact tension (CT) specimen to a crack extension size as long as possible, it is difficult to obtain reliable test results due to the phenomenon of rotation of the specimen. Therefore, when estimating the crack size during testing using the compliance method, compliance is measured with the test specimen rotated. At this time, in order to obtain reliable J-R curve data, accurate crack size estimation is required from the compliance measured on the rotated test specimen.

ASTM E1820 introduces a compliance correction equation to correct for the rotation effect of the test specimen. In our previous paper, the author proposed a new crack size estimation method that additionally considered the effect of load line changes due to specimen rotation, and proved its validity through testing. In this study, the mechanical mechanism for crack size estimation from rotated specimens has been investigated. In addition, the crack size prediction accuracy of the ASTM E1820 method and the proposed method has been compared and evaluated through finite element (FE) analysis of specimens deformed by rotation. In the FE analysis, evaluation has been performed when the specimen rotation was large or small, and crack size to specimen width ratio, a/W, was varied between 0.5 and 0.7. As a result of FE analysis, the proposed method showed better accuracy than the ASTM E1820 method. Thereby, it was verified that the author’s method for estimating crack size considering rotation of CT specimens has better accuracy in both FE analysis and experimental evaluation compared to the ASTM E1820 method.
Seismic Evaluation Method of Piping Systems By Inelastic Response Spectrum Analysis: Part 2 — Fatigue Assessment
Authors: Iida Satoshi , Tamura Ichiro , Ishimaru Yorihisa , Kamaya Masayuki
Published: November 2024

An inelastic response-spectrum analysis method for multi-degree-of-freedom systems was proposed. The method has lower analysis loads and predictable by the inelastic response-spectrum and is not an equivalent-linearization method. We propose a seismic evaluation method of piping systems to conduct seismic design using response-spectrum analysis. In the previous paper, the inelastic response-spectrum analysis of piping systems was proposed. The output of the analysis is the ductility factors of the pipe elements which are defined as a ratio of maximum deformation and yield deformation of them: pipes, elbows, etc. In this paper, fatigue assessment method of pipe elements is presented using the ductility factors. The strain ranges of elbows as a representative of pipe elements are determined from the ductility factors of them based on finite element analyses of various geometrical and boundary conditions. As a result, the equation for the relation between equivalent strain and ductility factors of pipe elements are obtained. The fatigue assessment of pipe elements can be conducted using this equation.
Design of High-Pressure Cylindrical Shells Against Plastic Collapse
Authors: Kirkemo Finn , Wormsen Anders
Published: November 2024

High-pressure equipment for the oil and gas industry is predominately designed per API, ASME, and NORSOK design codes. This paper briefly reviews some essential technical requirements for pressure-containing equipment where internal pressure and bending moment loading may govern the design. The paper intends to provide users and personnel in code committees with information to assist in evaluating the structural safety of operating pressure-containing equipment. The scope is limited to the design of cylindrical shells and straight pipes constructed of low alloy steels. The paper compares material requirements and design loads of the following codes: API 6A, API 16A, API 17D, API 17G, API 17TR8, ASME VIII.2, ASME VIII.3, and NORSOK U-001 Annex B. Recommendations are given to ensure consistency between design calculation assumptions and material requirements to obtain expected design margins and structural safety.
Development of ASME Section VIII Division 1 Code Case 3078 on Electrochemical Cell Stacks for Electrolysis
Authors: Xu Kang
Published: November 2024

Electrochemical Cell Stacks (ECS) are a critical component in electrolysis and fuel cell systems. The design of ECS typically consists of multiple layered cell packs that are secured by end plates and tie rods to achieve a leak tight construction. To achieve better efficiency and reduce operating cost, the development of ECS has evolved to larger sizes and higher operating pressures. It is not uncommon for ECS to have hundreds of stacked unit cells with a design pressure exceeding 500 psi (3.5 MPa) and maximum cross section diagonal exceeding several feet. ISO 22734 and ANSI/CSA B22734 provide some performance-based design guidelines for mechanical integrity of ECS. However, the detailed pressure stress design and material requirements are lacking. Having recognized that the construction of ECS is very similar to plate heat exchangers, ASME BPVC Section VIII Division 1 has developed specific code rules for ECS based on Mandatory Appendix 45 for plate exchangers. The rules are first introduced in a newly approved Section VIII Division 1 Code Case 3078, considering the metallic components such as end plates, tie rod and nozzles as pressure boundary. Due to the special electrochemical functionality of the cell pack, the cell pack itself is exempted from code rules provided that it meets certain performance-based requirements. This paper documents the technical basis and the development of Code Case 3078. As future development, considerations are being given to incorporate the Code Case as Mandatory Appendix in Section VIII Division 1.
XFEM Simulation and Parametric Analysis of Thick-Walled Cylindrical Mock-Ups Under Thermo-Shock
Authors: Mora Mendez Diego Fernando , Niffenegger Markus
Published: November 2024

Pressurized thermo-shock (PTS) evaluation is a crucial safety assessment for continued nuclear power plant operation. Given the challenges and cost constraints of full-scale PTS experiments on reactor pressure vessels (RPVs), at Paul Scherrer Institut (PSI) thermal shock-like cooling experiments on small, thick-walled cylindrical mock-ups have been conducted. These aim to understand the initiation, growth, and arrest of precracks. Simultaneously, ABAQUS simulations with a 2D extended finite element model (XFEM) focused on simulating precrack fracture behavior under thermal shock (TS) have been performed. These simulations exclude pressure, emphasizing inducing mode I fracture through pure tensile hoop stresses during rapid cooling, mimicking a loss of coolant accident (LOCA) scenario. Material considered is thermally treated RPV steel (17MoV 8-4), simulating end-of-life service conditions. The XFEM model’s sensitivity to mesh size and fracture criteria are discussed, emphasizing their importance in predicting crack paths. The research contributes to understanding extreme conditions, enhancing the safety and reliability of nuclear power generation.
A Review of Comparative Analysis of Heat Transfer in Pipe Clamps
Authors: Wiseman Phillip , Kulkarni Sanket , Muaviya Shaik M.
Published: November 2024

The determination of pipe support and restraint assemblies are predicated on loads, geometrical constraints (i.e. distance between building steel and the pipe), and temperatures of the environment, pipe, or component. When designing and analyzing pipe clamps, thermal stresses are not generally considered but the transfer of heat from pipe to the clamp plays a major role in material selection of the clamp. The bolting and connecting hardware to the assembly may not necessarily experience the same temperature that the part of the clamp that is in direct contact with the pipe. Thus, this may be optimized for the geometry or material to provide an economical solution. Additionally, the connecting parts of the assembly (i.e. strut, snubber, energy absorber) could potentially see temperatures above ambient depending on the geometry of the clamp. This work primarily investigates the heat transfer of the traditional 3-bolt clamps and the state-of-the-art yoke style clamps. The present study is a continuation of a publication that considered temperature reduction methods for pipe supports considering a variety of commonly used codes and standards. The steady-state finite element analysis results generated are utilized to provide a comparison of the thermal distribution of the aforementioned clamps thereby offering a more efficient and economical design.
A Proposed Weight Function Method for 2-D Embedded Cracks Subject to Arbitrary Stress Distribution
Authors: Altstadt Steven , Bouse Scott
Published: November 2024

The current library of API 579-1/ASME FFS-1 2021 Fitness-For-Service stress intensity factor solutions includes options for arbitrary stress distribution inputs for most surface crack configurations. However, for embedded cracks, the listed solutions are limited to fourth order order polynomial through-thickness stress distribution inputs, which can be a poor approximation in some applications. The current study independently investigated embedded 2-D cracks to develop a weight function method approach to extend the state of the art in API 579-1. The proposed method shares several theoretical and practical similarities with the API 579-1 Part 9B approach used for surface cracks subject to arbitrary stress distributions. However, as shown in the provided derivation, the proposed weight function approach for embedded cracks also has some distinct differences. Weight function derived stress intensity factor solutions were compared to linear elastic finite element results for representative geometries including plates, cylinders, and spheres commonly found in pressure equipment. As with the surface crack approach, the accuracy of the method is partially dependent on the number of weight function terms included. For typical fitness for service applications, reasonably accurate results are found when five terms with coefficients are included; however, fewer terms can be successfully used when the embedded crack size is very small compared to all other component dimensions.
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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Ductile Fracture Criterion Parameter Calibration and Analysis: X80 Pipe Steel
Authors: Zhu Xueming , Lv Zhiyang , Shuai Jian , Shi Lei , Yu Shengyang , Xia Gang
Published: November 2024

To investigate the ductile fracture mechanical properties of high strength pipeline steel under a series of stress states, the basic mechanical properties and fracture parameters of X80 pipeline steel were obtained from four types of tensile specimens with six different stress concentration factors and their symmetrical finite element models by an experimental-simulation hybrid method. The ductile fracture parameters of the fracture criterion were calibrated by selecting three specimen data, and the calibrated fracture criterion was imported into ABAQUS using the Vumat subroutine to perform tensile simulations and construct two-dimensional planar fracture trajectories of the materials, and the predictive effects of the ductile fracture criterion were analyzed. The study demonstrates that the fracture criteria can be calibrated using the experimental-simulation hybrid method for data extraction from specimens with varying stress concentrations; the DF2014 ductile fracture criterion characterizes fracture behavior accurately and flexibly under different stress states, which was more accurate for predicting ductile fracture of high strength pipe steel. This research can serve as a reference for evaluating the ductile fracture failure of high strength steel pipes using the ductile fracture criterion.
Effect of Winding Tension on the Mechanical Properties of Type IV High-Pressure Hydrogen Storage Vessel
Authors: Zhang Yunxiao , Fan Zhichao , Chen Xuedong
Published: November 2024

As a promising solution for hydrogen energy storage and transportation, plastic liner composite fully wound high-pressure hydrogen storage vessel (Type IV hydrogen storage vessel) has attracted the interest of many researchers in recent years. The manufacturing process of the type IV hydrogen storage vessel involves many process parameters, among which fiber tension has a significant effect on the mechanical properties of the liner and the whole structure. Because of the complex structure of a type IV hydrogen storage vessel, numerical simulation often replaces winding test as an effective means to optimize the design of winding process. In this work, based on the material constitutive behavior of the plastic liner, a high-fidelity finite element model including the angle and thickness of the carbon fiber layup was established for the type IV hydrogen storage vessel with a large length-to-diameter ratio. Considering the relationship between the fiber tension and fiber volume fraction, the influence of increased fiber tension on the residual stress emerging on the liner was analyzed by applying fiber tension through pre-defined stress method. Based on multiple failure modes of fiber-reinforced plastics, the potential effects of the fiber tension on the failure behaviors of carbon fiber and resin matrix were explored. Finally, a theoretical guidance for the winding tension design of type IV hydrogen storage vessel was obtained. These results can provide a reference for the winding design optimization of type IV hydrogen storage vessel and the burst pressure prediction method.
Evaluation of Mechanical and Corrosion Properties of Stainless Steel Weldment Using GMAW Modified Waveform Short Circuit Welding Process Without Backing Gas
Authors: Randhawa Dishoo , Penso Jorge , Soltaninia Shahab , Chiluvuri Sivakumar
Published: November 2024

This paper presents mechanical and corrosion resistance properties of stainless steel weldment with root pass deposited using GMAW modified waveform short circuit welding process without backing gas, referred to as No-Backing Gas (NBG) welding process in this paper. While other welding techniques exist that also omit backing gas for similar applications, the term No-Backing Gas (NBG) is employed here for simplicity’s sake. Data has been obtained using 316LSi stainless steel filler metal on 304L stainless steel base metal. Test work included a baseline coupon, deposited using a GTAW root pass back purged with inert gas, as this has traditionally been the industry best practice for welding stainless steel pipe to minimize internal surface contamination and oxidation. NBG test coupons were welded using GMAW-P for second pass and FCAW for remaining passes. Baseline GTAW coupon was welded using GTAW for second pass and FCAW for remaining passes. Test work included ASME BPVC Section IX required tests, Charpy v-notch impact test, ferrite test, macrograph, hardness examination, and corrosion immersion tests ASTM A262 Practice C and ASTM G48 Modified Method E. The obtained results were assessed for cryogenic temperature application requirements of ASME B31.3 Process Piping Code and for mildly corrosive service applications (see Note-1 below). The paper also discusses the challenges associated with ASTM G48 Method E for testing of 304 stainless steel weldments and use of a modified, fit-for-purpose G48 method to evaluate results. Furthermore, the authors share lessons learned and recommendations from their experience on a recent project on which NBG welding was extensively used on stainless steel piping.

Note-1: Corrosion tests are based on standardized solutions and may not be representative of all applications. Users should establish their own qualification for the intended service application.