bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the Very High Cycle Fatigue (VHCF) Behavior of AISI 347 and 304L Austenitic Stainless Steels Including Their Welds for Reactor Internals at Ambient and Operating Temperature
Authors: Rudolph Jürgen , Veile Georg , Regitz Elen , Smaga Marek , Fischer Udo , Grimm Michael , Weihe Stefan , Beck Tilman 
Published: November 2024

Abstract
The fatigue assessment of safety relevant components is of importance with regard to safety and reliability of nuclear power plants. Due to their excellent mechanical and technological properties as well as their corrosion resistance austenitic stainless steels are often used for reactor internals. Internals are subject to mechanical and thermo-mechanical loading in all fatigue regimes. This work presents the current status of the research project VHCF-II with the goal of improved fatigue life prediction for safety assessment of the materials AISI 304L, AISI 347 and ER 347. For improved fatigue life prediction, the static and cyclic material behavior is characterized at ambient and operation relevant temperatures. A detailed characterization of the material behavior is required to determine the components’ fatigue life up to 109 load cycles with Ultrasonic Fatigue Testing Systems (UFTS) working at 20 kHz. The characterized material data serve the purpose to expand the data for improving methods of fatigue calculations. For this purpose, numerical simulations of thermo-mechanically loaded components with focus on their welded joints are conducted. Experiments are conducted in order to further validate the methods of fatigue life assessment under operating conditions of nuclear power plants. Foreseen and ongoing work of the VHCF-II project is presented in this paper.
Damage Model Investigations to Predict Crack Initiation in a Tension Test for a Ductile Steel
Authors: Rainey Samuel , Smith Steven 
Published: November 2024

Abstract
Guarding against the initiation of cracks in pressure vessel design is of essential importance. In this paper, a damage model is investigated on its ability to estimate the initiation of cracks in standard uniaxial specimens. The damage model is used to predict the formation of a crack in a Q345R pressure vessel steel uniaxial tensile specimen during monotonic loading. An FEA mirroring the conditions of the original test is conducted, and the damage model applied to evaluate the stress and strain states at locations in the tensile specimen. It is found that the damage model can accurately predict the fracture strain, fracture location, and fracture orientation of the original tensile test specimen by identifying the load increment during which the cumulative damage on a given plane exceeds a critical value.
Testing Fracture Toughness of Composite Repair Bonding
Authors: Al Shabibi Abdullah M. , Al Ismaili Abdul-Majeed A. , Al Ghatrifi Mohammed A. , Al Kindi Hisham I. , Al Mashrafi Hussam S. 
Published: November 2024

Abstract
Pipelines, in petroleum industry in particular, are exposed to defects that can result in reducing their capacity of transferring oil. Composite repair wrapping is a new emerging method of repairing defected pipelines. To realize the extent of the load capacity for the repaired defected pipeline, it is important to understand the failure criteria for the composite wrapping. The aim of this study is to experimentally determine the failure pressure of a pipe with a through-wall defect repaired with a composite material. Defects of different sizes are to be considered.
Research on Stress in Obround and Out-of-Roundness Shells
Authors: Jin Yao 
Published: November 2024

Abstract
Using the closed-form solution of obround shell, the stress and displacement of obround shells were theoretically analyzed. With the straight segment introduced, the maximum stresses and displacement of obround shells increase significantly. The length of the straight segment is a key factor in determining the maximum stress and location. For obround shells, the maximum stress is the function of two dimensionless geometrical parameters. Parameter study results show that for most engineering applications, the maximum stress occurs in the middle section of the curved segment. The maximum displacement appears in the middle of the straight segment. The stress increment caused by the out-of-roundness of cylindrical shells was studied. A cylindrical shell with out-of-roundness is treated as an elliptical shell. Two methods are proposed to estimate the maximum stress in the out-of-roundness shells. The ovalized cylindrical method simplifies the numerical analysis model. Complex out-of-roundness details are replaced by ellipse. The virtual obround method provides a theoretical analysis tool. The analysis results show that the stress increase of out-of-roundness shell depends not only on the amount of distortion, but also on the type of distortion. The equivalent out-of-roundness is defined to normalize the distortion according to stress concentration level for each distortion type. Based on existing design codes, simply limiting the measured diameter differences does not appear to be sufficient. The analysis results show that even within the range of out-of-roundness value accepted by the codes, the stress increment caused by out-of-roundness may exceed expectations. In some situations, especially for thin- to medium-walled shells, the minimum required wall thickness estimated by the existing codes may be underestimated.
Research on Effects of Surface Finishing and Mean Stress on Fatigue Lives of Notched Specimens - Application of Elastic-Plastic FE Analyses for Notched Specimens of Low Alloy Steel
Authors: Takagoshi Daiki , Nomura Yuichiro , Asada Seiji , Kitamura Yoshihide 
Published: November 2024

Abstract
DFC and DFC2 subcommittees in the Japan Welding Engineering Society developed a new approach in fatigue analysis methodology. This fatigue analysis methodology has made several modifications and has been incorporated into the JSME Environmental Fatigue Evaluation Method 2022 Edition (JSME S NF1-2022). Research on the effects of surface finishing and mean stress on the fatigue lives of notched specimens were followed by DFC3 and DFC4 subcommittees. In this paper, the application of elastic-plastic Finite-Element Analysis (FEA) for fatigue evaluation of notched specimens of low alloy steel was investigated.
To verify the applicability of a simple analytical method to the fatigue life evaluation, elastic-plastic FEA were performed simulating fatigue testing with positive mean stress for notched specimens of low alloy steel, JIS-G3120 SQV2A. Local stress-strain behaviors at the notch root and mean stresses changes with increasing number of fatigue cycles were investigated by these analyses.
As a result of FEA, in the case of lower stress amplitude, plastic deformation occurred only at the first cycle and local mean stress was constant. On the other hand, in the case of higher stress amplitude, cyclic plastic deformation occurred throughout all cycles and local mean stress became lower with increasing fatigue cycles. After sufficient number of fatigue cycles were applied, local mean stress at the notch root became almost zero. These results were consistent with fatigue test results of SQV2A in another research, in which mean stress had little effect on the fatigue lives of notched specimens. Also, it was confirmed that the fatigue lives of notched specimens could be arranged on the identical S-N curve based on the fatigue lives of smooth specimens by using the equivalent strain amplitude, εaeq estimated by FEA. From these results, it was concluded that FEA is applicable for the evaluation of the fatigue lives of notched specimens.
Simulation of Crack Growth in Mini-C(T) Fracture Tests in the Ductile-to-Brittle Transition Using a Cohesive Zone Model: Application to Reactor Pressure Vessel Steels
Authors: Somera Audrey , Perales Frédéric , Vincent Pierre-Guy 
Published: November 2024

Abstract
The goal of this study is to simulate crack growth in mini-C(T) fracture tests using a Cohesive Zone Model (CZM) in order to derive the evolution of the toughness in the Ductile-to-Brittle Transition (DBT) region. The calibration method used is adapted from [1] and only requires low-temperature experiments. For a given temperature, it is assumed that the cohesive energy increases with the fracture probability, and that the shape of the CZM traction-separation law varies from a triangle to a trapezoid when the cohesive energy is greater than a value identified using elasto-plastic simulations. The cohesive parameters are determined using two calibration procedures. The first is performed using two experimental load-displacement curves. The second involves finding the cohesive energy leading to the right fracture toughness value given by the master curve for three different temperatures and two fracture probabilities. An exponential evolution of the cohesive energy with temperature is proposed. Cohesive energy is also assumed to depend on fracture probability.
Simulations of mini-C(T) toughness tests are then performed for cumulative failure probabilities of 2%, 50% and 98% at different temperatures. A good agreement is observed between the toughness computed from the simulations and the master curve approach.
Fundamental Study on Passive Safety Characteristics of Piping System Against Excessive Earthquake
Authors: Horinouchi Riku , Yamamoto Yotaro , Kasahara Naoto 
Published: November 2024

Abstract
As a lesson learned from the accident at the Fukushima Daiichi Nuclear Power Plant, it has become important not only to prevent failure occurrence, but also to mitigate failure consequence to catastrophic failure after an accident.
In this study, the behavior of bent round rods and support structures simulating a piping system subjected to vibration loading was tested and analyzed to demonstrate that the piping system has passive safety characteristics against excessive earthquake.
In the vibration tests, bent round rods and support points simulating the piping system were subjected to vibration loads. As a result of the vibration test, the natural frequency of the piping system, response acceleration, elbow strain, displacement, and other data were obtained. In the vibration analyses, a model was created under the same conditions as the vibration test and analyzed using finite element method analysis. As a result of the vibration analyses, data on the reaction force applied to each support point and the reaction force applied to the fixed end point during vibration were obtained.
Based on these results, it was concluded that the piping system transitions to a passive safety structure in which seismic forces are less likely to be transmitted from the floor to the piping system because the natural frequency of the piping system falls below the frequency of seismic waves due to failures in the support structure that have little effect on the cooling function.
Allowable Circumferential Flaw Sizes Based on Code Given and Actual Measured Flow Stresses for High Toughness Ductile Pipes Subjected to Bending and Tensile Loads
Authors: Negyesi Martin , Ha Yoosung , Hasegawa Kunio , Lacroix Valery 
Published: November 2024

Abstract
Allowable stresses for pipes are determined by combining failure stresses and safety factors. When predicting the plastic collapse failure stresses for high toughness ductile pipes, flow stresses of the pipe materials are indispensable. The flow stress is usually given by the average of the yield strength and the ultimate tensile strength. Inservice Inspection of the American Society of Mechanical Engineers (ASME) Code Section XI states to use the yield strengths and the ultimate tensile strengths defined by the ASME Code Section II Materials. The ASME Code Section XI also states that actual measured yield strengths and ultimate tensile strengths are possible to be used, alternatively. Values of yield strength and ultimate tensile strength given by the ASME Code Section II are conservative, corresponding to lower bound values. Then, it is easily inferred that the allowable stresses calculated by the code given flow stress are lower than the allowable stresses calculated by the actual measured flow stress. The objective of this paper is to compare the plastic collapse failure and allowable stresses based on both the code and actual flow stresses for pipes with circumferential flaws subjected to bending and tensile loading. In addition, it is demonstrated that allowable flaw sizes based on both flow stresses do not differ much at low allowable stress. However, when the allowable stress is large, the allowable flaw size based on the code flow stress is substantially lower compared to that based on the actual flow stress.
Advanced Vibrational Fatigue Monitoring Approaches With Varied Technical Application Fields
Authors: Rudolph Jürgen , Ziegler Rainer , Kopinec Milan , Bruckmüller Florian 
Published: November 2024

Abstract
Numerous industrial structures are subjected to vibrations which may induce fatigue damage and which can often not easily be mitigated by design and damping measures. In order to manage and control this ageing mechanism and to prevent unexpected fatigue damage a monitoring system is needed which is able to predict fatigue damage before it occurs. It is composed of a hardware part and a software part. The hardware consists of simple and robust accelerometers or displacement sensors that measure the vibrations at a few key selected points of the structure. The software is a program that identifies the contribution of each dynamic vibration mode in the measured vibrations and transforms this information into an estimation of remaining lifetime at each location of interest. Implementation steps are the one-time generation of a digital twin of the monitored structure, the continuous acceleration measurement and the cyclic signal processing. The comparison of each single mode displacement with the modal basis of the digital twin leads to the stress time history (full stress tensor as a function of time) at the fatigue relevant locations of the structure. A rainflow algorithm allows for the counting of the cycles and the identification of partial and cumulative fatigue usage factors. Extrapolation of results allows for a remaining fatigue lifetime estimation. The visualization of results includes the plot of fatigue usage as a function of operation time. Potential application examples are given in terms of distillation columns (chemical industry), wind mill tower structures (wind energy industry) and piping systems (chemical industry, nuclear and conventional power plants) including small bore piping with well-known fatigue sensitivities at socket welds. An exemplary hardware layout for wind mill tower structures will be given.
Design-by-Analysis Rules for ASME SECTION III, Division 5, Class B Components
Authors: Mahajan Heramb , Jetter Robert , Sham Ting-Leung , Wang Yanli 
Published: November 2024

Abstract
The current rules for elevated temperature ASME Section III, Division 5, Class B components, other than piping, were basically adapted from the Design-by-Rule approach for Section VIII, Division 1 vessels. A goal of the proposed new rules is to explicitly account for the design life and cyclic service while recognizing the less-rigorous requirements commensurate with lesser safety consideration. Further goals are to maximize the use of modern computational technology, for example finite element analysis in conjunction with reference stress concepts, and to avoid the need for stress classification. This paper summarizes the work done to address these issues. A summary of the design-by-analysis for primary loads, strain limit evaluation, and creep-fatigue damage assessment is presented. The proposed design-by-analysis creep-fatigue damage calculation approach uses a new elastic follow-up-based Isochronous Stress Strain Curve stress relaxation procedure. A set of sample problems are selected to validate the proposed design-by-analysis rules for creep-fatigue damage assessment. The proposed Class B rules are evaluated against the Class A elastic design rules and the experimental data obtained from a family of a simplified model test-based key-feature test results. The proposed Class B creep-fatigue damage assessment methodology yields conservative design cycles estimates compared to the experimental results.
Girth Weld Defect Identification Method and Application Research Based on MFL Internal Detection
Authors: Zhao Yatong , He Renbi , Shi Lei , Zhou Liguo 
Published: November 2024

Abstract
Aiming at the limitations of weld non-excavation inspection technology, non-excavation identification difficulties and other problems, this paper carries out the internal inspection and identification of oil and gas pipeline weld defects based on magnetic flux leakage internal inspection. We establish a finite element leakage simulation model containing defects in the circumferential weld, and identify and extract the inversion characteristics of the defect signal; according to the finite element analysis results, we guide and complete the internal inspection draw test and signal analysis, compare and contrast the characteristics of the draw test signal and the simulation inversion signal, and validate the validity of the simulation results; we study the method of characterizing the leakage signal of the circumferential weld and establish a method of classifying and identifying the defects based on the peak of the leakage signal characteristics. The method can be used for the identification and evaluation of weld defects under non-excavation conditions, which greatly reduces the cost associated with excavation inspection and provides technical support for the automatic identification of weld defects.
Preliminary Investigation of the Effects of Neutron Irradiation on the Weibull Modulus of Graphite
Authors: Campbell Anne A. 
Published: November 2024

Abstract
The tensile strength distribution of graphite has historically been estimated via the two- and three-parameter Weibull distributions due to the flaw distribution within the material. This is apparent within the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section III “Rules for Construction of Nuclear Facility Components”, Division 5 “High Temperature Reactors”, Subsection HH “Class SN Nonmetallic Core Components”, Subpart A “Graphite Materials”, where the materials data sheet (MDS) requires the calculation of both the two- and three-parameter Weibull distributions of the tensile strength for as-manufactured graphite. There is not currently a requirement to determine Weibull distribution of the strength of graphite post-irradiation, mainly because no results have been reported that suggest whether the Weibull parameters, most importantly the Weibull modulus, changes due to neutron irradiation damage. An irradiation program was performed at Oak Ridge National Laboratory where graphite grade ETU-10 was exposed to neutron damage at a range of temperatures and final neutron fluences. Within this experiment, ten strength coupons were irradiated at each temperature and fluence combination which when analyzed can provide information as to whether irradiation damage has altered the Weibull modulus. This paper will focus on the analysis of the post-irradiated equibiaxial flexural strength change via a Weibull analysis of each individual data set and discussion as to whether there appears to be statistically significant changes to the Weibull parameters.
Investigation of the API 579-1/ASME FFS-1 KPTC Stress Intensity Factor for Bending Stress
Authors: Altstadt Steven , Mellings Sharon , Bouse Scott , Butchers Ryan 
Published: November 2024

Abstract
The API 579-1/ASME FFS-1 2021 (API 579-1) Fitness-For-Service stress intensity factor solution for a plate with a through-wall center crack (KPTC) subject to bending stress was investigated. Finite element (FE) models of through-thickness center cracked plates subjected to bending stress fields were created and used to estimate stress intensity factors (KI) along the crack fronts, which were then used to establish influence coefficient values. For fitness-for-service applications it is a common practice to extrapolate K along the crack front to obtain an effective K at the surface. The method chosen for extrapolation can have a modest impact on the results. The method of extrapolation used for this assessment is similar to other through-thickness crack solutions in API 579-1. The new influence coefficient values presented herein are recommended for fitness-for-service assessments that involve KPTC subjected to bending stress. Most of the FE results were cross checked against results generated using the dual boundary element method, which showed excellent agreement. The comparison of the newly calculated stress intensity factors to the existing API 579-1 KPTC values showed modest differences for some cases and substantial differences for others. The largest differences were associated with high plate width-to-thickness ratios. The new influence coefficients were also compared to values published by Marie et al (2007). Good agreement was found for almost all cases, but there were some notable discrepancies for high plate width-to-thickness ratios. A comparison was also conducted for the BS7910 solution, which showed that the solution generally overpredicts the stress intensity factor. Some cautionary notes are provided to help delineate the range of applicability for fitness-for-service assessments.
Evaluation of Corrosion Resistance of Stainless Steel Piping With Fillet Weld on External Side in Comparison to Back Shielding Condition
Authors: Takahashi Atsushi , Tsuda Takahiro 
Published: November 2024

Abstract
Back shielding by inert gas is required to not only single-sided butt joints but also fillet joints of piping in accordance with specification or standard such as API RP582 [1] where chromium content of base metal is high, e.g., greater than 2.5 %, and wall thickness is thin, e.g., 1/4” (6.5 mm) or lesser, for preventing oxidation in atmospheric environment by welding heat input.
However, the volume of back shielding space on inside piping by fillet welding, such as joints between run pipe and piping support or reinforcing pad, is sometimes too large to purge oxygen out with economical rationality due to limitation of place of back shielding isolations, especially during piping erection period at construction site.
Recently, non-backing gas practices with gas metal arc welding in short circuit mode (GMAW-S) [2] and gas tungsten arc welding (GTAW) [3] have been developed and implemented to single-sided butt joints of stainless steel (SS) process piping in oil and gas industries with successful results [4]. Therefore, oxidation of the fluid-contacting side can be considered as nonmaterial from a corrosion resistance viewpoint regardless of welding method and back shielding.
This paper presents study results of corrosion resistance of fillet welds on SS piping in comparison to back shielding conditions and introduces the possibility of omission of back shielding for fillet welds.