bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative Study on the Nonlinear Calculation of Ratcheting Deformation Using Different Constitutive Model
Authors: Shao Xuejiao , Xie Hai , Xiong Furui , Fu Xiaolong , Shi Kaikai , Yu Xiaohuan 
Published: October 2020

Abstract
In the fatigue assessment of nuclear components following the RCC-M B3200, if the results using the simplified elastic-plastic method cannot meet the Code’s requirements, it is necessary to conduct a detailed elastic-plastic fatigue analysis of the component. In this paper, the A-F and Chaboche nonlinear kinematic hardening constitutive models are used to conduct an elasto-plastic fatigue analysis for a typical nozzle component, aiming to calculate the secondary cumulative cyclic plastic strain of the structure induced by the rapid temperature change transient.
The calculation method of nonlinear ratcheting behavior under cyclic loading is studied. The method of determining the parameters of constitutive model based on cyclic stable stress-strain curve is also studied. A sensitive study of the parameters for the same constitutive law is presented, including the results of cumulative plastic strain. The ratcheting behavior simulation calculated by different constitutive models are compared. The results show that the A-F model has a conservative prediction of ratcheting behavior as the dynamic recovery term is too strong. It was found that the Chaboche constitutive model is the better methodology for ratcheting analysis.
In order to evaluate the bearing ability of the section, the membrane strain and bending strain is obtained by linearizing the node strain along the cross section. The ratios of membrane strain and membrane plus bending strain to total strain are calculated, which is helpful to determining the limit criteria for the cumulative strain of structures.
FEM Stress Analysis and Leakage Behavior of Pipe-Socket Threaded Joints Subjected to Bending Moment and Internal Pressure
Authors: Nagata Satoshi , Fujita Shinichi , Sawa Toshiyuki 
Published: October 2020

Abstract
This paper is a report of the studies on the mechanical behaviors and leakage characteristics of pipe-socket threaded joints subjected to bending moment as well as internal pressure by means of experimental tests and finite element simulations. The paper dealt with the 3/4″ and 3″ joints, and the joints for both sizes have two different combinations of thread types in the pipe and socket, i.e. taper-taper thread combination or taper-parallel one, respectively. Experimental bending leak tests showed that the taper-taper joints could retain internal pressure under bending load up to nearly plastic collapse. The taper-parallel joints, however, could hardly keep internal pressure against bending moment even the sealing tape was applied to enhance the sealing performance. Finite element analysis was carried out to simulate those bending tests, especially to clarify the deformation and the stress distribution in the engaged threads in detail. The analysis demonstrated that the sealing performance of the joints highly depend on the contact conditions not only at the thread crest to thread root but also in between flank surfaces. A complicated leak path across the engaged threads under bending moment was identified by the simulation.
Effect of Hydrogen Content in Natural Gas Blend on the Mechanical Properties of a L485-MB Low-Alloyed Steel
Authors: Ez-Zaki Hamza , Christien Frederic , Bosch Cédric , Briottet Laurent , Bertin Maxime , Levasseur Olivier , Leriverain Alain 
Published: October 2020

Abstract
The purpose of the present work is to study the effect of the hydrogen content in a H2-NG (Natural Gas) blend on the mechanical behavior of a C-Mn low alloy steel L485-MB (NF EN ISO 3183) under monotonic loading. Different testing conditions were explored for the blend: 2% H2-NG, 25% H2-NG, 100% H2 and 100% NG at a total pressure of 8.5 MPa using two slow strain rates: 10−4 s−1 and 10−6 s−1. Tests in the blend were compared to those under pure hydrogen at the same partial pressures. Furthermore, two surface roughnesses have been explored, one corresponding to a mirror polish, the other as lathed. The embrittlement has been assessed by necking measurements and fracture analysis for the whole testing conditions. The results show a drop of ductility with the increase of partial pressure of hydrogen in NG. Besides, no significant effect of hydrogen were observed on flow stress. In addition, the L485-MB pipeline steel presents a shear type fracture mode in high partial pressure of hydrogen, whereas a cup and cone type fracture were observed in air, NG and low partial pressure of hydrogen in NG (0.2 MPa H2).
A New Proposal to Obtain the CTOD Fracture Parameter for Offshore Pipeline Steels by Using Only One Clip Gage
Authors: Silvestre Marcus Nathan , Sarzosa Diego F. B. , Hertelé Stjin 
Published: October 2020

Abstract
The production and exploitation of oil and natural gas reserves environmentally challenging regions imposes many technological challenges related to new design requirements. Engineering Critical Assessment (ECA) is an umbrella term for complex methodologies used o assess the criticality of defects in welded structures. ECA is commonly used for oil and gas industry to derive tolerable defect sizes during installation and operation of risers. Current standardization efforts make extensive use of single edge notch tension (or SENT) specimen to reduce the level of conservatism during the assessment. A great effort has been made to evaluate CTOD as a mean to assess fracture toughness, especially for offshore structures. The double clip gage method (DCGM) is an alternative CTOD test method, which produces less conservative values comparing with J-integral conversion into CTOD. In this paper, a novel CTOD definition is developed according to the philosophy of the DCGM, but requiring a single clip gauge and providing values similar to the J-integral converted CTOD. Further details need to be validated and studied to increase the applicability of the previous proposal. So, motivated by the earlier explanation, the goal of this paper is to present a new methodology to estimate the CTOD using geometrical relationship on crack opening displacement over the crack flank.
Rapid Prediction of High-Temperature Properties of Furnace Tube Alloys Using Deep Learning Approaches
Authors: Xiang Shulin , Chen Tao , Fan Zhichao , Chen Xuedong , Wu Zhigang , Lian Xiaoming 
Published: October 2020

Abstract
With the development of Materials Genome Initiative (MGI) and data mining technology, machine learning (ML) has emerged as an important tool in the research of materials science. For the heat resistant alloys used in furnace tubes, the rapid prediction of the high-temperature properties is critical but difficult until now. In this work, the ML method based on the deep learning algorithm is developed to establish the direct correlation between microstructure inputs and output stress rupture properties of Fe-Cr-Ni based heat resistant alloys. Two simple convolutional neural networks (CNN) and the complex network with VGG16 architecture are implemented and evaluated. The simple CNN and VGG16 models are trained from scratch and pre-trained, respectively. Due to the relatively few training samples in the dataset, the data augmentation configuration and the improved architecture are effective to mitigate overfitting in simple CNN models. The result also shows that in the case of transfer learning, the features extracted from other datasets can be used directly to this new visual task. It is demonstrated that both the simple CNN and VGG16 models reach the high prediction accuracies (more than 90 %) of high-temperature properties with a wide range of microstructures. In addition, the good prediction performance achieved in the small dataset also reveals the deep learning approaches can be used to construct powerful vision models in engineering practice, where very limited data is the common situation.
Development of Stress Intensification Factors for Collared Type Piping Joints
Authors: Ewing Cameron 
Published: October 2020

Abstract
Stress Intensification Factors or SIFs allow piping to be analyzed using beam theory, with a SIF representing local effects of specific piping geometry. However, the current piping codes do not explicitly provide SIFs for collared type piping joints for use in pipe stress calculations.
The objective of this paper is to describe the methodology on how a finite element analysis (FEA) was to model the behavior of collared joints, and to ultimately develop appropriate SIFs that can be used in pipe stress analyses.
This paper describes a real-life analysis example on collared joints installed on a set of existing fuel transfer lines. The lines, which ranged in size from DN200 to DN350, were concrete lined carbon steel with the collars fillet welded to the carbon steel section of the piping.
Test coupons cut from existing pipe-collar sections were tested in a laboratory to determine the forces required to break the collar welds. Using FEA, the same test coupons were modelled to replicate the failure tests.
Multiple iterations were undertaken to determine an appropriate bi-linear stress-strain curve fit for the weld material. The curves of different weld electrode materials were considered. The curve which lead to results similar to those observed in physical testing was selected. From this, a failure stress across the weld could be determined. This stress, 435MPa was then used in subsequent models to determine the point at which the weld fails under bending loads. Multiple tests were analyzed to allow for possible effects of inclusions and voids.
Finite element models of the collar geometries were constructed and non-linear analyses were undertaken using the weld strengths determined from the coupon testing data. A simple cantilever type arrangement with a point load at one end was analyzed, inducing a bending moment across the collar.
The peak stress resulting from the bending moment across the collar weld at the center of the cantilevered pipe arrangement, was investigated across various pipe diameters, wall thicknesses, weld sizes and collar geometries.
Based on the results, a relationship between the pipe geometry and SIF was developed. Hence a pipe stress model of the transfer lines could ultimately be developed using these SIFs to predict the behavior of the piping.
GRP Composite Pipe Elbows Subject to an Internal Pressure and In-Plane Bending: An Experimental Study
Authors: Ellul Grech Brian , Dimech Michael A. , Camilleri Duncan , Muscat Martin 
Published: October 2020

Abstract
The use of polymer composite materials in the piping industry is increasingly gaining popularity. However, the design rules of these novel materials are relatively more complex and high safety factors are applied, requiring costly experimental validation. Experimental tests on e-glass reinforced polymer (GRP) pipe elbows is limited and in view of these challenges, this study presents a set of experimental results obtained from a series of pressurization and in-plane bending tests of polyester pipe elbows reinforced with e-glass chopped strand and woven roving mats. Details of the specimen manufacturing procedure, testing fixture and loading setup, are also given. A data acquisition system was setup to control, monitor and record the applied loads, the resulting meridional and hoop strains around the mid-plane of the elbows. A total of 3 specimens were tested where the first specimen was subject to an increasing positive pressure until global failure and was used to serve as a benchmark for the other two specimens. The latter were similarly subject to a positive pressure limited to the first-ply-failure load region established from the initial test. Both specimens were unpressurized and then subjected to a two cycle opening and unloading in-plane bending moment. Results show that the GRP pipe elbows were capable of sustaining loads beyond the identified failure initiation and successive bending cycles produced pipe elbow stiffening effect.
Fatigue Assessment of Installed Thermowells: Fatigue Stress Evaluation Based on In-Situ Vibration Measurements and Dedicated Models
Authors: van Beek Pieter 
Published: October 2020

Abstract
For measurement of the gas temperature inside process piping, temperature sensors are installed in a thermowell. In most cases these cylindrical thermowells are installed perpendicular to the flow direction. Declining pressures of many aging oil & gas assets results in higher gas velocities. This will increase the so-called Strouhal frequency and amplitude of the dynamic forcing at the thermowell. If the frequency of this force coincides with the installed resonance frequency of the thermowell, this can lead to fatigue failure.
The design of thermowells is comprehensively described in ASME PTC19.3 TW Code. In a recent version the excitation of the so-called in-line resonance condition was introduced, which already occurs at half the flow velocity of the original transverse resonance condition. As a result, many already installed thermowells do not pass the so-called ‘frequency criterion’ anymore. However, when all other criteria in the ASME Code are passed, the thermowell may operate at higher flow velocities, only if the fatigue stress remains acceptable.
When calculating the fatigue stress with the tools as provided in the Code, in many cases this will lead to prediction of unacceptable fatigue stresses. Therefore, here a more detailed fatigue assessment method has been developed. It consists of in-situ vibration measurements at the tip of the thermowell and a numerical evaluation with a detailed FE model of the installed thermowell. With this approach the fatigue stress is then calculated and judged against a fatigue limit.
In the meanwhile, this detailed assessment method has been successfully applied to numerous high pressure, gas filled installations. In most cases this led to acceptable fatigue stresses and preservation of the desired gas production profiles.
Research and Development of Three-Dimensional Isolation System for Sodium-Cooled Fast Reactor: Part 6 — Development of High Speed Oil Damper for Isolated Building
Authors: Fukasawa Tsuyoshi , Somaki Takahiro , Miyagawa Takayuki , Uchita Masato , Yamamoto Tomohiko , Miyazaki Masashi , Okamura Shigeki , Fujita Satoshi 
Published: October 2020

Abstract
The design of seismically isolated structures has been required not only for damping devices with large damping capacities but also for those with high allowable velocities. This is because the seismic response assessment has been conducted using various ground motions, with high acceleration levels, to increase the structural integrity of buildings and components. However, the research focused on increasing the allowable velocity remains to be largely limited because the research involves a testing machine problem as well as a technical problem to increase the allowable velocity.
To solve these problems, the authors have developed a new oil damper for seismic isolation buildings with an allowable velocity that is two times higher than commercially available oil dampers, which is the largest damping capacity class in Japan, using the test machine with one of the largest dynamic loading performance in the world. This paper demonstrates the availability of the proposed oil damper through the following items:
The first is to clarify the damping force characteristics on the basis of the test results up to the maximum input velocity of 2.7 m/s. The second is to present the analytical model for the oil damper to apply to the seismic response analysis including the method to identify its variables. The third is to demonstrate the isolation performance through the seismic response analysis using the analytical model identified the variables obtained from the test results.
These results imply that the proposed oil damper will be able to contribute to expanding the feasible design range for the isolation technology as well as increasing the seismic safety margin of the components for SFR.
Study on the Predictive Evaluation Method of Load Acting on the Roof and Internal Components of Cylindrical Tanks by Nonlinear Sloshing
Authors: Morita Hideyuki , Takata Tomoshige , Madokoro Hideki , Sago Hiromi , Yokoi Shinobu , Yamamoto Tomohiko 
Published: October 2020

Abstract
When cylindrical tanks installed in the ground, such as oil tanks and liquid storage tanks, receive strong seismic waves, including the long-period component, motion of the free liquid surface inside the tank called sloshing may occur. If high-amplitude sloshing occurs and the waves collide with the tank roof, it may lead to accidents such as damage of the tank roof or outflow of internal liquid of the Tank. Therefore, it is important to predict the wave height of sloshing generated by earthquake motions.
Sloshing is a type of vibration of free liquid surface, and if the sloshing wave height is small, it can be approximated with a linear vibration model. In this case, the velocity-response-spectrum method using velocity potential can estimate the sloshing wave height under earthquake motions. However, if the sloshing wave height increases, the sloshing becomes nonlinear, and necessary to evaluate the wave height using other methods such as numerical analysis. Design earthquake magnitude levels in Japan tend to increase in recent years, long-period components of earthquake wave which act on the sloshing wave height also increase instead of introducing seismic isolation mechanisms. To evaluate load acting on the internal components of cylindrical tanks by nonlinear sloshing, there are few applications which quantitatively evaluated the crest impact load of nonlinear sloshing.
In order to evaluate the load acting on the internal components of cylindrical tanks, the range of applicability of the fluid flow analysis method which validated the analysis accuracy of impact load acting on the roof in a simple cylindrical tank in the past study (PVP2019-93442) is extended to cylindrical tanks with internal components.
Effect Ultrasonic Nanocrystal Surface Modification (UNSM) Treatment on Fatigue Strength of Additive Manufactured UNS S31603
Authors: Pyun Young Sik , Karimbaev Ruslan , Choi Seimi , Ro Jun Suek , Sanseong Choong Ho , Sembiring Jan , Kim Jong Seog , Amanov Auezhan , Kang Suk Hoon , Ahn Hee Sung 
Published: October 2020

Abstract
Additive Manufacturing (AM) which is also known as metal 3D printing technique is one of the promising manufacturing processes due to the capability to process a complex geometry component. This is implemented in wide range of applications in various industries such as automotive, aerospace, power plants, etc. The aging nuclear power plant components and the obsolescence of those components has become a concern in this industry, and AM has come as an alternative solution for this matter. The Board on Pressure and Technology Codes and Standards (BPTCS) and Board on Nuclear Codes and Standards (BNCS) Special Committees started to study the application of Powder Bed Fusion (PBF) technique for pressure retaining equipment made from UNS S31603. Also, later Korean International Working Group (KIWG) was also started a Task Group on Additive Manufacturing for Valves which focusing on Powder Bed Fusion (PBF) and Direct Energy Disposition (DED) process for pressure-retaining valve manufacturing especially for nuclear power plant application with the same material. However, the poor mechanical properties and performance, especially fatigue strength of AM materials become a concern due to the defects and flaws as the results of layering and multiple interfaces and welding related discontinuities. In this study, the fatigue strength of PBF and DED manufactured and Ultrasonic Nanocrystal Surface Modification (UNSM) treated UNS S31603 austenitic stainless steel was investigated.
Evaluation of Crack Growth Rate of Neutron Irradiated Austenitic Stainless Steels at High Stress Intensity Factor Levels
Authors: Seto Hitoshi , Koshiishi Masato , Tanaka Shigeaki , Obata Ryoji 
Published: October 2020

Abstract
Crack growth rates (CGRs) at high K levels (more than 30 MPa·m0.5) were obtained in simulated boiling water reactor normal water chemistry under constant K conditions for Type 316NG stainless steel irradiated up to 2.0 dpa. Valid CGRs were obtained even at high K conditions such as K ≈ 40 MPa·m0.5 although branching was observed on the fracture surface of the specimen after CGR testing. CGRs were compared with predictions by a theoretical model and a disposition curve and it was found that these predictions are applicable even to high K levels around K ≈ 40 MPa·m0.5.
Analysis of Seismic Experiment of Hexagonal Multi Bundle Model Using Core Assembly Mock-Up
Authors: Iwasaki Akihisa , Matsubara Shinichiro , Harada Hidenori , Yamamoto Tomohiko 
Published: October 2020

Abstract
The fast reactor core is composed of hundreds of core elements that stand independently on the core support plate, but does not have support to constrain vertical displacement in order to avoid effects such as thermal elongation. When the earthquake occurs, the group vibration behavior is shown, including the rising of core elements in vertical direction, the collision with adjacent core elements in horizontal direction, and the fluid structure interaction. The three dimensional core group vibration analysis code (REVIAN-3D) was constructed to evaluate them. In the case of fast reactor cores in Japan, the horizontal displacement of core elements at the outermost periphery is restricted by the core former (core barrel). However, since there is no core former in fast reactors other than Japan and the boundary conditions are different from those in Japan, the vibration behavior also differs.
In this study, to grasp and estimate the group vibration behavior with and without a core former under the earthquake motion, seismic experiment of hexagonal multi bundle model using core assembly mock-up was conducted [1]. These test results show that the horizontal displacements are larger and impact force between pads of core assembly mock-up is smaller without the core former. In this paper, the analysis was verified by group vibration tests with and without a core former.
Uplift Deformation of the Bottom Plate of the Cylindrical Shell Tanks Under Steady-State Response of Tank Rocking Motion
Authors: Yoshida Yuichi , Taniguchi Tomoyo , Nakashima Teruhiro 
Published: October 2020

Abstract
The uplift phenomenon of a flat-bottom cylindrical shell tank is a long-term unsolved problem. In this study, uplift deformation of a tank bottom plate calculated by an explicit finite element analysis (refer to PVP2016-63916) is observed, and a hand calculating model based on Euler–Bernoulli beam theory is examined by comparing with the results of the numerical analysis. First, this study analyzes the results of uplift displacement and uplift width calculated by the FE analysis. Then, the results of the relationship between the uplift displacement and the uplift width are observed. Moreover, comparing the results of the maximum uplift width of a thick bottom plate case and a thin bottom plate case, trends of the maximum uplift width that depends on the thickness of the tank bottom plate are obtained.
Seconds, this study tries to verify the hand calculating model based on Euler–Bernoulli beam theory. Compering the results of the deformation of the tank bottom plate calculated by the hand calculation and the FE analysis, accuracy of the hand calculating model is examined. The comparison implies that the hand calculating model may be able to estimate uplift deformation of the tank bottom plate until the uplift displacement of the juncture reaches some height even though the geometrical nonlinearity is not considered.