bluuebunny/crossref_metadata_2025_split huggingface dataset:
Test Protocol Definition to Measure Fracture Toughness J-Parameter Using Non-Standard Four-Point Bending Specimens
Authors: Ferreira Denis Alves , Pascualinotto Junior Vagner , Sarzosa Diego F. B. 
Published: October 2020

Abstract
This work proposes a new test methodology to characterize the fracture toughness values for either brittle or ductile materials, such as steels of risers and pipelines used in the oil and gas industry by using non-standard four-point bending specimens. Four-point bending (4PB) specimens show to be reliable configuration to characterize fracture toughness values. The methodology involves obtaining compliance equations, stress intensity factors, the proportionality factors between the deformation energy and J-integral, known as η-factor. This study evidences the impact of geometry variation on the crack-tip constraint. Laboratory tests were performed with four-point bending specimens. These experiments were compared with experimental data of standardized geometries SE(B) and SE(T). The results from the preliminary experimental campaign validated the numerical analysis. Thus, the proposed equations can be used to obtain the fracture toughness values using four-point bending specimens.
Bounding Acoustic Load Development for Boiling Water Reactor Shroud and Shroud Supports
Authors: Walter Matthew , Qin Minghao , Sommerville Daniel 
Published: October 2020

Abstract
As part of the license basis of a nuclear boiling water reactor pressure vessel, a sudden loss of coolant accident (LOCA) event needs to be analyzed. One of the loads that results from this event is a sudden depressurization of the recirculation line. This leads to an acoustic wave that propagates through the reactor coolant and impacts several structures inside the reactor pressure vessel (RPV). The authors have previously published a PVP paper (PVP2015-45769) which provides a survey of LOCA acoustic loads on boiling water reactor core shrouds. Acoustic loads are required for structural evaluation of core shrouds; therefore, a defensible load is required. The previous research compiled plant-specific data that was available at the time. Since then, additional data has become available which will add to the robustness of the bounding load methodology that was developed. Investigations are also made regarding the shroud support to RPV weld, which was neglected from the previous study. This will allow a practitioner a convenient method to calculate bounding acoustic loads on all shroud and shroud support welds in the absence of a plant-specific analysis.
Ductile Tearing Prediction of Ferritic Pipe Material by GTN Model for ATLAS+ European Project
Authors: Hojo Kiminobu , Hirota Takatoshi , Ogawa Naoki , Kumagai Satoshi 
Published: October 2020

Abstract
The main objective and mission of the European project ATLAS+ (Advanced Structural Integrity Assessment Tools for Safe Long Term Operation) are to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems. This project includes the development and validation of advanced simulation tools based on fracture mechanics methods using physically based mechanistic models. In the Work Package 3 (WP3), benchmark calculations using different available models are conducted to investigate the accuracy and the capability of the different models for ductile crack growth of different constraint condition, such as laboratory specimens and piping structure, which were tested in the Work Package 1 (WP 1). The authors joined the WP3 activity and investigated the effect of the parameters of the GTN (Gurson-Tvergaard-Needleman) model on the fracture behavior of the specimens. In this paper, the parameters of the GTN model were calibrated to simulate the fracture behavior of CT specimens, notched tensile (NT) specimens and single edge notched tensile (SENT) specimens of ferritic pipe material and the applicability of the GTN model. The adjusted parameters by the CT specimen predicted the fracture behavior of the SENT specimens, but did not those of the NT specimens. The adjusted parameters by the CT specimens were applied to the piping structure mock-up and they predicted the maximum load in high accuracy.
A Parametric Study of Variable Crack Initiation Criterion in XFEM on Pipeline Steel
Authors: Lin Meng , Li Yong , Salem Mohammad , Cheng J. J. Roger , Adeeb Samer , Kainat Muntaseer 
Published: October 2020

Abstract
The integrity decisions for cracked pipelines can be made based on the conventional Finite Element Method (FEM). However, it is extremely time-consuming due to the requirement of remeshing to continuously conform to the geometric discontinuities as the crack propagates. The more recently developed Extended Finite Element Method (XFEM) provides a more robust approach in which a crack can propagate through the finite element analysis mesh and thus alleviates the requirement for remeshing. However, the current criteria for crack initiation and propagation in XFEM framework have not been calibrated to pipeline steels. The current built-in criterion in Abaqus assumes a fixed value as the damage strain. Crack initiation occurs after this strain is exceeded. However, the accuracy of numerical crack propagating path is questionable, especially in a side-grooved single edge notched tension (SENT) model. Faster crack initiation at specimen side over the center conflicts with the actual crack propagating path obtained from a physical test. This paper develops a new crack initiation criterion which defines a variable damage strain as a function of the stress configuration at the crack tip. The criterion is modified from the Mohr-Coulomb fracture criterion as a function of stress triaxiality and Lode angle parameters. The damage strain exponentially decreases as the stress triaxiality increases. This paper presents a parametric study on the effects of material parameters considered in the criterion on the development of damage strain locus. The new crack initiation criterion is applied to a side-grooved SENT model, in which the corresponding failure mechanism is defined by the user’s subroutine UDMGINI in Abaqus.
Stored Elastic Strain Energy of Pressure Vessels and Their Consequential Effect on High Speed Projectiles
Authors: Kumar Abhimanyu , Kim Minsu , Wesevich James , Dereli Ozer , Ozbey Mehmet C. 
Published: October 2020

Abstract
The technological development of pressure systems is closely associated with the growth of various technologies in petrochemical, oil services, power, and aerospace industry. The closed boundary system such as a pressure vessel, pipe, tube, and barrel, in which an unforeseen ill design or installation imbalance between interior and external pressure conditions can result into a hazardous situation, and an unexpected catastrophic failure of the system. These accidental failures most likely lead to escalation of events due to hazardous projectiles impacting the surrounding environment.
The kinetic energy contained in the projectile are dependent on the size of pressure vessel, density of the fluid (gas or fluid), and pressure of contained media. Numerous studies have shown the relationship between the contained media within the pressure vessel and fragment velocity. However, a gap still persists in regard to the effect of elastic strain energy of the vessel itself on the projectile velocity. In this study, we study the correlation between elastic strain energy of a pressure vessel and the projectile velocity. Several parameters, such as contained media, internal pressure, fluid nozzeling, volumetric expansion with respect to diameter and thickness of pressure vessel were considered to investigate their influence on the level of consequence in an accidental event. The findings of this study aim to provide important guidance for the design and operation of high pressure systems and testing.
Verification of Flange Rigidity Index for Standard Flanges Using Finite Element Analysis
Authors: Choi Junho , Kim Minsu , Dereli Ozer , Ozbey Mehmet , Wesevich James 
Published: October 2020

Abstract
A flange connection consists of the flange, gasket, bolts, and pipe. In a flange design stage, the flange rigidity index is checked to ensure the leak tightness of the flange connection. Technically, the flange rigidity index was theoretically derived by the function of flexure induced into the flange by both bolt tension and internal pressure. However, some of the factors used to calculate the flange rigidity index were determined by regression formulas. On the other hand, the rotation angle of the flange is also limited to determine the allowable bolt pre-tension. To better understand the flange rigidity index, flange rigidity index and flange rotation angle were compared. The flange rotation angle was calculated using Finite Element Analysis (FEA). For the evaluation model, NPS 3, 6, 12, 18, 24 for classes 150, 300, 600, 900, 1500 integral-type flanges were selected. Typical gasket seating and operating conditions were considered in this study. In gasket seating condition, the required minimum bolt load was applied. In operating condition, internal pressure and uniform temperature were simultaneously applied to the FEA model. From the analysis results, it was concluded that the specified flange rigidity indexes may underestimate the leak tightness for lower pressure and large flange types.
Verification of Stress Model in Dissimilar Materials of Varying Cladded Pipes Using a Similar Cladded Plate Model
Authors: Kogo Bridget , Wang Bin , Chizari Mahmoud , Wrobel Luiz 
Published: October 2020

Abstract
This paper continues previous research performed by the authors on the modelling of dissimilar welded joints with varying clad thicknesses. This study aims to validate the use of a clad plate model as a replacement to the previous clad pipe model. To fulfill the hypothesis of the study, possible deformation or angular shrinkages occurring at weld joints have been simulated using a commercial finite element software. In parallel, angular shrinkages have been validated using the experimental data with the underlying concept of Gaussian transformation of plates into pipes. The welding of the two dissimilar materials has been carried out in-house with the aid of a Tungsten Arc weld with dynamic measurement of the temperature profile in the vicinity areas of the welding track using high temperature thermocouples. It was discovered that for each deformation angle of 11.5°, 22.75°, 40° and 45°, there exists shrinkage of the order of 0.01mm. Transient temperature curves have been generated for different cladding thicknesses (of stainless steel and mild steel). Comparison of the measured data versus the simulation results shows close agreement.
Influence of Structural Interface Opening of Bolted Joints Under Eccentric Load
Authors: Imura Makoto , Koyama Takayuki , Iizuka Motonobu , Hayasaka Yasushi 
Published: October 2020

Abstract
It is important to evaluate the safety of bolted joint under a load eccentric to a bolt axis. We examined tapped thread joints, with which a clamped plate is tightened with bolts to a base body, by applying eccentric loads to the bolts. The structural interface opening between the clamped plate and base body occurs due to the eccentric load based on the principle of leverage. During the growth of the interface opening, nonlinearity noticeably appears on the tensional and bending components of bolt stress, and these stress components become larger than expected in an early phase before a fatal bolt pull-out occurs. However, an evaluation method taking into account nonlinearity has not been investigated.
We propose a normalized-bolt-stress evaluation method for tapped thread joints that takes into account the effect of the nonlinearity of bolt stress during interface opening. We conducted numerical calculations, experiments, and finite element analyses to quantitatively validate the stress under the following conditions: (i) tapped thread joints with the clamped plate thinner than the bolt diameter and (ii) load eccentric to the bolt axis. We confirmed that the bolt preload and lever ratio should be fixed at an initial phase, in which has no interface openings for the appropriate normalization. By using the normalized-bolt-stress evaluation method, strength evaluation becomes easily applicable to layout changes of bolted joints as a similarity rule.
Continued Study on the Effect of Mean Stress on Ground Storage Vessels for Hydrogen Fueling
Authors: Peters Daniel T. , Parr Myles 
Published: October 2020

Abstract
The use of high pressure vessels for the purpose of storing gaseous fuels for land based transportation application is becoming common. Fuels such as natural gas and hydrogen are currently being stored at high pressure for use in fueling stations. This paper will investigate the use of various levels of autofrettage in high pressure storage cylinders and its effects on the life of a vessel used for hydrogen storage. Unlike many high-pressure vessels, the life is controlled by fatigue when cycled between a high pressure near the design pressure and a lower pressure due to the emptying of the content of the vessels. There are many misunderstandings regarding the need for cyclic life assessment in storage vessels and the impact that hydrogen has on that life. Some manufacturers are currently producing vessels using ASME Section VIII Division 1 to avoid the requirements for evaluation of cylinders in cyclic service. There are currently rules being considered in all of ASME Section VIII Division 1 and Division 2, and even potentially for Appendix 8 of ASME Section X. Recommendations on updating the ASME codes will be considered in this report.
Acoustic Emission Characterization of Damage Patterns in Composite Scarf Joints Using Unsupervised Learning
Authors: Xu D. , Chen Z. P. , Liu P. F. , Wu J. H. , Jiao P. , Gu Y. N. 
Published: October 2020

Abstract
Interest in damage detection and damage pattern recognition of engineering structures by non-destructive techniques has been increasingly growing. As a non-destructive technique, acoustic emission (AE) has developed rapidly to detect dynamic defects and their evolution behaviors of composite structures, based on the transient elastic waves produced by rapid energy release due to the geometry change of structures. In this paper, AE technology is utilized to monitor the real-time condition of the composite scarf joint (SJ) under tensile loading. First, after AE signal acquisition, dimensionality reduction of eight AE features is realized by employing principal component analysis such that the Curse of Dimensionality can be avoided. Second, feature selection is continued by introducing two evaluation indexes, i.e., correlation coefficient and Laplacian score. Third, after the optimal cluster number is determined, damage pattern recognition is accomplished by introducing k-means++ algorithm which explores the distribution of each pattern in the space constructed by four informative AE features. Based on the clustering results, damage initiation and evolution in SJ specimens under tensile loading are subsequently explored. The shear failure of the adhesive layer which is a characteristic damage pattern for SJ specimens shows a relatively-high activity after the early stage. Matrix cracking and fiber/matrix interface debonding are two fundamental damage patterns which keep active in the whole process.
An Investigation Into the Robustness of a Crystal Plasticity Finite Element Model
Authors: Taylor Megan , Agius Dylan , Knowles David , Mostafavi Mahmoud 
Published: October 2020

Abstract
A crystal plasticity model has been developed for describing the plastic and viscoplastic behaviour of 316H stainless steel. The model has been used successfully to predict the macroscopic response of the material for monotonic and cyclic loading, however the robustness of the model is now being scrutinised to ensure that it captures the underlying mechanisms and local meso-scale deformation characteristics correctly. In order to look at this in more detail, the model has been scripted to allow simulation of diffraction studies on the grains. This is being used to compare the simulation output with neutron and synchrotron experiments.
A theoretical study has been completed which adjusts the values of each material parameter within the crystal plasticity finite element (CPFE) framework in isolation to analyse the effect each has upon the shape of the hysteresis loop and how this relates to predictions. A further study had been conducted to investigate the amount of scatter that is produced by altering the initial microstructure of a relatively small volume. The results show that changing the initial microstructure has a negligible effect on the subsequent stress-strain response. This indicates the influence that the grain morphology will have upon the diffraction measurements and that there is no need to consider this further when testing small specimens.
To conclude this investigation two further aspects of the model have being scrutinised; the effects of constraining boundary conditions and altering the local environment of a single grain, again to explore the influences which these may have on diffraction studies. The plane boundaries of the volume are currently fixed at zero displacement which will influence the local grains on these boundaries as they are over constrained, but should not alter the overall stress-strain response. To investigate this, grains within the model that have boundary conditions applied have be discarded from the final results to leave the response from the central volume that should be free of the boundary condition effects. The results show that the macroscopic response of the bulk volume and the central volume are very similar but when the individual grain family responses are analysed, it can be seen that the boundary condition do alter the response of the representative volume element (RVE). To analyse how the local environment surrounding a single grain affects its stress-strain response, a centrally located grain will be selected and kept constant while the orientation of the surrounding grains are randomly altered. It has been found that changing the local environment surrounding a single grain will impact the stress-strain response seen by that grain.
Ultrasonic Nondestructive Evaluation of Stress Corrosion Crack in Welded Steel Plate
Authors: Ma Zhaoyun , Yu Lingyu , Lam Poh-Sang , Sindelar Robert L. , Duncan Andrew J. , Truong Thanh-Tam , Chao Yuh J. 
Published: October 2020

Abstract
Stress corrosion cracking (SCC) has been observed in the high-level nuclear waste tanks that were constructed by welding carbon steel plates. This paper aims to establish an ultrasonic inspection system and its fundamental ability for SCC inspection and quantification on thick welded steel plates. A welded steel plate was fabricated without heat treatment by joining two carbon steel plates through gas metal arc welding (GMAW) procedure. SCC growth, which was initiated with starter cracks across the weld, were observed in a few weeks after submerging the plate in 5 molar (5M) sodium nitrate (NaNO3) solution at about 90 °C. The SCC is inspected with an ultrasonic guided wave system, which employs a piezoelectric transducer for guided wave actuation and a scanning laser Doppler vibrometer (SLDV) for wavefield sensing. The measured wavefield can immediately show wave interactions with the crack. Wavefield images are further generated for the crack length quantification. To demonstrate the crack sizing capability of using the piezoelectric transducer and SLDV, the previous results from the magnetic particle test (MT) are compared. Reasonable agreement in crack length measurement is obtained with the ultrasonic test imaging technique.
Characteristics of Dynamic Loading Obtained From Braced Piping Support Under Sinusoidal Shaking Condition
Authors: Shimazu Ryuya , Tamura Ichiro , Matsuura Shinichi , Sakai Michiya , Ono Yohei 
Published: October 2020

Abstract
Loads applied to structures by means of vibration can be classified into load-controlled and displacement-controlled loads. The realistic elastic-plastic behavior of structures subjected to seismic loads is not fully understood, and the classification of the load applied to structures by means of earthquakes is unclear. The failure mode differs depending on the load classification, and thus clarifying the classification of the load applied to the structure is useful for designing the structure. This study clarified the realistic load classification of structures under an elastic-plastic response. Vibration tests were conducted using sinusoidal waves as inputs, and the elastic-plastic behavior of the piping supports undergoing buckling or fatigue failure was obtained. The maximum restoring force and the maximum deformation relationship were obtained from the envelope of the time history data of the test results. In addition, it was shown that the classification of the load could be determined from the maximum force-deformation diagram, even in cases involving buckling and fatigue. In the maximum force-deformation diagram, when the change in the ratio of dynamic restoring force to static restoring force is small, a load-controlled load is applied to the structure because the restoring force of the structure follows the change in the input wave. By contrast, when the change in the ratio of dynamic response displacement to static displacement is small, a displacement-controlled load is applied to the structure because the response displacement of the structure follows the change in the input wave.
European Project ATLAS+: Status of the WP1 Relative to the Experimental Program on Pipes and Specimens
Authors: Moinereau Dominique , Nicak Tomas , Dahl Anna 
Published: October 2020

Abstract
The 4-year European project ATLAS+ (Advanced Structural Integrity Assessment Tools for Safe long Term Operation) was launched in June 2017. One of its objectives is to study the transferability of ductile material properties from small scale specimens to large scale components and validate some advanced tools for structural integrity assessment.
The study of properties transferability is based on a wide experimental program — within the framework of work-package 1 (WP 1) — which includes a full set of fracture experiments conducted on conventional fracture specimens and on large scale components (mainly pipes).
Three materials are considered in the program: a low-alloy ferritic steel 15NiCuMoNb5 (WB36) typical from feedwater line in German PWR, an aged austenitic stainless steel weld typical (narrow gap) from EPR and a typical VVER austenitic stainless steel dissimilar weld (DMW).
Several European organizations are involved in the experimental work: EDF, CEA, Framatome, ARMINES, KIWA, Framatome GmbH, VTT, BZN, MTA-EK, and CIEMAT.