bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comprehensive Comparison Between Different Multiaxial Cycle Counting Procedure
Authors: Rovinelli Andrea , Messner Mark C. , Sham T.-L. 
Published: October 2021

Abstract
High-temperature nuclear design codes, such as Section III, Division 5 of the American ASME Boiler and Pressure Vessel Code and the French RCC-MRx, require evaluating fatigue damage for qualifying high-temperature components. Both codes provide clear guidance for counting cycles under uniaxial loading conditions, but neither provides a cycle counting procedure for multiaxial loading conditions. The ASTM E1049 also does not address multiaxial cycle counting. However, several widely utilized multiaxial cycle counting procedures are available in the open literature, but there is no agreement on the most appropriate method for high-temperature applications. Applying the different cycle counting methods to the same loading history generally produces different results. Comparisons between cycle counting procedures are available for low-temperature high-cycle fatigue but not for high-temperature low-cycle dwell-fatigue applications. This work presents an extensive comparison between different multiaxial cycle counting procedures potentially suitable for high-temperature low-cycle dwell-fatigue applications. Furthermore, how to conservatively assemble design transients to construct a loading history is also an open question. This work also investigates the uncertainty related to the loading sequence. The results guide the selection of the most appropriate cycle counting procedure, strain range metric, and cycle distribution for ASME Section III, Division 5 applications.
Evaluation of Load Reduction Effect Due to Through-Wall Crack in Surge Line Under Thermal Stratification Conditions
Authors: Kim Seung-Hyun , Park Hongsun , Kang Sun-Yeh , Kim Jong Min 
Published: October 2021

Abstract
The thermal stratification is a phenomenon in which layer is formed by density difference when high temperature fluid of pressurizer and low temperature fluid of hot leg nozzle are mixed in a surge line. A deflection and load of the surge line occurs due to thermal stratification. Therefore, the thermal stratification load is a major factor for the LBB (Leak-Before-Break) evaluation of surge line like the safe shutdown earthquake load. However, if a large amount of leakage occurs due to surge line break, the resulting load decreases because the crack itself and the plasticity around the crack region affect the load distribution of piping system. This load reduction effect is able to secure additional margin in LBB evaluation. The object of present study is to evaluate load reduction effect under thermal stratification due to the presence of a through-wall crack in surge line of nuclear power plant. Firstly, heat transfer analyses were performed under thermal stratification of surge line using FE (Finite Element) solid model. Secondly, the elastic-plastic analyses of FE model with a through-wall crack were performed by using the temperature distribution of surge line, and the reduced LBB loads due to the thermal stratification were derived. Finally, effect of load reduction and thermal stratification disappearance due to the leakage crack were evaluated and compared.
Vibration-Assisted Friction Stir Welding of AA 2024-T3 Plates
Authors: Sabry Ibrahim , Mourad Abdel-Hamid I. , Thekkuden Dinu Thomas 
Published: October 2021

Abstract
In this research, the weldability of AA 2024-T3 plates using vibration-assisted friction stir welding (VaFSW) is primarily inspected. The vibration imparted to the fixture holding the specimens in VaFSW differentiates this state-of-art process from the conventional friction stir welding (FSW) technique. For large-scale welding applications, it is ideal to vibrate the tool with the required amplitude and frequency for optimum performance. Due to limitation in applying vibration to the tool in a milling machine, the vibration is imparted to a custom-designed fixture and rig setup. The fixture, which holds the plates rigidly, is mechanically shaken during the friction stir welding process to boost the material strain in the weld region. The VaFSW is performed with 1800 rpm tool rotational speed, 16 mm/min travel speed and at four intermittent levels of vibrational frequencies (10.11 Hz, 13.56 Hz, 16.67 Hz, 25.17 Hz). The welding morphology and mechanical characteristics of joints produced using VaFSW and FSW are presented in the current work. Finally, the results of VaFSW are compared with conventional FSW. Results show that the tensile strength and, hardness in each of the zones — Nugget zone, heat affected zone, and base metal increased with the increase in the vibrational frequency in the vibration-assisted friction stir welding process. In addition, the ductility of the joints increased by the vibration in the vibration-assisted friction stir welding process due to excessive plasticized material resulting in a greater grain dislocation. Moreover, the mechanical characteristics of weld joints enhanced with the increase in the vibrational frequency. However, the tensile strength and hardness of conventional FSWed joint are slightly higher than the joint produced using VaFSW at 10.11 Hz. This study is promising for finding the capability of VaFSW over FSW to produce quality weld joints.
Review on the Current Progress of Thixoforming Process
Authors: Shitole Shubhra , Mourad Abdel-Hamid I. 
Published: October 2021

Abstract
Thixoforming is comparatively a recent semi-solid metal forming process that potentially uses the rheological behaviour of certain metals with non-dendritic microstructures. In contrast to the conventional forming process where the metals in either the solid or liquid state are subjected to a working load, the thixoforming uses a semi-solid slurry as feed material in which the non-dendritic solid particles are suspended in the liquid matrix. The thixoforming process is claimed to exhibit superior quality products by reducing the commonly observed defects such as shrinkage, porosity and macrosegration to a greater extent. As a result, many sectors have embraced the thixoforming technology such as the automotive industry for manyfacturing automotive comonet, piping systems and pistons without compromising on the efficiency. This review article focuses on the thixoforming processes for metal alloys, rheological, optimization of semi-solid slurry, potential applications, process parameters, heat treatment, advantages and disadvantages, and future scope.
Technical Basis for Increased Inspection Interval of Cold Leg Pressurized Water Reactor Dissimilar Metal Welds Using xLPR
Authors: Lohse Chris , Shim Do Jun , Dedhia Dilip , Dutta Rohan , Glunt Nathan 
Published: October 2021

Abstract
Alloy 82/182 Dissimilar Metal (DM) butt welds have been the subject of significant work due to their susceptibility to primary water stress corrosion cracking (PWSCC). The current rules for inspection of DM butt welds are contained in ASME Code Case N-770 (latest revision). These rules are based on crack growth rates that were originally published in MRP-115 in 2004. Since that time significant work has been performed to better understand the crack growth behavior of Alloy 82/182 materials in pressurized water reactors (PWRs) and updated crack growth rates have recently been published in MRP-420 (Rev. 1). These updated crack growth rates show a significant difference at lower temperatures which line up with the cold leg temperatures for PWRs (approx. 540–560°F). Additionally, the US Nuclear Regulatory Commission (NRC) working along with the Electric Power Research Institute (EPRI) recently released the xLPR computer code which is a probabilistic fracture mechanics code for evaluating DM butt welds. This paper evaluated various cold leg DM butt welds for PWRs using the xLPR probabilistic computer code to determine if a change in the frequency between inspections for unmitigated DM butt welds (Item B-1) from their current requirements in ASME Code Case N-770 is warranted. Failure probabilities were determined for the current technical basis using MRP-115 crack growth rates (with the current inspection duration) and compared to the probabilities using the new crack growth rates in MRP-420, Rev. 1 (with increased inspection durations). The evaluation results demonstrate that the duration between volumetric examinations for small and medium diameter DM butt welds from Code Case N-770, Inspection Item B-1, can be safely increased to once per 10-year ISI interval from the current requirement of once every 7 years when the specific requirements described in this paper are met.
Limit Loads of Bolted Flange Connections
Authors: Kirkemo Finn , Lutkiewicz Przemyslaw 
Published: October 2021

Abstract
High-pressure applications such as process piping, pressure vessels, risers, pipelines, and subsea production systems use bolted flange connections. Design of flanged joints may be done by design by rules and design by analysis. This paper presents a design by rules method applicable for flanges designed for face-to-face make-up. Limit loads are used to calculate the structural capacity (resistance) of the flanges, bolts, and metallic seal rings. Designers can use the calculation method to size bolted flange connections and calculate the structural capacity of existing bolted flange connections. Finite element analyses have been performed to verify the analytically based calculation method. The intention is to prepare for an ASME code case based on the calculation method presented in this paper.
Microstructural Based FEM-Calculation of Stress/Strain Fields in Steel AISI 316L and Its Validation by Digital Image Correlation
Authors: Niffenegger M. , Herrera Solaz V. 
Published: October 2021

Abstract
The prediction of damage mechanisms, such as fatigue in e.g. piping, requires the consideration of the microstructure because crack initiation starts at the grain level. Therefore, it is important to know the local strain/stress state, which due to the misorientation of neighboring grains, can reach significantly higher values than the nominal (macroscopic) ones. A finite element model for the calculation of stresses and strains as well as the formation of crack networks, based on the measured anisotropic microstructure of austenitic stainless steel, was developed at Paul Scherrer Institut (PSI). This mesoscale model (SNF) uses the sizes and crystallographic orientations of the grains, measured with 2- or 3-dimensional electron backscatter diffraction (EBSD) to generate a representative volume element (RVE) of the material. The anisotropic elastic properties and the anisotropic plastic behavior of each single crystal of the RVE, defined through the evolution of shear deformation in the slip plane with the highest Schmid factor, is considered. The corresponding single crystal properties have been preliminary determined by a standard tensile test followed by an inverse analysis procedure (Levenberg-Marquardt algorithm).
The SNF code uses a four-parameter damage model for crack initiation and growth and is based on the accumulated inelastic hysteresis energy. Besides the calculation of local stresses and strains in the microstructure, this model allows the calculation of high (HCF) and low cycle fatigue (LCF) lifetime and to perform sensitivity studies, e.g. to analyze the influence of grain sizes and orientation or multiaxial loading on the stress-strain curves.
The local strains in the microstructure, calculated by the SNF model, were validated by the crystal plasticity finite element (CPFEM) code CAPSUL and by measurements with a digital image correlation system (DIC). Good agreement between strains evaluated with these three different methods was observed up to nominal strains of about 4%. The analyses have shown that local strains can be up to a factor 2 higher than the applied global strain.
Furthermore, aspects such as the influence of 2D or 3D EBSD data and the approximation with corresponding columnar, synthetic or real grain geometries with finite elements (FE) on the accuracy of the calculated strains are also discussed.
Prediction of J-Integrals at Defects in W-9CR Steel Sandwich-Type Cooling Pipes
Authors: Calvet Tristan , Wang Yiqiang , Pham Minh-Son , Davies Catrin M. 
Published: October 2021

Abstract
Sandwich-type cooling pipes of the first wall of future fusion nuclear reactors (i.e. DEMO) will likely consist of tungsten brazed to a Reduced Activation Ferritic Martensitic (RAFM) steel. Under a high heat flux (HHF) (1–5 MW/m2) the mismatch in thermal expansion between tungsten and steel results in significant thermal stresses in the brazing region. These stresses can cause crack initiation and growth and thus compromise the structural integrity of such pipes. Finite element analyses have been performed on the brazed joints of a reference cooling assembly under HHF. Thermal stresses and resulting plastic strains were estimated for both the braze interlayer and parent materials. As images of brazed joints revealed, brazing processes are very likely to induce defects near the edges of the joints. A crack is therefore introduced in the brazed region where simulated stresses and strains are found to be the highest. J-integrals were calculated for cracks growing from an edge to the center of the considered piping assembly. The results are discussed in relation to the current sandwich-type piping design of the DEMO reactor.
Negative R Fatigue Short Crack Growth Rate Testing on Austenitic Stainless Steels
Authors: Griffiths Adam , Gill Peter , Coult Ben , Beswick Jack , Platts Norman , Mann Jonathan , Currie Chris , Airey Joe 
Published: October 2021

Abstract
The effect of an LWR environment on fatigue life is currently assessed using methods (such as NUREG/CR-6909) that may be excessively conservative when applied to plant components and loading transients. To reduce this conservatism, the ASME Working Group for Environmental Fatigue Evaluation Methods (WG-EFEM) has proposed the development of an improved assessment methodology for environmental fatigue based on a Total Life Prediction approach that would be adequately, but not excessively, conservative. Such an approach necessitates the development of analytical methods for the various stages of crack nucleation, short crack growth and long crack growth. Hence, there is a requirement to undertake testing within the short crack growth regime that would bridge the gap between fatigue nucleation and long crack growth (Paris Law) enabling better prediction of total life measured by fatigue endurance.
Previous negative R long crack growth testing using corner-crack specimens measured the effects of crack closure under compressive loading, and has been used to address some of the conservatism in existing assessment methods. This methodology has been developed further to enable negative R short crack growth testing with in-situ monitoring using DCPD. Testing has been undertaken in both high temperature air (300°C) and a simulated PWR primary water chemistry at 300°C on both cold-worked and non-cold-worked stainless steel specimens at a load ratio of R = −1. One heat of stainless steel has been tested, with another heat of different grain size to be tested imminently, in order to investigate the effect of grain size on short crack growth rates. FEA modelling has been undertaken to both correlate Direct Current Potential Drop (DCPD) response with crack growth measurements, and to determine the effective stress intensity factor ranges applied under the loading conditions based on the specific material properties.
This paper describes the methodology and findings from this negative R short crack growth test programme. Crack growth rates have been compared to ASME Code Sec. XI and Code Case N-809 reference curves and results from material specific in-house testing to assist the understanding of the behaviour of mechanically short cracks.
Prediction of Residual Stresses and Stress Intensity Factors in Fracture Mechanics Samples Manufactured by Laser Powder Bed Fusion
Authors: Fielden Michael , Davies Catrin M. 
Published: October 2021

Abstract
Laser Powder Bed Fusion (LPBF) is an effective form of additive manufacturing, but generates large residual stresses in the components which can be detrimental to their structural integrity and hence require quantification. Thermo-mechanical simulations of the build process of single edge notched fracture mechanics samples manufactured by LPBF from 316L stainless steel powder in horizontal & vertical orientation were developed in ABAQUS. The models examined the influence of crack introduction methods and specimen build orientation on crack tip stress distribution, to determine their potential effect on fatigue crack growth behavior. Contour plots of residual stresses show significant relaxation upon sample removal from the base plate in the horizontal samples due to the geometry of the component. Relaxation was observed in vertically orientated samples but to a much lesser extent and maximum principal stresses of around 400 MPa remained near the crack tip. It is concluded that residual stresses can be neglected in horizontally built samples of these dimensions, however residual stresses need careful consideration in vertically built samples.
Investigation of Highly Sensitive 3D-Printed Liquid Sensors Using Response Surface Methodology
Authors: Aliheidari Nahal , Ameli Amir 
Published: October 2021

Abstract
Traditional conductive polymer nanocomposite (CPN) liquid sensors have been studied for many years. However, they suffer from low sensitivity due to insufficient surface area and access points to the solvent. With increasing demand for highperformance smart sensors, the traditionally fabricated liquid sensors need major improvements in their performance. By introducing fused filament fabrication (FFF) smarter and environmentally friendlier parts can be made. The integration of FFF and CPN can provide increased degrees of freedom in the design and fabrication of liquid sensors.
In this work, design, 3D printing, and characterization of thermoplastic polyurethane/carbon nanotube (TPU/CNT) nanocomposites in response to acetone, toluene, and ethanol as solvents were conducted using a central composite design (CCD). CNT content, infill density, printing pattern, and solvent type were chosen as input factors and the sensor sensitivity was considered as the dependent response.
Response surface methodology (RSM) was employed to systematically assess the main effects and their quadratic terms and the two-way interactions of input parameters and identify the significant factors. The results showed that the solvent type, infill density, and CNT content are very significant factors while the infill pattern does not have a significant effect on the sensor sensitivity. The two-way interactions between the infill*solvent and CNT*solvent were found to have a P-value in the range of 0.05 and 0.1. A reduced model which offers a significant level of simplicity can be used to statistically describe the response behavior for further studying, design, and optimization of the sensors.
A Lumped Parameter Electro-Mechanical-Fluid Coupling Model for an Oscillating Beam in Fluids
Authors: Shan Xin , Bilgen Onur 
Published: October 2021

Abstract
A beam bonded with a Macro-Fiber Composite actuator can generate transverse deformations, enabling mechanism-free flapping wings and underwater oscillating fins. A piezocomposite beam can be actuated harmonically by a resistance-inductor-capacitor resonator, and interact with ambient fluid to yield flow vectoring, control, and/or propulsion. In this paper, an electro-mechanical-fluid coupled model is developed to obtain insight into the coupling mechanism, and provide guidance to investigate the system optimal parameters. To give prominence to the coupling mechanisms, the system is simplified to a lumped parameter model. The electromechanical coupling is modeled as a transformer, and the fluid-structure interaction is represented by the added mass and added damping effects, which are determined by solving linearized Navier-Stokes equations. The coupled model is converted into a transfer function, where the system input is voltage, and the output is displacement. A case study is conducted based on the coupled model, and important system properties are revealed.
No plate tectonics necessary to explain Eoarchean rocks at Isua (Greenland)
Authors: Rollinson Hugh 
Published: October 2021

Abstract
Trace element and isotopic data for basalts from the Isua greenstone belt, West Greenland, indicate that they were derived from a range of mantle reservoirs that included depleted lower mantle, the mantle transition zone, and a primitive mantle reservoir probably located in the shallow upper mantle. Modeling of trace element compositions indicates that the Isua basalts were formed through the mixing between and refertilization of these diverse sources and their resultant melts and that this took place in the shallow upper mantle. It is proposed that the melting and mixing were driven by the heat transferred from hot deep mantle sources. This geochemical interpretation leads to a geodynamic model in which deep mantle domains rise to melt in the shallow mantle where there is mixing between a range of sources and melts. There is no evidence for material descending from the shallow to deeper mantle and no necessity for the involvement of crustal materials. These processes imply the activity of a mantle plume and/or heat pipe.
Formation of low-gradient bedrock chutes by dry rockfall on planetary surfaces
Authors: Sun Zhongheng , Ulizio Thomas P. , Fischer Jade N. , Levin Janette N. , Beer Alexander R. , Dickson James L. , Lamb Michael P. 
Published: October 2021

AbstractChannel-like forms are ubiquitous on steep hillslopes on Earth, Mars, and other planetary bodies. On Earth and Mars, these landforms are commonly attributed to water activity, especially for slopes below the angle of repose (∼30°) where dry granular flows are considered ineffective. While the angle of repose characterizes loose sediment stability, it is unclear whether dry rockfall can traverse and erode channels in bedrock or cemented substrates. We used a large-scale experiment to show that bedrock chutes can form spontaneously at low gradients from dry rockfall. Our results, combined with observations of rocky outcrops and boulders on Mars, indicate that rockfall can be an important bedrock degradation process that can produce low-gradient channels in the absence of water.
Focused fluid-flow structures potentially caused by solitary porosity waves
Authors: Yarushina Viktoriya M. , Wang Lawrence Hongliang , Connolly David , Kocsis Gábor , Fæstø Ingrid , Polteau Stephane , Lakhlifi Assia 
Published: October 2021

AbstractGas chimneys, fluid-escape pipes, and diffused gas clouds are common geohazards above or below most petroleum reservoirs and in some CO2 storage sites. However, the processes driving the formation of such structures are poorly understood, as are the time scales associated with their growth or their role as long-term preferential fluid-migration pathways in sedimentary basins. We present results from a multidisciplinary study integrating advanced seismic processing techniques with high-resolution simulations of geological processes. Our analyses indicate that time-dependent rock (de)compaction yields ascending solitary porosity waves forming high-porosity and high-permeability vertical chimneys that will reach the surface. The size and location of chimneys depend on the reservoir topology and compaction length. Our simulation results suggest that chimneys in the studied area could have been formed and then lost their connection to the reservoir on a time scale of a few months.