bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of Tightness of Bolted Flange Connections Subjected to Combined Loads of Axial Load and Bending Moment
Authors: Kobayashi Takashi , Nogi Ryosuke 
Published: October 2020

Abstract
This paper deals with the safety evaluation of bolted flange connections subjected to combined loads of axial load and external bending moment. Bolted flanged connections sometimes experience bending moments exerted by the wind load or earthquakes under working conditions. Under these circumstances, leakage accidents may occur. Therefore, it is important to understand the sealing capacity under the combined load of axial load and bending moment.
The purpose of this study is to examine the minimum gasket stress to maintain the tightness of bolted flange connections when subjected to combined loads of axial load and bending moment. Bolted flange connections with gaskets were prepared for this purpose. The bolted flange connection was pressurized and subjected to the combined load. The pressure decays were measured with a pressure transducer and the leak rates were also measured using a mass flow meter. The relationship between the measured results and the combined load were examined and the combined load when large leakage caused was determined. The effects of gasket type and flange type were also examined.
The finite element analysis of the contact stresses of the bolted flange connection was carried out using ANSYS. The gasket stress distribution when the tightness of flange connection is lost was clarified. Summarizing the experimental and analytical results, the initial tightening force to maintain the tightness under combined load of axial load and an external bending moment is discussed.
Estimation of Uniaxial Material Properties by Miniature Small Punch Testing to Support Post-Irradiation Examination of RPV Steels
Authors: Holmström Stefan , Martin Oliver , Bakker Theo , Kolluri Murthy , Bruchhausen Matthias 
Published: October 2020

Abstract
The small punch (SP) test technique is expected to become a more common tool for estimating tensile properties since the technique has been approved for standardization and will be published early 2020 as EN-10371. The testing technique is naturally of interest in the nuclear field due to the small amount of material needed for estimating the properties of both virgin and irradiation damaged materials. In the project STRUMAT-LTO, supported within the Sustainable Nuclear Energy Technology Platform (SNETP), there is intention to use both miniature uniaxial test specimen as well as miniature SP specimen to assess the influence of high fluence irradiation on mechanical properties of the samples of the joint NRG-JRC irradiation campaign LYRA-10. The alloys represented in the irradiation campaign are variations of VVER and PWR reactor pressure vessel steels with tailor made chemical compositions. Four of the PWR model steels are tested here with miniature uniaxial specimens using the SP technique at room temperature (RT) and 100°C in as-received material state and at RT for heat treated (450°C / 40 h) material. The SP samples were extracted from used KLST (miniature Charpy) specimens. The results of this test program are expected to provide the basis for the future development of material property determination of irradiated materials.
Allowable Stress Development of Diffusion Bonded Alloy 800H for Section III
Authors: Mahajan Heramb P. , Jentz Ian , Hassan Tasnim 
Published: October 2020

Abstract
There is increased interest in the application of compact heat exchangers (CHXs) for nuclear service given their high thermal efficiency and compactness. CHXs are fabricated by joining a stack of etched plates with dense microchannels through diffusion bonding. Diffusion bonding material has basic mechanical properties that differ from a base material, requiring appropriate mechanical properties and allowable stresses for design. Existing nuclear code ASME Section III, Division 5 does not address diffusion bonded materials . Hence, there is a need to develop material properties and allowable stresses of diffusion bonded materials and weldments. In this paper, one candidate material, Alloy 800H, was selected for diffusion bonding trials. Preliminary results obtained from a series of tensile and creep tests suggest that the diffusion bonded material is weaker than the base metal 800H. These experimental data are used in determining recommended allowable stresses of the diffusion bonded 800H material. In this paper, tables of the strength reduction factors for various allowable stresses which includes Smt, So, St, Sy and Su for diffusion bonded Alloy 800H are presented. These reduction factors are applicable to CHX design. The Larson Miller Parameter (LMP) is used to extrapolate short term creep tests to longer creep life and lower temperatures, and estimate the onset of tertiary creep strain.
Mechanical and Microstructural Characterization of Diffusion Bonded 800H
Authors: Mahajan Heramb P. , Elbakhshwan Mohamed , Beihoff Bruce C. , Hassan Tasnim 
Published: October 2020

Abstract
Compact heat exchangers have high compactness and efficiency, which is achieved by joining a stack of chemically etched channeled plates through diffusion bonding. In the diffusion bonding process, compressive stress is applied on plates at elevated temperatures for a specified period. These conditions lead to atomic diffusion, which results in the joining of all plates into a monolithic block. The diffusion bonding temperatures are above recrystallization temperatures, which changes the mechanical and microstructural properties of the bonded metal. Hence, diffusion bonded material needs mechanical and microstructural property evaluation. In this study, Alloy 800H is selected to study the influence of the diffusion bonding process on mechanical and microstructure properties of base metal. A series of tensile, fatigue, creep, and creep-fatigue experiments are conducted on base metal 800H (BM 800H) and diffusion bonded 800H (DB 800H) to explore the mechanical properties. Microstructure evolution during diffusion bonding is studied and presented in the paper. The mechanical and microstructural observations indicated ductile fracture at room temperature and brittle failure with bond delamination at elevated temperatures. The microstructure evolution during diffusion bonding is studied through tensile, fatigue, creep and creep-fatigue tests, and the implied root causes for the mechanical property changes are investigated. Efforts are made to correlate the microstructure change with mechanical property change in DB 800H.
Diffracted Blast Loads Behind Structures
Authors: Geng Jihui , Thomas J. Kelly 
Published: October 2020

Abstract
An incident blast wave interacting with a building will diffract around the side walls and roof, resulting in reduced blast loads on the back wall. There is also a region behind the back wall where the blast loads will be attenuated (i.e., lower than the incident blast loads). This paper focuses on defining the attenuated blast load region as a function of the blast wave strength and building dimensions. Characteristic parameters are utilized to present the analysis results, including wave length, wave length normalized by a characteristic building dimension, and normalized standoff distance from the building back wall. Blast load adjustment factors (i.e., ratio of the diffracted to incident blast load) are used to define the blast load attenuation as a function of these characteristic parameters. The purpose of this work was to generate a database of the shock attenuation behind a structure for engineering modeling applications.
Structural Design and Stress Analysis of a Fully-Wrapped Composite CNG Gas Cylinder With Nominal Working Pressure of 30 MPa
Authors: Qin Xiaoqiang , Liang Lin , Zhang Xiaobing , Deng Guide , Liang Haifeng 
Published: October 2020

Abstract
China is the world’s largest user of compressed natural gas vehicles, with a total of nearly 6 million compressed natural gas (CNG) vehicles. The nominal working pressure of the cylinders used in the CNG vehicles in China is 20 MPa, as a result, CNG vehicles have a short range. In order to improve the range of CNG vehicles, the development of CNG vehicles with higher pressure is promoted by the CNG vehicle industry in China nowadays. In this paper, structural design of a fully-wrapped composite CNG gas cylinder with nominal working pressure of 30 MPa are carried out. The steel liner is made of 4130X seamless steel with design wall thickness of 5.9 mm, and the outer surface of steel liner is wrapped with resin based glass fiber composite material. The fully-wrapped composite adopts mixed fiber winding mode: low-angle helical winding, high-angle helical winding and hoop winding. Stress analysis and autofrettage pressure optimization of the designed composite gas cylinder are carried out with finite element method. The results show that the designed composite gas cylinder meets the requirements of ISO 11439-2013, and the best autofrettage pressure of the gas cylinder is 52 MPa after optimizing the autofrettage pressure.
Comparison of Fracture Toughness Curves Obtained by Single and Multi-Specimen Methodologies for a Pipe Having an Undermatched Girth Weld
Authors: Sarzosa Diego F. B. , Savioli R. , Ruggieri C. , Garmbis Alexandre Galiani 
Published: October 2020

Abstract
Preventing catastrophic failure of engineering components is critical during the exploration and production of oil and gas resources from the offshore deep-water fields in Brazil. Pre-salt reserves are associated with high concentration of aggregated elements to hydrocarbons, particularly carbon dioxide (CO2) and hydrogen sulfide (H2S) which, in the presence of water can produce highly corrosive elements. One solution to this problem is to apply a metal liner made of corrosion-resistant alloy (CRA) internally to the carbon steel pipe. Such a bi-metallic configuration, commonly referred to as a lined pipe or clad pipe, consists essentially of a relatively thin CRA material pipe physically or metallurgically joined to the main carbon steel outer pipe. This experimental study presents an investigation of the ductile tearing properties for the girth weld of a typical C-Mn pipe internally clad with Inconel 625 CRA alloy using experimentally measured crack growth resistance curves. Here, the material of the external pipe is an API 5L Grade X65 pipeline steel and the inner clad layer is made of Inconel nickel-chromium alloy 625 (UNS N06625). The higher mechanical strength and superior resistance to a wide range of corrosive environments of unusual severity for this material derived from the combination of the nickel-chromium matrix with other microalloying elements. Testing of the pipeline girth welds employed clamped SE(T) specimens with a weld centerline notch to determine the crack growth resistance curves based upon the unloading compliance (UC) method using a single specimen method and the multi-specimen technique. The SE(T) specimens were extracted from a clad pipe having an external diameter of 220 mm and thickness of 23 mm. Further, the current experimental characterization provides toughness data that serve to evaluate the effectiveness of current procedures in determining accurate experimentally measured R-curves for this class of material.
Isothermal Low-Cycle Fatigue Evaluation of External Weld Repair Using Alloy 182 Filler Metal With Backing Plate Design
Authors: Zhang Shutong , Romo Sebastian A. , Penso Jorge , Guo Haixia , Ely Lisa , Ramirez Antonio J. 
Published: October 2020

Abstract
Coke drums are pressure vessels used in the delayed coking process at oil refineries, which transform heavy residual oil into light-weight hydrocarbon molecules and solid coke through thermal cracking. Due to the severe thermal and mechanical loadings during operation, these vessels experienced low-cycle fatigue failure, which led to shell and skirt damage such as bulging and cracking. External weld repairs using the temper bead technique have been widely applied to repair damaged regions caused by bulging and cracking for preventing the leaks of the residual oil contents. However, a substantial proportion of the external repairs have been reported to experience post-repair cracking issues. In this study, an external weld repair mockup with a backing plate was evaluated through metallurgical characterizations and isothermal low-cycle fatigue tests. The micro-hardness mapping identified the mismatching interfaces from base metal to weld metal (WM) and from root passes to internal clad. Four types of dog-bone samples were extracted from the weld: weld metal, heat affected zone, internal clad and backing plate. These samples were used to evaluate the fatigue resistance of weld metal and transition zone under low-cycle fatigue tests. Failure analysis showed that weld metal samples were susceptible to multiple-crack initiations, while other transition samples failed at mismatching interfaces or stress concentration points at weld toes.
Fatigue Behavior of Metallic Pipes With Through-Wall Corrosion Damage Repaired With Bonded Metallic Patches
Authors: de Luca Camila , Sathler Julia , Souza João Fellipe , Mattos Heraldo 
Published: October 2020

Abstract
Composite repair systems have been gaining each time more space in industry, especially when it comes to repairing through-wall defects in pipes. They are simpler to apply, have no costly downtime and provide lower risks to the environment when compared to metallic repairs. ASME PCC-2 and ISO 24817 standards are responsible for defining the parameters necessary to a successful repair, however neither of them addresses a very common practice in such repairs, which is the addition of a bonded metallic patch over the defect. Several companies are adepts of such practice and it has already been proven that is actually the metallic patch and not the composite sleeve itself that sustains most of the load applied on the repair, and for that reason it becomes necessary to conduct further studies regarding the behavior of the patch alone. One important issue is to understand why the strength of similar repairs due to operation errors with very similar amplitude of pressure transients seems to vary randomly, with unexplained early failures. The present paper is concerned with an experimental study about how pressure variations can generate cyclic inelastic strains in the pipe, which can weaken the adhesion between pipe and patch, leading the repair to fail prematurely.
A Case Study for Using Engineering Judgement When Analyzing Finite Element Results
Authors: McGuffie Sean , Barkley Nathan 
Published: October 2020

Abstract
The authors were tasked with designing and fabricating a thick walled (t &gt; 4.5″) ASME Division 2 – Class 2 separator vessel. Due to its service requirements, the vessel is to be regularly hydrotested at 18.87 MPa (2,737 psig). Linear-elastic finite element (FE) evaluations of the vessel indicated that it passed all required Code checks, including the hydrotest check specified in Section VIII, Division 2, Paragraph 4.1.6.2.
To develop a greater understanding of the advantages and disadvantages of each method, the FE analyst on the project routinely reanalyzes vessels that have been evaluated per the linear-elastic procedures of Part 5 of the ASME Section VIII, Division 2 Code with the nonlinear procedures also specified in Part 5. This practice allows for direct comparisons of the linear and nonlinear results and for identification of situations where nonlinear analyses could provide benefit. Such an analysis was performed on this vessel under the hydro-static test condition. However, this analysis failed due to solver failure / gross instability (plastic collapse) before the full hydro-static load was applied. The solver failure was confirmed and repeated in multiple FE packages. This presented a conundrum for the authors: should the linear-elastic results be accepted since the vessel passed the linear evaluations, or should they be invalidated since the nonlinear evaluations indicated that failure could occur during a hydrotest, which given the vessel’s operations, will occur frequently?
This paper discusses the additional evaluations that were required to establish confidence that the vessel could be successfully hydrotested when fabricated. These included both the Code specified evaluations, and evaluations that allowed engineering judgement to be applied to the design.
Design and Testing of an Explosively Loaded Pressure Vessel System for Proton Radiography
Authors: Spernjak Dusan , Fehlmann Kevin , Cardon Devin , Yost Nathan , Hill Dallas , Llobet Anna 
Published: October 2020

Abstract
A containment system is being developed to expand the capability of proton radiography of small-scale shock physics experiments at Los Alamos National Laboratory (LANL). The detonation of high explosives (HE) drives materials to extreme loading conditions, which are imaged using a proton beam and an imaging system. A qualified confinement and containment boundary needs to exist between a high-explosive experiment and the environment, and is comprised of the Inner Pressure Confinement Vessel (IPCV) and the Outer Pressure Containment Vessel (OPCV). The Inner Vessel is designed to the criteria of the ASME Boiler and Pressure Vessel Code, Section VIII, Division 3, Code Case 2564. The vessel contains an Experimental Physics Package, fragment mitigation structure, and radiographic windows. The windows need to minimize radiographic blur contribution (thin, radiographically transparent material such as Beryllium) over the field of view for imaging, but also need to maintain the pressure boundary during and after the dynamic event. Further, the vessel covers need to seal before, during, and after the experiment . In addition, the covers have miscellaneous feedthroughs, to enable high-voltage signal (for HE detonator), instrumentation and control signals (e.g. valves, pressure and vacuum gauge, optical fibers). We present the preliminary design, analyses, and testing of the Inner Vessel components.
Residual Stress Measurements in a 316L Uniaxial Samples Manufactured by Laser Powder Bed Fusion
Authors: Davies C. M. , Sandmann P. , Ronneberg T. , Hooper P. A. , Kabra Saurabh 
Published: October 2020

Abstract
Uniaxial samples have been manufactured for tension/compression testing from 316L stainless steel by laser powder bed fusion (LPBF). Samples manufactured by LPBF are known to contain high levels of residual stresses. These uniaxial samples were built from a solid cylindrical rod and subsequently machined to reduce the central cross section of the sample to the required gauge diameter and improve the surface finish. Finite element (FE) models have been developed to simulate the LPBF process of the rods, their removal from the build plate and subsequent machining into the tension/compression samples. High tensile residual stresses were predicted at the surface of the samples, balances by similar magnitude compressive stresses along their axis. Post machining however, these stresses were reduced by around 80% or more. Residual stress measurements were performed on the samples post machining using the neutron diffraction techniques. These measurements confirmed that negligible residual stresses remained in the samples post removal from the build plate and machining.
Simulations of Crack Extensions in Arc-Shaped Tension Specimens of Uncharged and Tritium-Charged-and-Decayed Austenitic Stainless Steels Using Cohesive Zone Modeling
Authors: Wu Shengjia , Pan Jwo , Korinko Paul S. , Morgan Michael J. 
Published: October 2020

Abstract
Crack extensions in arc-shaped tension specimens of uncharged and tritium-charged-and-decayed conventionally forged (CF) 21-6-9 austenitic stainless steels are simulated by two-dimensional finite element analyses using the cohesive zone modeling (CZM) approach with the smooth trapezoidal traction-separation law. The J integrals at the deviation loads of the arc-shaped tension specimens are taken as the reference cohesive energies and the maximum opening stresses ahead of the initial crack tips in the arc-shaped tension specimens are taken as the reference cohesive strengths. The cohesive strengths and cohesive energies are then adjusted to match the maximum loads of the experimental load-displacement curves of the arc-shaped tension specimens. The computational results showed that the computational load-displacement, load-crack extension, crack extension-displacement, and J-R curves of the uncharged and tritium-charged-and-decayed CF steel specimens are compared well with the experimental data.
Sustainable Manufacturing and Optimization of Squeeze Stir Cast Rods Using Recycled Aluminum and Alumina Reinforcements
Authors: Christy John Victor , Mourad Abdel-Hamid I. , Arunachalam Ramanathan 
Published: October 2020

Abstract
This work focusses on the production of sustainable metal metrics composites MMCs. The scrap aluminum alloy wheel (SAAW) was used as a metrics and alumina is used as a reinforcement. The process parameters (namely squeeze pressure and time, die preheating temperature and stirrer speed) were optimized using Taguchi method to produce the alumina reinforced-aluminum matrix composites (AMCs). These stir-casted composites were characterized based on their hardness, tensile and compression strengths and wear/tribological properties. The results showed that addition of alumina to aluminum matrix has improved the mechanical and tribological performance. From, Taguchi analysis the optimized 9 approaches (L1 to L9) were obtained and, L5 and L6 methods showed optimum mechanical properties with 100 MPa squeeze pressure, 30 to 40 sec squeeze time, 250 to 350°C die preheating temperature and 450 to 525 rpm stirrer speed process parameters. It was found that properties are process parameters dependent. The produced AMCs have many potential industrial applications including applications in piping industry.
Impact of Grooves in Hydraulically Expanded Tube-to-Tubesheet Joints
Authors: Thekkuden Dinu Thomas , Mourad Abdel-Hamid I. , Bouzid Abdel-Hakim 
Published: October 2020

Abstract
The stress corrosion cracking of tube-to-tubesheet joints is one of the major faults causing heat exchanger failure. After the expansion process, the stresses are developed in a plastically deformed tube around the tube-to-tubesheet joint. These residual stressed joints, exposed to tube and shell side fluids, are the main crack initiation sites. Adequate contact pressure at the tube-to-tubesheet interface is required to produce a quality joint. Insufficient tube-to-tubesheet contact pressure leads to insufficient joint strength. Therefore, a study on the residual stress and contact pressure that have a great significance on the quality of the tube-to-tubesheet joint is highly demanded. In this research, a 2D axisymmetric numerical analysis is performed to study the effect of the presence of grooves in the tubesheet and the expansion pressure length on the distribution of contact pressure and stress during loading and unloading of 400 MPa expansion pressure. The results show that the maximum contact pressure is independent of the expansion pressure length. However, the presence of grooves significantly increased the maximum contact pressure. It is proven that the presence of grooves in the tubesheet is distinguishable from the maximum contact pressure and residual von mises equivalent stress. The tube pull-out strength increases with the expansion pressure and the number of grooves. In conclusion, the presence of the grooves affects the tube-to-tubesheet joints.