bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurements of Stress During Thermal Shock in Clad Reactor Pressure Vessel Material Using Time-Resolved In-Situ Synchrotron X-Ray Diffraction
Authors: Oliver Sam , Simpson Chris , James Andrew , Reinhard Christina , Collins David , Pavier Martyn , Mostafavi Mahmoud
Published: October 2018

Nuclear reactor pressure vessels must be able to withstand thermal shock due to emergency cooling during a loss of coolant accident. Demonstrating structural integrity during thermal shock is difficult due to the complex interaction between thermal stress, residual stress, and stress caused by internal pressure. Finite element and analytic approaches exist to calculate the combined stress, but validation is limited. This study describes an experiment which aims to measure stress in a slice of clad reactor pressure vessel during thermal shock using time-resolved synchrotron X-ray diffraction.

A test rig was designed to subject specimens to thermal shock, whilst simultaneously enabling synchrotron X-ray diffraction measurements of strain. The specimens were extracted from a block of SA508 Grade 4N reactor pressure vessel steel clad with Alloy 82 nickel-base alloy. Surface cracks were machined in the cladding. Electric heaters heat the specimens to 350°C and then the surface of the cladding is quenched in a bath of cold water, representing thermal shock. Six specimens were subjected to thermal shock on beamline I12 at Diamond Light Source, the UK’s national synchrotron X-ray facility. Time-resolved strain was measured during thermal shock at a single point close to the crack tip at a sample rate of 30 Hz. Hence, stress intensity factor vs time was calculated assuming K-controlled near-tip stress fields. This work describes the experimental method and presents some key results from a preliminary analysis of the data.
Crack Resistance Curve Measurement With Miniaturized CT Specimen
Authors: Chaouadi Rachid , Lambrecht Marlies , Gérard Robert
Published: October 2018

The use of miniature compact tension (mini-CT) specimens for fracture mechanics was experimentally demonstrated to allow the characterization of ferritic steels in the transition regime. In particular, the master curve transition temperature T0 can confidently be determined according to the ASTM E1921 standard using mini-CT specimens. This means that specimen size effect is well taken into account if loss of constraint is limited by restricting the test temperature range to remain below the allowed maximum loading level. In the upper shelf ductile regime, where stable crack growth occurs, a number of challenges should be overcome to use such a geometry to derive the crack resistance curve, or JR-curve, transferrable to a structure. Indeed, despite a large scatter, the experimental data on several materials suggest a size effect that underestimates the crack resistance when reducing specimen size.

The crack resistance behavior of several reactor pressure vessel materials was investigated with square-sized ligament compact tension specimens of various size ranging from 1 inch-thickness (B = 25 mm) to the smallest thickness (B = 4.2 mm) of the mini-CT. The main objective of this paper is to estimate the crack resistance behavior of RPV steels that would be obtained with a standard 1T-CT specimen by using mini-CT with the appropriate specimen size correction. After a series of scaling attempts that were not successful, based on a simple dimensional analysis, a simple analytical formulation based on specimen thickness and ligament is suggested to account for specimen size effect for the CT geometry. Reasonable agreement could generally be found on a number of RPV materials between crack resistance measured with mini-CT and standard 1T-CT specimens.
A Simplified Approach to Estimate Flow-Induced Vibrations on an Elbowed Piping System
Authors: Baramili André , Chatellier Ludovic , David Laurent , Ancian Loïc
Published: October 2018

A mixed experimental and numerical approach was undertaken in order to develop a data-based model of the flow-induced vibration levels attained in a piping system containing a 90° elbow. A closed water loop was used to provide unsteady flow data as well as wall pressure and vibration measurements. In parallel, the unsteady water flow through the elbow was computed using an incompressible Large-Eddy Simulation (LES). Proper Orthogonal Decomposition (POD) and Partial Least Squares Regression (PLSR) were used in order to build a relationship between the flow properties and the resulting excitation. This relationship was then used to estimate the evolution of the spatially distributed loadings, which were finally applied to a finite element model of the piping structure. The results consisted of an estimation of the vibration levels. The estimated vibrations were then compared to measurements in order to validate the proposed modeling strategy.
Comparison of Tube-Tube Collision Frequency With and Without the Use of Impingement Plate
Authors: Buzík Jiří , Létal Tomáš , Lošák Pavel , Naď Martin , Pernica Marek
Published: October 2018

The aim of the present work is to carry out the checking of the tube bundle of heat exchanger for the occurrence of tube-tube collision caused by cross-flow vibration with and without the use of impingement plate. This will be achieved using numerical 2D CFD (computational fluid dynamics) analysis. The 2D analysis is done using ANSYS Fluent software. Tube movement in the shell side is provided by UDF (user-defined function) DEFINE_SDOF_PROPERTIES. By determining the stiffness and weight of the tubes, two-way fluid and tube interaction can be achieved. Due to limitations of 2D CFD analysis, only the occurrence of the tube-tube or tube-shell collisions can be observed. Unfortunately, the first collision causes termination of the simulation due to negative volumes in dynamic mesh. Possible solutions to the issue are also discussed in presented paper.

The analyzed geometry of the shell side is taken from the Heat Exchanger Tube Vibration Data Bank [2]. This publication collects heat exchanger data for which vibration phenomena have been reported. The above-mentioned geometry is a domain with tube bundle at the shell side under the inlet. In the same domain, both the tie rod and the seal strips and the 45° turn of the partitions are considered.
Some Useful Mechanical Property Correlations for Nuclear Reactor Pressure Vessel Steels
Authors: Nanstad Randy K. , Server William L. , Sokolov Mikhail A. , Odette G. Robert , Almirall Nathan
Published: October 2018

The use of correlations is common in the research and development arena of the nuclear industry with the realization that some applications with direct implications to safety demand a more rigorous approach. Most correlations involve the relationship between two experimental properties, such as that between hardness and tensile strength. There are others that are much more complicated and are often designated models because they incorporate physically-based knowledge; examples of this are predictive correlations for irradiation-induced embrittlement of reactor pressure vessels (RPV). The objective of this paper is to collect and discuss many of the commonly used correlations for applications to nuclear RPVs. This paper identifies and discusses various correlations that relate easily measured properties to properties that are more difficult, more time consuming, or more expensive to measure. In the case of irradiated RPV materials, irradiation-induced changes in easily measured properties are related to the changes in those more difficult to measure. It is noted that recognition and understanding of the uncertainties associated with all correlations is highly important.
Assessment of Passively Actuated In-Situ Cyclic Surveillance Test Specimens for Advanced Non-Light Water Reactors
Authors: Messner M. C. , Phan V.-T. , Jetter R. I. , Sham T.-L.
Published: October 2018

The use of surveillance specimens was identified in a roadmap (Sims, 2010, ASME HTGR Code Development Roadmap, STP-NU-045, American Society of Mechanical Engineers, New York, NY) developed for the U.S. Nuclear Regulatory Commission for non-light water reactors that are intended to have very long design lives on the order of 500,000 hours. Creep-rupture, long term strain accumulation, creep-fatigue damage, and their interaction with environmental effects require significant extrapolation from shorter term tests. Surveillance specimens provide a means for confirmation of these extrapolations in-situ. The effects of cyclic service on creep-fatigue damage would be particularly challenging based on conventional mechanical testing. Proposed herein is a passive cyclic testing methodology that lends itself well to in-situ surveillance applications. The concept is based on utilizing the difference in the thermal expansion coefficient of candidate materials to generate cyclic loading based on operational thermal transients. Prototypical specimen designs are proposed and their in-situ response to representative plant operation are evaluated.
A Comprehensive Structural Strain Method Incorporating Strain-Hardening Effects: From LCF to Ratcheting Evaluations
Authors: Pei Xianjun , Dong Pingsha , Song Shaopin , Osage David
Published: October 2018

As a further extension to the structural strain method first introduced by Dong et al [1], this paper presents an enhanced structural strain method which incorporates material nonlinearity and for two typical weld structures, i.e. weldment with plate sections (e.g. gusset weld or cruciform weld etc.) and weldment with beam sections. (e.g. pipe structures). A modified Ramberg-Osgood is introduced to capture nonlinear stress strain behavior of the material. A set of numerical algorithms is used to deal with complex stress state induced by structural effect such as beam section and plane strain condition. The proposed structural strain method is then applied to analysis of fatigue data of weldment made from different materials including steel, aluminum and titanium. It is shown that the enhanced structural strain method provides a unified way to correlate fatigue life of weldment in both high cycle and low cycle fatigue regime. The method is also used to study ratcheting problem raised up by Bree. A modified Bree diagram is given by considering material nonlinearity.
Analysis of Three-Dimensional Clamped Single Edge Notched Tension (SENT) Specimens
Authors: Liu Zheng , Chen Xu , Wang Xin
Published: October 2018

In the present paper, three-dimensional clamped SENT specimens, which is one of the most widely used low-constraint and less-conservative specimen, are analyzed by using a crack compliance analysis approach and extensive finite element analysis. Considering the test standard (BS8571) recommended specimen sizes, the daylight to width ratio, H/W, is 10.0, the relative crack depth, a/W, is varied by 0.2, 0.3, 0.4, 0.5 or 0.6 and the relative plate thickness, B/W, is chosen by 1.0, 2.0 or 4.0, respectively. Complete solutions of fracture mechanics parameters, including stress intensity factor (K), in-plane T-stress (T11) and out-of-plane T-stress (T33) are calculated, and the results obtained from above two methods have a good agreement. Moreover, the combination of the effects of a/W and B/W on the stress intensity factor K, T11 and T33 stress are thus illustrated.
Engineering Application of Miniature Specimen Sampling Method on FFS Assessment of Corrosive Pits of In-Service Pressure Pipeline
Authors: Yang Yuqing , Du Xin , Zhang Ting , Hui Hu , Huang Yichang , Wang Jielu
Published: October 2018

This paper aims at in-service inspection of a petrochemical companies’ process pipeline which was found to have corrosive pits during a regular periodic inspection. By adopting miniature specimen sampling method, some (size of 12 × 12 × 1.3mm) sheets were obtained in the pipeline. Yield strength and tensile strength of the material can be obtained by small punch test method. Fitness-For-Service (FFS) procedures based on different standards are performed on the corrosive pits and the sampling areas to assess their safety. The research shows that it is feasible to obtain the actual mechanical properties of the material in the field by using the miniature specimen sampling method. The method mentioned in this paper is of guiding significance for FFS assessment on in-service pressure pipelines.
Evaluation of Through Wall Fracture Toughness Distribution of IAEA Reference Material JRQ by Mini-C(T) Specimens and the Master Curve Method
Authors: Yamamoto Masato , Kobayashi Tomohiro
Published: October 2018

The load and temperature history during pressurized thermal shock (PTS) event is highly depending on the crack edge location in wall thickness direction of a reactor pressure vessel (RPV) beltline region. Therefore, the consideration of plant specific through-wall fracture toughness distribution, which is not considered in the current codes and regulations [1,2], may improve the structural integrity assessment for PTS event.

The Master Curve (MC) method [3,4] is one of the methods, which can directory evaluate the fracture toughness of ferritic materials with relatively low number of any size of specimens. CRIEPI has proposed the use of very small C(T) (Mini-C(T)) specimens for the MC method. The appropriateness of Mini-C(T) technology has been demonstrated through a series of researches and round robin activities [5, 6, 7, 8, 9].

The present study evaluated the through-wall fracture toughness distribution of irradiated IAEA reference material (JRQ) by means of combination of MC method and Mini-C(T) specimens. Four thickness locations between inner surface to 1/4-T was selected. Those four layers were separately subjected to the Mini-C(T) MC evaluation in two different laboratories. Both laboratories could separately obtain valid and consistent reference temperature, To, from all the tested layers. Inner most layer exhibits 80 °C lower To compared to the 1/4-T location even though the layer has the highest fluence of 5.38 × 1019 n/cm2, while that in 1/4-T location is 2.54 × 1019 n/cm2. The results demonstrate that initial toughness distribution is dominant in the general trend of fracture toughness distribution even after the material was highly irradiated.
ASME PCC-1:2018: What Is New and Different?
Authors: Rodery Clay D. , Brown Warren
Published: October 2018

The next edition of ASME PCC-1, “Guidelines for Pressure Boundary Bolted Flange Joint Assembly” [1] will be published in 2018. This paper highlights the key revision items, the background behind them, and provides future insights toward what topics might be targeted for subsequent editions.
A Methodology for Constructing Complex 3D Cracked Body Finite Element Models Efficiently
Authors: Vorster Willem J. J. , Mann Alex
Published: October 2018

Design code design by analysis routes often require knowledge of collapse parameters while structural integrity fitness for purpose assessments require detailed knowledge of both collapse and fracture parameters. These parameters can be calculated using detailed Finite Element Analysis (FEA) simulation.

However, the process of constructing Finite Element (FE) models of complex components such as branches and branches located on pipework bends is often time consuming when considering aspects of weld design around branches attached to bends or the requirement for specialist knowledge when inserting crack-like features into FE models close to welds or areas with notable curvature such as that found in bends. This paper presents a technique which can be used to construct finite element models quickly so as to shift the effort of the structural integrity expert from modelling to assessment.

This paper provides a basic procedure for creating and manipulating FE models to enable inserting cracks in areas of structural discontinuities or in areas of significant curvature. The usefulness of this method is illustrated by considering the results of 3D defect free and cracked FE analyses of pipe bends. It illustrates the use of the method to create defect free branches and can be extended to include crack in these components. The analyses reported here use the commercial FEA software Abaqus. However, this technique can be adapted to any modern FEA software. This methodology would be of particular interest to industries relying on pipework and pressure vessel components and where the failure of such component can have serious safety and commercial implications.
Tentative Thickness for Torispherical and Ellipsoidal ASME Section III Class 1 Heads
Authors: Shah Pankajkumar K. , Belloni Mark , Wilson Robert M.
Published: October 2018

Class 1 nuclear vessel heads with ellipsoidal or torispherical geometries offer several advantages over spherical heads. They shorten the overall height of the vessel, reduce internal volume, lower the vessel center of gravity, and are more economical. At present Section III only offers tentative thickness formulas for spherical heads in NB-3324 [1]. This paper proposes the addition of tentative thickness formulas for Class 1 torispherical and ellipsoidal heads. A large family of finite element analyses over a practical range of vessel geometries and pressures is used to establish the new thickness equations.
Evaluation of Bending Limit of 9Cr-1Mo-V Steel by Master Curve and Failure Assessment Diagram Method: Evaluation of Welded Metal
Authors: Nakatani Mitsuyoshi , Oda Kazuo , Tanaka Tomohiro , Abe Masamitsu , Takashima Yasuhito , Minami Fumiyoshi
Published: October 2018

In this study, the bending and rolling limit of 9Cr-1Mo-V steel plate welded using submerged arc welding (SAW) was investigated. Hereafter in this report, the bending limit refers to bending by press or by roller. Since heat treatment after welding and before the bending process may be effective in preventing brittle fracture during bending, the effect of postweld heat treatment (PWHT) for improving toughness was evaluated by Larson-Miller parameter (LMP). Charpy impact tests of SAW welded parts made of 9Cr-1Mo-V steel plates were performed, and the absorbed energy of the weld metal was lower than that of the heat affected zone (HAZ) and the base metal, however the absorbed energy was recovered by PWHT. The absorbed energy increased as LMP increased.

The reference temperature T0 for the master curve method was estimated by the results of Charpy impact tests. The bending limit was estimated by the method proposed in the previous study. The fracture probability during the bending process seems to decrease as LMP increases.
Prediction for Plastic Collapse Stresses for Pipes With Inner and Outer Circumferential Flaws
Authors: Hasegawa Kunio , Li Yinsheng , Mares Vratislav , Lacroix Valery
Published: October 2018

Bending stresses at incipient plastic collapse for pipes with circumferential surface flaws are predicted by net-section stress approach. Appendix C-5320 of ASME B&PV Code Section XI provides a formula of bending stress at the plastic collapse, where the formula is applicable for both inner and outer surface flaws. That is, the collapse stresses for pipes with inner and outer surface flaws are the same, because of the pipe mean radius at the flawed section being entirely the same.

Authors considered the separated pipe mean radii at the flawed ligament and at the un-flawed ligament. Based on the balances of axial force and bending moment, formulas of plastic collapse stresses for each inner and outer flawed pipe were obtained. It is found that, when the flaw angle and depth are the same, the collapse stress for inner flawed pipe is slightly higher than that calculated by Appendix C-5320 formula, and the collapse stress for outer flawed pipe is slightly lower than that by Appendix C-5320 formula, as can be expected. The collapse stresses derived from the three formulas are almost the same in most instances. For less common case where the flaw angle and depth are very large for thick wall pipes, the differences amongst the three collapse stresses become large.
Development of Probabilistic Fracture Mechanics Analysis Code PASCAL Version 4 for Reactor Pressure Vessels
Authors: Lu Kai , Masaki Koichi , Katsuyama Jinya , Li Yinsheng , Uno Shumpei
Published: October 2018

In Japan, Japan Atomic Energy Agency has developed a PFM analysis code PASCAL (PFM Analysis of Structural Components in Aging LWRs) for structural integrity assessment of Japanese reactor pressure vessels (RPVs) considering neutron irradiation embrittlement and pressurized thermal shock transients. By reflecting the latest knowledge and findings, the PASCAL code has been continuously improved. In this paper, the development of PASCAL Version 4 (hereafter, PASCAL4) is described. Several analysis functions incorporated into PASCAL4 for evaluating the failure frequency of RPVs are introduced, for example, the evaluation function of confidence level of failure frequency considering epistemic and aleatory uncertainties in probabilistic variables, the recent stress intensity factor (KI) solutions and KI calculation methods considering complicated stress distributions, and the recent Japanese irradiation embrittlement prediction method. Finally, using PASCAL4, a PFM analysis example for a Japanese model RPV is presented.
Development of Degradation Management System for Bottom Plate Coating of Oil Storage Tank Using New Parameters
Authors: Ito Daisuke , Sekino Kouichi , Okazaki Shinji , Sekine Kazuyoshi , Ishihara Masaru
Published: October 2018

In Japan, according to the national policy, oil is stockpiled to keep the life of the people around 180 days. Stockpiling method are ground base tank, marine base tank, and underground bedrock base tank. Especially, the inspection of the ground tank is carried out every 8 years by Fire Defense Law. A high performance organic coating is used as the corrosion protection for inner bottom plate of the tank. Regarding the degradation of the coating, blisters and scratches are mainly found by visual inspection. In addition, as a non-destructive inspection of the degradation level of the coating, there is an evaluation using the tanδ1–2) value by the electrochemical impedance method. However, the tanδ value is the result of only one frequency region, and complicated degradation phenomenon cannot be explained. Therefore, in this study, two Constant Phase Element (CPE)3)-5) parameters were applied to the equivalent circuit analysis. CPE is a distributed constant element and may replace complicated degradation phenomena. We designed the elements separately for overall slow degradation phenomena (soundness) and specific degradation phenomena (damage). As a result of analysis based on the analysis parameter (T, p) using the data of the inspection of actual tanks, the characteristics of each tank could be evaluated with new indices.
3D FEM Modeling of Crack Initiation in a Reactor Pressure Vessel During a PTS Event (LBLOCA)
Authors: Mora Méndez Diego Fernando , Niffenegger Markus , Qian Guian , Jaros Michal , Niceno Bojan
Published: October 2018

To perform the integrity assessment of a reactor pressure vessel (RPV) related to Pressurized Thermal Shock (PTS), we model the RPV using the 3D finite element method (FEM). Accurate prediction of temperature and stress fields is determined by using 2-Phase computational fluid dynamics (CFD) simulation in combination with an appropriate finite element discretization of the RPV wall. The cladding and the ferritic low alloy steel are considered as two separated layers, which can be intersected by superficial cracks. The calculation of the stress intensity factor (SIF) in mode I is based on the linear fracture mechanics theory (LEFM) and hypothetical cracks are located in different locations to consider the most critical cases.

In the present study, the sub-modeling technique is implemented to refine the mesh required by the fracture analysis in the region of interest. Three types of cracks are considered: axial, circumferential and inclined. The performed integrity assessment uses the master curve approach. The stress intensity factor in the deepest point of a surface crack was compared with the material’s fracture toughness. In previous studies the integrity of the RPV subjected to medium and small break Loss-of-Coolant Accident (MBLOCA and SBLOCA, respectively) has been evaluated, therefore the concern in this contribution is the large break of Loss-Of-Coolant Accident (LBLOCA). The combination of 3D FEM with CFD simulations allows us to study the influence of the dynamic cooling plume on the stress intensity in more detail than with the conventional one dimensional method.
Vibration Analysis of Flexural Behavior of Straight Pipe With Non-Penetrating Circumferential Crack
Authors: Yinhang Cao , Gongmin Liu , Yucheng Zong
Published: October 2018

Flexural vibration behavior of a cracked straight pipeline, divided into two complete pipelines which were jointed together with a massless torsion spring simulating the outer surface circumferential crack, was analyzed with the Laplasse transform method and the transfer matrix theory, based on a straight pipeline FSI transverse vibration 4-equation model. At the same time, the equivalent spring method was also applied to simulate the elastic supports at both ends of the cracked straight pipeline, assuming that the pipeline was symmetrically supported and there were a line spring and a torsion spring at each end. The transverse vibration matrix equations model without or with frequency domain excitation force were finally obtained and then the natural frequencies were solved with Matlab. The natural frequency calculated results were compared with those of the finite element method to verify the correctness of the analysis process, and at last the influences of elastic support coefficient, crack angle, depth and location on the dynamic behaviors of the cracked straight pipeline were calculated and discussed.
Three-Dimensional Numerical Analysis for Bolted Flange Joints Considering Effect of Creep
Authors: Bi Lewen , Zhang Lanzhu
Published: October 2018

Bolted flange joints are widely used in petroleum, chemical, nuclear and power industries, etc. With more and more devices are used at high temperature, the performance of flange connections becomes more complex, especially with creep of different components in flange connection. At elevated temperature, with the loss of bolt force and gasket force due to creep, the joints are prone to leak. Based on this, this paper analyzed the relaxation of bolt force at elevated temperature due to creep of bolt, flange and gasket separately and simultaneously. Besides, the influence of different initial installation stress of bolts was also studied. The results showed bolted flange joints relaxed due to gasket creep during early short term service. However, contribution of bolt and flange creep became more and more significant with the extension of time. With considering the creep of bolt, flange and gasket simultaneously, 50% to 60% of the bolt material yield strength at room temperature was recommended as the bolt initial installation stress for the joint case studied in this paper.
Experimental Investigation of Interfacial and Permeation Leak Rates in Sheet Gaskets and Valve Stem Packing
Authors: Salah Omar Aweimer Ali , Bouzid Abdel-Hakim
Published: October 2018

The quantities of leak rate through sealing systems are being regulated because of the global concern on the hazardous pollutants being released into the atmosphere and their consequences on the environment and health. The maximum tolerated leak is becoming a design criterion, and the leak rate for an application under specific conditions is required to be estimated with reasonable accuracy. In this respect, experimental and theoretical studies are being conducted to characterize the gas flow through gaskets and packing rings. The amount of the total leak that is present in a gasketed joint or a valve stem packing is the sum of the permeation leak through the sealing material and the interfacial leak at the mating surfaces between the sealing element and mechanical clamp assembly. The existing models used to predict leakage do not separate these two types of leaks.

This paper deals with a study based on experimental testing that quantifies the amount of these two types of leaks in bolted gasketed joints and packed stuffing boxes. It shows the contribution of interfacial leak for low and high contact surface stresses and the influence of the surface finish as a result of a 32 and 250 micro-inch RAAH phonographic finish in the case of a bolted flange joint. The results indicate that most of the leak is interfacial reaching 99% at the low stress while the interfacial leak is in the same order of magnitude of the permeation leak at high stress reaching 10−6 and 10−8 mg/s in both packing and gaskets, respectively.
The Influence of Bauschinger Effect on the Stability of Residual Stresses in Autofrettaged High Pressure Tubes
Authors: Maderbacher Hermann , Pölzl Manfred
Published: October 2018

In the petrochemical industry, in particular for LDPE (Low-Density-Poly-Ethylene) and EVA-processes (Ethylene-Vinyl-Acetate), high strength quenched and tempered steels are used for seamless tubes subjected to ultra-high pressure. The high safety demands at pressures up to 4000bar require besides high fracture toughness and static strength also high fatigue endurance. The fatigue performance can be significantly impoved by the use of autofrettage. In this case residual compressive stresses are generated with simultaneous material work-hardening by targeted plastic deformation in the area of the inner wall of the tube. The positive effect of autofrettage mainly depends on the level of residual compressive stress. The maximum magnitude of these compressive stresses is always smaller than the yield strength of the material in tensile direction, even if the autofrettage level is increased. The amount by what this stress is smaller than the material yield strength depends on the characteristic of the so-called Bauschinger-effect, or on the kinematic hardening behavior of the material.

The target of the present work is to investigate the stability of residual stresses from autofrettage and their influence on the service life of high pressure tubes under cyclic internal pressure loading. For this purpose, in the first part, the quantitative character of the Bauschinger effect for a high strength quenched and tempered steel is determined by means of specimen tests. In the next step, the influence of the Bauschinger-effect on the resulting residual compressive stresses in a tube-like specimen is investigated. Autofrettage tests are performed on these specimens equipped with strain gages. In the second part of the work, the results of fatigue tests of the mentioned tube-like specimen are compared with the calculated fatigue endurance according to Division 3, Section VIII of the ASME Pressure Vessel Code (BPVC). Calculations are performed, which once use the residual stress correction for reverse yielding according to ASME Code and once consider the actual residual stresses from tests and simulation.
Analysis of Creep Crack Growth Behavior of the Brazed Joint Using Continuum Damage Mechanics Approach
Authors: Zhang Yu-Cai , Jiang Wenchun , Tu Shan-Tung , Zhang Xian-Cheng , Zhou Guo-Yan
Published: October 2018

Creep crack growth behavior of the Inconel625/BNi-2 brazed joint considering the diffusion zone at 650 °C was investigated by a continuum damage mechanics approach based on the finite element method. The results show that creep crack nucleate and develop at the region of the brazing filler metal. The crack initiates at about 0.2 mm ahead of the crack tip. When the load is 1000 N, the crack initiation time of the CT specimen is 1664 hour. While when the load is 1135 N, the crack initiation time is only about 891 hour. The simulated results correspond well with the experimental data, presenting that the used finite element method can accurately simulate the creep damage behavior of the brazed joint. When the mechanical properties of the diffusion zone are not considered, the crack initiation time and fracture time decrease significantly compared to the result with properties of the diffusion zone included, indicating that the result from the conventional simulating method without considering the diffusion zone is quite conservative compared to the experimental life of the component.
Ratchet Boundary for Superimposed Biaxial Membrane Stress States
Authors: Reinhardt Wolf
Published: October 2018

Thermal membrane and bending stress fields exist where the thermal expansion of pressure vessel components is constrained. When such stress fields interact with pressure stresses in a shell, ratcheting can occur below the ratchet boundary indicated by the Bree diagram that is implemented in the design Codes. The interaction of primary and thermal membrane stress fields with arbitrary biaxiality is not implemented presently in the thermal stress ratchet rules of the ASME Code, and is examined in this paper.

An analytical solution for the ratchet boundary is derived based on a non-cyclic method that uses a generalized static shakedown theorem. The solutions for specific applications in pressure vessels are discussed, and a comparison with the interaction diagrams for specific cases that can be found in the literature is performed.
Normative Technical Documentation of Association of Mechanical Engineers, Czech National Code of Equipment and Piping of Nuclear Power Plants of WWER Type
Authors: Junek Lubomír
Published: October 2018

The Standard Technical Documentation of the Association of Mechanical Engineers is elaborated by a team of experts on the base of an actual knowledge and practice as a part of a row of recommendations for an assessment of strength and reliability, choice of materials and solution of service problems of the Czech nuclear power plants. It was elaborated by the Association of Mechanical Engineers as an important help for a practice. This issue is published from the following main reasons:

1. The criteria for an assessment of reliability and safety of technical tasks have changed in a last decades by influence of development of fracture mechanics and a diagnostics of an actual components of the nuclear power plants, exposed to a static and dynamic strength in a service and to effects of an aggressive environment, leading to an origin of integrity failure. The access is changed now from an assessment of an original strength to a long-term operation and service reliability. A conception of a choice of suitable materials has changed, especially about an influence of production technology on barriers against a degradation of material mechanical characteristics. Imaginations also changed about increasing of a resistance against a damage of material components in complex service conditions. New scientific knowledge it is necessary to apply responsibly just in a construction of as important equipment as nuclear power plants are.

2. A social responsibility is increasing for economic and ecological behavior and hence manners of service control are always innovated. A problematic of a residual lifetime of those tasks is connected with. A prolongation of a lifetime without a risk of equipment failure hereto is a principal demand of capital-intensive units.

3. In a last decades a possibility of efficient use either an automatic service diagnostics or an inspection of component state in service brakes has deepened. It is necessary to enable a right engagement of this instrumentation and to interpret in a right way obtained information.

4. An international cooperation in this important region is developed, an elaboration of information and their common deepening has a substantial importance for a future of a nuclear energetic. A dissembling of service obstacles, an objective analysis of failure situations and a method of their control is today’s obvious duty of an international cooperation. Programs of all variants of a possible damage and its control must be prepared.

It is impossible at once to apply all those aspects in provisions and recommendations. Issued provisions however must be constantly improved and complemented.
Generalization of the primary tone phase variation method: An exclusive way of isolating the frequency-following response components
Authors: Lucchetti Federico , Deltenre Paul , Avan Paul , Giraudet Fabrice , Fan Xiaoya , Nonclercq Antoine
Published: October 2018

The primary tone phase variation (PTPV) technique combines selective sub-averaging with systematic variation of the phases of multitone stimuli. Each response component having a known phase relationship with the stimulus components phases can be isolated in the time domain. The method was generalized to the frequency-following response (FFR) evoked by a two-tone (f1 and f2) stimulus comprising both linear and non-linear, as well as transient components. The generalized PTPV technique isolated each spectral component present in the FFR, including those sharing the same frequency, allowing comparison of their latencies. After isolation of the envelope component f2 – f1 from its harmonic distortion 2f2 – 2f1 and from the transient auditory brainstem response, a computerized analysis of instantaneous amplitudes and phases was applied in order to objectively determine the onset and offset latencies of the response components. The successive activation of two generators separated by 3.7 ms could be detected in all (N = 12) awake adult normal subjects, but in none (N = 10) of the sleeping/sedated children with normal hearing thresholds. The method offers an unprecedented way of disentangling the various FFR subcomponents. These results open the way for renewed investigations of the FFR components in both human and animal research as well as for clinical applications.
Self-translation induced minimum audible angle
Authors: Rummukainen Olli S. , Schlecht Sebastian J. , Habets Emanuël A. P.
Published: October 2018

The minimum audible angle has been studied with a stationary listener and a stationary or a moving sound source. The study at hand focuses on a scenario where the angle is induced by listener self-translation in relation to a stationary sound source. First, the classic stationary listener minimum audible angle experiment is replicated using a headphone-based reproduction system. This experiment confirms that the reproduction system is able to produce a localization cue resolution comparable to loudspeaker reproduction. Next, the self-translation minimum audible angle is shown to be 3.3° in the horizontal plane in front of the listener.
Highly directional pressure sensing using the phase gradient
Authors: Lawrence Joseph S. , Gee Kent L. , Neilsen Tracianne B. , Sommerfeldt Scott D.
Published: October 2018

Many methods of two-microphone directional sensing have limited bandwidth. For active intensity, finite-difference error can be removed by using the phase and amplitude gradient estimator method. Using similar principles, a directional pressure sensor based on the phase gradient is developed that is accurate up to the spatial Nyquist frequency, and beyond if phase unwrapping is applied. A highly directional frequency-independent array response of arbitrary order can be achieved with two microphones. The method is compared against beamforming and traditional gradient sensing for single and multiple sources and is found to have improved localization capabilities and increased bandwidth.
Design of magnetic spirals in layered perovskites: Extending the stability range far beyond room temperature
Authors: Shang Tian , Canévet Emmanuel , Morin Mickaël , Sheptyakov Denis , Fernández-Díaz María Teresa , Pomjakushina Ekaterina , Medarde Marisa
Published: October 2018

A novel strategy to design magnetic spirals well above room temperature opens a way for their use in technological applications.
Zidovudine-Mediated Autophagy Inhibition Enhances Mitochondrial Toxicity in Muscle Cells
Authors: Lin H. , Stankov M. V. , Hegermann J. , Budida R. , Panayotova-Dimitrova D. , Schmidt R. E. , Behrens G. M. N.
Published: October 2018

Nucleoside reverse transcriptase inhibitors (NRTI), such as zidovudine (AZT), are constituents of HIV-1 therapy and are used for the prevention of mother-to-child transmission. Prolonged thymidine analogue exposure has been associated with mitochondrial toxicities to heart, liver, and skeletal muscle.
In Vivo
Efficacy of Humanized WCK 5222 (Cefepime-Zidebactam) Exposures against Carbapenem-Resistant Acinetobacter baumannii in the Neutropenic Thigh Model
Authors: Almarzoky Abuhussain Safa S. , Avery Lindsay M. , Abdelraouf Kamilia , Nicolau David P.
Published: October 2018

Herein, we describe the
in vivo
efficacy of human-simulated WCK 5222 (cefepime-zidebactam) exposure against carbapenem-resistant
Acinetobacter baumannii
strains in a neutropenic murine thigh infection model. Five of the six isolates examined expressed OXA-23 or OXA-24.
Strain-Level Diversity Analysis of Pseudomonas fragi after
In Situ
Pangenome Reconstruction Shows Distinctive Spoilage-Associated Metabolic Traits Clearly Selected by Different Storage Conditions
Authors: De Filippis Francesca , La Storia Antonietta , Villani Francesco , Ercolini Danilo
Published: October 2018

This work provides insights on the mechanisms involved in raw beef spoilage during refrigerated storage and on the selective pressure exerted by the packaging conditions. We highlighted the presence of different microbial metagenomes during the spoilage of beef packaged aerobically or under vacuum. The packaging condition was able to select specific
Pseudomonas fragi
strains with distinctive genomic repertoires. This study may help in deciphering the behavior of different biomes directly
in situ
in food and in understanding the specific contribution of different strains to food spoilage.
Prenatal diagnosis and management of fetal discordant alpha-thalassaemia in dichorionic diamniotic (DCDA) twins
Authors: Panchalee Tachjaree , Ruangvutilert Pornpimol , Limsiri Pattarawan , Sutcharitpongsa Pavit
Published: October 2018

A 29-year-old nulliparous woman with a dichorionic diamniotic (DCDA) twin pregnancy was referred to our hospital at 16 weeks’ gestation for prenatal diagnosis. She was diagnosed of Haemoglobin H Constant Spring (Hb H CS; --SEA/αCSα) and her husband of alpha thalassemia-1 trait (--SEA/αα). Detailed ultrasound showed that left twin had fetal anaemia and early signs of hydrops while the right one was normal. Both twins were female. Amniocentesis in each sac was performed for prenatal diagnosis of thalassemia after a proper counselling with the couple. DNA analysis confirmed that the left fetus was affected with haemoglobin Bart’s hydrops fetalis (--SEA/--SEA) while the right one was alpha thalassemia-1 trait (--SEA/αα). Selective feticide with intracardiac injection of KCl was successfully performed on the hydropic fetus. Identification of the affected fetus is crucial for selective termination. Family counselling about the procedure and complications is also necessary.
Systematic review of musculoskeletal injuries in professional golfers
Authors: Robinson Patrick G , Murray Iain R , Duckworth Andrew D , Hawkes Roger , Glover Danny , Tilley Nigel R , Hillman Rob , Oliver Christopher W , Murray Andrew D
Published: October 2018

Objective

The distribution of injuries affecting professional golfers is yet to be fully understood. We performed a systematic review of the clinical literature to establish the epidemiology of musculoskeletal injuries affecting professional golfers.

Design

Systematic review.

Data sources

Searched databases in July 2018 were PubMed, SPORTDiscus and Embase.

Eligibility criteria

Published observational research articles relating to the incidence or prevalence of musculoskeletal injuries in professional golfers, which were written in the English language and not restricted by age or gender.

Results

Of the 1863 studies identified on the initial search, 5 studies were found to satisfy the inclusion criteria for analysis. The mean age of the golfers in these studies was 34.8 (±3.6) years. The gender of patients in included studies compromised 72% males and 28% females. Four studies reported that lumbar spine injuries were the most common (range 22%–34%). Excluding injuries to the spine (lumbar, thoracic and cervical), the hand/wrist was the next most common region of injury (range 6%–37%). The quality of the studies was relatively poor with no study satisfying >50% of the quality assessment tool questions and only one study giving a clear definition of how they defined injury.

Conclusion

There is a paucity of well-designed epidemiological studies evaluating musculoskeletal injuries affecting professional golfers. Injuries to the spine are the most frequently affected region, followed by the hand/wrist. This study has identified targeted areas of future research that aims to improve the management of injuries among professional golfers.
Harmful effects of early hyperoxaemia in patients admitted to general wards: an observational cohort study in South Korea
Authors: Jeong Jin Hee , Kim Dong Hoon , Kim Tae Yun , Kang Changwoo , Lee Soo Hoon , Lee Sang Bong , Kim Seong Chun , Park Yong Joo
Published: October 2018

Objectives

We evaluated the association between hyperoxaemia induced by a non-invasive oxygen supply for 3 days after emergency department (ED) arrival and the clinical outcomes at day 5 after ED arrival.

Design

Observational cohort study.

Setting and patients

Consecutive ED patients ≥16 years of age with available arterial blood gas analysis results who were admitted to our hospital were enrolled from January 2010 to December 2016.

Interventions

The highest (PaO2MAX), average (PaO2AVG) and median (PaO2MED) PaO2(arterial oxygen pressure) values within 72 hours and the area under the curve divided by the time elapsed between ED admittance and the last PaO2result (AUC72) were used to assess hyperoxaemia. The AUC72values were calculated using the trapezoid rule.

Outcomes

The primary outcome was the 90-day in-hospital mortality rate. The secondary outcomes were intensive care unit (ICU) transfer and respiratory failure at day 5 after ED arrival, as well as new-onset cardiovascular, coagulation, hepatic and renal dysfunction at day 5 after ED arrival.

Results

Among the 10 141 patients, the mortality rate was 5.8%. The adjusted ORs of in-hospital mortality for PaO2MAX, PaO2AVG, PaO2MEDand AUC72were 0.79 (95% CI 0.61 to 1.02; p=0.0715), 0.92 (95% CI 0.69 to 1.24; p=0.5863), 0.82 (95% CI 0.61 to 1.11; p=0.2005) and 1.53 (95% CI 1.25 to 1.88; p<0.0001). All of the hyperoxaemia variables showed significant positive correlations with ICU transfer at day 5 after ED arrival (p<0.05). AUC72was positively correlated with respiratory failure, as well as cardiovascular, hepatic and renal dysfunction (p<0.05). PaO2MAXwas positively correlated with cardiovascular dysfunction. PaO2MAXand AUC72were negatively correlated with coagulation dysfunction (p<0.05).

Conclusions

Hyperoxaemia during the first 3 days in patients outside the ICU is associated with in-hospital mortality and ICU transfer at day 5 after arrival at the ED.