bluuebunny/crossref_metadata_2025 huggingface dataset:
Practical Design of a High Frequency Phased-Array Acoustic Microscope Probe: A Preliminary Study
Authors: Kim Jeong Nyeon , Tutwiler Richard L. , Todd Judith A.
Published: October 2017

Scanning acoustic microscopy (SAM) has been a well-recognized tool for both visualization and quantitative evaluation of materials at the microscale since its invention in 1974. While there have been multiple advances in SAM over the past four decades, some issues still remain to be addressed. First, the measurement speed is limited by the mechanical movement of the acoustic lens. Second, a single element transducer acoustic lens only delivers a predetermined beam pattern for a fixed focal length and incident angle, thereby limiting control of the inspection beam. Here, we propose to develop a phased-array probe as an alternative to overcome these issues. Preliminary studies to design a practical high frequency phased-array acoustic microscope probe were explored. A linear phased-array, comprising 32 elements and operating at 5 MHz, was modeled using PZFlex, a finite-element method software. This phased-array system was characterized in terms of electrical input impedance response, pulse-echo and impulse response, surface displacement profiles, mode shapes, and beam profiles. The results are presented in this paper.
Fitness-for-Service Assessment on Pressure Piping of Grade X70 Pipeline Steel (API Spec.5L) After Exposure to Fire
Authors: Zuo Yantian , Li Bo , Shu Wenhua , Tang Xiaoying
Published: October 2017

The technical evaluation core of pressure piping components after exposure to fire was performed by considering various factors affecting the pipelines subjected to fire damage, including the determination of material deterioration degree, and the fitness-for-service assessment of the piping equipment. Based on the analysis results and testing data, the safety status and performance loss of the pressure piping after exposure to fire could be obtained. On this view, the influences of fire test and heat exposure as the fire-condition simulation on the grade X70 pipeline steel (API Spec.5L), which was widely used for piping equipment, was carefully investigated. According to the division of fire zone with different factors of temperature and fire suffering preservation, the material micro-structure deterioration and performance degradation were analyzed in detail, after that the grade X70 pipeline steel was heat-treated in muffle furnace to simulate the fire exposure under different conditions of the temperature, heat holding period and cooling mode. In the present foundational research, the mechanical tensile tests, Charpy impact tests, hardness measurements and the metallographic examinations were then conducted in detail. Thus, the data accumulation of performance degradation was believed to benefit to the fitness-for-service assessment of piping components of the grade X70 pipeline steel. Moreover, the material thermal degradation mechanism and the fitness-for-service assessment process of the grade X70 pipeline steel after exposure to fire was further discussed.
Application of Sub-Modeling in the Finite Element Analysis of a Large Fixed Tubesheet Heat Exchanger
Authors: Gao Bingjun , Liu Bin , Dong Junhua , Shi JinHua
Published: October 2017

There are enormous tubes in large fixed tubesheet heat exchangers making it difficult to model all the tubes and tubesheet connections in detail for a finite element (FE) analysis. Alternatively, an equivalent solid plate with various simplified tube connections are employed in the FE modeling. But this fails to yield an accurate stress field around the connecting region of tubes and the tubesheet. Given that the maximum stress of the equivalent solid plate generally occurs adjacent to the solid tubesheet, a novel finite element modeling methodology is proposed in this paper. A two part process is used. The first part is a coarse FE model and the second part is a more detailed FE model. In the coarse FE model, the equivalent solid plate is employed in the central region of the tubesheet with simplified tube connections such as equivalent cylinder by multi-points contacting. And quasi detailed tube and tubesheet connections are used in the coarse FE model for the region adjacent to the solid plate, in which the tube and the tubesheet are simply connected with same nodes. This means that both tubesheet and tubes are established in this quasi detailed FE modeling region. Although both the weld and contacting condition between the tube and the tubesheet are not included, the coarse model is enough to yield a believable stress field for the determination of the maximum stress point of the quasi detailed FE modeling region. In the second part, the sub-model methodology is utilized in the predetermined maximum stress point, in which the detailed connecting structure of the tube and the tubesheet is included, such as the weld and the contact condition. The proposed modeling methodology is helpful to have an insight into the stress around the connecting region of the tube and tubesheet for the effective evaluation of the tubesheet and the connection.
RSE-M Nuclear In-Service Inspection Code New Flaw Interaction Rules
Authors: Faidy Claude
Published: October 2017

After a quick overview of RSE-M scope now used on more than 100 Nuclear Power Plants in the World, this paper will present the flaw evaluation rules of RSE-M Appendix 5.

This Appendix considers cracks, volumetric defects and thinning areas. Periodically updated on a yearly bases, the rules cover cracks in different components, for different material, in different location. It consider defects interaction in Appendix 5 - Chapter 5-1.

In the case of multiple defects, after determining the dimensions for each defect according to the rules in previous chapters, the non-interaction conditions between the elementary defects given shall be checked. If these conditions are not met, the defects shall be grouped according to a dedicated chapter.

This review is done on the basis of RSE-M 2015 edition and last modifications of 2016 edition.
Technical Basis for Proposed ASME Code Case Based on N-513 for Higher Pressure Applications
Authors: McGill Robert O. , Janowiak Ronald J. , Houston Eric J. , Shim Do Jun
Published: October 2017

Code Case N-513 provides evaluation rules and criteria for temporary acceptance of flaws, including through-wall flaws, in moderate energy piping. The application of the Code Case is restricted to Class 2 and 3 systems, so that safety issues regarding short-term system operation are minimized. The first version of the Code Case was published in 2000. Since then, there have been four revisions to the Code Case that have been published by ASME. The technical bases for the original version of the Code Case and the four revisions have been previously published.

There is currently work underway to employ the methods given in N-513 for a new and separate Code Case for higher pressure piping applications. This paper provides the technical basis for the proposed Code Case that includes a structural integrity evaluation and consideration of potential jet thrust forces. In addition, discussion is provided on additional Code Case requirements considering the application to higher pressure systems in order to bolster defense-in-depth. Note that the proposed Code Case still maintains the temperature limit given in N-513.
Analysis on the Transient-State of the Gas-Condensate Pipeline
Authors: Shi Guoyun , Li Xiaoping , Wang Zhi , Wang Dan , Gong Jing
Published: October 2017

The mixture energy equation of the pipeline is developed. By introducing the mass transfer between the two phases, the two-fluid model is extended to two phase flow simulation in pipeline. Taking the space limit of the pipe in pipeline multiphase flow into account, the combined continuity equation is established to represent the interaction between phases, and a segregated solution method is promoted and adopted in this study. A numerical method coupled with phase behavior, flow pattern and hydro-thermodynamic is presented through combing mixture energy equation and two-fluid model developed in transient condition, and is used to simulate the transient-state two-phase in gas-condensate pipeline. In discretization, high-resolution scheme is adopted for conquering nonphysical oscillation caused by step distribution of air void fraction on premise of at least second accuracy. Simulation results have a good performance on the fluctuation of the pipeline multiphase flow and on depressing the dispersion and dissipation. Compared with the OLGA (a commercial software), the maximum difference of the liquid phase fraction is 0.075, the pressure is 0.08MPa and the temperature is 0.6°C.
Visualization of Thermal Fatigue Damage Distribution With Simplified Stress Range Calculations
Authors: Miura Junya , Fujioka Terutaka , Shindo Yasuhiro
Published: October 2017

This paper proposes methods to calculate stress ranges for fatigue assessment in a component subjected to cyclic thermal loads. The aim was to perform the calculations with a PC of moderate power within a reasonably short computation time. Three simplified methods for defining stress ranges were proposed in place of the method in the ASME Section III procedures. A cyclic thermal transient test performed on a 304ss cylinder was simulated. To validate the proposed simplified methods, the simulation results were compared with those of the previously performed thermal transient test. The stress range distribution was visualized using the graphic user interface of a commercial finite-element analysis code. The maximum elastic stress ranges achieved using the four methods at the inner surface of the thick cylinder specimen agreed well with each other. In addition, these maximum stress ranges were consistent with the distribution of the cracks observed in the test.
Safety Analyses for Preventing PCV Damage by FCI in Kashiwazaki-Kariwa 6,7
Authors: Hayakawa Akinori , Suehiro Shouichi , Mizuno Satoshi , Oyama Yoshihiro , Kawamura Shinichi
Published: October 2017

The containment vessel failure mode, “molten fuel-coolant interaction outside the reactor pressure vessel” (“ex-vessel FCI”) is a phenomenon of rapid increase in the pressure inside the containment vessel or steam explosion caused by the contact between the molten reactor core and cooling water outside the reactor pressure vessel after the reactor core is damaged.

To evaluate the viability of keeping confinement function of the containment vessels of Units 6 and 7 (ABWRs) of Kashiwazaki-Kariwa Nuclear Power Station against “ex-vessel FCI,” we conducted a code-based event progression analysis. For evaluation of the rapid increase, we employed the severe accident analysis code, MAAP, after organizing the critical phenomena of the event. In addition, assuming a case of steam explosion occurrence, we conducted an analysis with employing the steam explosion analysis code, JASMINE, and the structural response analysis code, AUTODYN-2D.

As a result of the evaluation, the maximum pressure and temperature inside the containment vessels were lower than their limits. Moreover, the maximum stress applied to the lower part of the containment vessels was lower than the yield stress on support structure of the lower part of the containment vessels. Therefore, we could confirm that the containment vessels can keep their integrity.
A Study of Ductility Dip Cracking of Inconel 690 Welding Filler Metal: Development of a Refusion Cracking Test
Authors: Rapetti Abel , Todeschini Patrick , Hendili Sofiane , Christien Frédéric , Tancret Franck
Published: October 2017

Inconel® alloy 690 is nowadays commonly used instead of 600 for the manufacturing of certain components of the primary circuit of pressurized water reactor (PWR) nuclear power plants, due to its superior resistance to corrosion and stress corrosion cracking. However 690 alloy, and the corresponding welding filler metals (types 52 and 152), can be sensitive to a solid state hot cracking phenomenon during welding, called “ductility dip cracking” (DDC) associated to grain boundary cracking. This work is undertaken to determine more precisely the thermomechanical conditions of the occurrence of DDC in two types of materials: filler metals 52M and 152. To do this, we designed a simple hot crack susceptibility test. This test is based on multiple welding beads on a cuboidal mockup. This test clearly demonstrates the effect of multiple passes on the occurrence of DDC. In parallel, hot tensile tests following fast heating were performed to determine the DDC temperature range, to try and correlate DDC to the thermomechanical behavior.
Confinement Effects on Added Mass of Cylindrical Structures in a Potential Flow
Authors: Capanna R. , Ricciardi G. , Eloy C. , Sarrouy E.
Published: October 2017

Efficient modelling and accurate knowledge of the mechanical behaviour of the reactor core are needed to estimate the effects of seismic excitation on a nuclear power plant. The fuel assemblies (in the reactor core) are subjected to an axial water flow which modifies their dynamical behaviour. Several fluid-structure models simulating the response of the core to a seismic load has been developed in recent years; most of them require high computational costs. The work which is presented here is a first step in order to simplify the fluid forces modelling, and thus to be able to catch the main features of the mechanical behaviour of reactor core with low computational costs. The main assumption made in this work is to consider the fluid flow as an inviscid potential flow. Thus, the flow can be described only using one scalar function (velocity potential) instead of a vector field and strongly simplifies the fluid mechanics equations, avoiding the necessity to solve Navier-Stokes equations. The pressure distribution around a cylinder is first solved in Fourier space for different values of the parameters (wavenumber, confinement size).

The method is applied to a simple geometry (cylinder in an axial flow with a variable confinement) in order to test its effectiveness. The empirical model is then compared to simulations and reference works in literature. The configuration with large confinement has been solved, and results were in agreement with Slender Body Theory. The dependency on the confinement size strongly depends on the wavenumber, but in any case added mass increases as the confinement size decreases. Finally, future perspectives to extend the model to a group of cylinders and to improve the model are discussed (i.e. add viscosity to the model).
Core Seismic Experiment and Analysis of Hexagonal Bundle Model for Fast Reactor
Authors: Iwasaki Akihisa , Matsubara Shinichiro , Yamamoto Tomohiko , Kitamura Seiji , Okamura Shigeki
Published: October 2017

To design fast reactor (FR) core components, seismic response must be evaluated in order to ensure structural integrity. Therefore, advanced analysis method must be developed to calculate seismic response of a fast reactor core. The fast reactor core is generally made of several hundred core elements which are hexagonal flexible beams embedded at the lower support plate in hexagonal arrangement. When a big earthquake occurs, large horizontal displacement, vertical displacement (rising) and impact force of each core element may cause a trouble for control rod insertability and core element intensity. Therefore, a seismic analysis method of a fast reactor core considering three-dimensional nonlinear behavior, such as impact, fluid-structure interaction, was developed. 1/1.5 scale 37 core element mock-ups hexagonal-matrix experiment was performed to validate the core elements vibration analysis code in three dimensions (REVIAN-3D). Vertical behavior (rising displacement) and horizontal behavior (impact force) were good agreement with experiments by the validation of REVIAN-3D.
Comparison of Experimental Results and Numerical Simulations of Penetration Tests With Damping Concrete
Authors: Scheidemann Robert , Qiao Linan , Müller Karsten
Published: October 2017

The shock absorbing material damping concrete is for the foundation in dry interim storage facilities for radioactive waste in Germany. In case of a potential cask drop damping concrete minimizes the mechanical loads to the cask. In course of safety analyzes this accident scenario is considered by numerical simulations using the finite element method. To get reliable results of numerical simulations a suitable material model is needed to take the characteristics of damping concrete into account. Due to the lack of sufficient material knowledge a research project was started to characterize the material’s behavior under different load conditions. This paper presents the test program to analyze the material behavior of damping concrete which is characterized by large volume change and strain rate hardening dependence. The determined parameters were used to adapt an existing material model of the FE-code ABAQUS®. This model has to handle the mechanical damage behavior of damping concrete which occurs under compression and shear loads during a potential cask drop. To verify the material model numerical simulations are compared with dynamic penetration tests, which were conducted with specimens assembled similar to the real application of the damping concrete footings. The transferability of the material model to a real accident scenario was verified by a drop test with a full-scale cask on a damping concrete footing.
Testing and Numerical Simulation of Elastomers: From Specimen Tests to Simulation of Seal Behavior Under Assembly Conditions
Authors: Weber Mike , Kömmling Anja , Jaunich Matthias , Wolff Dietmar , Zencker Uwe , Völzke Holger , Schulze Dietmar , Probst Ulrich
Published: October 2017

Extended periods of interim storage are more relevant in Germany due to delays in the siting procedure to establish a deep geological repository for spent nuclear fuel, high level radioactive waste and in low/intermediate level waste container storage designated for the Konrad repository. BAM is involved in national cask licensing procedures and responsible for the evaluation of cask-related long-term safety issues.

The long-term performance of elastomer seals for lid systems of transport and storage casks, whether used as auxiliary seals in spent fuel casks or as primary seals for low and intermediate level waste packages, is an important issue in this context. The polymeric structure of these seals causes a complex mechanical behavior with time-dependent sealing force reduction.

The results of a comprehensive purpose-designed test program consisting of basic compression and tension tests as well as relaxation tests on unaged specimens of representative types of elastomers (fluorocarbon rubber (FKM) and ethylene propylene diene rubber (EPDM)) at different temperatures and strain rates are presented. They were used to identify the constitutive behavior and to obtain parameters for finite element material models provided by the computer code ABAQUS®. After estimating the influence of parameters such as Poisson’s ratio and friction coefficient by sensitivity analyses, the chosen values for the finite element simulation were validated by comparison with specimen test results.

Based on this preliminary work the simulation of a specific laboratory test configuration containing a typical elastomer seal with circular cross section is presented. The chosen finite element material model and the related parameters had to show that they are able to represent not only the specimen behavior under predominantly uniaxial load but also the more complex stress states in real components. Deviations between the measured and calculated results are pointed out and discussed.

The results from this work will be utilized in future simulations of aged elastomer behavior.
Strain Waveform Effects for Low Cycle Fatigue in Simulated PWR Water
Authors: Seppänen Tommi , Alhainen Jouni , Arilahti Esko , Solin Jussi
Published: October 2017

In order to perform design code (ASME III, RCC-M, JSME) compatible direct strain-controlled tests in simulated PWR water, a unique environmental fatigue testing facility was previously developed. Pneumatic bellows are used to generate strain in the stainless steel specimen mid-section, while eddy current based measurement is used as a feedback signal.

The NUREG/CR-6909 report gathered a large database of test results and proposed environmental reduction factors (Fen) to account for a reduction in fatigue life in simulated LWR environment when comparing to a reference value in air. The database was composed of non-stabilized stainless steels tested using methods which are not directly comparable to those used in air to define the reference curves. Applicability of the stainless steel Fen factors has already been challenged in previous PVP papers (PVP2013-97500, PVP2014-28465, PVP2016-63294).

Results in this paper continue to show this trend of lower experimental Fen factors compared to predictions made by the NUREG report. Dual strain rate tests were performed, specifically focusing on the effect of strain waveform shape on fatigue life. Similarly to last year’s results (PVP2016-63294) a distinct effect of strain waveform, presently inadequately accounted for in Fen predictions, was observed.
New Approach on Solid State Joining of Stainless Steel Tube to Tube Sheet Joints
Authors: Roos Arne , Winkler Marcus , Wimmer Georg , Dos Santos Jorge F. , Hanke Stefanie
Published: October 2017

Hybrid friction diffusion bonding (HFDB) is a solid-state bonding process first introduced by Helmholtz-Centre Geesthacht, Germany, to join aluminium tube-to-tube sheet joints of coil-wound heat exchangers (CWHE) for liquefaction of natural gas (LNG). This study describes how HFDB was in a first step successfully transferred to create austenitic S32100 single hole tube-to-tube sheet joints. Process parameters are presented and results from subsequent non-destructive bubble leak testing and destructive tensile pull-out testing are discussed. After pull out testing the bonded areas were further investigated using optical microscopy as well as scanning electron microscopy.

Leak tight joints were generated due to the formation of a metallic bond close to the planar friction area of the employed tools, and failure in pull-out tests occurred by ductile fracture. The results show that the HFDB approach developed for Al-alloys may well be transferred to steel, and in the future possibly to other high-temperature alloys. It thereby offers an alternative route for joining tube to tube-sheet connections in solid state, with the corresponding advantages, such as no open flames or arc, no spatter and no need for filler material.
Review and Comparison of Buckling Methodologies for ASME B&PV Code Linear Piping and Component Restraints
Authors: Wiseman Phillip , Hoch Zara Z. , Nargund Shrikant S.
Published: October 2017

Piping and component restraints are required to follow the design requirements as mentioned in ASME Boiler and Pressure Vessel Code, Section III, Subsection NF. One of the requirements indicates the necessity of calculating the critical buckling stresses for the members that are subjected to a compressive loading. This paper discusses the prescribed requirements in the Code that specifically address the considerations of the stability and buckling load capacities of linear piping and component restraints (i.e., struts). The finite element modeling of various strut geometries and the results of the buckling analyses of slender structural members (slenderness ratio, Kl/r, greater than or equal to 100) using various finite element solution techniques are presented herein. Specifically, three types of finite element analyses are conducted in an effort to define the critical buckling load for the subject structural member. These three finite element analyses include the traditional linear (Eigen value) Euler method; the nonlinear, second order large deformation method; and finally, the nonlinear large deformation method that incorporates nonlinear elastic-plastic material behavior.

Additionally, two closed form solutions using strain energy method and Euler-Bernoulli beam theory are conducted on the same strut geometries. The results obtained from the aforementioned techniques are then compared both numerically and qualitatively with an appropriate explanation of the purpose and usefulness of each particular result with respect to the intent of the ASME B&PV Code, Section III, Subsection NF requirements. The results show significant variations based on differences in the assumptions and techniques employed in the respective analyses and simply applying the identical margin of safety to each technique does not yield consistent outcomes.

As a result of the discussion we get an insight about the axial compression allowable stress equations and factors as defined in the ASME B&PV Code and how they should be refined depending on the type of buckling analysis we choose to conduct.
An Overview of Time Dependent Crack Growth Models Used for ERW Seam Weld Analyses
Authors: Olson Richard , Young Bruce , O’Brian Jennifer
Published: October 2017

In response to the National Transportation Safety Board (NTSB) Recommendation P-09-1, the Department of Transportation (DOT) Pipeline and Hazardous Material Safety Administration (PHMSA) initiated a comprehensive study to identify actions that could be implemented by pipeline operators to significantly reduce longitudinal seam failures in electric resistance weld (ERW) pipe. As part of the project, Task 4 in Phase II was designed to validate existing failure prediction models and, where gaps exist, refine or develop the models needed to assess and quantify defect severity for cold welds, hook cracks, and selective seam weld corrosion (SSWC) (the primary ERW/Flash Weld seam threats) for failure subject to loadings that develop both during hydrotests and in service. These models would then be used to develop new software to support integrity management of seam welds with enough flexibility to benefit from the experience gained during this project.

The purpose of this paper is to review the time-dependent crack growth model used in the development of the PipeAssess PI™ pipeline integrity management software. The model will be discussed in the context of its underlying theory, validation, and application to a set of test cases. Both the stress-activated creep model and consequential tie to fatigue crack growth models are presented, which describe crack growth under hydrostatic holds and subsequent pressure cycles. Full-scale experiments are used to validate the models.

The reports generated during the course of the project are publically available and are located at the PHMSA website: HTTP://PRIMIS.PHMSA.DOT.GOV/MATRIX/PRJHOME.RDM?PRJ=390.
Benchmarking Probabilistic Code for LBB Analysis for Circumferential Cracks
Authors: Kurth Robert E. , Sallaberry Cédric J. , Young Bruce A. , Scott Paul , Brust Frederick W. , Kurth Elizabeth
Published: October 2017

NRC Standard Review Plan (SRP) 3.6.3 describes Leak-Before-Break (LBB) assessment procedures that can be used to assess compliance with the 10CFR50 Appendix A, GDC-4 requirement that primary system pressure piping exhibit an extremely low probability of rupture. SRP 3.6.3 does not allow for assessment of piping systems with active degradation mechanisms, such as Primary Water Stress Corrosion Cracking (PWSCC) which is currently occurring in systems that have been granted LBB approvals.

There are several codes available for addressing the requirements of GDC-4. This paper addresses three of these codes: (1) xLPR 2.0; (2) PROLOCA; and (3) PROMETHEUS. Each of these codes is described and applied to a representative plant where active degradation mechanisms have been found. Conclusions about the design, results, and interpretation of the results is then provided. In all cases the probability of failure of the pipe is found to be extremely low when the crack inspections and leak detection systems are modeled.
Technical Basis for Conversion of Non-Mandatory Appendix F of Section III of the ASME Boiler and Pressure Vessel Code to a Mandatory Appendix: Part II — Associated Code Book Updates
Authors: McKillop Suzanne , Wen Jie , Keating Robert , Adams Timothy M.
Published: October 2017

In 1974, the Level D Service Limits for Section III, Division 1, Class 1 components were published in Non-Mandatory Appendix F titled “Rules for Evaluation of Service Loading with Level D Service Limits”. Over the past 40 years, the scope of the Appendix F has been expanded to be applicable to certain Class 1, Class 2 and Class 3 components and supports in Division 1 as well as in Division 3 and Division 5. With each addition, the organization and implementation of the rules in Appendix F became more cumbersome for the user and consistency between the Appendix and the Code Books1 was not maintained. At the same time, the use of these rules has evolved to the point where the non-Mandatory Appendix is essential the default for Level D Service Limits. Starting in the 2017 Code edition, the component design rules will reference Mandatory Appendix XXVII when Design by Analysis is used to determine Level D Service Limits. In particular, the component design rules, or rules specific to design of components and not Design by Analysis, were removed from Appendix XXVII and placed in the appropriate Code Book. This approach resulted in noteworthy updates to the support rules in Subsection NF, the core support rules in Subsection NG, the valve rules in NB-3500, and the piping rules in NB/NC/ND-3600. The detailed approach used to incorporate the component design rules into each Code Book are presented in this paper.
Improved Elastic Compliance Equation and its Inverse Solution for Compact Tension Specimens
Authors: Zhu Xian-Kui
Published: October 2017

ASTM E1820 is a well-developed fracture test standard and has been used worldwide for fracture toughness testing on ductile materials in terms of the J-integral or J-R curve. This standard recommends the elastic unloading compliance technique for measuring crack length in a single specimen test, and an accurate elastic compliance equation is needed to estimate physical crack length. Compact tension (CT) specimen is one of the most often used standard specimens with crack length ratios of 0.45≤a/W≤0.70 prescribed in E1820 for J-R curve testing. The stress intensity factor K of CT specimens used in E1820 was developed by Srawley (IJF, 1976) and has been commonly accepted as the most accurate solution. The compliance equation of CT specimens was developed by Saxena and Hudak (IJF, 1978) and has been used in ASTM E1820 for decades. However, recent results showed that the load-line displacement (LLD) compliance equation is not consistent with that determined from its K solution, and the maximum error of LLD compliance can be larger than 7% at a/W = 0.32 and ∼ 5% at a/W = 0.45 (E1820 standard crack size). The FEA results confirmed that the K solution in E1820 is indeed very accurate, but its compliance equation is less accurate. Thus, an improved compliance equation with high accuracy is developed from the accurate K solution using the numerical integration technique and shooting method.
Fatigue Crack Initiation and Growth Behaviour of 316L Stainless Steel Manufactured Through Selective Laser Melting
Authors: Davies C. M. , Thomlinson H. , Hooper P. A.
Published: October 2017

Selective Laser Melting (SLM) is a relatively new manufacturing technique that offers many benefits. However the utilisation of SLM manufactured components depends on the assurance of their integrity during operation. Tensile and high cycle fatigue tests have been performed on uniaxial samples manufactured using SLM of 316L stainless steel to examine the elastic-plastic deformation and fatigue crack initiation behaviour of the material. In addition, the fatigue crack growth behaviour has been determined from tests on compact tension samples manufactured using SLM. The influence of build orientation has been examined on the compact tension samples. The results are compared to values obtained from conventional manufacturing methods. The tensile samples have a higher strength but significantly lower ductility than wrought material. The fatigue strength of the SLM material was substantially less than wrought material, though a similar fatigue limit maybe seen, this may be attributed to porosity in the material. The fatigue crack growth rate of the SLM material was 5–10 times faster, for a given stress intensity factor, than wrought materials and strongly depended on crack orientation in relation to the build direction.
Bending-Torsional Flutter of a Slender Web in a Cross Flow
Authors: Hiroaki Keiichi , Kawai Nobuhito , Watanabe Masahiro
Published: October 2017

This paper presents a flutter analysis of a slender web in a cross air flow. In the flutter analysis, a Doublet-point method (DPM) [1] based on an unsteady lifting surface theory is used to calculate the unsteady fluid force acting on the sheet surface. The equation of motion of the web with tension is derived by using the finite element method (FEM). Flutter velocity, frequency and mode are examined through the root locus of the flutter determinant of the system with changing flow velocity of air. In this study, these flutter characteristics derived by flutter analysis are compared with wind-tunnel experiments. The influence of tension of the web on flutter velocity, frequency and mode is clarified.

As tension of the web becomes higher, the flutter velocity and corresponding frequency increase. In any tension, coupled mode flutter of bending and torsional modes occurs. Then, local work done by the fluid force around the upstream end of the web is positive. On the other hand, near the downstream end of the web, the local work is negative.
Fabrication and Wear Analysis of Aluminium Matrix Composite Reinforced by SiC Micro and Nano Particles
Authors: Idrisi Amir Hussain , Mourad Abdel-Hamid Ismail
Published: October 2017

Metal matrix composites (MMCs) constitute an important class of weight-efficient structural material which empowering every field of engineering applications. Aluminium based metal matrix composites contains potential for high specific strength and advanced structural applications, as well as good elevated temperature resistance along with light weight application. However, need for improved tribological performance has led to the fabrication of newer variants of the composite. In the present work, aluminium based metal matrix composite (MMCs) developed through stir casting route by reinforcing different weight percentage of SiC micro (5% and 10%) and nano (1% and 2%) particles. In this research, 5083 aluminium alloy is used as matrix phase due its broad range of industrial applications. Wear behaviour of the developed aluminium matrix composite (AMC) was investigated under different conditions of applied load, operation time and speed. The analysis carried out at room temperature for three different loads (10N, 20N, and 30N) with varying four different operation times (30 mins, 60 mins, 90 mins, and 120 mins). The speed was kept constant at 1450 rpm during all experiments. The results of all considered composites are investigated and the composite with 2% SiC nano reinforcement is identified as a superior among all other composition for tribological applications point of view. Also the developed aluminium matrix composites have potential applications in many industries such as pressure vessels, pipe fittings, boat hulls, gears and pistons.
Reactor Damage Categorization and Damage Repair
Authors: Antalffy Les , Yasutomi Akitada , Tahara Takayasu , Rajguru Anil , Millet Barry
Published: October 2017

This paper outlines some of the major problems that can occur during the service life of hydroprocessing reactors resulting from operating at high stress levels in a high temperature and high pressure hydrogen environment. The paper discusses the influence of flaws such as weld defects, sigma phase formation in the weld overlaid ring joint grooves and at catalyst bed supports and discusses other causes of damage such as temper embrittlement, weld overlay disbonding and fatigue. The paper also outlines how reactor damage problems may be detected and assessed to determine the course of action for repair if needed. The paper outlines service life improvements of modern reactors based upon advanced materials of construction and improvements in design, fabrication and welding technology.
Impulsively-Generated Pressure Transients and Strains in a Cylindrical Fluid-Filled Tube Terminated by a Converging Section
Authors: Veilleux Jean-Christophe , Shepherd Joseph E.
Published: October 2017

The syringe in a subcutaneous autoinjector may be subjected to internal pressure transients due to the normal operation of the injection mechanism. These transients are similar to transients in fluid-filled pipelines observed during water hammer events. In this paper, the effect of an air gap in the syringe and a converging section are studied experimentally and numerically in a model system which consists of a fluid-filled metal tube that is impulsively loaded with a projectile to simulate the action of the autoinjector mechanism operation.

The air between the buffer and the water results in a complex interaction between the projectile and the buffer. Also, there are tension waves inside the tube due to the presence of a free surface, and this causes distributed cavitation which, in turn, gives rise to steepening of the pressure waves. The converging section can amplify the pressure waves if the wave front is sharp. Pressures as high as 50 MPa have been measured at the apex of the cone with impact velocities of 5.5 m/s.
Impact Toughness of Grade 92 Steel Aging at 700°C
Authors: Baolan Gu , Tong Xu
Published: October 2017

The evolution of microstructures and the variation of impact toughness of Grade 92 steel aged 200,500, 800, 1000 hours at 700 °C were studied in this paper. The results show that the impact energy of Grade 92 steel was reduced significantly with the aging time increase. After 200 h aging, the value of impact energy decreased about 10%; then the impact energy variation trends to be stable with 500 h aging. When the aging time increase to 800 h, the impacts energy decreased about 26% compared with the original sample; and then the variation trends stable with 1000 h aging. The precipitation and growth of M23C6 Phases at the prior austenite grain boundaries and martensitie lath boundaries during aging are major reasons of the impact energy decrease. 200 h aging, M23C6 carbides precipitate at the grain boundaries. Laves phase was discovered after 500 h aging, then the M23C6 and Laves phase coarsening with the aging time. This made the impact toughness degradation more.
Feasibility of Reduced-Size Spinning Cylinder Specimens for Pressurised Thermal Shock Testing
Authors: Coules H. E. , Orrock P. J. , Truman C. E.
Published: October 2017

Pressurised Thermal Shock (PTS) is one potential risk to the integrity of the reactor pressure vessel in a pressurised water reactor. It has been postulated that PTS could occur as a result of various initiating events such as loss-of-coolant accidents with subsequent re-pressurisation. Experimental studies of PTS are typically very difficult and expensive to perform because both a severe thermal shock and a primary load must be applied to the test specimen, while the specimen itself must be very large to imitate the behaviour of the RPV wall. We investigated the feasibility of using scaled-down PTS test specimens based on the spinning-cylinder concept. The use of scaled-down specimens could greatly reduce the difficulty and cost of experimental PTS testing. To explore this concept, we used a particularly well-characterised spinning-cylinder PTS test: the NESC-1 test which was performed in the late 1990s. A large parametric set of elastic-plastic finite element models was used determine a combination of specimen dimensions and test conditions that would very closely mimic the crack tip conditions which occurred during NESC-1. Specifically, the modelling demonstrated that it was indeed possible to replicate the KJ vs. temperature trajectory, and crack tip constraint, at a critical point on the crack tip line from which tearing initiated during the actual NESC-1 test. The reduced-size specimen must be carefully designed: it cannot be a simple linear scale-down due to the inherent non-linearity of both the thermal and mechanical processes which occur during PTS.
The OECD-NEA Programme on Metallic Component Margins Under High Seismic Loads (MECOS): Towards New Criteria
Authors: Sollogoub Pierre
Published: October 2017

MECOS is a Post-Fukushima OECD/NEA initiative, with the following main objectives:

• To quantify the existing margins in seismic analysis of safety class components and assess the existing design practices within a benchmark activity.

• To make proposals for new design/evaluation criteria of pressurized piping systems, accounting for their actual failure mode under strong input motions.

The first part of MECOS consisted of gathering information on i) current design practices and ii) dynamic seismic tests on piping system carried out around the world that could be suitable for benchmarking. Part 2 is a benchmark exercise on piping system tests, and Part 3 are proposals for new criteria. The purpose of the proposed paper is to introduce the work which is undertaken in Part 3 in order to propose design criteria that address the observed fatigue-ratchetting failure modes as well as plastic instability. It includes revisiting the past test results as well as the interpretations that were carried out and conclusions that were drawn at that time, and reanalyzing them in the light of recent developments. Recent experimental programs carried out in Japan and in India will also be addressed.
Modeling of Hypervelocity Impact Experiments Using Gamma-SPH Technique
Authors: Limido Jérôme , Trabia Mohamed , Roy Shawoon , O’Toole Brendan , Jennings Richard , Mindle Wayne L. , Pena Michael , Daykin Edward , Hixson Robert , Matthes Melissa
Published: October 2017

A series of experiments were performed to study plastic deformation of metallic plates under hypervelocity impact at the University of Nevada, Las Vegas (UNLV) Center for Materials and Structures using a two-stage light gas gun. In these experiments, cylindrical Lexan projectiles were fired at A36 steel target plates with velocities range of 4.5–6.0 km/s. Experiments were designed to produce a front side impact crater and a permanent bulging deformation on the back surface of the target without inducing complete perforation of the plates. Free surface velocities from the back surface of target plate were measured using the newly developed Multiplexed Photonic Doppler Velocimetry (MPDV) system.

To simulate the experiments, a Lagrangian-based smooth particle hydrodynamics (SPH) is typically used to avoid the problems associated with mesh instability. Despite their intrinsic capability for simulation of violent impacts, particle methods have a few drawbacks that may considerably affect their accuracy and performance including, lack of interpolation completeness, tensile instability, and existence of spurious pressure. Moreover, computational time is also a strong limitation that often necessitates the use of reduced 2D axisymmetric models. To address these shortcomings, IMPETUS Afea Solver® implemented a newly developed SPH formulation that can solve the problems regarding spurious pressures and tensile instability. The algorithm takes full advantage of GPU Technology for parallelization of the computation and opens the door for running large 3D models (20,000,000 particles). The combination of accurate algorithms and drastically reduced computation time now makes it possible to run a high fidelity hypervelocity impact model.
A Comparative Study of Concentrically and Eccentrically Pierced Flat Unstayed Heads
Authors: Chandiramani Dipak K. , Gopalakrishnan Shyam , Mathkar Ameya , Nawandar Suresh K.
Published: October 2017

Clause UG - 39 of ASME Section VIII Division 1 [1] provide rules for compensation of openings in flat stayed/ flat unstayed heads having fitted nozzles.

The rules provided in Clause UG - 39 and its sub clauses apply to all openings other than small openings covered by UG - 36 (c)(3)(a) and provide rules for compensation of openings to those geometries which confirms to the geometric limitations specified therein.

The rules provided in Clause UG - 39 of ASME Section VIII Division 1 are based on area replacement method. This method is also elaborated in WRC Bulletin 335 Aug 1988[4]. The conclusion of this bulletin is applicable to ASME Section VIII Div 1, ASME Section I, ASME B 31.1 and ASME Section III Class 2 and 3. This method requires that the metal cut out by an opening be replaced by reinforcement within a prescribed zone around the opening. This methodology is relatively simple and vast majority of the piping and pressure vessels with openings conforming to this methodology have given satisfactory service.

In Code [1], as such there appears to be no restriction on the location of the nozzle opening, i.e., a header flat head pierced concentrically or eccentrically to locate the nozzle opening as long as the required area is obtained and the stresses are within allowable limits. While both these alternatives would be acceptable in Code [1] constructions, the actual stresses at the header flat heads/nozzle junction may vary considerably.

The work reported in this paper was undertaken to make a comparative study on the effect of unstayed flat head pierced concentrically or eccentrically by using ASME Section VIII Division 1 and to study the stress pattern in both the cases using Finite Element Analysis (FEA) as a referral methodology.
Turbulent Structure Study on Flow-Induced Vibration in Tee Junction Pipe
Authors: Ishigami Takahiro , Nishiguchi Masato , Maekawa Munenori , Izuchi Hisao
Published: October 2017

Flow-Induced Vibration (FIV) caused by turbulent flow inside a pipe could lead to fatigue failure with shell mode vibration. Our previous study investigated the excitation source of the FIV for tee junctions experimentally to understand the FIV mechanism and provided Power Spectral Density (PSD) profiles of pressure fluctuation. In the present study, experiments were performed with more extensive measurement points for both 90- and 45-degree tees to understand a more detailed mechanism. PSD plots were provided, featuring different pressure fluctuation characteristics at each measurement point among both angle tees. It also emerged that the PSD level declined with increasing distance from the impingement point. Unsteady Computational Fluid Dynamics (CFD) simulations with the Large Eddy Simulation (LES) model were also performed to understand the turbulent structure for the tee junctions. The frequency characteristic of the simulated pressure fluctuation effectively matched those of the experiments at each measurement point, which implies that CFD simulation with an LES model could reveal reasonable predictions of the FIV excitation source for tee junctions. Simulation results showed that the relatively large vortex shed from the branch pipe impinged periodically on the main pipe bottom and the large vortex was dissipated downstream. These vortex behaviors would be the main mechanism generating the FIV excitation source.