bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flaw Design for d-c EP Monitoring of Crack Initiation and Growth During Full-Size Pipe Experiments
Authors: Hong J. K. , Brongers M. , Kalyanam S. , Hioe Y. , Wilkowski G. , Zeng Y. , Hallai J. F. 
Published: October 2020

Abstract
A design for flaw placement in a full-scale pipe test was developed to both detect crack initiation and measure crack growth rate upon internal pressurization of a pipe exposed to a sulfide stress cracking (SSC) environment. The objective of this work was to model different sizes of longitudinally oriented, inside diameter (ID) surface flaws and lay them out on the pipe in such a manner that (1) the flaws experience their target stress intensity factor (K) value at a chosen value of internal pressure, (2) the stress interaction between flaws is minimized, and (3) the flaw layout is optimized for detecting both crack initiation and growth using a direct-current (d-c) electric potential (EP) technique.
The approach to the flaw design and layout used finite element analysis (FEA) modeling and consisted of optimizing K-profiles. First, the K-profiles were optimized by designing curved-bottom flaws such that the target K along the flaw front occurred along most of the flaw length. Then, stress interactions between the flaws were checked to confirm minimum interactions were achieved and that the proposed flaw layout around the pipe circumference was acceptable. In addition, the FE models were used to predict strains on the pipe outside surface. Finally, global (single large current supply), local (individual small current supplies) and hybrid (individual medium-sized current supplies at larger distance) approaches to the d-c EP measurements were evaluated to select which methodology would be most appropriate to detect both crack initiation and growth of the flaws. The results of the analysis show that optimizing all these design factors provides a solid basis for achieving experimental success.
Asset Integrity Management and Fitness-for-Service Assessment of a Pipe Elbow With Metal Loss
Authors: Thorwald Greg , Brendecke Devon , Webb Stephen 
Published: October 2020

Abstract
The objective of this paper is to describe the inspection process and examine a piping elbow found to have metal loss within the context of Asset Integrity Management (AIM). During the last five years, Industry 4.0 technology involving mobile tablet and cloud technology has merged with the proven concepts of AIM enterprise systems. Before this shift, inspectors, engineers, and managers relied on unreliable and time-consuming methods. New technologies allow inspectors and mangers to think, react, and communicate quickly and proactively when integrity threats are discovered.
A piping elbow was identified at a thickness monitoring location (TML) within a larger system due to existing internal corrosion and/or erosion. Since the metal loss is internal, an external visual examination was not sufficient to monitor the metal loss. External ultrasonic (UT) inspection was used to measure the thickness at multiple points on a grid pattern drawn on the elbow’s external surface. The thickness measurements provide the data needed for a local metal loss assessment.
An AIM program was used to assess the risks, aid in inspection, and develop an assessment for ascertaining the degradation pattern. With a heightened understanding of the asset’s degradation pattern, the risk to the asset is reassessed continuously until it has been reduced to an acceptable level as defined by the stake holders.
Effect of Cladding-Induced Stresses on Crack Driving Force in the Fracture Analysis of Pressure Vessels
Authors: Emslie Julian , White Josh , Pellereau Ben , Wood Andrew 
Published: October 2020

Abstract
The inner surfaces of ferritic steel pressure vessels are often coated with a weld-deposited layer of austenitic cladding for the purpose of corrosion resistance.
UK practice of assessing the defect tolerance by postulating defects in components leads to the requirement for a fracture assessment that includes cladding. Section XI requires that the cladding be considered in the fracture analysis, including cladding-induced stresses in the KI evaluation; these stresses largely arise due to the different coefficients of thermal expansion of the cladding and base material, and can also be known as cladding residual stresses.
It is thought that in some assessments of clad pressure vessels, the cladding residual stress is either not included, or assumed to be of a significantly reduced magnitude — due to it decreasing at typical operating temperatures and/or being relaxed by prior overloads such as a hydrostatic test.
This paper describes finite element analysis to determine the effect of cladding residual stress, comparing J values for loading with and without cladding stresses. Comparisons are also made with J-estimations using the R6 fracture assessment procedure. It is argued that cladding-induced stresses would not contribute to ductile failure as they would be reduced by prior loading, with remaining residual stresses being overcome under large plasticity before failure, due to their secondary nature. Further, it may be misleading to include them in an R6 assessment when using simplified approaches, as their contribution can be exaggerated through pessimistic calculations of the V factor.
Progressive Fatigue Life Prediction of Composite Materials Based on Residual Material Property Degradation Model
Authors: Nakai-Chapman J. , Park Y. H. , Sakai J. 
Published: October 2020

Abstract
Anisotropic composite materials have been extensively utilized in mechanical, automotive, aerospace and other engineering areas due to high strength-to-weight ratio, superb corrosion resistance, and exceptional thermal performance. As the use of composite materials increases, determination of material properties, mechanical analysis and failure of the structure become important for the design of composite structure. In particular, the fatigue failure is important to ensure that structures can survive in harsh environmental conditions. The non-homogeneous character of composites induces diverse failure modes of the constituent including fiber fracture, matrix cracking, fiber-matrix interface failure, and delamination. Non-homogeneity of composite materials makes their fatigue behavior very complex in comparison with traditional engineering materials. In this study, a progressive damage theory is extended to simulate fatigue failure of composite laminates under fatigue loading conditions. A residual material property degradation model was employed to predict fatigue damage due to arbitrary stress ratio without performing excessive quantities of testing. This generalized residual material property degradation rule is implemented into user subroutine USDFLD in ABAQUS through which material degradation states are updated over the progressive fatigue loading. The present computational method is verified by comparing the simulated results with the experimental data available in the literature.
Maintenance Optimization: Finding the Best Frequencies of Maintenance Activities
Authors: Cluever Joseph , Esselman Thomas , Bruck Paul 
Published: October 2020

Abstract
The nuclear industry has recently been shifting to value-based maintenance in order to keep nuclear power competitive in the power generation market. A key challenge in value-based maintenance is the optimization of a maintenance schedule. With most components having ten to fifteen available maintenances, the complexity of the optimization grows quite quickly. This paper presents a methodology for combining maintenance effectiveness, cost estimates, failure impacts, and overall reliability data to estimate an expected life cycle cost (LCC) for a component. The maintenance types are categorized into three types: monitoring, wear-rate reducing (e.g. oil change), or life-restoring (e.g. refurbishment). Each maintenance type has a different effect on problem detection, degradation rate, and future life expectancy. A Markov model uses the maintenance effects to estimate the distribution of what state of degradation a component is in at a specific time and concurrently, the component failures, maintenance costs, and failure impacts are tallied up in order to provide an expected life cycle cost for a given maintenance schedule. Optimization of the maintenance schedule is performed using the genetic algorithm where multiple maintenance schedules are simultaneously calculated, compared, and evolved in order to find the lowest expected life cycle costs. The genetic algorithm was selected as a suitable optimization algorithm for its ability to find relatively close approximations to the global optimum with relative ease while concurrently being able to handle non-smooth objective functions.
Damage Detection Using Multiphysics Guided Wave Propagation
Authors: Dana J. , Park Y. H. , Gonzales C. 
Published: October 2020

Abstract
In order to improve the safety, reliability, and life of diverse structures, the development of effective methodologies for structural health monitoring is critical. Among damage detection techniques, guided ultrasonic Lamb waves are particularly suitable for damage detection applications for plate-like and shell-like structures, such as aircraft wing-box structures, heat exchanger tubing, stiffened panels, and nuclear steam generator tubing, due to their sensitivity to damage. Computational models can play a critical role to study wave propagation for monitoring structural health and develop a technique to detect structural damage. Due to complexity of guided wave behavior, efficient and accurate computation tools are essential to study the mechanisms that account for coupling, dispersion, and interaction with damage. In this study, a numerical technique is presented for guided waves propagation in metallic structure by employing co-simulation using ABAQUS Standard module and ABAQUS Explicit module simultaneously to simulate transient wave propagation from an PZT actuator into a metallic plate. The present co-simulation analysis couples multiphysics (piezoelectric) analysis with transient dynamics (wave propagation) analysis. A numerical test is conducted using a PZT actuator for exciting planar Lamb waves and a sensor for acquiring wave signals. The signals achieved from defected and pristine models by FEA are then compared to identify and detect damage in the structure.
General Criteria and Evaluations for the Selection of ASME Section VIII, Division 1 or 2 for New Construction Pressure Vessels
Authors: Barkley Nathan , Riley Matt 
Published: October 2020

Abstract
For new ASME pressure vessel designs that have a design pressure less than 10,000 psi (70 MPa), it is commonly questioned whether Section VIII, Division 1 or Division 2 should be used as the code of construction. Each code offers specific advantages and disadvantages depending on the specific vessel considered. Further complicating the various considerations is the new Mandatory Appendix 46 of Division 1 which allows the design rules of Division 2 to be used for Division 1 designs. With the various options available, determining the best approach can be challenging and is often more complex than only determining which code provides the thinnest wall thickness.
This paper attempts to address many of the typical considerations that determine the use of Division 1 or Division 2 as the code of construction. Items to be considered may include administrative burden, certification process, design margins, design rules, and examination and testing requirements. From the considerations presented, specific comparisons are made between the two divisions with notable differences highlighted. Finally, sample evaluations are presented to illustrate the differences between each code of construction for identical design conditions. Also, material and labor estimates are compiled for each case study to provide a realistic comparison of the expected differential cost between the construction codes.
Influence of Elastic-Plastic Bending on the Relationship Between Applied Load and Maximum Bending Stress for Straight and Curved Bars
Authors: Metzger Don 
Published: October 2020

Abstract
Bending capacity in excess of the load required to cause yielding is due to a combination of work hardening and the effect of the plastic zone spreading toward the neutral axis. For materials of sufficiently high ductility, a fully developed plastic zone is achieved and the bulk of the section is stressed beyond yield. For lower ductility materials, failure may occur prior to full development of the plastic zone such that only a fraction of the cross section is at or above the yield stress. In such cases, the relationship between applied load and maximum bending stress becomes sensitive to the shape of the stress-strain curve near the yield point. This relationship is examined for straight and curved bars of rectangular and trapezoidal cross-section for tensile stress-strain curves characterized by nonlinear functions. The stress distribution as a function of applied load is determined analytically by enforcing moment equilibrium across the section. The strain distribution is determined through the classical condition of “planes remain plane” during deformation.
The solutions provide analytically smooth load curves such that maximum stress can be directly plotted as a function of applied load. These plots exhibit three distinct regimes of response: 1) elastic, 2) development of plastic zone, and 3) fully developed plastic zone. Since the response is analytically smooth, the detailed relationship through the knee of the tensile curve can be examined. The results indicate that bending capacity is influenced significantly by the development of small amounts of plastic strain prior to reaching a yield point defined by the usual 0.2% plastic strain offset method. The results also show how loss of ductility with respect to tensile elongation translates into reduced bending load capacity in a non-linear relationship.
VistaDam: A Physics Based Ductile Fracture Model for Pressurized Pipe Failure
Authors: Mobasher Mostafa E. , Londono Juan G. , Woelke Pawel B. 
Published: October 2020

Abstract
We present VistaDam, a physics-based ductile fracture material model that is tailored to predict failure in thin metal sheets. VistaDam is based on a three invariant plasticity model in which metal fracture is dependent on the combined evolution of the triaxial stresses as well as the third invariant of deviatoric stress. Thus, VistaDam can predict damage due to combined volumetric void growth and shear dilation; which provides VistaDam with a superior capability to describe and predict fracture in a wide range of loading ranges. VistaDam relies on three independent material parameters that can be calibrated from experimental data at different triaxiality. Calibration is achieved through the automated calibration tool VistaCal. The calibrated VistaDam material card can be readily used in explicit FEM packages such as Abaqus and LS-DYNA. In addition, the calibrated VistaDam model can be used as a virtual testing platform that can generate data required by data-driven models such as GISSMO and Johnson-Cook. This process is currently automated within VistaCal’s graphical user interface. VistaDam and VistaCal have been developed for Navy applications and have been deployed successfully to predict pressurized pipes and vessel deformation and fracture under extreme loading conditions.
A 3D Parallel High-Order Solver With Curved Local Mesh Refinement for Predicting Arterial Flow Through Varied Degrees of Stenoses
Authors: Chen Kuangxu , Zhang Bin , Liang Chunlei 
Published: October 2020

Abstract
A 3D parallel high-order spectral difference (SD) solver with curved local mesh refinement is developed in this research to simulate flow through stenoses of varied degrees (50%, 60%, 65%, 70% and 75%) of radius constriction at inlet Reynolds number of 500. This solver employs high-order curved mesh in the vicinity of arterial wall and the local mesh refinement technique reduces the overall computational cost by distributing more elements in critical regions. In simulation of flow through stenosis of 50% radius constriction, velocity profiles predicted from the SD solver agree well with previous DNS results and experimental data. Mesh independency study shows that numerical results from a conforming and a non-conforming mesh agree well with each other. When the constriction degree is larger than 50%, visualizations through iso-surfaces of Q-criterion show that vortex rings are ejected from the stenosis throat, advecting downstream before they hit the vessel walls and they finally break down and merge into a large bulk region of small-scale turbulence. The observation is consistent with the vorticity contour which is characterized by development of the Kelvin-Helmholtz instability when shear layers are formed, rolled up and advected downstream between the central jet and the recirculation region. When the constriction degree turns to 75%, the flow transitions rapidly downstream of stenosis throat and dramatic pressure drop is witnessed. This provides a fluid-dynamic explanation for clinical definition of critical stenosis (i.e. over 75% luminal radius narrowing). Furthermore, pressure drop across a stenosis is found to be proportional to square of ratio of non-stenosed area to minimum area at the stenosis throat with a linear correlation coefficient equal to 0.9998. Finally, this solver is proven to have excellent scalability on massively parallel computers when multi-level refinement of meshes is performed to capture small-scale structures in the turbulence region.
Environmental Fatigue Screening for Subsequent License Renewal
Authors: Walker Adam P. , Imbrogno Gregory M. , Gray Mark A. , Tomes Charles A. 
Published: October 2020

Abstract
Nuclear Regulatory Commission (NRC) guidance for Subsequent License Renewal (SLR) applicants is provided in the NUREG-2191. Specifically, Section X.M1 of the NUREG-2191 includes guidance for aging management programs (AMP) which has two aspects related to fatigue analyses, one that verifies the continued acceptability of existing analyses through cycle counting and the other that provides periodically updated evaluations of the fatigue analyses to demonstrate that they continue to meet the appropriate limits. In addition, the NUREG-2191 provides requirements to account for reactor water environment by deriving cumulative fatigue usage (CUF) including environmental effects (CUFen) in component fatigue analyses for a set of sample critical components for the plant outlined in NUREG/CR-6260. Furthermore each applicant is required to determine plant-specific component locations in the reactor coolant pressure boundary that may be more limiting than those considered in NUREG/CR–6260. This paper presents a methodology to identify plant-specific primary equipment component locations that are potentially more limiting than the locations identified in NUREG/CR-6260, through a detailed review and ranking of the analyses of record (AORs) for a plant. The ranking approach implemented in this methodology assesses the level of technical rigor required to derive the CUF values and provides a means to appropriately compare CUF values within the same transient section. This paper also illustrates how this methodology was applied for a recent license renewal application.
Preload Assurance in Bolted Flanges With a Model and Test Based Optimized Assembly Procedure
Authors: Du Michael , Song Fei , Li Haoming , Li Ke 
Published: October 2020

Abstract
Bolted flanges are widely used to connect pipelines in many industries. To assure sealability of a flange, generation of proper preloads in the bolts during the assembly process is critical. However, in the existing standard practice, identical torques are typically applied to all bolts to assemble the flange. Due to elastic interactions between the bolts, tightening one bolt can alter the tensile loads in the other bolts. Hence, the resultant preloads can vary significantly. Even with an improved makeup sequence, the variation in the bolt preloads can be still substantial, as high as 60%. This could pose a risk of leakage. When the bolted flange works under non-benign conditions, such as vibration, pressure and temperature variation, the risk could become even higher.
This paper introduces a new methodology to greatly enhance the preload assurance in bolted flanges with an optimized assembly procedure, which is enabled with advanced numerical modeling. A significantly improved uniform distribution of bolt preloads is achieved by optimizing the makeup torques, which is implemented by using physical test data as input and uniformly distributed preloads as the target function. The complexity of the elastic interactions between the flange, the sealing gasket, and the bolts presents uncertainties for the numerical model for quantitative prediction of the torque distribution that is required to yield uniform resultant bolt preloads. This paper resolves this modeling limitation through iterations between modeling and testing. These iterations calibrate and finally validate the model to generate the optimized makeup torque distribution which then leads to improved bolt preload uniformity. Based on the tests conducted on two different sizes of API flanges, 3-API-15K and 5-API-10K, the final preload distribution variation has been reduced to around 30% by utilizing the optimized makeup torque distributions.
Analysis of Spent Nuclear Fuel Multipurpose Canister Dynamics During Rail Transportation
Authors: Kadooka Kevin , Klymyshyn Nicholas 
Published: October 2020

Abstract
The primary mode of spent nuclear fuel transportation within the United States will be by railcar. One such system is the Atlas railcar, which is designed to transport 17 different spent nuclear fuel cask systems, including bare fuel systems and canister fuel systems. In the latter configuration, multipurpose canisters containing spent nuclear fuel may be placed within an overpack for storage, or within a cask for transportation. Compared to bare fuel systems, canister fuel systems have additional degrees of freedom for motion during transportation, because clearance between the cask and canister allows for some motion of the canister to occur relative to the cask. This work investigates the effect of canister motion on the shock and vibration imparted to the spent nuclear fuel within. Structural dynamic analyses have been conducted to identify the effects of canister to cask clearance, presence and type of dunnage, and loading direction and frequency. This modeling study calculates anticipated cask motion, canister motion, and spent nuclear fuel structural dynamic response to normal conditions of transportation railcar motion using finite element analysis methods that were developed to model the rail segment of the ENSA/DOE (Equipos Nucleares S.A., U.S. Department of Energy) multimodal transportation test of 2017.