bluuebunny/crossref_metadata_2025 huggingface dataset:
Proposed New Fatigue Design Curves for Carbon and Low Alloy Steels in High Temperature Water
Authors: O’Donnell William J. , O’Donnell William John , O’Donnell Thomas P.
Published: August 2008

High temperature (> 300 °F, 149 °C) water has been found to greatly accelerate fatigue crack growth rates in carbon and low alloy steels. Current ASME Code fatigue design curves are based entirely on data obtained in air. While a factor of two on life was applied to the air data to account for environmental effects, the actual effects have been found to be an order of magnitude greater in the low cycle regime. A great deal of work has been carried out on these environmental effects by talented investigators worldwide. The ASME Code Subgroup on Fatigue Strength has been working for 20 years on the development of new fatigue design methods and curves to account for high temperature water environmental effects. This paper presents an overview of the data and analyses used to formulate proposed new environmental fatigue design curves which maintain the same safety margins as existing Code fatigue design curves for air environments.
A Novel Technological Assessment for Welding Heavy Wall Stainless Steel
Authors: Messer Barry , Seitz Shawn , Patrick Charles , Armstrong Ken
Published: August 2008

In an effort to maximize quality and production in both field and shop fabrication while minimizing cost, Fluor and PCL, in a joint venture, assessed new welding technology comparing power sources, arc transfer modes, and shielding gas mixtures using various semi-automatic welding processes. The results were combined with “No-Backing Gas” (NBG) root technique to provide ASME code acceptable welds with excellent corrosion and crack resistance for type 321 Stainless Steel [1]. Welds were deposited in approximately one third the time commonly demanded by conventional welding. The strategies for the selection of a welding power source, arc transfer modes, shielding gas mixtures, and the successful bridging from quality and integrity validation to shop and field implementation are discussed.
Successful Sealing of Heat Exchangers Due to the Implementation of New Technology in a Gasket System
Authors: Simonton Julie L. , Reeves David W.
Published: August 2008

Research into the historical use and subsequent failure of double-jacketed type gaskets in heat exchangers has yielded the characteristics necessary for leak elimination and the realization that maintaining a seal cannot be achieved by gasket specification alone. An evaluation of the heat exchanger, stud load, tightening method, gasket specification, proper installation procedures, process conditions, as well as stud selection must each be carefully considered to consistently create an effective seal. This paper highlights field test data from a refinery on the differential thermal expansion of flanges and how the gasketed connection is affected. Laboratory test data, specifically Radial Shear Tightness Test, or Ra.S.T., data, which mimics the radial shearing effects on a gasket in a heat exchanger, as well as verifying the effects on the gaskets in the field, is also presented. The details of the new technology in a gasket system for heat exchangers, perfected in conjunction with Chevron and Lamons Gasket Company, will be presented along with its successful implementation at a major petrochemical refinery.
Destruction of Cryogenic Pressure Vessel and Piping by Shock Wave
Authors: Watanabe Toshiaki , Ebihara Kazumasa , Hokamoto Kazuyuki , Itoh Shigeru
Published: August 2008

In recent years, a use for cryogenic fluids as a coolant has been increasing because of the industrial development of low temperature technology. Therefore, the use of the cryogenic pressure vessel and piping become general. LNG-tank, LN2, O2-tank at food factory and medical facilities are given for example. In the cryogenic pressure vessel and piping, reducing the thermal insulation of that by initial small damage, leads to an internal pressure rise and occurring of flashing, and causing secondary crush of pressure vessel and piping also. Then, we conducted the experiment, which imitates crush when the pressure vessel and piping, which were filled with cryogenic temperature fluid, receive a shock wave. The inner pressure time history in such as this situation was measured, and safety of cryogenic pressure vessel and piping was considered.
Hydrodynamic Pressure Load on Folsom Dam Tainter-Gate at Onset of Failure Due to Flow-Induced Vibrations
Authors: Anami Keiko , Ishii Noriaki , Knisely Charles W. , Oku Tatsuya
Published: August 2008

An analysis of a Folsom dam Tainter-gate which failed during operation in 1995 is presented. First, an empirical evaluation of the excessive push-and-draw hydrodynamic pressure induced by streamwise rotational vibration of the inclined circular-arc skinplate over the curved dam crest with a vertical step down at the upstream side is developed. This development is based on a theoretical analysis for a simplified flow field model. The simplified model consisted of a vertical flat rigid weir plate undergoing streamwise rotational vibration and a horizontal flat bed surface with a vertical step down at the gate position. Secondly, the resultant hydrodynamic load on the skinplate is determined. Thirdly, the dynamic instability of the Tainter-gate is theoretically examined and the major characteristics of this instability are presented. Finally, an FEM analysis of the structure reveals that the small vibration amplitude of at most 11.9mm at the spanwise center and bottom end of the skinplate induced the excessive hydrodynamic pressure load of about 1.6 times the static load, thus causing incipient failure of 4 bolts connecting a diagonal member to the main struts.
The Structural Safety Test Research for 300 MW PWR Control Rod Driver Machine Pressured Shell
Authors: Sun Weiming , Ren Xing , Zhang Kangda
Published: August 2008

The safety analysis and test research are done to inspect the safety of 300MW control rod drive machine (CRDM) pressured shell structure in a systematic way. The test result agrees accords with FEA result. In actual operating mode (300 °C) inner-pressure fatigue simulative test, the axial and hoop pre-cracks are made, and the fatigue crack growth is observed. The load-bearing capability and deformation are tested in shell-burst test. Based on test research, this paper analyses theoretical load-bearing capability and safety margin in accordance with ASME CODE Sec. III design is calculated. Elastic-plastic fracture mechanics theory and GEGB.R6 method is used to analyze structure safety. The test results show pressure shell’s safety allowance is large enough.
The Effects of Residual Stress Distribution and Geometry of Component on the Stress Intensity Factor of Surface Crack
Authors: Miyazaki Katsumasa , Mochizuki Masahito
Published: August 2008

The stress intensity factor estimated by using the appropriate modeling of components is essential for evaluation of crack growth behavior in stress corrosion cracking. For the appropriate modeling of welded components with a crack, it is important to understand the effects of residual stress distribution and geometry of component on the stress intensity factor of surface crack. In this study, the stress intensity factors of surface crack under two assumed residual stress fields were calculated. As residual stress field, the bending type stress field (tension-compression) and the self-equilibrating stress field (tension-compression-tension) through the thickness were assumed. The geometries of components were plate and piping. The assumed surface cracks for evaluations were long crack in surface direction and semi-elliptical surface crack. Furthermore, the crack growth evaluations were conducted to understand the effects of residual stress distribution and geometry of component. Here, the crack growth evaluation means the simulation of increments of crack depth and length by using the crack growth property and stress intensity factors. From the comparison of stress intensity factors and crack growth evaluation for surface crack under residual stress field, the effects of residual stress distribution and geometry of component on the stress intensity factor of surface crack and appropriate modeling of cracked components were discussed.
A Decrement Method for Quantifying Non-Linear and Linear Damping
Authors: Meskell Craig
Published: August 2008

A method is presented which can estimate the linear and non-linear damping parameters in a lightly damped system. Only a single response measurement from a free decay test is required as input. This ensures that the magnitude of the damping parameters is not compromised by phase distortion between measurements. The method uses the instantaneous energy to describe the long-term evolution of the system. Practically this is achieved by using only the peak amplitudes in each period. In this way the stiffness is effectively ignored, and only the damping forces are considered. For this reason, the method is not unlike the familiar decrement method, which can be used to estimate the linear damping in linear systems. The method is developed in the context of a weakly non-linear, lightly damping system, with both linear and cubic damping. Simulated response data is used to demonstrate the accuracy of the technique. The non-linear damping parameter is extracted from the response data to within 5% of the exact value, even though the non-linear term contributes less than 1% to the total force in the system.
Environmental Fatigue Testing of Type 316 Stainless Steel in 310 °C Water
Authors: Cho Hyunchul , Kim Byoung Koo , Kim In Sup , Oh Seung Jong , Jung Dae Yul , Byeon Seong Cheol
Published: August 2008

Low cycle fatigue tests were conducted to investigate fatigue behaviors of Type 316 stainless steel in 310 °C low oxygen water. In the tests, strain rates were 4 × 10−4, 8 × 10−5 s−1 and applied strain amplitudes were 0.4, 0.6, 0.8, and 1.0%. The test environment was pure water at a temperature of 310 °C, pressure of 15 MPa, and dissolved oxygen concentration of < 1 ppb. Type 316 stainless steel underwent a primary hardening, followed by a moderate softening for both strain rates in 310 °C low oxygen water. The primary hardening was much less pronounced and secondary hardening was observed at lower strain amplitude. On the other hand, the cyclic stress response in room temperature air exhibited gradual softening and did not show any hardening. The fatigue life of the studied steel in 310 °C low oxygen water was shorter than that of the statistical model in air. The reduction of fatigue life was enhanced with decreasing strain rate from 4 × 10−4 to 8 × 10−5 s−1.
Tensile Strength of a Girth Weld With a Low-Strength AWSR45 Buttering Layer
Authors: Vargas Pedro M.
Published: August 2008

A four-metal connection, in which a carbon steel pipe is welded to duplex stainless steel pipe, is analyzed. The four metals are shown in Table 1. A106B and 2205 Duplex are the two different pipe materials, 2209 is the weld filler material, and AWSR45 is the buttering layer that is used to control the cracking susceptibility of the welded girth joint. (Butter and buttering refer to the welding of a layer of low strength material, AWSR45 in this case, and are commonly used terms within the welding community). Due to the lower strength of the AWSR45 material, the question arises whether this joint performance would affect pressure containment capacity and meet the B31.3 code (and API 1104) tensile strength requirements. Nonlinear FEA [1] was used to determine the girth weld joint pressure containment capacity and evaluate tensile strength requirements. This study found that: 1. The butter layer has no effect on burst capacity for typical weld dimensions.2. The acceptable butter layer may approach approximately 70% of the wall thickness for approximated real material properties. However, a full pipe cross-section test will be required to show that the weld joint has the necessary strength.3. If this is impractical, a lower butter limit of 25% of wall thickness would be necessary for the API-1104 recommended 1-inch wide tensile specimen to show that the weld joint has the necessary strength assuming approximated real material properties.4. Strains exceeding 50% in the soft AWRS45 layer are possible in the root, face or side bend test. This may cause tearing making the code requirements difficult to meet.5. The AWRS45 material must exhibit a smooth continuously increasing hardening behavior. If the soft AWRS45 layer exhibits lu¨der-band type tensile instabilities, the recommendations in this study may need to be revisited. In this study analyses is limited to the single-slope bevel and the double-slope bevel geometries recommended in [2] (See Figure 1). Any significant deviation from the specific materials and geometry may justify follow-up FEA analyses efforts prior to weld qualification. In particular, it may be possible to increase the allowable butter length for different weld geometries (e.g. J-bevel) than the two explored in this study. Also, for the full cross-section tensile case, additional 3-dimensional analyses may be needed to ensure that all possible modes of strain localization (e.g. non-axisymmetric deformation modes) have been addressd.
Evaluation of Turbulence Models for Thermal Striping in a Triple-Jet
Authors: Choi Seok-Ki , Nam Ho-Yun , Wi Myung-Hwan , Kim Seong-O , Jo Jong-Chull , Choi Hoon-Ki
Published: August 2008

A computational study for the evaluation of the current turbulence models for the prediction of a thermal striping in a triple-jet is performed. The tested turbulence models are the two-layer model, the shear stress transport model and the elliptic relaxation model. These three turbulence models are applied to the prediction of the thermal striping in a triple-jet in which detailed experimental data are available. The performances of the tested turbulence models are evaluated through comparisons with the experimental data. The predicted mean and root-mean-square values of the temperature are compared with the experimental data, and the capability of predicting the oscillatory behavior of the ensemble-averaged temperature is investigated. From these works it is shown that only the elliptic relaxation model is capable of predicting the oscillatory behavior of the ensemble-averaged temperature. It is also shown that the elliptic relaxation model predicts best the time-averaged and root-mean-square of the temperature fluctuation. However, this model predicts a slower mixing at the far downstream of the jet.
A Mechanics Based Parametric Description of Residual Stress Profiles for Fracture and Fatigue Assessment
Authors: Dong Pingsha
Published: August 2008

It has been shown in a series of recent publications that any arbitrary residual stress distribution can be decomposited into through-wall “self-equlibrating” and “bending”. In this paper, a mechanics based parametric description of through-wall residual stress profiles is provided for fracture and fatigue assessment of girth welds. This parametric equation contains two fundamental parameters: (1) relative heat input and (2) pipe thickness to radius ratio. For a given welding procedure and heat input, the through-thickness resdual stress distributions as well as magnitude are shown to exhibit a continuous transition from bending to self-equilibrating as r/t ratio increases. As a result, a single parametric equation can be established for describing through-wall residual stress distributions for a full range of pipe diameters and thicknesses as well as weld configurations. A series of detailed finite element simulations were also performed to validate the predictions by the parametric equiations proposed.
Classification of Shell Stresses Resulting From Piping Nozzle Loads
Authors: Seipp Trevor G. , George Shiju V. P. , Morrison Shawn W.
Published: August 2008

In a previous paper, the authors discussed the classification of membrane stresses caused by piping loads resulting from restrained free thermal expansion. In that paper the authors proposed that although these stresses exhibit both primary and secondary characteristics, it is more appropriate to classify the resulting stresses as primary. In this paper, the authors present further FEA-based justification of this hypothesis. First, the vessel-nozzle intersection is modeled with 3D solid elements. Next, an elastic-plastic analysis of the previously examined piping/vessel layout is presented, with an examination of the final strain levels. Finally, a shakedown evaluation is performed. The results of these evaluations show that, unless additional analysis indicates otherwise, the membrane stresses resulting from restrained free thermal expansion piping loads should be classified as primary.
Optimum Design of Multi-Layered Vessels
Authors: Jahed Hamid , Farshi Behrooz , Karimi Morvarid
Published: August 2008

Multi-layered pressure vessels are widely used in the field of high pressure technology. To enhance their load bearing capacity and life, different beneficial processes such as shrink-fit and autofrettage are usually employed. Shrink-fit process, increases load capacity but maximum interference is generally limited. Autofrettage, makes steep stress gradients moving away from bore but Bauschinger effect limits maximum feasible compression level. A combination of both, can conceivably give better stress distribution in layered vessels. The optimum design of a three-layer vessel for maximum life expectancy has been considered here, under the combined effects of autofrettage and shrink-fit. The numerical optimization procedure known as the Simplex search method is employed to get the optimum design. The layer thicknesses, shrink-fit pressures, and autofrettage percentages are treated as design variables. Under stress constraints, the operational sequences of the above processes, for assembly of the layered vessel have also been formulated so as to lead to best results. The fatigue life consideration is based on ASME code and standard for high pressure vessel technology defining the allowable final crack depth in multi-layered vessels. The proposed procedure is carried out on a number of examples. The results show that significant life enhancement can be achieved using the optimization procedure with proper combination of operations.
Strain Measures for Fatigue Assessment Using Elastic-Plastic FEA
Authors: Reinhardt W.
Published: August 2008

In the ASME Code, Section III NB-3228.4(c) requires that if an elastic-plastic fatigue analysis is performed, the fatigue curve shall be entered with the numerically maximum principal total (elastic plus plastic) strain range multiplied by one-half the modulus of elasticity of the material at the mean cycle temperature. This paper discusses the choice of the principal strain range as well as other possible strain range measures for elastic-plastic fatigue analysis. Several generic observations that form the basis for the discussion are outlined.
Alternate Design Formulae for a Full Structural Weld Overlay Repair
Authors: Sommerville Daniel V.
Published: August 2008

This paper describes a new set of design formulae for a Full Structural Weld Overlay. The formulae presented herein are derived using similar assumptions as were used to develop the net section collapse formulae contained in Appendix C of the ASME B&PV Code, Section XI; however, they are developed specifically for a WOL geometry. By considering the WOL geometry during derivation of the plastic collapse load, a set of WOL design formulae are obtained which contain the WOL thickness as a solution variable. For WOL design this formulation is inherently easier and more efficient to use than adapting the part through wall flaw formulation contained in Appendix C. Sample WOL designs are presented in which both the new and existing formulae are used. The results obtained demonstrate that the new formulae produce a WOL thickness consistent with that calculated by properly using the existing method contained in Appendix C.
A Plastic Load Criterion for Inelastic Design by Analysis
Authors: Mackenzie Donald , Li Hongjun
Published: August 2008

The allowable plastic load in pressure vessel Design by Analysis is determined by applying a graphical construction to a characteristic load-deformation plot of the collapse behavior of the vessel. This paper presents an alternative approach to the problem. The plastic response is characterized by considering the curvature of a plot of plastic work dissipated in the vessel against the applied load. It is proposed that salient points of curvature correspond to critical stages in the evolution of the gross plastic deformation mechanism. Application of the proposed criterion is illustrated by considering the elastic-plastic response of a simple cantilever beam in bending and a complex 3-D Finite Element Analysis of a nozzle intersection.
Validation of the Small Boundary Displacement Model of Fluid-Structure Coupling for Predicting Fluid-Elastic Lock-In
Authors: Manko David J. , Sussman M. M.
Published: August 2008

This paper describes the validation of the Small Boundary Displacement Model (SBDM) of fluid-structure coupling for predicting fluid-elastic lock-in response of a D-shaped cylinder in crossflow. This coupling model extends structural small displacement theory to fluid-structure interfaces, eliminating the need for temporally changing meshes when structural motion is small compared with problem dimensions. The SBDM algorithm accurately predicts the range and characteristics of lock-in behavior when compared to an independent two-dimensional numerical solution. Further validation of the SBDM simulations is provided by comparisons to fluid-only solutions at the limits of lock-in where the cylinder boundary is forced to oscillate at the same amplitudes as the corresponding coupled simulations. The SBDM predicted fluid-elastic response exceeds the 20 dB limit commonly used for experimentally identifying lock-in behavior.
Self-Loosening of Threaded Fasteners Due to Cyclic Transverse Loads
Authors: Nassar S. A. , Housari B. A.
Published: August 2008

A mathematical model and an experimental procedure are presented for studying the self-loosening phenomenon of threaded fasteners that are subjected to cyclic transverse loads. The effect of thread and underhead friction coefficients, the hole clearance, and the frequency and the amplitude of the transverse excitation are investigated. The experimental set up is made of a single-bolt joint, which is subjected to a cyclic transverse displacement or force. For each variable, the drop in the fastener tension and the joint clamp load versus the number of cycles is recorded and analyzed. In the mathematical model, the linear and angular motion of the bolt head is formulated in terms of the system properties and the external cyclic transverse excitation. The mathematical model provides the bolt rotation in the loosening direction, which causes the partial or full loss of the clamp load. An iterative MATLAB code is developed and used for the calculation of tension drop-off in the fastener tension due the self-loosening. Mathematical and experimental results are compared for various levels of system and external loading variables.
CFD-Tool for Assessment of the Reactor Pressure Vessel Integrity in Pressure Thermal Shock Conditions: Influence of Temperature Safety Injection and Fluid-Structure Thermal Coupling
Authors: Martin A. , Monfort D. , Bezdikian G. , Beaud F. , Lestang F. , Vit C.
Published: August 2008

Integrity evaluation methods for nuclear Reactor Pressure Vessels (RPVs) under Pressurised Thermal Shock (PTS) loading are applied by French Utility. They are based on the analysis of the behavior of relatively shallow cracks under loading PTS conditions due to the emergency cooling during SBLOCA (Small Break Loss of Coolant Accident) transients. This paper presents the Research and Development program started at E.D.F on the Computational Fluid Dynamic (CFD) determination of the cooling phenomena of a PWR vessel during a Pressurised Thermal Shock. The numerical results are obtained with the thermal-hydraulic tool Code_Saturne, in combination with the thermal-solid code SYRTHES to take into account the coupled effect of heat transfer between the fluid flow and the vessel. Based on the global and local Thermal-hydraulic analysis of a Small Break Loss of Coolant Accident transient, the paper presents mainly a parametric study whose purpose is to understand the main phenomena which can lead to better estimating the margin factors. The geometry studied represents a third of a PWR pressure vessel and the configuration investigated is related to the injection of cold water in the vessel during a SBLOCA transient. Conservative initial and boundary conditions for the CFD calculation are derived from the global Thermal-hydraulic analysis. Both the fluid behavior and its impact on the solid part formed by cladding and base metal are considered. On the whole, the main purpose of the numerical thermal-hydraulic studies is to accurately estimate the distribution of fluid temperature in the down comer and the heat transfer coefficients on the inner RPV surface for a fracture mechanics computation which will subsequently assess the associated RPV safety margin factors.
Optimum Design in Cylindrical and Spherical Autofrettaged-Treated Components
Authors: Adibi-Asl R.
Published: August 2008

Autofrettage-treated components are used in application with both static and cyclic loading conditions. Therefore, finding the optimum autofrettage design for these two different conditions is needed. This paper shows a study on the optimum autofrettage level and pressure in cylindrical and spherical components, considering both strength and fatigue design analysis. Bilinear material model with Bauschinger effect is used in this study. The results verify the significant influence of Bauschinger effect on the strength and fatigue life of autofrettage-treated pressure components.
Hysteresis Model for RC Structural Element Accounting Bi-Directional Lateral Load Interaction
Authors: Chowdhury Rajib , Rao B. N. , Prasad A. Meher
Published: August 2008

Experimental investigations on cyclic behaviour of reinforced concrete (RC) structures have demonstrated that, bidirectional flexural deformation is much more, compared to unidirectional responses separately. Biaxial lateral load interaction, therefore, has a significant role on the dynamic responses of structure. The present paper projected a new formulation of the biaxial force-deformation model, accounting strength and stiffness degradation in a rather simplistic manner. Also the modelling scheme dose not requires much computational rigour. The present effort is based on yield surface approach of biaxial modelling scheme. The validity of the proposed model is appraised through available biaxial test of RC column. Compared to other existing models, present model requires simple input parameters and the prediction of hysteretic responses are quite faithful. In the RC containment structures, which are the prime concern to the safety of nuclear power plant, this model may pertain to evaluate the hysteretic responses with fair accuracy during seismic loading.
Licensing of the ES-3100 Type B Shipping Container: Replacement of the DOT 6M Container
Authors: Arbital Jeffrey G. , Tousley Dean R. , Anderson James C.
Published: August 2008

The National Nuclear Security Administration (NNSA) is shipping bulk quantities of fissile materials for disposition purposes, primarily highly enriched uranium (HEU), over the next 15 to 20 years. The U.S. Department of Transportation (DOT) specification 6M container has been the workhorse for NNSA and many other shippers of radioactive material. However, the 6M does not conform to the safety requirements in the Code of Federal Regulations (10 CFR 71[1]) and, for that reason, is being phased out for use in the secure transportation system of the U.S. Department of Energy (DOE) in early 2006. BWXT Y-12 is currently developing the replacement for the DOT 6M container for NNSA and other users. The new package is based on state-of-the-art, proven, and patented technologies that have been successfully applied in the design of other packages. The new package will have a 50% greater capacity for HEU than the 6M, and it will be easier to use with a state-of-the-art closure system on the containment vessel. This new package is extremely important to the future of fissile, radioactive material transportation. An application for license was submitted to the U.S. Nuclear Regulatory Commission (NRC) in February 2005. This paper reviews the license submittal, the licensing process, and the proposed contents of this new state-of-the-art shipping container.
A Fluid-Solid Finite Element Method for the Analysis of Reactor Safety Problems
Authors: Mitra Santanu , Kumar Ashutosh , Sinhamahapatra K. P.
Published: August 2008

The work presented herein can broadly be categorized as a fluid-structure interaction problem. The response of a circular cylindrical structure subjected to cross flow is examined using the finite element method for both the liquid and the structure domains. The cylindrical tube is mounted elastically at the ends and is free to move under the action of the unsteady flow-induced forces. The fluid is considered to be partially compressible and viscous. The flow field is solved using a finite element method applied to the time-dependent Navier-Stokes equations. The cylinder motion is modeled using a five-degrees of freedom generalized shell element structural dynamics model. The numerical simulations of the response of the calandria tubes/pressure tubes, adjustor rod and shut-off rod of a nuclear reactor are presented. A few typical results are presented to assess the accuracy of the developed modules.
Measurement of Residual Stresses in Large Industrial Components Using the Deep Hole Drilling Technique
Authors: Ficquet X. , Truman C. E. , Smith D. J. , Brown T. B. , Dauda T. A.
Published: August 2008

“ELIXIR – Extending Plant Life Through Improved Fabrication and Advanced Repair Methodology” was a European Union FP5 sponsored project. During the duration of the Elixir project, much work was directed at providing the necessary data for the validation of numerical modelling techniques applied to residual stress generation and hydrogen diffusion arising from the welding process. The project focussed around four industrial applications, namely petrochemical, boiler, offshore and submarine. This paper presents through-thickness residual stress measurements obtained by the University of Bristol on two of the large industrial components. The results were obtained using the deep hole drilling technique and compared to Finite Element predictions provided by other partners. The components considered are a large P275 steel set-in nozzle, typical of a boiler application and a large S690 steel set-on nozzle, typical of an offshore application. The boiler application consisted of a nozzle of diameter 600mm and thickness 50mm, on a pipe of diameter 1100mm and 100mm thickness. The offshore application was a nozzle of diameter 900mm and thickness 50mm, on a pipe of diameter 1050mm and 50mm thickness. Both the longitudinal and transverse stresses measured using deep hole drilling showed excellent agreement with Finite Element predictions through the thickness of the boiler sample. On the top surface, a zone of tensile residual stresses, over a distance of approximately 40mm, was revealed, which was equilibrated by a zone of compressive residual stresses over the final 50mm of thickness. Results for the offshore application demonstrated that at the front surface, both of the stress components were essentially zero, but both the longitudinal and transverse components rose rapidly to maxima of approximately 500MPa and 220MPa, respectively. Tensile residual stresses were supported over a distance of approximately 30mm. Over the final 20mm of thickness, compressive residual stresses existed, which again fell to approximately zero on the back face. There is excellent agreement between measurements and the Finite Element predictions for the transverse stress component, but less good agreement between measurements and predictions of the longitudinal stress component.
T-Stress Solutions for Multiple Edge Cracks in Thick-Walled Cylinders
Authors: Li J. , Wang X. , Tan C. L.
Published: August 2008

In this paper, the boundary element method (BEM) is employed to obtain T-stress solutions for multiple internal edge-cracks in thick-walled cylinders under complex stress distributions. Thick-walled cylinders with two, four and eight internal edge cracks, respectively, are analyzed for a wide range of radius ratios and relative crack lengths. The load cases considered for the cracked cylinder are: i) crack face pressure with uniform, linear, quadratic and cubic stress distributions and ii) internal pressure in the cylinder. The T-stress results for the uniform and the linear distribution crack face pressure cases are used as the reference solutions to derive weight function solutions for the T-stress for the corresponding geometries. The direct boundary element results of the T-stress for the other nonlinear stress distributions are used to validate the derived T-stress weight functions. Excellent agreements between the BEM results and weight function predictions are obtained. The weight functions derived are suitable for obtaining T-stress solutions for the corresponding cracked thick-walled cylinder under any complex stress fields.
Metallographic Examination of Thermal Effects in Hypervelocity Gouging
Authors: Cinnamon John D. , Palazotto Anthony N.
Published: August 2008

In this work, a gouged section of 1080 railroad rail steel is examined using metallographic techniques to characterize the nature of the damage. The gouging was performed by a rocket sled at Holloman Air Force Base, riding on VascoMax 300 steel shoes at 1.5 to 3.0 km/sec. Similar in approach to Gerstle, et al. [1], the damaged rail is evaluated in detail to examine material phase changes, shear bands, and heat effects. The results can be compared to samples of the virgin material, machined and prepared exactly as the rail and shoe are prior to the Holloman AFB High Speed Test Track (HHSTT) runs. The gouged section was examined longitudinally and in a transverse manner using optical microscopy and a Scanning Electron Microscope (SEM). Pictures are presented of the resulting microstructure. Comparisons to the virgin material confirm material mixing consistent with a high energy gouging event. In addition, the material phase change evident in this approach allows us to estimate the non-equilibrium thermal conditions present during the formation of the gouge. The creation of shear bands, predicted by the previous modeling efforts, is also confirmed.
Hydrogen Embrittlement of Metals in 70 MPa Hydrogen at Room Temperature
Authors: Fukuyama Seiji , Imade Masaaki , Lin Zhang , Yokogawa Kiyoshi
Published: August 2008

Hydrogen embrittlement (HE) of metals used in the system of fuel-cell vehicles, i.e., high-pressure hydrogen storage tanks and vessels, compressors, valves and pipes, is investigated in 70 MPa hydrogen at room temperature. The materials tested are austenitic stainless steels (i.e., SUS304; in the Japanese Industrial Standard (JIS), SUS316, SUS316L, and SUS316LN), a low-alloy steel (i.e., SCM440), carbon steels (i.e., SUY, S15C, S35C, S55C and S80C), a Ni-based superalloy (i.e., Inconel 718), and an aluminum alloy (i.e., A6061). Tensile tests were conducted at room temperature using a specially designed equipment developed by our laboratory, which was designed to measure the actual load on the specimen with an external load cell irrespective of the axial load caused by the high pressure and friction at sliding seals. SUS304 and SUS316 showed severe HE, while SUS316L and SUS316LN showed slight HE. Fracture occurred on strain-induced martensite of the austenitic stainless steels in hydrogen. SCM440 showed extreme HE depending on heat-treatment; in particular, quenched materials showed marked HE. The carbon steels showed extreme and severe HE depending on carbon content. Inconel 718 also showed severe HE, while A6061 showed negligible HE. These results and other HE testing results which AIST has done previously are summarized in the AIST HE data table. HE behavior of the material in high-pressure hydrogen is discussed in this paper.
Metrology and Modeling Techniques Used to Compare Highly Accurate As-Built 3D Models to FEA Weld Distortion Predictions
Authors: Hand Steven D. , Clark James F. F.
Published: August 2008

High accuracy laser scanning and three-dimensional modeling are critical requirements of weld distortion research and ultimately to the management of weld distortion. The significance of these requirements is based on an on-going fabrication project designed to validate FEA predictions of weld distortions typical of large curved steel structures. As built 3D models of a series of 1,300 square foot test beams are measured using Coherent Laser Radar for the purpose of determining deformations caused by the thermal affects of welding, i.e.: bending, warping and buckling. This paper describes tools and techniques currently used to minimize the un-certainty of measurements and maintain accuracy during the processing of point clouds into surfaced models. Further techniques are defined for generating 3D parametric models from finite element analysis results, and utilizing these models for direct comparison to the as-built 3D modeled results.
Assessment of Environmental Fatigue (FEN) Approaches
Authors: Stevens G. L. , Carey J. J. , Davis J. M. , Deardorff A. F.
Published: August 2008

Since 1998, many U. S. utilities have embarked upon efforts to renew their nuclear plant operating licenses. One of the key areas of uncertainty relates to fatigue of pressure boundary components. Although the Nuclear Regulatory Commission (NRC) has determined that fatigue is not a significant contributor to core damage frequency, they believe that the frequency of pipe leakage may increase significantly with operating time. Therefore, as a part of the license renewal process, the NRC has requested that license renewal applicants perform an engineering assessment to determine the effects of reactor water coolant environment on fatigue and, where appropriate, manage this effect during the license renewal period. As the license renewal application process progressed starting in 1998, utilities have committed significant resources to license renewal activities related to fatigue. In response to this, several possible approaches have emerged from a variety of industry efforts that may be taken to address fatigue environmental effects in a license renewal application. This paper summarizes an assessment that was performed under funding by the Materials Reliability Program (MRP) for several of the currently-documented environmental fatigue (Fen) approaches. Practical application of these Fen approaches was performed for typical power plant components. In addition to the results obtained from this assessment, this paper summarizes several issues associated with the practical application of these methods to typical power plant components. For some of these issues, recommended solutions are proposed to satisfactorily apply the methods. For remaining issues, recommendations for further studies are provided that would assist in the development of refined methods and guidance to eliminate the issues.
An Overview of the Pressurized Thermal Shock Re-Evaluation Project
Authors: Dickson Terry L. , EricksonKirk M. T.
Published: August 2008

In 1999, a study sponsored by the United States Nuclear Regulatory Commission (NRC) suggested that advances in the technologies associated with the physics of pressurized-thermal-shock (PTS) events developed since the derivation of the PTS regulations (established in the early-mid eighties) had the potential to establish a technical basis that could justify a relaxation in the current PTS-related regulations. A relaxation of these regulations could have profound implications for plant license extension considerations. Subsequently, the NRC initiated the interdisciplinary PTS Re-evaluation Project. During the five year project, an updated comprehensive computational methodology evolved, within the framework established by modern probabilistic risk assessment (PRA) techniques, through interactions among experts in relevant disciplines from the NRC staff, their contractors, and representatives from the nuclear industry. During 2004, the updated computational methodology was applied to three domestic commercial pressurized water reactors (PWRs). The most recent results of the PTS Re-evaluation Project provide a technical basis to support a relaxation of the current PTS regulations while continuing to provide reasonable assurance of adequate protection to public health and safety. The details of the updated computational methodology, the mathematical models, the analysis results, key findings, and supporting information have recently been drafted in several very detailed and lengthy formal reports. These reports are currently under review at the NRC. An objective of this paper is to provide a short overview of the improved computational methodology, analysis results, and key findings of the PTS re-evaluation project. To demonstrate that a technical basis has been established to support a relaxation of the current PTS regulations, it is helpful to understand the derivation of the current PTS regulations; therefore, another objective of this paper is to contrast the interpretation of the analysis results of the PTS re-evaluation to those performed in the eighties from which the current PTS regulations were derived.
Use of Conical-Shaped Anchors to Reduce Stresses in Thermoplastic Dual Containment Piping Systems
Authors: Ziu Christopher G. , Chen Yaofeng
Published: August 2008

Double containment piping systems are used extensively for handling the conveyance of critical waste systems in industries such as pharmaceuticals and biotechnology manufacturing and research. Often, these services involve the conveyance of critical fluids at elevated temperatures. An example would be in the discharge and transport of spent fermentation by-products in the biotech industry, where the vessel contents are sanitized by the addition of water at up to 210°F and then discharged through double containment piping. Materials of construction used in such systems include thermoplastic, RTRP (fiberglass), stainless steel systems, and combinations thereof. This paper compares systems that are fully restrained by means of patented internal anchors designed to reduce stresses in components and evenly distribute the stresses to the secondary containment components. The systems are compared to the conventional methods of using thermoplastic systems restrained by unitary anchors. In addition to finite element analysis, physical tests are also performed to demonstrate the effectiveness of the conical shaped anchors.
Analysis of Creep Induced Strains and Stresses in Notches Subjected to Cyclic Load
Authors: Nunez Enrique , Glinka Gregorz
Published: August 2008

A method for the estimation of time-dependent strains and stresses in notches subjected to cyclic load is discussed in the paper. The proposed solution is an extension of the methodology proposed previously for notches under steady external load. A new algorithm is proposed to predict creep response near notches in plane stress components subjected to cyclic loads. Predictions were compared against finite element data and good agreement was obtained for various geometrical and material configurations.
Plastic Limit Analysis of Perforated Material Under Finite Deformation
Authors: Duan Xinjian , Weck Arnaud , Wilkinson David S. , Metzger Don R.
Published: August 2008

In this paper, the fracture pattern of a perforated aluminum sheet is studied experimentally and numerically using finite element models on two different length scales: a full-scale structural and a local cell models based on the large deformation theory. Through appropriate application of boundary conditions, the more efficient local cell model is shown to produce almost the same results as the full structural model. It is also found that the failure path is significantly affected by the loading conditions (uniaxial vs. biaxial) and the hole distribution pattern. By plotting the instantaneous contour of plastic strain rate, the fracture path could clearly be distinguished by the time that the overall engineering strain had reached 3%.
Effect of Solution Annealing on Critical Potentials of Alloy 22
Authors: Etien R. A. , Gordon S. R. , Ilevbare G. O.
Published: August 2008

The effect of solution annealing on localized corrosion resistance of Alloy 22 was studied in electrolytes of varying composition. The experiments were carried out on Alloy 22 specimens with the resultant thick dark brown oxide film from the solution annealing process still intact. The effect of solution annealing on the localized corrosion resistance of Alloy 22 was found to be electrolyte specific within the temperature range investigated.
Explicit Coupling Methods in Hydrodynamic Impacts
Authors: Aquelet N. , Souli M.
Published: August 2008

The purpose of this paper is to study and compare two finite element coupling methods to simulate the problem of a body penetrating a free surface. The hydrodynamic impact problem concerns industrial designers in shipbuilding domain. In rough seas, sometimes ships suffer local damages from large water impact loads called slamming impacts. In the framework of a collaboration with a french research company in shipbuilding (Principia Marine) a numerical prediction of the local impulse load on a wedge striking a free surface is investigated by using two methods: penalty and Lagrange multiplier formulations. These methods of coupling, which makes it possible to transmit the efforts in pressure from the Eulerian formulation to the Lagrangian formulation and conversely are relatively recent algorithmic developments. The Euler/Lagrange penalty method was successfully used in many scientific and industrial applications: the modeling of the attack of birds on the fuselage of a Jet for the Boeing Corporation, the underwater explosion shaking the oil platforms, the airbag simulation... The explicit coupling based on multiplier approach is a new development, which is compared to the penalty method. For both methods, a parametric study of the local pressure peak is investigated for impact angles from 0 to 30 degrees.
Acoustic Resonance in a Package Boiler and Its Solution: A Case Study
Authors: Eisinger Franktisek L. , Sullivan Robert E.
Published: August 2008

Strong acoustic resonance with acoustic pressures reaching up to 165 dB developed in the boiler bank of a package boiler at full load. At first, the resonance developed at a lower frequency in the downstream portion of the tube bank and it was suppressed by an acoustic baffle covering the downstream section of the flow channel. After about one year of operation, a second resonant condition developed. Tests confirmed that again a strong resonant condition developed at a higher frequency in the unbaffled upstream portion of the flow channel. Computer analysis confirmed that the initial resonance occurred at the first acoustic mode of the flow channel while the follow-up resonance occurred at the second mode of the flow channel expressed as a first mode resonance in a different (upstream) location. An extension of the acoustic baffle covering the entire depth of the tube bank eliminated the vibration. The paper gives a description of the problem and summarizes the theoretical and experimental results substantiating the findings.