bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite Element Analysis and Design of an Annular Tank
Authors: Hari Yogeshwar
Published: August 2008

The objective of this paper is to design an annular tank. The annular tank is to store various criticality liquids used in today’s industry. The initial over all dimensions of the annular tank are determined from the capacity of the stored liquids. The design function is performed using the ASME Code Sec VIII Div 1. The annular tank design is broken up into (a) outer cylinder, (b) inner cylinder, (c) top cover, and (d) bottom head. It is supported at the bottom. It is anchored at the top. The deflection of the annular space is a critical requirement. Stresses are usually acceptable because the requirement is on the deflection. For vacuum condition the outer cylinder can be treated for external pressure and the inner cylinder can be treated for internal pressure. For internal pressure condition the design pressure consists of working internal pressure plus static head. For this the outer cylinder can be treated for internal pressure and the inner cylinder can be treated for external pressure. The covers are designed for internal pressure at the bottom where the pressure is the maximum. The designed dimensions are used to recalculate the stresses for the annular tank. The dimensioned annular tank is modeled using STAAD III finite element Software. The stresses from the finite element Software are compared to the stresses obtained from recalculated stresses obtained using ASME Code Sec VIII Div 1. The difference in the stress values is explained. This paper’s main objective is to compare the ASME Code to the finite element analysis. The design is found to be safe for the specific configuration considered. In addition the annular tank is checked for temperature and seismic load conditions, which the code does not address.
Study of Gaps Between Components During Dynamic Loading
Authors: Bitner Jerry L. , Raj David
Published: August 2008

Gaps between mating parts of large industrial components are required for assembly and to allow for free thermal or pressure growth. However, the gaps should not be so large as to invalidate linear analysis assumptions for dynamic loadings. Large components may have locations where there are tightly controlled dimensions to accommodate mating parts. At these locations there are specified gaps that are crucial in manufacturing and installing the parts and assemblies. These gaps are strategically determined to provide reasonable assurance that the components can be economically manufactured and assembled without violating structural and functional requirements for the components. In general, large gaps are desirable to facilitate assembly. Small gaps may be necessary to ensure the validity of linear-elastic dynamic analysis and to control leakage. Industry practices for 1/8-inch to 1/4-inch gaps are cited for pipes supported by box frames. The justification for the use of these gap sizes is not readily available in the open literature. This paper presents the results of a preliminary investigation into the effect of gaps on the dynamic analysis of internal components of heavy pressure vessels. Parameteric analytical studies using simple finite element beam models show that loads and stresses increase with gap size. For example, using the results for 1/16-inch gap as the basis, the maximum stresses and loads for a 1/8-inch gap increase by a maximum of approximately 30%.
Toughness Rules in the New ASME Section VIII Division 2 Code
Authors: Prager Martin
Published: August 2008

The PVRC proposal to ASME for the new Section VIII Division 2 incorporates fracture mechanics more rigorously than before in setting the toughness requirements for materials. The concepts of driving force for fracture and materials resistance as a function of temperature are linked through the concept of a FAD, that is now widely accepted. On the driving force side the latest technologies are available for incorporation via PVRC and MPC in the form of improved expressions for stress intensities, recently calculated by FEA and available in WRC Bulletins or API 579 on Fitness for Service. These do not require elaboration here. One aspect of the driving force side that will be noted, however, is the allowed reduction in MDMT associated with reduction of applied stress or pressure to values below the maximum permitted values. Recent analysis of the principles implicit in the current of ASME indicates that a new rational taking greater cognizance of the effects of secondary or residual stresses and the effects of heat treatment is appropriate.
Development of ISO Standards for Cryogenic Vessels
Authors: Rana Mahendra D. , Barthelemy Herve´
Published: August 2008

ISO/TC220 was formed in the year 2000 to develop new standards for design and fabrication of cryogenic vessels and the operational requirements. Several draft standards have been developed are being reviewed by the ISO TC 220 WG1 Committee members. Important aspects of design, material, and toughness considerations for stationary vessels are presented in this paper.
Development of JIS Standards B8265: Harmonizing Japanese Pressure Vessel Regulations
Authors: Tahara Takayasu
Published: August 2008

In recent years in Japan, the concepts of the regulation system and technical standards have been changed a lot with following major items: 1) Changing concept of regulation from specification basis to performance basis. 2) Although specification base regulation had prescribed detailed construction, design method, applicable material and methods of inspection and testing, the performance base regulation only requires total function on reservation of safety and security. If required performance is proved on pressure equipment during manufacturing and/or operation, it will accept to use fundamentally. Performance base regulation will allow applying new technology timely but it is rather difficult in specification basis.
The European Pressure Equipment Directive 97/23/EC (PED): An Overview
Authors: Garbolevsky Alexander F.
Published: August 2008

Development of the European Pressure Equipment Directive 97/23/EC, better known as the “PED was set into motion on April 19, 1994 when the European Parliament delivered its opinion at the first reading on the proposal for a “European Parliament and Council Directive on the approximation of the laws of the Member States concerning pressure equipment”. The Parliament and Council adopted the Directive, bearing that official title, on May 29, 1997. On May 29, 2002, the PED became mandatory in the countries of the European Economic Area (EEA).
The Relationship Between ISO 9000 and PED Quality Modules
Authors: Norman Michael D.
Published: August 2008

The Pressure Equipment Directive (97/23/EC) [PED] was adopted by the European Parliament and the European Council in May 1997. Following a two-and-a-half year transition phase, the PED became mandatory on May 29, 2002. Its purpose is to harmonize national laws of Member States regarding the design, manufacture, testing and conformity assessment of pressure equipment and their assemblies, and thus ensure the free placing on the market and putting into service of pressure equipment within the European Economic Area.
Differences Between EN 13445 and Other International Standards
Authors: Nash David
Published: August 2008

The harmonized standard EN 13445 [1] provides the means by which a manufacturer can claim presumption of conformity to the essential safety requirements of the Pressure Equipment Directive. In addition, it aims to bring together the best available European pressure vessel technology in a single unified document. Use of this standard however, has still to be established in an industry which has been slow to accept change, especially when other well-known codes remain in use. This paper highlights the main technical differences between EN 13445-3 and other international standards (principally PD5500 [2] and ASME VIII [3]) and considers the implications for industry, research organisations and the various code-writing bodies.
ASME Section III Subsection NF Linear Current and Future Concepts
Authors: Masterson Robert J.
Published: August 2008

Over the past thirty years Subsection NF of the ASME Boiler and Pressure Vessel Code, Section III, has been transformed from a basic set of structural rules to evaluate and qualify component supports to a dynamic Code that recognized the difference between pressure retaining and structural elements. Initially, with the publication of the 1974 Edition of the ASME Code, Subsection NF identified essentially two different types of supports, Plate & Shell and Linear. Plate & Shell supports were evaluated using in effect the same rules in Subsections NB, NC and ND for pressure retaining elements. Linear supports, on the other hand, were an odd group. The ASME Code was a pressure Code providing rules for pressure retaining components such as vessels, piping, valves, pumps, tanks etc. In 1963, when the first Edition of ASME Section III for nuclear plants was published, there wasn’t any place for non-pressure retaining elements such as component supports. This continued for eleven years until supports made their debut in the 1974 Edition of Section III (actually the 1973 Winter Addenda to the 1971 Edition). At this time the AISC Manual for Steel Construction was the premier set of rules for the design and construction of steel structures. Since many supports were comprised of structural steel elements due to the nature of loading (thermal and seismic) at nuclear power plants, the AISC Code seemed to be the ideal set of rules to adopt for the construction of supports. Additional requirements for temperature and seismic considerations were incorporated in Subsection NF to account for supports on nuclear plants.
An Overview of Current ASME Section XI Activities
Authors: Gimple Richard E.
Published: August 2008

An overview of current Section XI activities is presented by looking at the current goals of the Section XI committees, by discussing a few of the current issues facing Section XI committees, and by taking a brief look at the future issues and activities facing Section XI.
Advances in Risk-Informed Application Within ASME Section XI
Authors: Park Gary
Published: August 2008

The ASME Section XI Committees have published three Code Cases that support an alternative in using Risk-Informed application in the selection of piping welds (Category B-F, B-J, C-F-1 and C-F-2). The Code Cases (N-560, N-577, and N-578) have been revised based on industry feedback to keep them up-to-date. These Code Cases have been widely used and the Westinghouse and EPRI Topical Reports have received the Nuclear Regulatory Commission (NRC) approval. However, the Code Cases themselves still need to be submitted to the NRC on a case-by-case evaluation.
Response of the Explosive Destruction System Containment Vessel to Internal Detonations
Authors: Haroldsen Brent L. , Didlake John E. , Stofleth Jerome H.
Published: August 2008

The Explosive Destruction System (EDS) is a transportable system used by the Army to destroy recovered, explosively configured, chemical munitions. The system uses shaped charges to detonate the burster explosives and to cut the munition and access the agent, all inside of a sealed, stainless-steel, containment vessel. Sandia has built four EDS systems. The largest system, with an internal volume of about 620 liters, was designed to handle munitions as large as 8-inch artillery shells. This paper presents an overview of the system with emphasis on the response of the cylindrical vessel to internal detonations. The vessel response was determined through a combination of full-scale testing, sub-scale testing, and computer simulation. Tests with both bare charges and munitions have been conducted in seven vessels ranging in diameter from 19 to 91 centimeters. The paper discusses dynamic strain measurements on the vessel wall and scaling relationships associated with different sized vessels and different quantities of explosives.
Behavior of Facilities Under Explosive Loading Due to Malevolent Acts
Authors: Autrusson B. , Brochard D.
Published: August 2008

As required in the French regulations, the behavior of the nuclear fuel reprocessing or fabrication plants and nuclear power plants must be assessed for a set of various normal and accidental situations including explosions due to operation hazards or malevolent acts. In this last case, the assessment gathers both safety and security aspects and lead to undertake studies accounting for loads due either to an explosion resulting from an aggression with a large amount of explosive or to an attack with a High Energy Density Device as a conical shaped charge. In order to provide the Authority with elements of appreciation and in support of the expertise of the studies performed by the operators, the Institut de Radioprotection et de Suˆrete´ Nucle´aire (IRSN) has initiated a program including experiments and development of numerical models concerning the evaluation of the consequences of such aggression in terms of mechanical damage to the plants and radiological release in the environment. The French approach for assessing the consequences of malevolent acts is based on a sensitivity study aiming at determining the critical components, followed by a vulnerability study for assessing the behavior of the facilities, depending on the type of weapons chosen in compliance with the threats. So for introduction, this approach will be briefly recall. The paper will focus on the technical tools to perform the vulnerability study in the case of an aggression by explosion.
Study of the Dynamic Response of Large Scale Buildings Using Simplified Approaches
Authors: Loiseau Olivier , Cheval Karine , Autrusson Bruno , Brochard Didier
Published: August 2008

The dynamic response of large scale concrete buildings submitted to an explosion cannot always be obtained by means of classical FE analysis codes at reasonable costs. Indeed, the precision level required to predict efficiently the local failure of structural elements needs very fine meshes, which rapidly becomes unaffordable especially in the case of dynamics. The approach presented in this paper relies on a partitioning of the phenomena and their study by simplified methods: (1) The loading of the structure resulting from the detonation of an explosive charge is computed by a numerical implementation of semi-empirical formulas (Kinney and Graham, 1985, Baker et al., 1983); (2) The response of external walls elements, directly impacted by the aerial shock wave, is studied by a modal projection method, based on the use of analytical solutions from the thin plate theory; (3) Longitudinal propagation of the shock through the floors and walls of the building, including material and structural damping, is modeled by a 1D approach. This allows to determine finally whether the resistance limit of the constituting material is locally exceeded or not. Examples taken from a representative building study are presented in order to illustrate the approach.
Blast-Resistant Window Concepts
Authors: Strickland W. S. , Anderson Mark , Dover Dov
Published: August 2008

Terrorist bombs threaten American civilians and military personnel both at home and abroad. Analysis of data from previous terror attacks indicates the largest number of injuries result from projected glass shards from shattered windows and facades. Three key issues have led to increased interest in new window materials, as well as changes in building design codes: (1) actual terror attacks; (2) the threat of future terror attacks; and (3) monetary losses due to hurricanes. New protective products include a wide variation of films and laminated glasses for retrofit / replacement. Air Force Research Laboratory (AFRL) research has shown that these protective films will reduce the fragmentation of the enclosed glass. However, protective films that are not anchored will not provide retention of the film/glass system under the severe blast loadings expected from terror bombs. The paper introduces the Flex window, a patent-pending blast-resistant window developed at AFRL, along with key design concepts. In addition, the paper presents results from actual blast tests of the Flex window. Tabular data and photo-documentation is used to illustrate the ability of the Flex window to handle blast pressures a full order of magnitude greater than the typical commercial “blast proof” window. New AFRL methods for modeling both exterior and interior loading functions are presented. In addition, possible response modes are discussed, based on observations of high-speed video recordings.
Advanced Design Methods for Packing Cups of Hypercompressor Cylinders
Authors: Giacomelli Enzo , Graziani Franco , Pratesi Simone , Campo Nicola
Published: August 2008

Reciprocating Compressors for LDPE applications operating at pressures over 3000 bars require advanced methods for designing cylinders components. Packing cups undergoing very high-pressure fluctuations and severe operating conditions are designed by FEM to determine the stress level in a more accurate way. Considering boundary conditions, complex geometry and the consequent stress risers, the procedure allows to optimize the cups profile, giving a strong contribution to machine performance and plant availability. Challenging performance and capacity change requirements are faced by using innovative solutions related to simulation methods, technologies and diagnostic systems. FEM is used to make a comparison of the stress state during normal operating conditions, between the original solution and a modified one. The modified application requires a higher capacity and consequently a bigger plunger diameter and a different geometry of packing cups. In addition, site feedback and Service engineering are essential to improve safety, reliability, availability, and maintainability, as well as general performance of the machines, particularly for high-pressure cylinder components.
NDE of Pipe Inner Corrosion With Delayed Echoes of SV Wave Propagated Circumferentially in Liquid-Filled Pipes
Authors: Nagamizo Hisashi , Kawashima Koichiro , Miyauchi Jyunji
Published: August 2008

A new ultrasonic NDT method is proposed for detecting inner corrosion of pipes with circumferential vertical shear wave, SV wave, propagated within the pipe wall and longitudinal wave propagated in liquid for liquid-filled pipes. When SV wave excited at the outer surface of a pipe impinges the inner surface, a part of the wave energy leaks into the liquid. Longitudinal wave excited there propagates in liquid and reaches other points on the inner surface of the pipe. At there, longitudinal, Rayleigh and SV waves are excited and propagated again within/or along the pipe wall. With angle-beam SV wave transducer, we can detect delayed echoes caused by slow velocity in liquid. Using the simple ray theory, we estimated the propagation paths of the delayed echoes and confirmed them by experiments with a water-filled pipe of partial shielding on the inner surface. The results show that only limited propagation paths exist for given measurement configuration, i.e., geometry of a pipe, incident and receiving angles of the transducers, property of liquid in a pipe. Using this new method, we detected the degree of corrosion on the inner wall of pipes.
Evaluation of WB Coatings by Scanned Imaging Microscopy
Authors: Du Jikai , Tittmann Bernhard R.
Published: August 2008

Organic thick coatings (epoxy, polyurethane, and acrylic-urethane) have been widely applied to high modulus substrates (e.g., steel) for anticorrosion protection. To improve performance, reinforced components (clay, bochmite, nanopaticles, etc.) are usually added to these coatings. However, the acoustic evaluation of these coatings is difficult due to their low acoustic velocities and high attenuation coefficients. In this paper, first, the scanning acoustic microscope (SAM) is used to image sub-surfaces, coating/substrate interfaces, and to measure acoustic velocities. Different phases can be observed on some coatings and defects can be found at some interfaces. Secondly, the atomic force microscope (AFM) is applied to image surfaces at high resolution (compared to SAM). These results agree with SAM images. Thirdly, a nano-indentation technique is utilized to measure the reduced Young’s modulus and absolute hardness of the coatings. The results show that epoxy has the highest Young’s modulus and acrylic-urethane has the lowest. Reinforced components can either increase or decrease Young’s modulus, and hardness depending on the coating material. Finally, results from the SAM, AFM and nano-indentation are compared and analyzed to optimize the evaluation.
Application of the Linear Matching Method to the Integrity Assessment for the High Temperature Response of Structures
Authors: Chen Haofeng , Ponter Alan R. S.
Published: August 2008

The paper describes a first attempt to produce a complete system of calculations that cover the entire range of assessments required in the Life Assessment method R5 based on a new programming method, the Linear Matching Method, and using shakedown and related concepts. We show that two solutions types are possible, the first assuming a constant residual stress field that provides shakedown and related limits. The second method involves the evaluation of the amplitude of the changing residual stress field. This provides the first stage for the ratchet limit and the amplitude of plastic strain. By adaptation the elastic follow-up factor corresponding to creep dwell periods may also be evaluated.
Approximate Analysis of Creep Strains and Stresses at Notches
Authors: Nun˜ez J. E. , Glinka G.
Published: August 2008

A method for the estimation of creep induced strains and stresses at notches has been developed. The purpose of the method is to generate a solution for the time-dependent strain and stress at the notch root based on the linear-elastic stress state, the constitutive law, and the material creep model. The proposed solution is an extension of Neuber’s rule used for the case of time-independent plasticity. The method was derived for both localized and non-localized creep in a notched body. Predictions were compared with finite element data and good agreement was obtained for various geometrical and material configurations in plane stress conditions.
A Non-Cyclic Method for Plastic Shakedown Analysis
Authors: Reinhardt W.
Published: August 2008

Shakedown is a cyclic phenomenon, and for its analysis it seems natural to employ a cyclic analysis method. Two problems are associated when this direct approach is used in finite element analysis. Firstly, the analysis typically needs to be stabilized over several cycles, and the analysis of each individual cycle may need a considerable amount of computing time. Secondly, even in cases where a stable cycle is known to exist, the finite element analysis can show a small continuing amount of strain accumulation. For elastic shakedown, non-cyclic analysis methods that use Melan’s theorem have been proposed. The present paper extends non-cyclic lower bound methods to the analysis of plastic shakedown. The proposed method is demonstrated with several example problems.
Stress Analysis of a Pin and Clevis Assembly
Authors: Pechatsko Brian , Stambolia James , Shields Elvin B. , Davenport Jack B. , Orning Arnold D.
Published: August 2008

The shear yield strength of the material is one of the controlling factors in determining the pin diameters for a pin and clevis connection. Typically, for steels used in machine fabrication, an accepted method is to approximate the shear yield strength as 75% of the material’s ultimate tensile strength Blodgett [1]. In a pin and clevis connection, the pin can be subjected to static and dynamic loads that can generate stresses on the order of the shear yield strength of the steel. The loads produce bending and shear stresses in the pin. The highest stressed region is the clearance gap between the blade and clevis. Finite Element Analysis (FEA) results produced valuable insight into the problem. The various methods available to constrain the computer models produced different results. Enhanced FEA computer models provided the most realistic insight into the actual pin stresses. Full-scale steel test hardware was tested with static loads until pin failure occurred. A standardized pin size of 12.7 mm (0.500 in) diameter was used in order to maintain the loads at a manageable testing level. Strain gages placed in the clearance gap recorded bending strains. The pins failed from shear stress in the area of the gap region.
Modelling Studies of the Fatigue Behaviour of a Nozzle-to-Vessel Intersection
Authors: De Jesus Abi´lio M. P. , Ribeiro Alfredo S. , Fernandes Anto´nio A.
Published: August 2008

In this paper the fatigue behaviour of a nozzle-to-vessel intersection is studied. This geometry is typical in pressure vessels. Numerical models are investigated in order to predict the fatigue life. These studies are validated by an experimental program including a fatigue test of a real size pressure vessel, fatigue tests of structural details and fatigue tests of small scale and smooth specimens. Comparisons between predictions obtained using proposed models and predictions obtained using procedures included in design codes are carried out.
Calculation of the Temperature Field of the Solidifying Ceramic Material EUCOR
Authors: Kavicka Frantisek , Stetina Josef , Heger Jaromir , Sekanina Bohumil , Ramik Pavel , Dobrovska Jana
Published: August 2008

EUCOR, a corundo-badelleyit material, which is not only resistant to wear but also to extremely high temperatures, is seldom discussed in literature. The solidification and cooling of this ceramic material in a non-metallic mould is a very complicated problem of heat and mass transfer with a phase and structure change. Investigation of the temperature field, which can be described by the three-dimensional (3D) Fourier equation, is not possible without the employing of a numerical model of the temperature field of the entire system—comprising the casting, the mould and the surroundings. The temperature field had been investigated on a 350×200×400 mm block casting—the so-called “stone”—with a riser of 400 mm, and using a numerical model with graphical input and output. The computation included the automatic generation of the mesh, and the successive display of the temperature field using iso-zones and iso-lines. The thermophysical properties of the cast, as well as the mould materials, were gathered, and the initial derivation of the boundary conditions was conducted on all boundaries of the system. The initial measurements were conducted using thermocouples in a limited number of points. The paper provides results of the initial computation of the temperature field, which prove that the transfer of heat is solvable, and also, using the numerical model, it is possible to optimise the technology of production of this ceramic material, which enhances its utilisation. The results are complemented with an approximated measurement of the chemical heterogeneity of EUCOR.
Transient Analysis of Heat Conduction in Orthotropic Medium by the DQEM and EDQ Based Time Integration Schemes
Authors: Chen Chang-New
Published: August 2008

The transient heat conduction in orthotropic medium is solved by using the DQEM to the spacial discretization and EDQ to the temporal discretization. In the DQEM discretization, DQ is used to define the discrete element model. Discrete transient equations defined at interior nodes in all elements, transition conditions defined on the inter-element boundary of two adjacent elements and boundary conditions at the structural boundary form a transient equation system at a specified time stage. The transient equation system is solved by the direct time integration schemes of time-element by time-element method and stages by stages method which are developed by using EDQ and DQ. Numerical results obtained by the developed numerical algorithms are presented. They demonstrate the developed numerical solution procedure.
Continuum Shape Sensitivity Analysis of Mode-I Fracture in Functionally Graded Materials
Authors: Rao B. N. , Rahman S.
Published: August 2008

This paper presents a new method for continuum shape sensitivity analysis of a crack in an isotropic, linear-elastic functionally graded material. The method involves the material derivative concept of continuum mechanics, domain integral representation of the J-integral and direct differentiation. Unlike virtual crack extension techniques, no mesh perturbation is needed in the proposed method to calculate the sensitivity of stress-intensity factors. Since the governing variational equation is differentiated prior to the process of discretization, the resulting sensitivity equations are independent of approximate numerical techniques, such as the meshless method, finite element method, boundary element method, or others. In addition, since the J-integral is represented by domain integration, only the first-order sensitivity of the displacement field is needed. Numerical results show that first-order sensitivities of J-integral obtained by using the proposed method are in excellent agreement with the reference solutions obtained from finite-difference methods for the structural and crack geometries considered in this study.
An Efficient Methodology for Fatigue Reliability Analysis of Mechanical Components Based on the Stress-Life Prediction Approach
Authors: Tang Jun , Park Young Ho
Published: August 2008

An efficient methodology for fatigue reliability assessment and its corresponding fatigue life prediction of mechanical components using the First-Order Reliability Method (FORM) is developed in this paper. Using the proposed method, a family of reliability defined S-N curves, called R-S-N curves, can be constructed. In exploring the ability to predict spectral fatigue life and assessing the corresponding reliability under a specified dynamics environment, the theoretical background and the algorithm of a simple approach for reliability analysis will first be introduced based on fatigue failure modes of mechanical components. It will then be explained how this integrated method will carry out the spectral fatigue damage and failure reliability analysis. By using this proposed methodology, mechanical component fatigue reliability can be predicted according to different mission requirements.
Coupled Finite Element/Meshfree Simulation of Manufacturing Problems
Authors: Wang Hui-Ping , Botkin Mark E. , Wu Cheng-Tang , He Sijun
Published: August 2008

This paper studies the performance of a newly developed coupled finite element/meshfree tool in manufacturing problem simulation. Two manufacturing problems, a battery tray forming and an axisymmetric forging, are used for demonstration. In both problems, the coupled finite element/meshfree analysis is compared with the traditional finite element analysis. The numerical studies show that the coupled finite element/meshfree solution is as accurate as the finite element solution for the problems without mesh distortion difficulties. For the ones involving excessive deformation, the coupled method provides more reliable solutions than the traditional finite element method, but higher CPU is required.
A New Interaction Integral Method for Analysis of Cracks in Orthotropic Functionally Graded Materials
Authors: Rao B. N. , Rahman S.
Published: August 2008

This paper presents two new interaction integrals for calculating stress-intensity factors (SIFs) for a stationary crack in two-dimensional orthotropic functionally graded materials of arbitrary geometry. The method involves the finite element discretization, where the material properties are smooth functions of spatial co-ordinates and two newly developed interaction integrals for mixed-mode fracture analysis. These integrals can also be implemented in conjunction with other numerical methods, such as meshless method, boundary element method, and others. Three numerical examples including both mode-I and mixed-mode problems are presented to evaluate the accuracy of SIFs calculated by the proposed interaction integrals. Comparisons have been made between the SIFs predicted by the proposed interaction integrals and available reference solutions in the literature, generated either analytically or by finite element method using various other fracture integrals or analyses. An excellent agreement is obtained between the results of the proposed interaction integrals and the reference solutions.
Rigid-Plastic Meshfree Method for Metal Forming Simulation
Authors: Park Young H.
Published: August 2008

In this paper, material processing simulation is carried out using a meshfree method. With the use of a meshfree method, the domain of the workpiece is discretized by a set of particles without using a structured mesh to avoid mesh distortion difficulties which occurred during the course of large plastic deformation. The proposed meshfree method is formulated for rigid-plastic material. This approach uses the flow formulation based on the assumption that elastic effects are insignificant in the metal forming operation. In the rigid-plastic analysis, the main variable of the problem becomes flow velocity rather than displacement. A numerical example is solved to validate the proposed method.
Generalized Application of Periodic Symmetry in Molecular Simulations
Authors: Pan Li , Metzger Don , Niewczas Marek
Published: August 2008

Periodic symmetry is widely used in molecular simulations to mimic the presence of an infinite bulk surrounding an N-atom model system. However, the traditional methods of applying periodic symmetry end up enforcing over-restrictive kinematic constraints between the periodic boundaries. After a brief overview of the periodic symmetry, the nature of the constraint is discussed briefly in this paper. Thereafter, the objective is to provide a means to ensure that periodicity is upheld while avoiding unnecessary constraint of the repeating cell boundaries. This paper demonstrates the usual application of periodic symmetry into a molecular simulation algorithm through a typical example. Meanwhile, a novel method is introduced, which uses equivalent external forces applied to physical boundary atoms. Comparisons between the classic treatment and the new method using one-dimensional and two-dimensional models are made. Moreover, the potential application of the new method in regular Finite Element Analysis is discussed.
On a Proposed New Kinematic Assumption for Analysis of Laminated, Fiber-Reinforced Composite Shells: Part 1
Authors: Steinbrink Scott E.
Published: August 2008

A proposal is made for a new form of kinematic assumption for inclusion into a theory of laminated shells. The proposed form is a variant of the first-order transverse shear deformation theory, incorporating a stiffness-based discontinuity term at lamina interfaces, in order to provide complete, a priori satisfaction of interlaminar continuity of transverse shear and transverse normal stresses, and correspondent intelaminar discontinuity of thickness-direction gradients of displacement. Continuity of displacement is maintained, as is the possibility of interlaminar discontinuity of in-plane stresses. It is hoped that this kinematic form will enhance the utility of shell theories for analysis of laminated structures. The paper deals only with the development of the kinematic assumption, and not its implementation into analysis code.
A New Graphical Tool for Building Logic-Gate Trees
Authors: Bott Terry F. , Eisenhawer Stephen W. , Kingson Jonathan , Key Brian P.
Published: August 2008

Tree structures that use logic gates to model system behavior have proven very useful in safety and reliability studies. In particular process trees are the basic structure used in a decision analysis methodology developed at Los Alamos called Logic Evolved Decision modeling (LED). LED TOOLS is the initial attempt to provide LED-based decision analysis tools in a state of the art software package. The initial release of the software, Version 2.0, addresses the first step in LED — determination of the possibilities. LED TOOLS is an object-oriented application written in Visual Basic for Windows NT based operating systems. It provides an innovative graphical user interface that was designed to emphasize the visual characteristics of logic trees and to make their development efficient and accessible to the subject matter experts who possess the detailed knowledge incorporated in the process trees. This eliminates the need for the current interface between subject matter experts and logic modeling experts. This paper provides an introduction to LED TOOLS. We begin with a description of the programming environment. The construction of a process tree is described and the simplicity and efficiency of the approach incorporated in the software is discussed. We consider the nature of the logical equations that the tree represents and show how solution of the equations yield natural language “paths.” Finally we discuss the planned improvements to the software.
Reliability Analysis of the Tube Hydroforming Process Based on Forming Limit Diagram
Authors: Li Bing , Metzger Don R. , Nye T. J.
Published: August 2008

Tube hydroforming has become an increasingly attractive manufacturing process in automotive industry due to it having several advantages over alternative methods. The forming limit diagram has been extensively used in metal forming as the criteria of formability. A method to assess the probability of failure of the process based on reliability theory and the forming limit diagram is proposed in this paper. The tube hydroforming process is affected by many parameters such as geometry, material properties, and process conditions. Finite element simulation was used to predict the relationship between the strain and these parameters, and a numerical method was applied to get the statistical distribution of the strain. Based on the forming limit band in the forming limit diagram, the reliability of the forming process can be evaluated. A tube hydroforming process of free bulging is then introduced as an example to illustrate the approach. The results show this reliability evaluation technique to be an innovative approach for product designers and process engineers to avoid failure during tube hydroforming.
Computer Simulation of Pipeline Deformations on the Basis of Data From an Intelligent Caliper Inspection Tool
Authors: Blyukher Boris , Niezgoda Tadeusz , Malachowski Jerzy , Szymczyk Wieslaw
Published: August 2008

The method of pipeline inspection data usage for needs of numerical analysis of technical condition of pipeline is considered. A real crude oil pipeline was taken into considerations to make numerical assessment of stress state in case of large deformations which were measured by an intelligent caliper inspection tool. The pipeline was rested on concrete supporting blocks in a boggy terrain. The tool detected very large deformations of the pipe in the areas of these supports which were caused by washouts. Data from the tool were processed into the format readable for MSC/PATRAN-graphical pre-processor of the computational system MSC/NASTRAN based on the Finite Element Method – FEM. Then a mesh of discrete model was generated by means of MSC/PATRAN.
Human Factor in the Life Cycle and Safety of Machines and Pipelines
Authors: Timashev Sviatoslav A.
Published: August 2008

The paper is an overview (using references listed below) and describes the main components, means and methods of a holistic and quantitative human reliability analysis (QHRA) using quantitative values of human error when performing Fault Tree Analysis (FTA) and Event Tree Analysis (ETA). It also deals with qualitative assessment of the influence of the human factor (HF) reliability on safety and risk analysis of potentially dangerous man-machine-structures-environment systems (PDMMSES). Qualitative risk analysis of such man-machine-structures-environment (MMSE) systems is based on using the event-decision technique in combination with a generalized socio-psychological model of the decision making person (DMP). Three types of DMP’s are considered: members of maintenance/repair crews, diagnosticians and different rank DMP’s that operate or own the PDMMSES.
Risk Assessment for Damaged Pressure Tank Cars
Authors: Kirkpatrick Steven W. , Klopp Richard W.
Published: August 2008

Following an accident or derailment involving a freight train, emergency response, salvage, and repair personnel need to clear the right-of-way, repair the tracks, and remove the damaged rail cars. If the train contains pressure tank cars the potential hazard and safe handling procedures need to be determined prior to salvage and repair activities. The severity of the damage determines the appropriate course of action such as rerailing or unloading the damaged cars. The operations must avoid the risk to response personnel of a delayed rupture. A research program was performed to establish the validity of the existing industry guidelines for assessment of damaged pressure tank cars. The research program first focused on evaluating the technical foundation for the existing guidelines and the degree to which they have been validated. We then designed a program of experiments and analyses to validate the guidelines and estimate their margins of safety. The experimental effort used laboratory specimens to provide material property data as well as validation data for the analyses. The analyses used three different approaches: nonlinear elasto-plastic finite element simulations for modeling denting behavior, elasto-plastic fracture mechanics for analysis of cracks, and nonlinear finite element simulations combined with local fracture theories to quantify the severity of scores, gouges, and rail bums (longitudinal damage features caused by sliding a tank along a rail). This paper emphasizes the latter aspect of the work.
Corrosion Fatigue Failure Analysis and Life Prediction
Authors: Ellis Fred V. , Tordonato Sebastian
Published: August 2008

A metallurgical failure analysis and life prediction was performed for an economizer tube. The tube failed after approximately nine years of service. The failure was a pin hole leak, elliptically shaped with the long axis in the circumferential direction. On the inside surface of the tube, there were several circumferential cracks and numerous oxygen pits on the top half. The cracks were transgranular and initiated at pits. The failure mechanism is corrosion fatigue and is believed to be due to a cyclic applied bending moment. Life predictions were performed using two crack geometries and zero-tension loading cycle. The geometries were a thumbnail shaped ID crack with an a/c of 0.2 and a 360° ID cracked cylinder. A parametric approach was used with two initial crack depths based on the measured pit depths and three remote stresses centered around the minimum yield strength of the SA-178-A tube material. The failure criteria was the reference stress equal to the flow stress. For the thumbnail crack geometry at a remote load of 179 MPa (equal to minimum specified yield strength), the calculated lives were 15,960 cycles for an initial crack depth of 5% and 3,450 cycles for an initial crack depth of 10%. The cyclic lives of the 360° crack geometry were approximately half of those for the thumbnail crack geometry. The slope of the log life-log stress curve was approximately −5.8.
Simplified J-Integral Evaluation Method for Evaluation of Reactor Pressure Vessel in the Upper-Shelf Region
Authors: Urabe Yoshio , Asada Seiji , Hirota Takatoshi , Nakano Morihito , Maeda Ryuuichi
Published: August 2008

It is well-known that the Upper-Shelf Energy of reactor pressure vessel (RPV) steels is reduced due to neutron irradiation and J-integral (J-applied) is used for the structural integrity evaluation in upper-shelf region. It is very time consuming to calculate the J-integral in detail by using 3-dimensional elastic-plastic FE analysis. U.S. Regulatory Guide 1.161[1] applies a simplified J-applied calculation method based on elastic calculation of the stress intensity factor, KI. However, this method for thermal stress can be applied only for constant cooling rates. From this point of view, a simplified J-applied evaluation method which can be applied to design transients and has high accuracy has been studied. In order to develop the new evaluation method, KI based on 1-dimensional elastic analysis, KI based on 3-dimensional elastic FE analysis and J-applied based on 3-dimensional elastic-plastic FE analysis are calculated and compared with each other. An accurate J estimation method for design transients from 1-dimensional elastic analysis results is proposed and the severest transient in each condition of each RPV group is evaluated in this paper.
Comparison of a Life Consumption Analysis to Section III, Subsection NH Design Rules for a Main Steam Girth Weld Creep Crack
Authors: Cohn Marvin J.
Published: August 2008

Creep damage of high energy piping (HEP) systems in fossil fuel power plants results from operation at creep range temperatures and high stresses over many years. Typically, the operating stresses in an HEP piping system are substantially below the yield stress. They tend to be load controlled and time dependent. In spring 1999, Arizona Public Service Company performed an examination of several girth welds of a main steam piping system at Cholla Power Station, Unit 2. A significant creep-related crack was found in a weld after 158,000 operating hours. The American Society of Mechanical Engineers (ASME) Subsection NH methodology was used to evaluate the load controlled stress design rules for nuclear Class 1 components in elevated temperature service as applied to this piping system. A high energy piping life consumption (HEPLC) analysis was performed prior to the examination to select and rank the most critical welds. After obtaining critical information during the outage, the software was also used to estimate the life exhaustion at the most critical weld. A discussion of results for the two approaches is provided in this paper.
Study of the Effect of Boundary Conditions on Residual Stresses in Welding Using Element Birth and Element Movement Techniques
Authors: Fanous Ihab F. Z. , Younan Maher Y. A. , Wifi Abdalla S.
Published: August 2008

The structure in which the welding process is performed highly affects the residual stresses generated in the welding. This effect is simulated by choosing the appropriate boundary conditions in modeling the welding process. The major parameters of the boundary conditions are the method by which the base metal is being fixed and the amount of heat being applied through the torch. Other parameters may include the coefficients of thermal heat loss from the plate which may simulate the media in which the welding is taking place. In modeling the welding process, 2D forms of approximation were developed in analyzing most of the models of such problem. 3D models analyzing the welding process were developed in limited applications due to its high computation time and cost. With the development of new finite element tools, namely the element movement technique developed by the authors, full 3D analysis of the welding process is becoming in hand. In the present work, three different boundary conditions shall be modeled companng their effect on the welding. These boundary conditions shall be applied to two models of the welding process: one using the element birth technique and the other using the element movement technique showing the similarity in their responses verifying the effectiveness of the latter being accomplished in a shorter time.