bluuebunny/crossref_metadata_2025 huggingface dataset:
Ignition Resistance of Polymeric Materials to Particle Impact in High-Pressure Oxygen
Authors: Forsyth ET , Gallus TD , Stoltzfus JM
Published: April 2008

Particle impact ignition has been the primary cause of numerous fires in oxygen systems. This ignition phenomenon is known to occur where particles are present in high-velocity gas and where impact occurs on a flammable material. The particle impact ignition behavior of many metals has been widely studied, but the particle impact ignition behavior of polymeric materials is relatively unknown. Particle impact ignition in polymeric materials is a concern because these materials are commonly used in component seat and seal applications where high-velocity particle impacts can occur. This study evaluates several polymeric materials and compares the threshold temperature, which is the minimum temperature required for ignition, of these materials: Kel-F 81® (CTFE), Teflon® (TFE), polyetheretherketone (PEEK), and Vespel SP-1®(polyimide). The materials were configured as targets in the high-velocity particle impact test system at the NASA White Sands Test Facility. Gaseous oxygen was flowed at 27.5 MPa (4000 psig) and sonic velocity, and the targets were impacted with 2000-μm (0.078-in.) aluminum 2017 particles. This paper discusses the results of these tests and ranks the materials according to their threshold temperatures at these conditions.
Discussion on Steel Burning in Oxygen (from a Steelmaking Metallurgist's Perspective)
Authors: Lanyi MD
Published: April 2008

A fundamental understanding of iron and steel combustion in oxygen is important to the safe selection and specification of these materials for oxygen service. Much is, and should be, known on this topic -- for reactions involving iron and steel with pure oxygen have been both commercially employed and extensively researched for decades in the field of steelmaking process metallurgy. This paper takes inventory of what is generally understood by the process metallurgist concerning steel/oxygen reactions, and discusses its relevance to the topic of steel compatibility and combustion propagation in oxygen. An argument is made on the expected importance of the steel's carbon content in combustion propagation.
Potential Ignition Mechanism of Buna-N O-Rings in Liquid-Oxygen
Authors: Newton BE , Wilson DB , Stradling JS
Published: April 2008

Buna-N O-rings used in liquid-oxygen dewars have been implicated in fires when subjected to a shearing load. Such a loading occurs when the dewar flange receives a mechanical impact due to the dewar falling over. The ignition event has been replicated under controlled conditions but only when the O-ring has been previously distorted such as could occur during improper seating of the seal in the upper flange, or when forced extrusion of the seal occurs while exposed to liquid-oxygen. This paper applies an ignition model to the experimental system to extend the parameterization of oxygen pressure/temperature to the extent of O-ring damage, shear energy and oxygen flow. The model allows for heat loss and variable generation rates.
The Mechanisms of Smolder of Cellulosic Materials
Authors: Dyakonov AJ , Grider DA , Ihrig AM
Published: April 2008

A model of smolder for cellulose-containing materials is presented. The components of a system are determined to include the products of cellulosic defragmentation, oxygen, water, alkali and transition metals, radical initiators and inhibitors. Smolder and combustion of cellulosic fabrics were investigated by means of DSC/TG/MS, TPR/GC, and IR thermographic systems in inert and O2 -containing atmosphere. Mass diffusion, heat transfer, and reaction kinetic parameters of cellulosic smolder were experimentally determined. Smolder of an upholstery fabric was found to be controlled by oxygen diffusion. A chemical model of oxygen and water-driven alkali-assisted decomposition of cellulose was suggested. Some peculiarities in a smolder behavior of dyed fabrics were investigated and explained by a competitive action of alkali metal compounds and pigment compounds. The mechanism of production of carbon oxides during smolder process has been studied.
Test System to Study the Ignition of Metals by Polymers in Oxygen
Authors: Shoffstall M , Stoltzfus J
Published: April 2008

A new test system that uses laser energy to ignite a polymer promoter has been developed at the NASA White Sands Test Facility (WSTF). It will facilitate the study of kindling chain ignition, such as the spread of fire from a burning polymer material to surrounding metal. The test system can be used to answer questions regarding configurational effects on ignition and combustion.

Test results from this system verify that ignition of a metallic sample by kindling chain ignition propagation is dependent not only on pressure, material type, and temperature, but also on the configuration of both the polymer promoter and metallic sample. Both 6061 aluminum and 316 stainless steel rods were tested with Buna-N, silicone, Teflon®, and Viton® O-rings as promoters. The system ignited all four types of O-rings in oxygen at pressures ranging from ambient to 69 MPa. However, neither the 316 stainless steel nor the 6061 aluminum rods on which the O-rings were mounted were ignited in any tests.

Future testing may be done on the rod and O-ring configuration to evaluate the lack of ignition in these tests. Other configurations may be tested including samples pressurized on one side only and configurations based on fire-damaged components. Any ignition propagation data obtained from this test system could also be used to develop mathematical models for analyzing the effects of configuration on ignition and combustion.
Mechanism of Adhesive in Secondary Bonding of Fiberglass Composites with Peel Ply Surface Preparation
Authors: Kieronski EA , Knock KK , Fallon WP , Walker GM
Published: April 2008

The surface composition and morphology of fiberglass/epoxy composites prepared by the use of “bondable” peel ply and sanding will be presented. “Bondable” peel ply is a material which provides a surface ready for secondary bonding following peel ply removal without requiring further treatment. The available results indicate mechanisms which may degrade bonds using “bondable” peel ply. Those same results also give insight into how “bondable” peel ply achieves a bondable surface when conditions are optimal. Optimal conditions can produce a surface whose 90° peel strength is 12–15 lbs/in-width versus suboptimal conditions which produce strengths of 1–4 lbs/in-width. The case studied in this effort is 350°F curing fiberglass/epoxy bonded secondarily with 250°F curing toughened epoxy adhesive.
Static and Dynamic Strength of Scarf-Repaired Thick-Section Composite Plates
Authors: Gama BA , Mahdi S , Cichanowski C , Yarlagadda S , Gillespie JW
Published: April 2008

Composite structural armor is typically a sandwich construction consisting of thick-section polymer composite, rubber, and ceramic layers, which are combined to provide an optimal balance of structural and ballistic performance at minimum weight. Design guidelines and repair techniques are needed for this unique class of multifunctional construction. Our focus is on the scarf repair of the thick-section composite backing plate subjected to static and dynamic loading. Composite backing plates of plain weave S2-glass fabric and SC15 epoxy resin were manufactured by the VARTM process. Deliberate damage to backing plates was repaired at elevated temperatures using induction heating and at room temperature. The static response of control and repaired plates was compared via four-point bend testing. The effect of three scarf angles (45°, 18.4°, and 11.3°) and four repair adhesives (two room-temperature and two elevated-temperature cure systems) was quantified. Using these repair techniques, renewal of stiffness was achievable, except for the case of the highly ductile, low stiffness adhesive. The renewal of moment capacity of the repair beams was highly dependent on the scarf angle for various adhesives, and a maximum renewal of strength was 60%. The dynamic strength of scarf patch repaired composite specimens was investigated through axial compression strength testing using a split Hopkinson bar. Under dynamic loading the axial strength was found to be dependent on the scarf angle and rate of loading. Loci of failure are reported for the various materials, scarf angles, and loading conditions.
The Kizhi Pogost Architectural Complex in Old Photographs
Authors: Miltchik M
Published: April 2008

The aim of this article is to present the architectural ensemble known as “Kizhi Pogost,” as it appeared prior to its restoration and before it was surrounded by an open-air museum. The presentation is based on photographs from the period 1912 through the 1920's, as well as the first accurate map of the entire island of Kizhi in Lake Onega in the State of Karelia, Russia, which dates from 1868.

The pogost ensemble — consisting of the Preobrazhenskaya Tserkva (Church of the Transfiguration) and the Pokrova Bogoroditsy Sobor (Church of the Intercession of the Holy Virgin), its wall of boulders, cemetery, and, beyond the cemetery, the clergymen's house and landing stage — is described. The parishioners lived outside the pogost walls in the numerous villages on the island, which are shown on the map, and also on the neighboring islands and the mainland.

The plan of both churches, their structure, and the iron-clad roofs are described. The process of the repair of the churches in the nineteenth century is documented. The interior of Preobrazhenskaya Tserkva is also described. The photographs of the Preobrazhenskaya Tserkva show the altar, the icon screen, and “heaven” (the ceiling, which was destroyed during the war). The majority of the photographs, as well as the map of the island, are published here for the first time.
Concepts of Repair, Restoration, and Reinforcement of the Church of the Transfiguration
Authors: Piskunov YV
Published: April 2008

With 22 domes, 33 meters high up to the base of the central cross, the Church of the Transfiguration on Kizhi Island, built in 1714, is a real masterpiece, where any spare parts are absent.

During the 1950s, the building's condition started to cause particular anxiety. This was the reason for numerous examinations of the building, in order to evaluate its real strength and to determine the restoration strategy. The absence of reliable methods for the analysis of notched-log buildings was a problem. Any theoretical analysis had to be approximate. As a result of this uncertainty, a metal frame was installed in the church's interior, while some significant structural elements were removed or were considerably weakened during this installation. It was assumed that this building could not be saved and replacing it was considered to be the only way to preserve it. In 1987, it became feasible to reconsider this approach. A new phase of research began. Its goal was to evaluate a number of aspects of restoring the structure and its functional quality.

The objectives of this article is to present an analysis of complicated structures found in architectural monuments and, specifically, to evaluate the strength, stability, and serviceability of the Church of The Transfiguration.
Alternative Strategies in Restoring a Medieval Barn
Authors: Yeomans DT , Smith AC
Published: April 2008

The restoration of a barn in Sussex, England raised issues which are common to many such projects. In particular, issues arose related to the alternative strategies of in- situ repair or dismantling for repair, both of which may be possible for a timber structure. The issues were stated clearly in this case because the parties involved disagreed over which strategy should be adopted and as each was used for different parts of the building the different outcomes resulting were perhaps more clearly seen here than in many cases. This paper illustrates the differences between these strategies by examining how each would have resolved the problems of structural deterioration and deformation inherent in the building, looking at their impact on both structural action and appearance. Finally, it briefly addresses the issue of whether to retain earlier repairs or to remove them as part of a current restoration.
Diagnosis of Wood Timbers: “La Longa” Building in Valencia, Spain
Authors: Palaia-Pérez L
Published: April 2008

This paper deals with a methodology of diagnosis for timber structural elements, applied on a significant historic building of Valencia, Spain—“La Lonja” and Sea Consulate. In 1469, the council of merchants at Valencia, resolved to construct a new building so that the Taula of Valencia could operate. The construction began in 1482, and was completed in 1537. “La Lonja” remains as one of the most important gothic buildings of the city of Valencia.

In 1994, termite attack as well as fungi decay was detected. For that reason, the wooden structure received a chemical treatment. Consequently, the authorities who care for the building decided to carry out a study to evaluate the condition of the wooden structure before doing further treatments. The purpose of this survey was to determine the extent of deterioration of the structure.

The author studied the timber structural elements, applying a reasoned approach to the problem. The study carried out was as follows: survey of the wooden structure, recording the locations and dimensions of the various timber elements; inspection of the timber elements using traditional investigative methods; diagnosis of the damages; evaluation of the actual structural capability; and recommendations for treatment and reinforcement.

Even though the building was quite complex, the diagnosis had to be completed in a short time. It was recommended that chemical treatments be applied after necessary reinforcements were carried out. Specifications were also prepared to define future works to be performed on the building.
Structural Stabilization Challenges of a Presidential Home
Authors: O'Bright AW
Published: April 2008

From his first visit in 1843 until his death in 1885, Ulysses S. Grant participated in the development of a Missouri “plantation” called White Haven, located near St. Louis, Missouri. Constructed in 1818 and enlarged over a period of five decades, the Main House at White Haven consisted of a variety of wood framing systems. The house remained virtually unchanged for almost 100 years until two early additions were demolished during extensive 1940 renovation work. Faulty initial structural design, istallation of contemporary conveniences, insect infestations, and poor 20th century repair practices combined to severely compromise the structural integrity of the house. This paper examines the history of 19th century structural design and repairs, recent condition of a portion of the deteriorated heavy timber section of the house, planning process, conservation goals, and alternative and ultimate stabilization treatments.
Addressing 150 Years of Structural Modifications: The Charles Arnold and Julia Sprigg Houses at Lincoln Home National Historic Site
Authors: Drone CA
Published: April 2008

This paper discusses the preservation and restoration challenges and treatments for the problems encountered at two wood-framed historic structures. The structural modifications to be discussed are divided into the following categories: (1) the foundation components, (2) the floor framing components, (3) the roof framing components, and (4) the wall framing components. The existing conditions of each of the structural components and the problems inherent in the existing conditions, as well as the problem solving approach and solution to those problems, is reviewed in detail. Since, in all cases, the foremost consideration was retention of the historic fabric, different problem solving approaches and treatments for both houses became necessary due to the unique character of the existing conditions and the varying presence of historic fabric in each structure. However, each house did share some common or similar solutions.
Totem Pole and House Post Conservation
Authors: Sheetz RE
Published: April 2008

The totem poles and house posts located in Sitka National Historical Park, Sitka Alaska, are located in an environment which has an annual rainfall of 95 inches. Fungal decay flourishes, with the most decay occurring around the bases where the totems enter the ground, the tops of poles, and the horizontally carved surfaces. Over the years numerous chemicals were applied to try to lengthen their lifespan. In 1991 a Totem Preservation Conference was held in Sitka and a condition survey was performed. As a result of the survey, it was decided to treat the totem poles with sodium borates. This paper focuses on the treatments used over the years, the decision to use borate preservatives, and the results of that decision.
A Micromechanical Evaluation of the Master Curve
Authors: Natishan ME , Kirk MT
Published: April 2008

The cleavage fracture model of Wallin et al. [1] suggests that the variation of median and bounding values of fracture toughness with temperature is predictable on a micro-mechanical basis. ASTM has recently adopted a standard [ASTM Standard Test Method for the Determination of Reference Temperature, To, for Ferritic Steels in the Transition Range (E 1921–98)] for characterizing the variation of the fracture toughness of ferritic steels in the transition temperature range that draws heavily on the work of Wallin et al. and on subsequent developments [1–5]. The new standard expresses the median toughness transition for a 1T specimen as: KJc|median=30+70⋅exp⁡[0.019(T−To)] where temperature is measured in degrees Celsius and KJc is measured in MPa√m. Similar equations express the variation of bounding toughness values (e.g., 95% lower bound) with temperature. The numeric coefficients in all of these equations do not depend on the type of steel tested. This invariance suggests that chemistry, heat treatment, and other metallurgical variables are not thought to influence the exponential increase with temperature of the plastic work necessary for crack propagation, the dominance of carbides as the particles that initiate cleavage fracture, or the distribution of carbide particles.

The ASTM E 1921 Master Curve represents existing fracture toughness data well for nuclear pressure vessel steels and their weldments [6]. This empirical evidence suggests that the material invariance attributed to the Master Curve coefficients in ASTM E 1921 is at least approximately correct for this class of steel. But the microstructural bounds of applicability for the Master Curve are not clear.

In this paper we examine the physical basis for the Wallin et al. Master Curve with the aim of distinguishing the classes of steels to which the methodology applies from those to which it does not. We use this physical understanding to calculate the temperature dependence of the plastic work for ferritic steels to demonstrate theoretical validity of a single “master curve.”
Development of Consistent Size Criteria for ASTM Combined Fracture Mechanics Standards
Authors: Joyce JA , Tregoning RL
Published: April 2008

Recent ASTM Subcommittee E08.08 on Elastic-Plastic Fracture Technology activities have concentrated on the development of a common fracture test standard that allows the evaluation of elastic and elastic-plastic fracture toughness properties from tests on a single specimen. Many technical changes have been made to allow this process to go forward, but one area in which progress has not been made is in clarifying the various specimen size requirements that were part of the earlier standards. Instead, the size requirements in the new toughness testing standard E1820 have been extracted from the earlier standards, like ASTM E399 and ASTM E813 and extended to the new standard without change, in spite of their clear inconsistency.

A review of the development of the E399 size criteria [1] seems to make it clear that the E399 size criterion was meant by its originators to represent only a requirement that allowed the 0.95 secant offset method to adequately evaluate a consistent measure of crack initiation. The later J-integral-based size criteria of E813, E1152, E1737, E1820, and the recent To Reference Temperature standard E1921 are based on finite element analysis [2], which ensures that a minimal deviation from small-scale yielding (SSY) occurs. This is intended to generate consistent crack tip constraint as the specimen size decreases or the crack length increases.

In this work, specimens from three materials, a 6061-T651 aluminum, a 6Al-4V titanium alloy, and a 4340 steel alloy, were tested to investigate what the proper size criteria should be for a combined fracture mechanics test standard. Larger specimens from each material were tested to obtain KIc values meeting the stringent size criteria of ASTM E399. Smaller specimens of each material were tested that intentionally failed the E399 size criteria, but satisfied the less stringent criteria of ASTM E813 and E1820. The unloading compliance method has been used in the testing of the smaller specimens so that an estimate of the true crack initiation point on the specimen load displacement record can be measured.

The fracture toughness at the onset of ductile crack extension is measured in terms of the J integral and converted to an equivalent stress intensity KJ value using the standard relationship. The fracture toughness at this crack initiation point can then be compared with the KQ obtained using the 0.95 secant offset initiation point specified by the E399 KIc procedure, and the validity of the various measures of initiation toughness can be determined with respect to the different size criteria.
Standardized Testing Procedures and Developments in Partial Discharge Measurement
Authors: Bartnikas R
Published: April 2008

A comparison of the various standardized methods of partial discharge detection and measurement on electrical components, apparatus and cables indicates that, for the most part, the methods are more concerned with the detection of the presence of partial discharges rather than the determination of arbitrary discharge energy thresholds that may induce degradation and eventual breakdown of electrical insulating systems. Particular attention is given to IEEE and IEC partial discharge measurement standards and their relation and similarity to the ASTM standard. The ASTM test method is shown to constitute the basis for most other standards and existing measurement techniques, with the exception of those on rotating machines and compressed gas cables where higher frequency methods are utilized. A discussion is presented on certain advanced topics, dealing with partial discharge pulse-height and discharge epoch distribution analysis and the associated digital measurement techniques, none of which have yet attained any standardization status. In addition, a number of partial discharge site location techniques, which may have some potential for standardization, are described.
Ultra-Thin Film Dielectric Reliability Characterization
Authors: Suehle JS
Published: April 2008

The reliability of gate oxides is becoming a critical concern as oxide thickness is scaled below 4 nm in future technology. The breakdown detection algorithms in traditional reliability characterization techniques must be modified for sub-4 nm thick SiO2 films that exhibit excessive tunneling currents and soft breakdown. It becomes essential to fully understand the physical mechanism(s) responsible for gate oxide wear-out and breakdown if reliability projections are based on the results of highly accelerated wafer-level GOI tests. Issues relating to the reliability testing of ultra-thin oxides are discussed with examples.
Fatigue Strength of Welded Joints Under Multiaxial Loading: Comparison Between Experiments and Calculations
Authors: Witt M , Yousefi F , Zenner H
Published: April 2008

In reality most welded components are loaded with a combination of different variable forces and moments which often cause a state of multiaxial stress in the fatigue critical areas of the weldment. If the multiaxial loading is nonproportional, conventional hypotheses are not able to give a satisfying lifetime prediction. This investigation is a cooperation of three German research institutes to build an experimental database for the verification of different concepts of lifetime prediction. In accordance with former investigations, a flange-tube connection made of steel P460 is used. The test program is divided into constant amplitude and variable amplitude tests. The ratio between the nominal bending and shear stress is 1. The ratio between the local shear and normal stress at the critical point is 0.6. For the variable amplitude tests, a Gaussian standard is used.

A lifetime prediction software for multiaxial state of cyclic stress was developed. The software has a modular structure and allows calculations with different hypotheses and methods. The calculations are based on the local elastic stresses. This is an acceptable method for high-cycle fatigue. The failure criteria “critical plane approach” and “integral damage approach” are used in the software. Lifetime predictions for the flange-tube connection were performed using various hypotheses and concepts. In this work, one type of calculation, the integral approach with elementary Miner's Rule and damage sum D = 1, is illustrated. The calculations correspond well with the experimental results.
The Effect of Periodic Overloads on Biaxial Fatigue of Normalized SAE 1045 Steel
Authors: Bonnen JJF , Topper TH
Published: April 2008

During the past decade it has been observed that periodically applied overloads of yield stress magnitude can significantly reduce or eliminate crack closure under uniaxial or Mode I loading. This paper reports the results of a series of biaxial in-phase tension-torsion experiments that were performed to evaluate the effects of overloads on the fatigue life of smooth tubes constructed of normalized SAE 1045 steel. Five strain ratios were investigated, including uniaxial (λ = εxy/εxx = 0), pure torsion (λ = ∞), and three intermediate ratios (λ = 3/4, 3/2, and 3). Periodically applied overloads of yield stress magnitude allowed cracks to grow under crack face interference-free conditions. Strain-life curves were developed by computationally removing the overload cycle damage from test results and calculating equivalent fatigue lives. A factor of two reduction in the fatigue limit was found at all ratios when these results were compared with constant-amplitude results. Cracking behavior was observed and it was noted that for strain ratios greater than one, cracks initiated along the rolling direction (longitudinally); otherwise, the cracks initiated on maximum shear planes. This observation was used to help explain the similarity in fatigue life results for all strain ratios for both constant-amplitude and overload data. Parameter-life curves were developed using the equivalent fatigue life data and several common multiaxial damage parameters, and the damage parameters were evaluated. It was found that the simple maximum shear strain criterion together with uniaxial overload data provided a good estimate of the fatigue behavior for all strain ratios.
In-Phase and Out-of-Phase Combined Bending-Torsion Fatigue of a Notched Specimen
Authors: Park J , Nelson DV
Published: April 2008

An experimental study of the high-cycle biaxial fatigue behavior of notched specimens is reported. Solid round bars of 1%Cr-Mo-V steel having a circumferential semicircular groove were tested under fully reversed constant-amplitude bending, torsion, and combined bending and torsion, inphase, and 90° out-of-phase. Smooth specimens of the same material were also tested under bending as well as torsion to provide baseline data. Observed fatigue life data are used to evaluate several multiaxial fatigue life prediction models, including a critical plane method, a von Mises approach, and an energy-based approach. Crack growth behavior as observed on the surface in smooth and notched specimens is presented and discussed.
The Application of a Biaxial Isothermal Fatigue Model to Thermomechanical Loading for Austenitic Stainless Steel
Authors: Zamrik SY , Renauld ML
Published: April 2008

A biaxial thermomechanical fatigue (TMF) model has been developed by extending a biaxial fatigue model for isothermal condition. The proposed model assesses the in-phase and out-of-phase type cycle incorporating the effect of oxidation and creep. The isothermal fatigue model utilizes the concept of triaxiality factor (TF), which accounts for the state of stress effect on the material's fracture ductility. The TMF biaxial strain ratios varied from 0 to 3.65 at cyclic temperatures of 399 to 621 °C (750 to 1150°F). All tests were strain controlled using tubular specimens. Heating was by induction and the cooling was by natural convection.
Wood Structures: A Global Forum on the Treatment, Conservation, and Repair of Cultural Heritage
Authors: Kelley SJ , Loferski JR , Salenikovich AJ , Stern EG
Published: April 2008

Description

This unique, new ASTM publication gives you a global perspective of various wooden monuments that are part of the great architectural heritage of Russia, the former Soviet States, Scandinavia, other European countries, and the United States. In addition to historical background, it details the latest techniques used in restoring and preserving these fragile wooden constructions. Much of the information is translated into English for the first time. 19 peer-reviewed papers are grouped into the following chapters:

A Primer on Wood Heritage--discusses the history of the northern Slav wood-built heritage from a worldwide point of view.

The Church of the Transfiguration on Kizhi Island--concentrates on this 18th Century masterpiece of log engineering and UNESCO World heritage site, located in Karelia, Russia. Topics include structural problems, wood condition, monitoring deformations, restoration, and reinforcement concepts.

Challenges of Log Structures--discusses the latest evaluation, conservation, and restoration techniques in northern and eastern Europe. This section also covers certain environmental problems, including how toxic chemicals used in wood preservation can affect the environment and human health.

Challenges of Frame Structures--details various preservation strategies used on wood frame structures in western Europe and the United States.

Special Studies--concentrates on two special conservation cases dealing with the totem poles of Sitka, Alaska and historic wooden structures from abandoned research colonies in Antarctica.
A New Multiaxial Fatigue Life and Crack Growth Rate Model for Various In-Phase and Out-of-Phase Strain Paths
Authors: Varvani-Farahani A , Topper TH
Published: April 2008

A new multiaxial fatigue parameter for in-phase and out-of-phase straining is proposed. The parameter proposed is the sum of the normal energy range and the shear energy range calculated for the critical plane on which the stress and strain Mohr's circles are the largest during the loading and unloading parts of a cycle. The normal and shear energies used in this parameter are divided by the tensile and shear fatigue properties, respectively. The proposed parameter, unlike many other parameters, does not use an empirical fitting factor. The proposed parameter successfully correlates multiaxial fatigue lives for: (a) various in-phase and out-of-phase multiaxial fatigue straining conditions, (b) tests in which a mean stress was applied normal to the maximum shear plane, and (c) out-of-phase tests in which there was additional hardening.

An effective (closure free) intensity factor range, ΔKeff, was derived based on the proposed parameter. This effective intensity factor successfully correlated the closure-free crack growth rates for straining of various biaxial strain ratios.
Modeling of Short Crack Growth Under Biaxial Fatigue: Comparison Between Simulation and Experiment
Authors: Suhartono HA , Pötter K , Schram A , Zenner H
Published: April 2008

Grain boundaries, microstructural barriers and differences in stress/strain state play a dominant role in the early stages of the fatigue crack growth of metals. Many studies on the growth of short cracks have revealed anomalies in the behavior predicted by LEFM analysis. A simulation of fatigue crack growth is presented. The polycrystalline metal was modeled as an aggregate of hexagonal grains with a different crystallographic orientation of each grain. The effect of grain boundaries on Stage I crack growth is considered in the model. The mode of shear crack growth is used to compute the crack growth. This mode is analyzed on the basis of microstructural crack growth within the first few grains, where the crack growth decelerates as the crack tip gets closer to the grain boundary. Normal crack growth has been considered for those cracks which are longer than microstructural cracking (physically short cracks). The transition from Stage I to Stage II growth is considered. The model is applied for thin-walled tubular specimens of the ferritic steel AISI 1015 and the aluminum alloy AlMgSi1 subjected to tension and torsion loading as well as in-phase and out-of-phase combined tension-torsion loading, sequential tension and torsion loading. The microstructural crack pattern and crack distribution can be successfully simulated with the model, and the simulated microstructural crack growth rate is presented.
System Design for Multiaxial High-Strain Fatigue Testing
Authors: Lohr RD
Published: April 2008

System design starts with the specimen and the forces that need to be applied to simulate service conditions by creating specified combinations of multiaxial stress or strain. Based on this premise a semigraphical tabular presentation is used to review the technical and cost-related advantages, and disadvantages, of alternative design schemes. References to real-world multiaxial test systems illustrate progress to the present day.

This paper sets out to review salient features that have marked out progress in the design of multiaxial systems over the past 50 years. It also aims to provide foresight in the specification of future equipment and to improve the understanding of those factors, other than intrinsic material behavior, which influence the characterization of high-strain multiaxial fatigue life.
Design of Specimens and Reusable Fixturing for Testing Advanced Aeropropulsion Materials Under In-Plane Biaxial Loading
Authors: Ellis JR , Sandlass GS , Bayyari M
Published: April 2008

A design study was undertaken to investigate the feasibility of using simple specimen designs and reusable fixturing for in-plane biaxial tests planned for advanced aeropropulsion materials. Materials of interest in this work include: advanced metallics, polymeric matrix composites, metal and intermetallic matrix composites, and ceramic matrix composites. Early experience with advanced metallics showed that the cruciform specimen design typically used in this type of testing was impractical for these materials, primarily because of concerns regarding complexity and cost. The objective of this research was to develop specimen designs, fixturing, and procedures that would allow in-plane biaxial tests to be conducted on a wide range of aeropropulsion materials while at the same time keeping costs within acceptable limits. With this goal in mind, a conceptual design was developed centered on a specimen incorporating a relatively simple arrangement of slots and fingers for attachment and loading purposes. The ANSYS finite-element code was used to demonstrate the feasibility of the approach and also to develop a number of optimized specimen designs. The same computer code was used to develop the reusable fixturing needed to position and grip the specimens in the load frame. The design adopted uses an assembly of slotted fingers which can be reconfigured as necessary to obtain optimum biaxial stress states in the specimen gage area. Most recently, prototype fixturing was manufactured and is being evaluated over a range of uniaxial and biaxial loading conditions.
Fracture Mechanics of Mechanically Fastened Joints—A Bibliography
Authors: Reemsnyder HS
Published: April 2008

The application of fracture mechanics to mechanical fasteners requires stress-intensity-factor solutions for cracks at fastener holes and in threaded, round bars. This bibliography lists references that present stress-intensity-factor solutions for cracks at circular holes and a wide range of cylindrical, solid and hollow, round bars, unnotched, and circumferentially notched, subjected to axial loads, bending. Notched cases include shoulder fillets, multiple thread-like circumferential projections, and thread-like single circumferential grooves in round bars. In these cases, the projections and grooves were not helical. Instead, the planes of the projections and grooves were perpendicular to the axis of the round bar. The geometries of cracks in round bars include circumferential cracks and cracks initiated at a point on the surface of the cylinder. The latter crack geometries include straight, curved, semicircular, semi-elliptical, and sickle-shaped crack fronts. A few references treat high-strength bolts.
Nondestructive Evaluation of Dimension Stone Using Impulse-Generated Stress Waves: Part 1 — Theoretical Aspects and Experimental Prospects
Authors: dos Reis HLM , Habboub AK
Published: April 2008

Energy-related processes in dimension stones are numerous and may collectively describe the mechanical and physical features of stone such as its viscoelastic and microstructural properties. Viscoelastic properties are concerned with evaluating the complex, stress-relaxation, and creep-compliance moduli. Microstructural properties include grain-size distribution, grain type, shape, texture, bedding anisotropy, and grain coating/surface-contact conditions. Other related energy-based intrinsic properties include noise-abatement and transport properties such as porosity, permeability, and tortuosity. Therefore, the study of the energy evolution processes within a given stone component/system by means of an impulse-generated stress-wave field may reveal the nature of the required stone features. Using principles of statistical energy analysis, SEA, diffuse-wave-fields, and analogies to solid media of architectural-acoustic theories on reverberant enclosures, the evolution of the wave field is studied and discussed, and the experimental means of performing spectral and energy analyses from a single impulse-echo test is presented.
Thin Stone Veneer/Study and Remediation
Authors: Solinski JP
Published: April 2008

Thin stone veneer panels have been used in exterior wall cladding systems for many years. The advent of computerized engineering has enabled designers to devise systems that are structurally sound, lightweight, and cost effective. Unfortunately, even with all the engineering evaluation, component detailing, and testing, stone cladding has been installed improperly on many buildings despite sound theoretical analysis. Condition surveys and maintenance reviews have detected installation deficiencies within thin stone veneer systems that have cost building owners millions of dollars to remedy. Two case studies involving stone veneer systems are presented, outlining the problems found and the solutions used in remediation.
Permeability Properties of Cement Mortars Blended with Silica Fume, Fly Ash, and Blast Furnace Slag
Authors: de Gutiérrez R , Delvasto S , Talero R
Published: April 2008

Deterioration of concrete structures due to reinforcement corrosion because of chloride ingress is a growing problem in many countries throughout the world. Partial replacement of portland cement by mineral additions, such as ground granulated blast furnace (GGBS), silica fume and fly ash influences the resistance of the pastes and mortars to the chloride environments. The rate of chloride ingress into mortar depends on the pore structure and the capacity of the hydration products to bind chlorides

This paper reports the comparative results of mechanical and permeability properties of blended mortars. Mortar specimens were made with slag replacement levels of 60%, 70%, and 80%, fly ash replacement levels of 20%, 30%, 40%, and 50% and silica fume replacement levels of 5%, 10%, 15%, and 20%. The following tests were performed: compressive strength, water absorption, rapid chloride permeability, mercury intrusion porosimetry, and X-ray diffraction.

Mortars with fly ash and slag reported lower strengths than silica fume mortars. The silica fume mortars show a 50% pore size of that for the mortar without addition. The densifying effect of these materials on the microstructure is attributed to the sealing of pore openings and the narrowing of pore channels by the hydration products of pozzolanic reactions. This results in a reduction in permeability. In general, the use of these admixtures improves the resistance of portland cement mortars against chloride attack. The slag added mortar obtained the best performance.
Time Dependent and Nonlinear Effects in Polymers and Composites
Authors: Schapery RA , Sun CT
Published: April 2008

Description

STP 1357 describes worldwide recent developments on this topic and examines their practical applications. It also identifies important unsolved fundamental problems. 18 peer-reviewed papers are grouped under the subheadings of Polymers and Composites.

Polymers covers

Composites addresses

Audience: Engineers and researchers who are interested in durability of composite materials; specific issues of time dependent and non-linear behavior; and the mechanics of composites.
Reactor Pressure Vessel Neutron Dosimetry Assessments for UK PWR Plant
Authors: Thornton DA , Lewis TA , Mossop JR , Page CJ , Haddock SA
Published: April 2008

Reactor pressure vessel (RPV) dose assessments for UK PWR plant have been performed using the AEA Technology Monte Carlo radiation transport code MCBEND.

Monte Carlo models of the plant are validated against fast neutron activation measurements performed on flux monitor wires from surveillance capsules removed at the end of each cycle. These monitors have a range of time and spectrum dependencies. A computationally efficient method has been developed that calculates dosimeter activation values in a single calculation per reaction. This utilizes MCBEND's advanced acceleration techniques as well as an innovative treatment of neutron source data. The method employs plant validated, three-dimensionsal (3D) time-dependent neutron source data obtained from the UK reactor physics code PANTHER.

Mean ratios of calculation (C) to experiment (E) obtained for the surveillance capsules removed to date are 1.02, 0.99 and 1.04.

RPV dose distributions in axial, azimuthal and radial detail are obtained with a single calculation per reactor octant. Normalization to mean C/E provides best estimate dose data for the RPV inner surface and quarter thickness. A similar calculation provides dose data for the RPV top weld.
Integral Testing of Spallation Cross Sections for Neutron Dosimetry at 113 and 256 MeV
Authors: Greenwood LR
Published: April 2008

Activation rates were measured in Al, Au, Co, Cu, Fe, In, Nb, Ni, Ti, and Zr foils at well-defined geometries in neutron fields created by stopping 113 and 256 MeV proton beams in thick Al and U targets. The neutron spectra were independently measured using time-of-flight spectrometry. Comparison of these data sets provides integral testing and some adjustment of the poorly known activation cross sections at higher energies.
Modeling of BWR for Neutron and Gamma Fields Using PENTRAN™
Authors: Kucukboyaci V , Haghighat A , Sjoden GE , Petrovic B
Published: April 2008

We have developed a three-dimensional (3-D) model of a BWR to determine the radiation fields (neutron and gamma) throughout the core shroud in order to investigate the role of irradiation on the observed cracks. To handle large computational requirements, we have used the PENTRAN™ (Parallel Environment Neutral-particle TRANsport) 3-D, parallel SN code. Coupled neutron and gamma (67-group) calculations have been performed using S8 level symmetric quadrature set and BUGLE-96 cross-section library with P3 anisotropic scattering order. We have compared 3-D results with two-dimensional (2-D) results and concluded that 3-D calculations are necessary. In order to verify the 3-D multigroup PENTRAN™ results, we have performed 3-D multigroup TORT and continuous-energy A3MCNP™ (Automated Adjoint Accelerated MCNP) calculations and have obtained very good agreement. Timing studies have demonstrated that PENTRAN™ is highly scalable (∼90%).
Development of 3D MCNP-Based BWR Fluence Computational Software Package: MF3D
Authors: Chiang R-T , Sitaraman S
Published: April 2008

A three-dimensional MCNP-based fluence computational software package is developed for accurate, BWR, three-dimensional, continuous-energy, neutron and gamma fluence and dose computation. The 3D MCNP model is established based on actual heterogeneous BWR core geometry rather than on conventional homogenized reactor core geometry. This software package will be a useful tool for computing accurate BWR fluence and for benchmarking existing, less precise methodologies.
Fusion Neutron Irradiation Effects on Some Electronic Devices
Authors: Iida T , Tanimura Y , Sato F , Tanaka T
Published: April 2008

In order to examine the difference in the irradiation effects on Si electronic devices between deuterium-tritium (DT) and deuterium-deuterium (DD) fusion neutrons, several types of memory integrated circuits (ICs), charge coupled device (CCD) image sensors and a Si surface barrier detector (Si-SBD) were irradiated with neutrons from a deuteron accelerator. The transient effects (i.e., neutron-induced background noises) and permanent effects (i.e., neutron damage) on them were measured in situ during irradiation. Regarding the transient effects, soft error upsets, brightening spot noises and induced-charge noises were measured for the memory ICs, CCDs and the Si-SBD, respectively. As for the permanent effects, the number of damaged cells of the CCDs and the leakage current of the Si-SBD increased with neutron fluence. We also developed a Monte-Carlo code which used the code TRIM for charged particle transport to evaluate the DT and DD neutron effects on the Si devices. The calculated correlation factor of DT and DD neutron damage for the Si devices agreed approximately with the correlation factor obtained from the irradiation experiments on the CCDs and Si-SBD.
Neutron and Gamma Ray Dosimetry in Spent-Fuel Radiation Environments Using Silicon Carbide Semiconductor Radiation Detectors
Authors: Dulloo AR , Ruddy FH , Seidel JG , Flinchbaugh T , Davison C , Daubenspeck T
Published: April 2008

Silicon carbide semiconductor radiation detectors are resistant to radiation induced damage and can be operated at elevated and changing temperatures., Silicon carbide radiation detectors have been shown to have linear responses to both neutrons and gamma rays. Furthermore, these responses are separable on the basis of pulse height, making simultaneous monitoring of both neutrons and gamma rays possible. The neutron and gamma ray sensitivities of silicon carbide radiation detectors are well-matched to the radiation environments characteristic of spent nuclear fuel. Measurements have been carried out in mixed gamma/neutron fields in a hot cell and at a reactor facility under conditions chosen to approximate the radiation fields typically encountered in the vicinity of spent nuclear fuel assemblies. The results of these measurements and the application of silicon carbide radiation detectors to spent fuel dosimetry are discussed.