bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Unified Creep-Plasticity Theory for Solder Alloys
Authors: McDowell DL , Miller MP , Brooks DC 
Published: March 2009

Sn-Pb solders exhibit creep-plasticity interaction and significant strain-rate dependence at operating temperatures of electronic circuits. A major problem is fatigue and creep-fatigue interaction due to thermomechanical cycling. Reversed plasticity, creep, and creep-plasticity interactions dominate the behavior for these types of histories. Furthermore, thermal softening plays a strong role in the time dependence of the mechanical behavior. However, classical forms of decoupled plasticity and creep theories have been shown to be quite inferior for modeling cyclic plasticity, creep, and interaction effects. The goals of this study were to: (a) develop a thermomechanical unified creep-plasticity model which can characterize the response of solders, and (b) characterize a selected solder alloy through mechanical testing and correlation with the model across a range of strain rates, temperatures, aging times, and loading-unloading conditions.
Solder alloys in general are mechanically soft and are employed routinely at very high homologous temperatures. The microstructure is often unstable at normal circuit board operating temperatures and the extent of alteration to the microstructure is a function of the applied stress or strain, temperature, etc. Many alloys recrystallize below 77°F (25°C) and therefore can change with time at room temperature.
A program of characterization involving tension tests at various temperatures and strain rates, creep tests, cyclic loading tests, and tension tests after prior high-temperature exposure was pursued to develop a broad-based understanding of the behavior of eutectic Sn-Pb solder, the most commonly used industrial solder alloy. A model for thermomechanical temperature and rate-dependent behavior of metallic alloys has been developed. Many of the typical, complex behaviors of solders can be addressed with this model, including temperature dependence and strain-rate dependence, creep-plasticity interaction, viscous cyclic strain ratchetting, softening effects due to static thermal recovery, and potential effects of aging (microstructural changes due to exposure at high temperature).
Stress and Thermal Analysis of Resistance Temperature Detectors
Authors: Wilson DA , Katherisan A 
Published: March 2009

In many industries the failure of temperature devices such as resistance temperature detectors (RTDs) are of significance to process control. Therefore, a study was instituted to evaluate these failures. RTDs from various manufacturers were monitored and periodically calibrated until failure. Sensors that developed open circuits were then examined. Upon examination of the sensors, it was found that failures were occurring at or near the solder connection between the platinum lead-out and copper wire. A two-dimensional (2-D) finite element analysis of this joint was then developed.
Finite element models were created to evaluate stresses at 100, 200, and 300°C. The thermal expansion mismatch between the wires joined by the solder results in high-stress gradients at the corners of the solder joint. Photomicrographs were produced of the joint failures with a scanning electron microscope to study the crack nucleation and propagation. Aging of the solder due to long-term temperature exposure may also play a key role in the fracture behavior. The need for improved joint design and special coating materials is of primary importance to improve the life of the solder joints in many applications. This will improve the reliability of the components.
Effects of Fission and Fusion Neutron Irradiations on Mechanical Properties and Defect Recovery Behavior in α-Iron
Authors: Aono Y , Kuramoto E , Yoshida N , Kurishita H , Kayano H 
Published: March 2009

Comparison is made of data on mechanical properties of high-purity iron single crystals irradiated with fission neutrons at the Japan Materials Testing Reactor (JMTR) and 14-MeV D-T neutrons at the Rotating Target Neutron Source (RTNS-II) at low fluences below 1022 n/m2. Both irradiations below 363 K led to irradiation hardening and the suppression of a hump appearing on the temperature dependence of yield stress of unirradiated high-purity iron, which suggests that radiation-induced defects formed at low temperatures significantly influence thermally activated deformation of iron.In the isochronal annealing experiments of yield stress, the RTNS-II-irradiated irons showed a high annealing resistance accompanied by three recovery stages: stage I (RT to 450 K), stage II (650 to 750 K) and stage III (900 to 950 K). Recovery stages of the JMTR-irradiated irons were observed in the temperature ranges of 500 to 600 K (state Ij) and 700 to 780 K (stage IIj), followed by no radiation effect above 800 K. These recovery stages, except for stage III, were explained from a series of annealing of interstitial clusters with size distribution. Defects responsible for stage III were associated with complex vacancy type defect-nuclear reaction products (helium or hydrogen).
Isotopic Tailoring with 59Ni to Study Helium Generation Rates and Their Effect on Tensile Properties of Neutron-Irradiated Fe-Cr-Ni Alloys
Authors: Garner FA , Hamilton ML , Greenwood LR , Stubbins JF , Oliver BM 
Published: March 2009

Tensile testing on three model Fe-Cr-Ni alloys removed from four discharges of the 59Ni isotopic doping experiment in FFTF-MOTA indicates that helium/dpa ratios typical of fusion reactors do not produce changes in the yield strength or elongation that are significantly different from those at much lower helium generation rates. It also appears that tensile properties approach a saturation level that is dependent only on the final irradiation temperature, but not prior temperature history or thermomechanical starting condition. The saturation in mechanical properties reflects a similar saturation in microstructure that is independent of starting condition.
The successful conduct of an isotopic doping experiment was found to require post-irradiation measurement of the helium levels in order to compensate for uncertainties in the cross sections for burn-out and burn-in of 59Ni and for uncertainties in neutron flux and spectra in the vicinity of the edge of the core.
Influence of Overload and Temperature on Stress Corrosion Crack Growth Behavior in a Low-Alloy Steel
Authors: Venugopal V , Putatunda SK 
Published: March 2009

An investigation was carried out to examine the influence of temperature and overload plastic zone size on stress corrosion crack (SCC) growth behavior in a low-alloy steel. Compact tension specimens with TL orientation prepared from SAE 4140 steel in hardened and tempered condition were used. Two pertinent variable conditions were chosen: (1) cold deionized water at 23°C and (2) hot deionized water at 80°C. The specimens were precracked in fatigue and then overloaded to various extent (5, 10, 25, and 50%). The SCC behavior of these specimens was studied, keeping them submerged in hot and cold deionized water.
The results of the present investigation demonstrate that the incubation period for crack growth decreases with increasing initial stress intensity factor and increasing temperature. The incubation period for crack growth was found to increase as an exponential function of the overload plastic zone size. In overloaded specimens, once the crack growth initiated, the crack growth rate was observed to be much higher than in the non-overloaded specimens. The crack growth rate in Region I was found to increase with increasing initial stress intensity factor andtemperature. The crack growth rate in Region II was also found to increase with temperature, but was independent of the stress intensity factor.
A Model for Environmentally Assisted Crack Growth Rate
Authors: Gabetta G , Rinaldi C , Pozzi D 
Published: March 2009

A superposition model for corrosion fatigue formulated for reactor pressure vessel (RPV) steel is described in this paper. The three components of crack growth rate are associated to pure fatigue, true corrosion fatigue, and stress corrosion.
The true corrosion fatigue behavior can be correlated with the material properties with regard to the resistance to generalized corrosion: the stress corrosion behavior can be correlated to the stress corrosion susceptibility of the material/environment couple.
While in pure fatigue and true corrosion fatigue the crack growth rate is depending on the applied ΔK (following Paris law), the stress corrosion component is time dependent. The onset of the stress corrosion component is associated with a critical ΔK (ΔKC), whose is depending on frequency.
The meaning of ΔKC is discussed and compared with the classical stress corrosion parameter KISCC.
The good prediction obtained for RPV steels suggests to extend this approach to other materials; an application to AISI 304 stainless steel is proposed.
Cyclic Tension Corrosion Fatigue of High-Strength Steels in Seawater
Authors: Jones WJD , Blackie AP 
Published: March 2009

Four low-alloy steels with nickel contents varying from 0.2 to 4.0% (BS 970:722M24, 817M40, 976M33, and 835M30) quench hardened and tempered to give yield or 0.2% proof strengths of approximately 800 MPa were tested in cyclic tensile loading (R = 0.05) at a frequency of 0.167 Hz in plain and notched (SCF = 2) forms in air, freely corroding in ASTM synthetic seawater (temperature 8°C and pH 8.2) and with cathodic protection of - 850 mV and - 1050 mV to establish S-N data for offshore platform design.
The steels suffered considerable reductions in fatigue performance in the freely corroding condition. Cathodic protection at — 850 mV improved the performance of all four steels and in one case (817M40) restored it to that in air. Notched specimens were not improved to the same degree as plain specimens.
Cathodic protection at - 1050 mV fully restored the fatigue performance of plain and notched steel 817M40 but the others showed a reduction in performance due to intergranular cracking in initiation and early crack propagation life in place of the otherwise ductile transgranular fracture; this was attributed to hydrogen absorption.
Wide-Plate Testing of Weldments: Introduction
Authors: Denys RM 
Published: March 2009

No one single source currently exists which gives an overall picture of the meaning and usefulness of wide-plate test data. The intent of this series of papers is to provide a summary of the status of available knowledge—attained by the author as the result of almost 20 years of experience and study of the literature in the field of wide-plate testing—relating to the prevention of (brittle) fracture initiation.
In terms of organization, this series of papers begins with a short general introduction to show why the papers were written. The wide-plate test is then reviewed from various viewpoints. As the reader will see, the subject is presented in three self-contained papers, bearing the following titles: Part I—Wide-Plate Testing in Perspective Part II—Wide-Plate Evaluation of Notch Toughness Part III—Heat-Affected-Zone Wide-Plate Studies
Part I is concerned with a brief review of the historical development of wide-plate testing in relation to the major achievements of wide-plate/small-scale test correlations. From these considerations, the future role of wide-plate tests in fracture performance evaluations and design practice are discussed. Part II presents the various wide-plate and defect designs for evaluating the overall stress/strain behavior of plain and welded plates. Furthermore, the performance requirements in relation to the purpose of the test are critically reviewed. Part III considers the present state of the art in heat-affected-zone wide-plate testing procedures. The presentation provides a step-by-step analysis of the actual testing requirements. Particularly, emphasis is given to detailed metallographic posttest validation requirements for the crack tip location.
Quantitative Comparison and Evaluation of Various Notch Machining Methods and How They Affect ASTM E23 and ISO R442 Testing Equipment Results
Authors: Fink DA 
Published: March 2009

The differences obtained when conducting Charpy impact tests using an ASTM method E23 specification, versus the ISO type impact tester have been reported with little agreement upon the comparisons. There has also been historically much controversy as far as the proper method of machining the notch into the Charpy specimen. This paper compares the effects of the two different types of impact testing equipment and evaluates machining of the notch by the methods of grinding, broaching and milling with a single toothed fly cutter.
It was determined that results obtained with the ISO type impact machine were elevated by approximately 4%. It was also determined that a slightly lower impact value was obtained with broached specimens. Photomicrographs of typical notch profiles were also obtained.
Electric-Potential-Drop Studies of Fatigue Crack Development in Tensile-Shear Spot Welds
Authors: Swellam MH , Kurath P , Lawrence FV 
Published: March 2009

The development of fatigue cracks in galvanized low carbon and high-strength-low-alloy steel, tensile-shear-spot weldments was investigated using a d-c electrical-potential-drop technique which sensed the depth of fatigue cracks as they propagated through the thickness of the specimens. These resistivity changes were correlated with the actual crack depths measured on sectioned specimens. This correlation was used to identify lives at which certain crack depths were achieved: the duration of Stage I (initiation) corresponded to a crack depth of about 18% of the sheet thickness (≈0.16 to 0.48 mm), and the duration of Stage II (through-thickness propagation) corresponded to a crack depth equal to the sheet thickness (0.89 to 2.72 mm). The final failure of the specimen determined the conclusion of Stage III (cross-width crack propagation).
The effects of sheet thickness, specimen width, and nugget diameter were studied. Sheet thickness was found to have the largest effect on fatigue life, while the nugget diameter had the least. The fatigue life of the galvanized high-strength-low-alloy specimens was found to be dominated by through-thickness propagation (Stage II), while the fatigue life of the galvanized low carbon specimens was dominated by Stage I. The fatigue life of all specimens tested at a given R ratio could be correlated with the initial value of stress intensity factor for the combined effects of Mode I and II loading conditions.
Updating a Land-Planning Database from Landsat-5 Thematic Mapper Data
Authors: Blaser TJ , Lyon RJ P , Lanz K 
Published: March 2009

Lansat-5 Thematic Mapper (Landsat-5 TM) images are evaluated for their use to upgrade a land-cover/land-use database in Switzerland. The Hectometric Information Grid or Hectaraster consists of a database, covering all of Switzerland according to 12 Level-I landcover/land-use categories. In this study Level-I and Level-II “build-up” and “forest” classes are computed using Landsat-5 TM spectral data of the study area of Switzerland. A procedure has been developed that automatically determines the dominant land-cover/land-use inside each hectare or “hectel” of the Hectaraster. The newly created Hectaraster results in a more accurate representation of the actual land-cover/land-use situation in the Nyon test area, as compared to the traditional 1972 Hectaraster. Also, more detail is available, since Level-II categories have been added to the Level-I land-cover/land-use categories.The study indicates how classified Landsat-5 TM images can efficiently contribute to the management and planning of low density build-up zones. The integration of classified remote-sensing data into a geographic information system (GIS) allows the extraction of new land-use categories by examining their spatial relationships. Thus, in addition to built-up categories, computed from automated classification procedures, potential construction sites and nonused construction areas have been determined through GIS operations.Methods are presented, which allow the classification of forest stands according to their surface and their shape. The perpendicular vegetation index (PVI) is computed for deciduous and coniferous forest stands. Deciduous and coniferous forests are studied separately. Coniferous forests revealed essentially low PVI values. Dense deciduous forest had the highest PVI values, while open deciduous and deciduous/coniferous stands had intermediate PVI values.
Effects of Aggregate Properties on Flexible Pavement Rutting in Alabama
Authors: Parker F , Brown ER 
Published: March 2009

Pavement rutting which results in a distorted pavement surface is the accumulation of permanent deformation in all or a portion of the layers in a pavement structure. The objective of this study was to examine the effects of aggregate properties on the rutting of asphalt concrete mixtures. This objective was accomplished by analyzing rutting data from the Alabama Highway Department's pavement condition database. Field sites were evaluated and sampled and laboratory tests performed on aggregate from field samples.
Analyses of the Department's pavement condition database indicate that rutting in Alabama is increasing, and that this increase is attributable to either increased loading intensity or increased asphalt concrete rutting susceptibility. The analyses also indicate that rutting varies geographically and that this variation can be explained by quality of locally available aggregate. Those areas with crushed stone and angular natural sands are less susceptible to rutting.
Analyses of data from field test sites indicate that permanent deformation causing rutting is generally confined to the top 7 to 10 cm (surface and binder courses). There was little evidence that lower base/subbase courses or subgrade were significant contributors to rutting. A rate of rutting of 5.0 × 10-4cm/√ESAL or 2.5 × 10-7cm/ESAL delineated good and poor performing pavements.
Aggregate properties studied include: gradation, coarse aggregate percent fractured faces, and fine aggregate particle shape and texture. The correlation coefficients for most of these properties were low, however, there appeared to be definite trends. The poor correlations show that rutting is a very complicated process that is affected by multiple factors, and demonstrates the importance of both aggregate properties and asphalt content during material selection and mix design.
Effect of Aggregate Size and Other Factors on Refusal Density of Asphalt Concrete by Vibratory Compaction
Authors: Shuler TS , Huber GA 
Published: March 2009

The physical behavior of asphalt concrete is related to the volumetric characteristics of the mixture. A significant challenge facing asphalt pavement engineers is predicting the future density and air voids of asphalt paving mixtures after construction and during service. How rapidly changes in density and voids occur during service can be related to the ability of the pavement to withstand forces imposed from vehicles and the environment. Densification of asphalt concrete after construction and during trafficking varies between mixtures and is related to the method of laboratory compaction, design criteria, and construction technique. This study describes a procedure for quantifying compactibility of mixtures and suggests a procedure for considering densification rate as a criteria for describing optimum asphalt mixtures.
The so-called refusal density of six types of asphalt concrete mixtures was evaluated in this study as function of vibratory hammer compaction. Three aggregate gradings ranging from 1–1/2 inch to 3/8 inch (37.5 to 9.5 mm) maximum aggregate size were compacted in the laboratory using three models of portable vibratory compactors administered by two operators. The resulting factorial experiment was analyzed to determine effect on volumetric properties due to hammer, aggregate grading, asphalt content and operator.
Vibratory compaction was compared with Marshall, kneading, and gyratory compaction procedures to determine differences between each method and for each grading with respect to density and voids characteristics. A new procedure is outlined for using the vibratory compaction technique for development of a new asphalt concrete design method and for adapting the technique for determining the sensitivity of asphalt concrete mixtures to further densification under traffic.
Results of the study indicate that all three vibratory hammers evaluated compacted asphalt concrete to higher levels of density than achievable by conventional Marshall, Hveem or gyratory methods and therefore, should be capable of producing mixtures with higher density than could be obtained after trafficking. The implication of this efficiency during laboratory compaction is a design tool that could provide information regarding the potential for mixtures to reach a plastic condition in service as related to void content.
Factors Affecting the Durability of Sealants in Contact with the Finish Coating of EIF Systems
Authors: Kenney RJ , Piper RS 
Published: March 2009

Failure of relatively new joint seals where the sealant was applied directly to the finish coat of the exterior insulation and finish system (EIFS) was first noted by the authors in 1975. During 1984, the failure of horizontal sealant joints in vertical surfaces on various projects with various types of sealants prompted an investigation into the cause or causes of joint seal failure.
From 1984 to 1991, a number of laboratory and field tests have been performed in order to correlate field and laboratory data. This paper discusses the effects of moisture accumulation within the wall system on the finish coat properties and the effect on the bond between various sealants and the finish coat when the properties of the finish coat are altered by elevated moisture levels.
Building Seals and Sealants for Parking Garage Decks in Hawaii
Authors: Yanoviak AC 
Published: March 2009

Seven case studies of problems and solutions using building seals and sealants in parking garages and parking decks in Honolulu, Hawaii are described including: the Royal Iolani Condominium, the Parkside Towers, the Kapiolani Commercial Center, the Heritage House Condominium, the Discovery Bay Condominium, the Canterbury Place, and the Imperial Hawaii Resort Hotel.
An illustrated slide lecture was presented that exemplified serious water infiltration problems involving property damage and manufactured product application failures, architectural and structural design detailing problems, and defective specifications for combinations of various building materials. Examples of unsuccessful attempts at remedial repair solutions, and concern for maintenance and replacement factors are given. Various materials and design standards being used for building seals and sealants on waterproofed decks and walls, with considerations for concrete chemistry, reinforcement steel placement, construction and expansion joints, etc., are discussed.
Design challenges by architects, developers, and building owners for contractors and manufacturers of building seals and sealants on ten or twelve other projects in Honolulu, including the Hawaii State Capitol, Kukui Plaza, Queen Emma Apartments, Tamarind Park, Ilikai Hotel, Admiral Thomas Condominium, Hyatt Regency at Hemmeter Center in Waikiki, Century Square Plaza, and the Ala Moana Shopping Center are described with due consideration for standards development.