bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue Lifetime Monitoring in Power Plants
Authors: Riccardella PC , Deardorff AF , Griesbach TJ
Published: March 2009

Metal fatigue is a potentially life limiting mechanism for pressure retaining components in nuclear and fossil-fueled power plants. Fatigue cracking may occur at high stress locations due to the accumulation of startup-shutdown cycles and other thermal transients or load cycles during plant operation. This is accentuated in fossil power plants because of higher operating temperatures and the interaction between creep and fatigue effects.

Under sponsorship of the Electric Power Research Institute (EPRI), an automated fatigue lifetime monitoring technology has been developed that utilizes plant process data to perform a continuous prediction of fatigue damage accumulation in critical components. The methodology was demonstrated in two field tests at operating nuclear plants and has since been installed on a production basis in a number of plants. A demonstration fossil plant application has also been developed and installed, adding creep-fatigue damage and crack growth algorithms to the basic nuclear plant technology.

The methodology has been incorporated into a PC-based computer program called FatiguePro. This program acquires plant process computer data (temperatures, pressures, flows, valve positions, etc.) and interprets them to predict local loads and temperatures in the monitored components. Green's functions are then used to determine transient thermal stresses at high stress locations in these components and to account for thermal history effects. A fatigue evaluation is then made based on the computed transient stress history. The fatigue analysis, based on Miner's Rule, is accomplished in accordance with ASME Boiler and Pressure Vessel Code stress and fatigue analysis procedures. Methodology is also available to perform fatigue and creep crack growth analyses.

The major benefit of on-line monitoring is that the actual challenge to structural integrity is measured, instead of simply counting design-basis cycles, as was the practice before the development of this system. Since actual plant operating cycles are typically less severe than those included in design, extension of predicted design lifetime can usually be obtained.
Fatigue Analysis Techniques for Vintage Steam Turbine/Generator Components
Authors: Jhansale HR , McCann DR
Published: March 2009

This paper describes some of the state-of-the-art engineering techniques utilized for the remaining life assessment and condition improvement of steam turbine/generator components in service. These include the finite element method for thermal and stress analyses, the inelastic strain-based fatigue analysis, and fracture mechanics for remaining life assessment. Special techniques for fabricating test specimens from small samples and testing for current fatigue and fracture properties are also described.
Development of Spatial Data Guidelines and Standards: Spatial Data Set Documentation to Support Hydrologic Analysis in the U.S. Geological Survey
Authors: Fulton JL
Published: March 2009

Spatial data analysis has become an integral component in many surface and subsurface hydrologic investigations within the U.S. Geological Survey (USGS). Currently, one of the largest costs in applying spatial data analysis is the cost of developing the needed spatial data. Therefore, guidelines and standards are required for the development of spatial data in order to allow for data sharing and reuse; this eliminates costly redevelopment. In order to attain this goal, the USGS is expanding efforts to identify guidelines and standards for the development of spatial data for hydrologie analysis. Because of the variety of project and database needs, the USGS has concentrated on developing standards for documenting spatial data sets to aid in the assessment of data set quality and compatibility of different data sets.

An interim data set documentation standard (1990) has been developed that provides a mechanism for associating a wide variety of information with a data set, including data about source material, data automation and editing procedures used, projection parameters, data statistics, descriptions of features and feature attributes, information on organizational contacts, lists of operations performed on the data, and free-form comments and notes about the data, made at various times in the evolution of the data set. The interim data set documentation standard has been automated using a commercial geographic information system (GIS) and data set documentation software developed by the USGS. Where possible, USGS developed software is used to enter data into the data set documentation file automatically. The GIS software closely associates a data set with its data set documentation file; the documentation file is retained with the data set whenever it is modified, copied, or transferred to another computer system. The Water Resources Division of the USGS is continuing to develop spatial data and data processing standards, with emphasis on standards needed to support hydrologic analysis, hydrologic data processing, and publication of hydrologic thematic maps. There is a need for the GIS vendor community to develop data set documentation tools similar to those developed by the USGS, or to incorporate USGS developed tools in their software.
An Approach to Data Exchange: The Spatial Data Transfer Standard
Authors: Rossmeissl HJ , Rugg RD
Published: March 2009

Significant developments have taken place in the disciplines of cartography and geography in recent years with the advent of computer hardware and software that manipulate and process digital cartographic and geographic data more efficiently. The availability of inexpensive and powerful hardware and software systems offers the capability of displaying and analyzing spatial data to a growing number of users. As a result, developing and using existing digital cartographic databases are becoming very popular. However, the absence of uniform standards for the transfer of digital spatial data is hindering the exchange of data and increasing costs.

Several agencies of the U.S. government and the academic community have been working hard over the last few years to develop a spatial data transfer standard that includes definitions of standard terminology, a spatial data transfer specification, recommendations on reporting digital cartographic data quality, and standard topographic and hydrographic entity terms and definitions. This proposed standard was published in the January 1988 issue of The American Cartographer. Efforts to test and promote this standard were coordinated by the U.S. Geological Survey. A Technical Review Board was appointed with representatives from the U.S. government, the private sector, and the academic community to complete the standard for submittal to the National Institute of Standards and Technology for approval as a Federal Information Processing Standard. The proposed standard was submitted in February 1992 for final approval.
Overview of the Use and Formulation of Geographic Information Systems (GIS) Standards Within the U.S. Environmental Protection Agency
Authors: Hewitt MJ , Stone HF , Slonecker ET
Published: March 2009

The U.S. Environmental Protection Agency (EPA) has regulatory authority over the Nation's air, water, hazardous waste, and toxic substance control laws. Over the last two years, the Agency has introduced geographic information systems (GIS) into the decision-making process. As the EPA has employed the technology, questions regarding consistency of use, cost, decision quality, data integration, and data exchange have been asked. Having adopted a structured management approach to implementation, the EPA is in the process of defining standards. Participation in ASTM is seen as a means to a large forum for standards discussion. This paper will describe the GIS standards the EPA is addressing and make recommendations on priorities and implementation methods.
Using Common Database and Spreadsheet/Plotting Programs as Inexpensive Geographic Information Systems
Authors: Rubin T
Published: March 2009

A commonly used database program (Macintosh HyperCard) and a spreadsheet/plotting program (Lotus 123) are demonstrated to be useful for organizing, displaying, and analyzing geographically coded data with multiple attributes. The data include multiple remote sensing images and geologic maps, and hundreds of high resolution infrared reflectance measurements, all from the same geographic area. The HyperCard database is most useful for indexing and retrieving the remote sensing data and geologic maps. Lotus 123 is most useful for displaying and analyzing the geographic distribution of interpretive analyses of the infrared spectra. Both programs are commonly available and simple to use. The techniques presented here should be helpful in analyzing any problem involving numerous, multiple-attribute datasets where the spatial distribution of data and results are important.
An Overview of the Global Positioning System and Its Use in Geographic Information Systems
Authors: Lange AF
Published: March 2009

The NAVSTAR global positioning system (GPS) provides accurate position data which can be used to aid the users of geographic information systems (GIS) in several ways. GPS is a satellite-based navigation, positioning, and timing system. From the data emitted by the GPS satellites, the receivers are able to calculate either two-dimensional (latitude and longitude) or three-dimensional (latitude, longitude, and altitude) positions. GPS, when used autonomously, is accurate to approximately 12 m circular error probable (CEP). In differential GPS, when used with a base station, the accuracy of GPS position fixes improves 2 to 5 m (CEP). For surveying applications, survey-grade receivers are available which are accurate in millimetres. The GIS applications of GPS include: georeferencing photogrammetric or digital map data; ground-checking satellite imagery data; and creating or updating GIS databases with point, line, or polygon digital data. For these applications, commercial GPS receivers are available which are portable, rugged, and easy to use, although a good understanding of the principles of GPS is required to correctly interpret the data involved.
Using USDA Soil Conservation Service County Soils Data with a Geographic Information System
Authors: Franchek RJ , Biggam PF
Published: March 2009

A county level soil data set for use in geographic information systems is being developed by the U.S. Department of Agriculture Soil Conservation Service. In addition, attribute information will be developed to provide information that is based on soil characteristics. Santa Rosa County, Florida soil survey was used as a sample data set to illustrate the use of the data. Interpretations on severe limitations for septic tank absorption fields and flooding frequency were developed for the county. This is a small sample of the types of information that are available. The main difficulties encountered in using the data are the size of the spatial and attribute information and the identification of needed information from the attribute tables.
Regional Soil Loss Prediction Utilizing the RUSLE/GIS Interface
Authors: Blaszczynski J
Published: March 2009

The revised universal soil loss equation (RUSLE) for rangelands was successfully interfaced with geographic information systems (GIS). The procedure utilizes raster processing capabilities of the map analysis and processing system (MAPS) to overlay data themes containing spatially distributed values for differentRUSLE factors. Within the limitations in accuracy of the USLE style calculation, cell processing, and information contained in input data layers, the methodology produces a map of relative levels of soil erosion potential which reflects the effects of rainfall, soil type, terrain, vegetation, and erosion control practice on soil loss. Improvements in processing to obtain the terrain (LS) factor from digital elevation models (DEMs) permit quick calculation of soil loss potential for large areas. Since the resolution of the product is determined by the quality and availability of the data, the methodology could be applied differentially to various areas and data sets to produce maps of low, medium, and high resolution. The flexibility of the procedure permits modeling of various management alternatives by changing values for the appropriate factors to reflect changing conditions. Furthermore, the RUSLE/GIS interface can be interfaced with other GIS models. All of the preceding indicate that the RUSLE/GIS interface has potential for and could be adapted for soil degradation studies on a global scale. The following is a conceptual summary of the procedure and is meant to provide only a quick overview of the methodology.
Estimation of Distribution of Subsurface Soil Layers in the Mexico City Earthquake Area Based on the Database
Authors: Kawamura M , Arai T , Ozawa T
Published: March 2009

Characteristics of the subsurface soils are considered to be one of the causes of the tremendous damage in Mexico City due to the 1985 Michoacan Mexico earthquake. In order to estimate the distribution of the subsurface soils in a horizontal plane, profiles of the soil layers, and a discussion of the relationship between the damage and the ground conditions, the authors developed the database system for the subsurface zone in Mexico City which shows the distribution of the soils on the maps and in the vertical sections.

The database system is composed fundamentally of several subsystems: data input, analyses, retrieval, and graphic display. The whole system is managed on the microcomputer. The characterisic of this system is that the interpolation analysis for water content and soil names is included in the subsystem for analyses. Cluster analysis is provided for the prediction of vertical sections of subsurface soil layers. On the graphic display the distribution of soil name, N-value, and water content in the vertical direction can be retrieved along the arbitrary section which are pointed up on the cathode ray tube display.

Those results were applied for the prediction of the seismic intensity in Mexico City, and the analyzed earthquake motion coincided quite well with those recorded in the 1985 Mexico earthquake because of the proper estimation of subsurface soils. When a geographic information system is developed, this kind of examination of the system is important.
Use of Geographic Information Systems for Design and Construction of New Waddell Dam
Authors: Paul DB , McDonald M
Published: March 2009

The Central Arizona Project is the largest single water-delivery project ever authorized by Congress. Construction of the project began in 1973, and it is anticipated to be completed by the mid-1990s.

The Bureau of Reclamation management wanted a system that would provide efficient data storage and transfer to assist in meeting deadlines and provide an effective database for planning, management, and operations. Delays were encountered because data required by different offices could not be transferred digitally. Often automated data had to be re-entered because of hardware and other system incompatibilities. The datum, by its nature, is cumulative. Current analog recording methods are compounding data management problems. Development of an integrated database, a geographic information system (GIS), was developed to help solve these problems.

The GIS stores, displays, retrieves, and analyzes data and many different disciplines (engineering, planning, hydrology, geology, etc.) and make use of spatial data. A flexible system has been built which provides a means of extracting only the data that are pertinent to their specific needs. Since these investigations utilize maps, aerial photography, and other types of remote sensor data, accurate measurements and data integration techniques are vital to the success of our projects.

Using the survey and photogrammetric methods, additional georeferenced data and products have been generated. Some of the more important are: drill-hole coordinates, geologic strata coordinates, profiles, canal alignment, dams and structures positioning, section lines, rights-of-way (road and transmission lines), distance and area measurements, and reservoir capacities.

The GIS was used extensively to provide georeferenced data for design and construction of the New Waddell Dam.
Classifying and Mapping Wetlands and Peat Resources Using Digital Cartography
Authors: Cameron CC , Emery DA
Published: March 2009

Digital cartography allows the portrayal of spatial associations among diverse data types and is ideally suited for land use and resource analysis. We have developed methodology that uses digital cartography for the classification of wetlands and their associated peat resources and applied it to a 1:24 000 scale map area in New Hampshire.

Classifying and mapping wetlands involves integrating the spatial distribution of wetlands types with depth variations in associated peat quality and character. A hierarchically structured classification that integrates the spatial distribution of variations in (1) vegetation, (2) soil type, (3) hydrology, (4) geologic aspects, and (5) peat characteristics has been developed and can be used to build digital cartographic files for resource and land use analysis. The first three parameters are the bases used by the National Wetlands Inventory to classify wetlands and deepwater habitats of the United States. The fourth parameter, geological aspects, includes slope, relief, depth of wetland (from surface to underlying rock or substrate), wetland stratigraphy, and the type and structure of solid and unconsolidated rock surrounding and underlying the wetland. The fifth parameter, peat characteristics, includes the subsurface variation in ash, acidity, moisture, heating value (Btu), sulfur content, and other chemical properties as shown in specimens obtained from core holes. These parameters can be shown as a series of map data overlays with tables that can be integrated for resource or land use analysis.
Using a Geographic Information System to Manage Data from a Ground-Water Remediation Program
Authors: Hammock JK , Lorenz R
Published: March 2009

As the attention to environmental issues has grown over the past several years, so has the focus on ground-water protection. Addressing the task of ground-water remediation often involves a large-scale program with numerous wells and enormous amounts of analytical data. These data must be manipulated and analyzed in an efficient manner for the remediation program to be truly effective. Geographic information systems (GIS) have proven to be an extremely effective tool in handling and interpreting ground-water data. The purpose of this paper is to introduce the audience to the Savannah River Site (SRS), describe how GIS technology is being utilized in the ground-water remediation program, and discuss future plans for GIS at SRS.
Geographic Information System (GIS) Application During a Feasibility Study for a Ground-Water Model
Authors: Stibitz M , Hoebenreich L
Published: March 2009

A feasibility study has been completed with the aim to evaluate the possibility of application of a ground-water simulation model for regional hydrogeological investigation in the southern Vienna basin in Lower Austria. The specific hydrogeological structure targeted is the graben called the Mitterndorfer Senke.

Mitterndorfer Senke is an elongate northeast-southwest trending quaternary-tertiary inter montaine basin of 50 km length and width varying between 2 to 10 km with a depth of quaternary deposits of 20 to 150 m. According to previous geohydrological studies, the quaternary aquifer which is composed mainly of gravels and sands is assumed to be isolated from the tertiary marls, clays, and fine sands although ascendant ground-water leakage from tertiary as well as horizontal ground-water communication will have to be checked. A ground-water modeling study is being prepared to: (1) simulate ground-water flow to evaluate influence of pumping from various wells on aquifer exploitation; and (2) simulate solute transport to evaluate ground-water polychlorinated biphenyl (PCB) contamination caused by various industrial facilities and waste disposal sites in the area.

The geographic information system (GIS) has been applied to represent and compare data transferred from databases of various institutions as well as collected during the extensive literature search. Information and data distribution of the following basic thematic groups have been evaluated and visualized: topography; geology, stratigraphy, and tectonics; hydrogeology; and surface hydrology.

GIS has been used not only for data visualization but also for comparison of compiled data from various sources and volumetric computations.

Currently, an interface between GIS and a complex three-dimensional finite-element ground water model is being developed. In the following stages of the Mitterndorfer Senke study, GIS will continue to serve as a useful tool for data pre- and post-processing.
Accuracy and Precision of Well Casing Surveys and Water-Level Measurements and Their Impact on Water-Level Contour Maps
Authors: Schalla R , Lewis AK , Bates DJ
Published: March 2009

Relatively stringent accuracy and precision requirements for well casing surveys and associated water-level measurements are generally difficult to achieve. Field experience and research indicate that the achieved accuracy is commonly less than expected. Realistic accuracy expectations require that the investigator know what is achievable for a site and how to convey the proper information to the surveyor. The point-difference accuracy of vertical surveys is calculated, based on the measured inaccuracy of the vertical survey divided by the square root of the length of the survey, and therefore by the size of the study area and number of wells surveyed. The accuracy of water-level measurements and contour maps is determined primarily by the equipment and procedures used for measuring the depth to water in the well casings. When setting accuracy requirements for water-level measurements and contour maps, the investigator must consider the end use of the data. Composite error from the two primary sources of error determines how much precision and accuracy are reasonably achievable.
Selection of Aggregate Properties to Minimize Rutting of Heavy Duty Pavements
Authors: Cross SA , Brown ER
Published: March 2009

Samples of pavements from 14 states across the United States were obtained to evaluate the aggregate properties that affect rutting. Twelve pavements had provided excellent service for five or more years and 30 pavements had experienced premature rutting in less than five years of service. The aggregates from cores obtained at 0.3 meter (1 foot) intervals across each pavement were tested for gradation and maximum aggregate size, fractured face count, and the National Aggregate Association Flow Test. The cores were also tested for in-place void content and asphalt cement content. The remaining cores were reheated and recompacted using the Gyratory Testing Machine (GTM).

The data show that aggregate properties have little effect on rutting when the voids are low. When the voids are above 2.5%, mixes with higher fractured face counts and more angular fine aggregate are more resistant to premature rutting.
Evaluation of Percent Fracture of Hot Mix Asphalt Gravels in Indiana
Authors: Sanders CA , Dukatz EL
Published: March 2009

The Indiana Department of Transportation prompted by major concerns in 1987 over permanent deformation (rutting) decided to increase the level of one face fractured gravel coarse aggregate particles in asphalt mixtures. Previous levels of 40% for base course, 55% for binder course and 70% for surface were essentially increased to 95% for all mixtures used in higher traffic volume work. This paper subsequently addresses two questions: 1. Is it always necessary to increase gravel fracture percentage to offset rutting and if so, what level is appropriate? 2. Since both stone and gravel asphalt pavements in Indiana have experienced rutting, what other mixture properties and/or construction techniques influence rutting potential?
Effects of Minus No. 200-Sized Aggregate on Fracture Behavior of Dense-Graded Hot-Mix Asphalt
Authors: Anderson DA , Dongre R , Christensen DW , Dukatz EL
Published: March 2009

The effect of minus No. 200-sized material (mineral filler) on the fundamental mechanical properties of hot-mix asphalt is not well understood. In the work reported in this paper a series of minus No. 200 (75 μm) mineral fillers were used to prepare and characterize filler-asphalt mastics and hot-mix asphalt concrete. The mineral fillers were blends of dust of fracture and baghouse dust was sampled from seven sources. The gradation and the void-filling characteristics of the mineral fillers were determined. Mastics prepared with the fillers were characterized with viscosity measurements at 60°C (140°F) and dynamic mechanical properties, storage modulus, loss modulus, and tan delta, over a wide temperature range. Mixtures containing the mineral fillers were prepared using several different filler-asphalt ratios. Originally, the behavior of the mixes was to be evaluated with a fatigue test in which a test beam is supported on an elastic (lowmodulus rubber) foundation. This test method proved unacceptable because the failures that occurred were in shear rather than bending fatigue. As an alternative, the single-edge-notched-beam (SENB) fracture toughness test was used. With this procedure it was possible to determine the fracture toughness of the mixes as a function of temperature. The source of the mineral filler, as reflected by the properties of the mineral filler-asphalt mastics, was correlated with the fracture toughness properties of the mixes.
Effect of Quality and Quantity of Locally Produced Filler (Passing Sieve No. 200) on Asphaltic Mixtures in Dubai
Authors: Shahrour MA , Saloukeh BG
Published: March 2009

Failures commonly observed in the Emirate of Dubai roads are rutting and cracking. The objective of this study is to evaluate the influence of different fillers extracted from the different local aggregate sources on the performance of asphaltic mixtures. In addition, cement, hydrated lime, and a sodium silicate based filler (Bagrat KS-300) were also considered in the study.

A total of ten types of fillers were tested in the laboratory for grading, particle shape, surface texture, voids when compacted, absorption and specific gravity.

The quality of each type of filler was studied by adding different fillers to bitumen at two filler to bitumen ratios ( 0.5 and 1.5 by weight) where characteristics of the bitumen cement properties (penetration, softening point, kinematic viscosity at 135 degrees Celsius, and penetration index “P.I.”) were studied.

A Marshall mix design study was made using all types of fillers and different ratios to evaluate the performance of different types and filler quantities in the asphalt mixture.
Providing Sufficient Void Space for Asphalt Cement: Relationship of Mineral Aggregate Voids and Aggregate Gradation
Authors: Huber GA , Shuler TS
Published: March 2009

Since the 1960's, the Asphalt Institute has recommended voids in the mineral aggregate (VMA) to control minimum asphalt content in asphalt aggregate mixtures. VMA criteria are based on aggregate nominal maximum sieve size. Use of VMA criteria requires a clear understanding of the relationship of VMA to aggregate gradation. Nominal maximum size and maximum density lines must also be understood.

In the asphalt industry today, significant confusion exists concerning different methods used to draw “maximum” density lines. A need exists to determine which method represents the maximum packing of aggregate materials. Maximum density lines are required to modify gradations and change VMA. Closely related to maximum density lines is the definition of aggregate nominal maximum size which also requires clear definition.

This paper reports the relationship of VMA to aggregate gradation and particle characteristics for a controlled experiment. Using results from this experiment plus three other databases of mix designs, different methods of drawing maximum density lines are evaluated. A definition of nominal maximum sieve size which is more specific than the current ASTM definition is proposed.
Effect of Aggregate on Asphalt Mixture Cracking Using Time-Dependent Fracture Mechanics Approach
Authors: Abdulshafi O
Published: March 2009

Fatigue failure can be attributed to cyclic (dynamic) loading energy which induces stresses and/or strains below the allowable strength and/or fracture strain level of a material. Since fatigue failures evolve over time, damage theories have been postulated to describe the mechanism by which this failure occurs. When a crack exists or forms early in the life of a pavement, fracture mechanics becomes the most relevant theory to explain the damage process. If conditions prevail to promote brittle fracture, the stress intensity factor and its critical value, Kc (or Gc) , becomes the most relevant parameter controlling the cracking and fatigue damage process. If conditions prevail to promote ductile fracture, the ductile fracture parameter, Jc, becomes the parameter for consideration. If conditions prevail to promote creep fracture, the C* - Line Integral offers the most relevant fracture criteria. Since the definition of Jc or C* in fracture mechanics imposes the condition that either parameter will degenerate into Kc (or Gc) when brittle fracture conditions, prevail, the utilization of Jc or C* provides the user with a powerful tool to characterize the fatigue/fracture process in a more general form. Since asphaltic mixtures can exhibit brittle and/or creep fracture, it is apparent that the C* - Line Integral can more closely capture the fatigue/fracture damage process than Kc or Jc. In this paper, a simple laboratory procedure to determine the C* - Integral, which is interpreted as the energy release rate, is presented. In addition, a mixture efficiency factor (`η*) is introduced. The mixture efficiency factor is used to examine and compare the efficiency of asphaltic concrete mixture in resisting fracture cracking using different aggregates and asphalt cement binders.
A New Approach for Prediction of Permanent Deformation
Authors: Perdomo D , Button JW , Lytton RL
Published: March 2009

A laboratory investigation was performed in which the influence on resistance to plastic deformation as demonstrated when rounded, smooth, sand-sized aggregate particles were replaced by rough, angular, porous particles while other aggregates and the total gradation remain the unchanged. Five asphalt concrete mixtures with varying amounts of these aggregates were tested. Resulting data were used to (1) evaluate the ability of certain test procedures to differentiate rutting potential of the mixtures, (2) develop a new rutting model for predicting pavement performance which incorporates aggregate characteristics, (3) examine fractal dimension analysis as a method of quantifying aggregate angularity and surface texture, and (4) demonstrate that octahedral shear stress theory can properly differentiate the rutting potential of asphalt concrete mixes.
The Impact of Curing Conditions on the Appearance of Sealant Before and After Artificial Weathering
Authors: Myers JC , Nelson PE
Published: March 2009

This paper presents our preliminary laboratory research to determine the effects of various moisture and temperature conditions during cure, and joint extension after cure, on the internal and external appearance of a two-part polyurethane sealant before and after artificial weathering. We examined the impact of these conditions on the development of voids within the sealant, softening or tackiness on the sealant, and crazing and splitting at the sealant surface. Improper mixing created most of the large internal voids. Application of sealant on a damp substrate produced foaming in the sealant at the bond surface. Contact with water during cure softened the sealant surface, but not the entire thickness of the sealant. Artificial weathering caused surface crazing, but combining artificial weathering and constant extension produced deep cracks and splits through the sealant, with the depth of cracking increasing with greater extension. We performed additional testing on other sealants, including some that are not two-part polyurethane, by artificially weathering them at a constant extension. The crazing and splitting with these other sealants varied with the particular brand of sealant from no crazing to through-splits.
The Effect of Movement During Cure on Sealant Strength Development
Authors: Margeson J
Published: March 2009

The effect of sealant movement on early strength development was investigated. Some specimens were subjected to intermittent cycles of compression and extension while curing, some were cured in a fixed position and then cycled, and others were continuously cycled while curing. The stresses at ±5 and ±10% deformation were used to monitor changes in sealant behavior. Movement rates of 0.5 and 0.05 mm/min were examined.

The strength development curves suggest that the sealant was essentially fully cured after seven to ten days. Intermittent movement during cure did not alter the final properties of the cured sealant, but continuously cycled specimens exhibited significantly lower modulus compared to specimens that were cured in a fixed position. The results were not influenced by the rate of movement. The claimed movement capability for the fully cured sealant used in this research is ±50%, but it was demonstrated that the sealant can accommodate no more than 10 to 15% deformation in its partially cured state.
Polysulfide Sealants in Water-Retaining Structures
Authors: Lee T , Rees T , Wilford A
Published: March 2009

The current methods for determining the suitability of sealants for use in water environments are discussed. In particular the paper outlines the factors governing the durability of polysulfide sealants to long-term water immersion in building and civil engineering applications. Particular reference is made to the sealant formulation and the guidelines that should be followed to ensure longevity of adhesion in water-retaining structures and bioresistance in sewage plants. Parameters such as polymer content, curative type, and the nature and level of other compounding ingredients as they relate to long-term performance in water are examined. The role of primers is considered.

The nature of the biodeterioration of sealants is discussed, and an accelerated test for determining the performance of polysulfide sealants in bacteria-rich environments and how it correlates to field tests is described. The results of a ten-year trial at a sewage treatment plant are given.

International regulations for the use of nonmetallic materials in potable water and their significance to the sealant industry are reviewed.
Sealants for Construction Joints Subjected to Continuous Water Immersion
Authors: Randazzo S
Published: March 2009

Polysulfide polymers and urethane elastomers have been used for a long time to seal a variety of construction joints. These materials perform well when selected for the proper applications. The sealing of potable water reservoirs requires products with stringent requirements that are difficult to attain when formulating either with conventional polysulfide or polyurethane polymers. Excellent hydrolytic stability, resistance to cold flow, retention of elasticity, and adhesion are a few of the desired properties of these products. New polymers which possess the good properties of the polysulfide and polyurethane polymers within the same polymer structure have been developed. These polymers are known as mercaptan-terminated polyoxypropylene materials.

These polymers can be formulated into potable water reservior sealants without the use of heavy metals or toxic substances. Results on adhesion to concrete, physical properties, hydrolytic stability, and performance after long immersion of these sealants in water are presented. The chemistry and curing mechanism of these polymers are discussed, illustrating how these new sealants provide a new dimension in the potable water reservoir sealant industry.
Design, Fabrication, and Performance Considerations for Insulating Glass Edge Seals
Authors: Spetz JL
Published: March 2009

Of critical importance to the successful performance of an insulating glass unit is the quality and continuing integrity of its edge seal. There are numerous factors to be considered relative to achieving a durable and satisfactory performing product. This paper describes the present state of the art relative to the design, basic components, fabrication, performance criteria, and standards available for insulating glass, with particular emphasis on the edge seal.
A Load-Displacement Model for Structural Glazing Joints in Tension and Shear
Authors: Sandberg LB , Tan IP
Published: March 2009

An empirically based load-displacement model for typical silicone structural glazing joints is presented. The model is capable of simulating behavior under combined tensile and transverse shear loadings up to failure. Load and displacement are related by exponential equations of the form, F = A(1 - exp{-BΔ}). In this equation, F is the applied force (either tensile or shear). A and B are functions of tensile and shear displacements. The pairs of functions for tensile force and shear force are different. Δ is the resultant of tensile and shear displacements. The forms and constants for the functions A and B were obtained by regression analyses of test data at six different combinations of tensile and shear displacement, from pure tension to pure shear. An exponential equation with constants for A and B was fit to the data for each displacement combination. The constants were plotted versus a measure of relative tensile and shear displacements. Curves fit to these plots define the approximate expressions for A and B under any set of tensile and shear displacements below the failure limit. Comparisons of the model with the experimental data are shown. A simplified approach to obtaining the load-displacement model is also proposed and compared to experimental data. The application of the model to analysis of joint behavior in structural glazing systems is briefly discussed.
Stress Redistribution in Structural Glazing Joints
Authors: Sandberg LB , Chang K , DeClercq MA
Published: March 2009

This paper examines the behavior of structural sealant glazing joints loaded to failure. Experimental data are presented from a beam analog for a structural sealant glazed window edge. Analytical results are given for a typical structural sealant glazed unit. The characteristic, service load level, “double-hump” stress and elongation pattern along the glass edge was simulated by a tee-beam specimen with the stem and flange joined by a silicone bead. Point loads were used to produce a double-hump elongation pattern. The results clearly showed the ability of a structural sealant joint to redistribute stresses along its length when loaded to failure. A finite element analysis was made of stress redistribution along the edges of a structural sealant glazed unit under negative wind overloading, approximating a failure condition in the sealant joint. The model included a full stress range, combined tension and shear model for the joints and geometric nonlinearity in the glass. Transverse shear deformations of the joint, due to geometric nonlinearity, were found to have a significant effect on the tensile response of the joint. As a result, the extensive redistribution of tensile stresses seen in the tee-beam specimen did not develop. Instead, only a partial spreading of the double-hump pattern was seen. The implications of the research results are discussed.
Thermal Movement Analyses for Panelized Polymer-Based Exterior Insulation and Finish System (PB EIFS) Claddings
Authors: Williams MF , Williams BL
Published: March 2009

Based on case study material, two different analyses of thermal movement on a panelized polymer-based exterior insulation and finish system (PB EIFS) cladding are presented. The first analysis employs mathematical calculations. The second analysis involves linear thermal expansion measurements obtained by laboratory procedure. The data derived from each analysis are used to determine minimum joint width. Recommendations for sealant joint design on panelized PB EIFS are provided.
Analysis of Field-Fabricated Building Deck Waterproofing Systems and Renovation Design Considerations—Case Studies
Authors: Peterson RH , Dias AF
Published: March 2009

This paper reviews the construction and failure modes of two field-fabricated, traffic-bearing plaza deck waterproofing systems over various substrates. The study involved field review of the two installations, analysis of the inherent shortcomings and defects in each, and the replacement systems design process. Observed defects and component deterioration for each installation are analyzed and separated into the categories of design deficiency, material performance, improper installation or workmanship, and lack of or improper maintenance.

Available data from original construction plans and specifications as well as that obtained during field investigations and sampling during system demolition is presented.
Thermomechanical Deformation Behavior of a Dynamic Strain Aging Alloy, Hastelloy X™
Authors: Castelli MG , Miner RV , Robinson DN
Published: March 2009

An experimental study was performed to identify the effects of dynamic strain aging (solute drag) and metallurgical instabilities under thermomechanical loading conditions. The study involved a series of closely controlled thermomechanical deformation (TMD) tests on the solid-solution-strengthened nickel-base superalloy, Hastelloy X.™4 This alloy exhibits a strong isothermal strain aging peak at approximately 600°C promoted by the combined effects of solute drag and precipitation hardening. Macroscopic thermomechanical hardening trends are correlated with microstructural characteristics through the use of transmission electron microscopy. These observations are also compared and contrasted with isothermal conditions. Thermomechanical behavior unique to the isothermal database is identified and discussed. The microstructural characteristics were shown to be dominated by effects associated with the highest temperature of the thermomechanical cycle. Results clearly reveal that the deformation behavior of Hastelloy X is thermomechanically path dependent. In addition, guidance is given pertaining to deformation modeling in the context of a macroscopic unified thermoviscoplastic constitutive theory. An internal state variable is formulated to qualitatively reflect the isotropic hardening trends identified in the TMD experiments.
Damage Mechanisms in Bithermal and Thermomechanical Fatigue of Haynes 188
Authors: Kalluri S , Halford GR
Published: March 2009

Post failure fractographic and metallographic studies were conducted on Haynes 188 specimens fatigued under bithermal and thermomechanical loading conditions between 316 and 760°C. Bithermal fatigue specimens examined included those tested under high strain rate in-phase and out-of-phase, tensile creep in-phase, and compressive creep out-of-phase loading conditions. Specimens tested under in-phase and out-of-phase thermomechanical fatigue were also examined. The nature of the failure mode (transgranular versus intergranular), the topography of the fracture surface, and the roles of oxidation and metallurgical changes were investigated for each type of bithermal and thermomechanical fatigue test.
Cumulative Damage Concepts in Thermomechanical Fatigue
Authors: McGaw MA
Published: March 2009

A recently developed cumulative creep-fatigue damage model is applied to the prediction of thermomechanical and isothermal cumulative creep-fatigue loading histories. The model utilizes damage curve expressions to describe cumulative damage evolution under creep-fatigue conditions, qualitatively grouped according to dominant damage mechanism or mode. The damage coupling concept of McGaw is employed to describe the cumulative interaction among different mechanisms and modes. In this study, experiments consisting of two-level loadings of thermomechanical fatigue (both in-phase and out-of-phase) followed by isothermal fatigue to failure, were conducted on 316 stainless steel. It was found that the model gave good predictions for the out-of-phase two-level tests and provided reasonable bounds for the in-phase two-level tests.
Improved Techniques for Thermomechanical Testing in Support of Deformation Modeling
Authors: Castelli MG , Ellis JR
Published: March 2009

The feasibility of generating precise thermomechanical deformation data to support constitutive model development was investigated. Here, the requirement is for experimental data that is free from anomalies caused by less than ideal equipment and procedures. A series of exploratory tests conducted on Hastelloy X showed that generally accepted techniques for strain controlled tests were lacking in at least three areas. Specifically, problems were encountered with specimen stability, thermal strain compensation and temperature/mechanical strain phasing. The present study was undertaken to identify the source of these difficulties and to develop improved thermomechanical testing techniques to correct them. These goals were achieved by developing improved procedures for measuring and controlling thermal gradients and by designing a specimen specifically for thermomechanical testing. In addition, innovative control strategies were developed to correctly proportion and phase the thermal and mechanical components of strain. Subsequently, the improved techniques were used to generate definitive deformation data for Hastelloy X over the temperature range, 200 to 1000°C.
Prediction of Thermal-Mechanical Fatigue Life for Gas Turbine Blades in Electric Power Generation
Authors: Bernstein HL , Grant TS , McClung RC , Allen JM
Published: March 2009

Thermal-mechanical fatigue (TMF) cracking is the primary mode of mechanical failure of first stage blades in gas turbines used for electric power generation. Because of the high replacement costs of these superalloy components, it is important that accurate predictions of TMF life be made so that blades can be reconditioned before cracks initiate and propagate beyond repair limits. This paper describes the development of a TMF life prediction methodology for first stage blades, which is part of a Life Management System developed by the Electric Power Research Institute (EPRI).

The TMF life model is based on laboratory TMF tests of the superalloy IN-738LC in both the coated and uncoated conditions. Results for TMF crack initiation life are presented and modeled. The life model is based upon the strain range, the dwell time, and the strain A-ratio. The dwell time term accounts for the time dependence of the fatigue life due to environmental attack and creep. The strain ratio term helps account for the effect of mean stress in the cycle. The ability of the life model to predict the fatigue lives of the current test data and the fatigue lives of IN-738 test samples for various test conditions reported in the literature is presented. The effect of coatings and environment upon the TMF life is also discussed.

The strain-temperature response of the blade was obtained from the manufacturer. The life prediction methodology is presented and applied to the prediction of TMF life of blades from a number of engines. Miner's rule is used to sum cumulative damage from the different engine cycles that occur. Good agreement is obtained between the service experience and the life predictions.