bluuebunny/crossref_metadata_2025_split huggingface dataset:
Air Intrusion Effects on the Performance of Permeable Insulation Systems
Authors: Berlad AL , Tutu N , Yeh Y-J , Jaung R , Krajewski R , Hoppe R , Salzano FJ 
Published: March 2009

The R-values of permeable insulation systems are generally determined in test apparatuses designed to assure one-dimensional heat transfer and to assure no air intrusion effects. Such classical R-values are then calculationally employed to help describe in situ heat-transfer rates through insulation systems.
The research reported herein reexamines the applicability of these classical R-values to commonly encountered insulation systems where air intrusion is physically possible. Several kinds of findings are reported: (a) Laboratory-determined R-values for several types and thicknesses of permeable insulators, under conditions of no externally imposed flows. (b) Laboratory-determined heat-transfer rates for several permeable insulators under conditions of externally imposed flows (air intrusion). (c) Theoretically calculated heat-transfer rates for permeable insulation systems which sustain infiltrative-exfiltrative air intrusion effects.
The results obtained show that the thermal insulation provided by a permeable insulation system may differ substantially from that which is predicted by simple application of classical R-values.
Effects of Extreme Aircraft Storage and Flight Environments on Graphite/Epoxy
Authors: Shyprykevich P , Wolter W 
Published: March 2009

The ability of graphite/epoxy composites to absorb moisture from the environment and the consequent degradation of resin-dependent strength properties is well understood under conditions of constant temperature and humidity. However, if the environment consists of high humidity exposure with intermittent high temperature excursions, anomalous diffusion behavior occurs accompanied by further reductions in strength. This paper reports the results obtained from a test program in which graphite/epoxy specimens were exposed to a tropical environment representative of extreme aircraft runway storage and frequent 127°C temperature excursions of long duration representative of supersonic flights.
The tests were conducted in a specially developed apparatus which held specimens in chains of five each with accompanying travelers while exposing the specimens to prescribed daily environmental conditions. The duration of the real-time simulation test was 15 months. After various intervals of exposure, weight data were gathered using accompanying travelers, and residual static tests were performed at room temperature and 127°C. The test results for the extreme environment are compared to test results obtained for specimens exposed to the same flight profile, but temperate runway storage. The results indicate that the moisture gains of the extreme environment specimens are much greater than what is thought possible to be held by the resin. Since the static compressive strength is reduced with increases in moisture content, the degradation in compressive strength is greater than what was expected.
A semiempirical transport model based on Fickian diffusion and hygrothermal history dependent material properties was developed to account for changes in absorptivity characteristics as a function of glass transition temperature (Tg) exceedances. The test data for model development were obtained from an accelerated environment test which attempted to find economic alternatives to real-time exposure tests. The moisture predictions with the new model gave reasonable correlation with real-time test observations.
Static and Fatigue Strength of Glass Chopped Strand Mat/Polyester Resin Laminates
Authors: Owen MJ 
Published: March 2009

Chopped strand mat/polyester resin laminates are regarded as plane isotropic. However, under load the aligned fibers provide reinforcement, whereas the transverse fibers initiate progressive damage by filament debonding and resin cracking. This transverse damage rapidly involves the aligned fibers, particularly under repeated loading. Static and fatigue strength data have been developed for recognizable states of damage as well as final separation of the specimens. The effect of mean load on stress amplitude has been studied, together with cumulative damage and the effect of stress concentrators. Failure theories for biaxial stress conditions have been examined using thin-walled tubes. The biaxial tensile condition is particularly damaging.
There appear to be three main difficulties in applying conventional data to design. The S-N curves appear to be straight lines and there is difficulty in extrapolating to long lives; there is a marked adverse size effect on strength; and designing to avoid incipient damage at stress concentrators gives very uncompetitive designs. Fracture toughness and macroscopic crack growth studies appear to offer an alternative approach to the prediction of strength.
Corrosion of Structural Steels in High-Salinity Geothermal Brine
Authors: Lee WT , Kramer D 
Published: March 2009

In support of geothermal power plant development, Rockwell International's Energy Systems Group (ESG) has conducted extensive studies and tests on the behavior of materials in geothermal environments. The materials tested include both metallic and nonmetallic materials. This paper presents Rockwell's recent stress corrosion test data on structural steels and their weldments under uniaxial loading (stress, 80 percent of yield strength) in static Sinclair 4 geothermal brine at 204°C for 1700 h (10 weeks). The alloys tested were 26Cr-1Mo, 18Cr-2Mo, 9Cr-1Mo, and Type 316 stainless steel and their weldments. Under these test conditions, the following results were obtained: 1. In testing without air contamination: (a) Alloys 26Cr-1Mo, 18Cr-2Mo, and 9Cr-1Mo and their weldments were resistant to stress corrosion cracking; and (b) the average corrosion rates for the welded specimens made of 26Cr-1Mo, 18Cr-2Mo, and 9Cr-1Mo were 7.7 μm/year, 7.4 μm/year, and 18.2 μm/year, respectively. 2. In testing with air contamination: (a) the 18Cr-2Mo and 9Cr-1Mo ferritic steels were found to be resistant to stress corrosion cracking in air-contaminated brine; (b) Alloy 26Cr-1Mo and Type 316 stainless steel exhibited cracking typical of stress corrosion; and (c) the average corrosion rates were much higher than those obtained for the alloys without air contamination.
Results of the posttest mechanical properties testing and metallographic analysis are also presented.
Grout for Reinforced Masonry
Authors: Isberner AW 
Published: March 2009

Grout for reinforced masonry is reviewed through national product specifications and national masonry standards and codes. The role of grout and the factors affecting grout performance lead into a review of ASTM Specification for Mortar and Grout for Reinforced Masonry (C 476-71). A critical review of the specification shows that provisions for grout design, materials, and testing are deficient or nonexistent.
Past and present research on grout for reinforced masonry was reviewed and found deficient. Early research allowed measuring the bond of grout to reinforcing steel. Material changes warrant further testing. Recent grouted masonry testing shows grout compressive strength per se is a poor indicator of the interaction of grout in masonry. Research areas deemed essential include grout mix design, grout placement, and grout physical properties of equal or greater significance than compressive strength.
Low-Cycle Fatigue under Biaxial Strain
Authors: Moguerou A , Vassal R , Vessiere G , Bahuaud J 
Published: March 2009

The present work aims to obtain some information about the crack initiation criterion under biaxial low-cycle fatigue strain in phase or 180 deg out of phase. The investigation was carried out on A 316 stainless steel.
A servohydraulic experimental rig was developed for application of biaxial high-strain reversed cycles. The strains were controlled and the axes of principal strain were fixed during these tests. The test specimens are thin-walled tube on which we apply axial tension-compression and internal-external pressure difference by using two hydraulic servosystems. The results obtained for three different strain ratios are plotted as a function of half of the equivalent Tresca strain.
The Tresca criterion has been shown to be nonconservative for cases where the axes of principal strain rotate continuously, but in our tests we observe that torsion is less damaging than plane strain, which is less severe than tension. In other words the Tresca criterion is conservative, which is in agreement with the ASME code.
Finally, the fatigue crack growth is studied by a scanning electron microscope, and a propagation law is proposed.
Fatigue Life Evaluation of the A-7E Arresting Gear Hook Shank
Authors: White DJ , Ellis JR , Dumesnil CE , Gray TD 
Published: March 2009

This paper describes a program conducted to develop criteria, based on test results, to safely extend the service life of the A-7E arresting gear hook shank. Fracture mechanics techniques provided a method for assessing the significance of proof testing and correlating proof loads with remaining life under operating loads. Additional tests were performed to validate the proof-test criteria.
The proof load developed in this program defined the maximum possible flaw size that could exist in the structure and provided data for establishing remaining life under operating loads. In addition, local yielding resulted in residual stresses that maximized crack growth retardation. As a result, an increase in fatigue life was produced by periodically inserting the proof load into the operating load spectrum. The primary impact of this program was to demonstrate that the proof test interval for the hook shank could be extended from 100 to 550 arrested landing cycles, and that the total service life could be extended from 500 to an indeterminate number of arrestments.
Materials-Data Needs for Fatigue Design of Pressure Vessel Systems
Authors: Jaske CE 
Published: March 2009

Materials data are essential to the proper formulation of fatigue-design guidelines for pressure-vessel systems. These data are needed for two main reasons: (1) to develop and evaluate prediction methods used in fatigue-damage analysis and (2) to quantify the fatigue behavior of various alloys from which pressure vessels are fabricated. The former reason involves verification of models of the fatigue-damage process and must include both deformation and life prediction as well as demonstrating that the reference damage basis and damage rules are relevant to actual hardware. The latter reason relates to the establishment of an adequate data base and must incorporate material variability, environmental effects, and temperature effects.
In the above context, this paper addresses the data needs within the framework of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Low-temperature (negligible creep) and high-temperature (significant creep) regimes and crack-initiation and crack-propagation damage criteria are addressed. The background for existing fatigue-design guidelines of the ASME Code is briefly reviewed. Areas where fatigue-damage criteria need to be improved are creep/fatigue/environmental interaction at low strain ranges and long times, thermal-mechanical fatigue, multiaxial fatigue, and long-life fatigue. Existing guidelines for crack initiation are based mainly on strain cycling of uniaxially loaded specimens. There are some crack-initiation data on notch effects at low temperature, but more information is needed for high temperatures and welded components. Additionally, crack-initiation data are needed for multiaxial conditions, especially nonproportional loading, for thermal-mechanical cycling, and for high-cycle fatigue. To apply fatigue crack growth methodology, data on the size, shape, and distribution of initial flaws, methods of dealing with small cracks, and techniques for treating cracks in inelastic strain fields are required. With these requirements in mind, guidelines for the development of fatigue data are discussed, and recommended guidelines for data development are outlined.
Advantages and Disadvantages of Using Invertebrates in Toxicity Testing
Authors: Maciorowski HD , Clarke RMV 
Published: March 2009

Aquatic invertebrates should be included in toxicity tests to assess the hazards of toxicants because of their ecological and economic importance and their morphological, physiological, and ecological diversity. The practical advantages to the use of aquatic invertebrates in toxicity tests are the small size and short life cycles of most species, and the fact that it is possible to produce genetically uniform cultures of certain species and to standardize stocks of other species. Considerations in designing toxicity tests with aquatic invertebrates include the lack of culture methods for many species, the variation in sensitivity of aquatic invertebrates throughout the life cycle and with previous exposure to toxicants, and the difficulty in ascertaining death.
Most laboratory toxicity tests are measures of acute lethality obtained under controlled and constant conditions; the data are available for relatively few species and usually have been obtained using single species. Since such data do not reflect environmental conditions and the complexity of aquatic ecosystems, they are often of limited use in predicting effects of toxicants on aquatic ecosystems or on aquatic organisms valued by man. The utility of laboratory toxicity tests can be increased by the use of protocols that emphasize the most sensitive procedures, such as life-cycle studies or tests with model ecosystems, and such tests should include several aquatic invertebrates from different levels in the food chain, exhibiting different responses to toxicants, plus other aquatic organisms. Laboratory test conditions should reflect, as far as possible, the test organism's ecological requirements and should not constrain the test organism's natural behavior. Additional studies also are required to describe the effect of toxicants on natural aquatic ecosystems to ensure that toxicity tests do predict the actual effects of toxicants on aquatic ecosystems.
Formulating Acceptable Levels of Fire Risk
Authors: Cohn BM 
Published: March 2009

Building codes and standards traditionally have set levels of performance based on the experienced judgment of the code writer. Occasionally, a certain level of safety is envisioned, but the objective tends to be expressed in imprecise terms, such as the “minimum” or “reasonable” level of safety. There is a need to set goals for fire safety in terms which can be measured so that they can be specified in building codes and standards. With such quantification, systematic fire safety analyses will be more meaningful.
A probabilistic approach can be used to set fire safety goals. Sufficient statistics are available today to set realistic goals, and the state of the art in fire safety systems analysis is sufficiently advanced to develop the methodology needed to calculate the failure probabilities for specific events. Such a methodology is described. It assigns probabilities to events associated with fire development in a building and allows these probabilities for a specific set of conditions to be related to the risk being evaluated (loss of life, property damage, business interruption, and so on). Statistics of industry experience help to relate the relative safety levels to the actual loss forecasts. Similar statistical analysis can be used to establish goals for fire safety in building codes, regulations, and standards.
Sampling and Chemical Characterization of Concentrated Smokes
Authors: Jenkins RA , Gayle TM , Wike JS , Manning DL 
Published: March 2009

Because of rapid change in both their chemical and physical properties, concentrated (0.5 to 100 g/m3) aerosols, such as a diesel fuel-based military obscurant and tobacco smoke, represent a unique challenge to the analytical chemist. Sampling procedures must minize the alteration of phase concentrations of particular constituents. For example, collection of tobacco smoke particulate matter on glass fiber filters is limited to linear velocities of ∼100 cm/min to prevent evaporation of nicotine. Trapping of reactive constituents must be performed rapidly so as to prevent loss through side reactions with other smoke constituents.
Chemical characterization studies are directed at comparing laboratory generated test aerosols with those existing under field or “real world” conditions. For the diesel fuel aerosol, a tiered analytical scheme, high-performance liquid chromatographic (HPLC) fractionation followed by high resolution gas chromatography, has proved useful for the determination of major constituents. Limited comparisons have suggested that observed differences result from differences in fuel composition and sampling conditions, rather than generation procedures. For tobacco smoke, comparisons are made between the composition of smokes generated under standard conditions by smoking machines and that of smokes to which animals are actually exposed. In some cases, exposure smokes have been found to be depleted in particulate matter, relative to the vapor phase. However, gross changes in the composition of the particulate matter do not occur.
On-line instrumental monitoring of smoke concentrations provides an important adjunct to chemical measurements. An optical particle monitor measures back-scattered infrared radiation as being proportional to smoke concentration. Systems employing the particle sensor are being used now to quantitatively determine particle concentrations in tobacco smoke and diesel fuel aerosol inhalation toxicology studies.
Respiratory Activity of Fish as a Predictor of Chronic Fish Toxicity Values for Surfactants
Authors: Maki AW 
Published: March 2009

A system was developed to monitor the ventilation frequency of bluegills (Lepomis macrochirus) under continuous-flow exposure to test compounds. The nerve-action potential associated with the opening and closing of the buccal cavity, branchial arches, and operculum was simultaneously monitored for 16 fish, four each from three exposure concentrations and four controls.
The system was used to determine the effects of several representative surfactants on the diurnal respiratory activity of the test fish. The test compounds were selected on the basis of previously existing full-life-cycle chronic fish data with which to compare the respiratory data. Good correlations are demonstrated between the chronic maximum acceptable toxicant concentration for fathead minnows and the concentrations of surfactants that elicit statistically significant changes in the diurnal ventilation frequencies of exposed bluegills. A simplified statistical procedure, employing the log 10 of observed rates, was developed, allowing determination of the changes in rates over the entire day and night exposure periods. It appears that the monitoring of aberrant respiratory activity in bluegills for a two-day period has potential predictive value as a scanning tool for a rapid prediction of chronic fish toxicity values.
Behavior of Inorganic Materials in Fire
Authors: Abrams MS 
Published: March 2009

Behavior of inorganic materials exposed to fire depends upon the time-temperature relationship during exposure. Exposing these materials to heat generally causes significant changes in strength, elastic, and thermal properties. Temperature-distribution information developed during exposure and changes in properties occurring over the exposure temperature range are essential for evaluating the behavior of a structure where these materials are used.
This report provides information on changes in strength, elastic, and thermal properties due to increasing temperatures for various concretes, steels, and concrete masonry. Also, some thermal-property information is given for common brick, gypsum, ceiling tile, plasterboard, and asbestos-board. Use of temperature distribution and property information in predicting the performance of fire-exposed structures is described.
Finally, information on some actual fires in structures is presented to demonstrate how a knowledge of the behavior of inorganic materials exposed to fire can be used to predict the performance of structures.
Understanding and Modeling Preflashover Compartment Fires
Authors: Pape R , Waterman TE 
Published: March 2009

The evolution of preflashover compartment fire modeling is discussed. Early understanding of fire development in enclosures came largely from observing full scale experiments, and the need for modeling arose due to the high costs of running such large experiments. First, experimental modeling techniques were tried, and eventually mathematical models were developed.
The discussion begins with Ingberg's severity equivalent presented in 1928. The history of preflashover compartment fire modeling is carried to the present time. At present, there is considerable emphasis on developing mathematical enclosure fire models. Three types of mathematical room fire models exist. These are the probabilistic, modular, and differential field equation models. Three of the modular models (the IITRI RFIRES Code, the Harvard Computer Fire Code, and the UDRI DACFIR Code) are compared in order to present the techniques currently employed.
Identification and Quantitation of Brominated Fire Retardants
Authors: Zweidinger RA , Cooper SD , Pellizzari ED 
Published: March 2009

Qualitative and quantitative analysis of water and sediment samples for semivolatile brominated fire retardants was conducted. Four brominated fire retardants were identified and quantitated. Sample analysis included solvent extraction followed by gas-liquid chromatography/mass spectrometry (GLC-MS) and thin-layer chromatography/scanning spectrodensitometry (TLC-SD).
The fire retardants decabromobiphenyl ether (DBBE) and tris(2,3-dibromopropyl) phosphate (tris) presented special analytical problems related to their very low volatility and thermal instability, respectively. More than one analytical method was developed for some of the fire retardants under investigation. For most brominated compounds gas-liquid chromatography/electron capture detector (GLC-ECD) was the most sensitive method. Tris required a very short [0.2 cm inside diameter by 42 cm long, 2 percent OV-101 on Chromosorb W(HP) ] column to avoid extensive thermal degradation, and decabromobiphenyl ether could not be readily analyzed by GLC-ECD due to the very high temperature at which it must be chromatographed and GLC-MS or TLC was used for its quantitation with GLC-MS confirmation of identity. The very low volatility of DBBE required the use of a short [0.2 cm inside diameter by 42 cm long, 2 percent OV-101 on Chromosorb W(HP)] column. The GLC-MS methods for DBBE are also applicable to 2,2-bis(dibromo-4-hydroxy- phenyl)propane (Tetrabromobisphenol A, TBBA) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE, Firemaster 680).
Samples from the vicinity of manufacturing sites were examined. The analytical procedures employed and representative samples of qualitative and quantitative data from these samples will be presented.