bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis and Testing of a Composite Sandwich Shell Horizontal Tail
Authors: Sherrouse MA , McWhorter JC
Published: March 2009

This paper presents the preliminary results of an investigation into the use of a sandwich shell without spars or ribs as a horizontal tail on a light general aviation aircraft. The primary motivations for designing such a structure are simplicity, ease of construction, and the reduction of fasteners.

The structure investigated consisted of two symmetric, quasi-isotropic sandwich skins with four plies of graphite-epoxy unidirectional prepreg per face and 10-mm honeycomb core laid up in an airfoil-shaped mold and cured at 120°C. The two halves were joined by adhesive to form a tapered cantilevered beam with airfoil cross section truncated at the 56.7% chord line. Two internal ribs were installed at the fuselage contour near the center of the tail to provide attachment to a frame. Symmetric point loads were applied to produce varying amounts of torsion and bending, and the results were compared with analysis from a NASTRAN model using elements with composite material properties. The structure was loaded to failure, and the results were compared with analysis from a NASTRAN buckling routine.

A structurally intact portion of the failed test piece was modified to create one half of a fullsize forward-swept tail. Again, experimental results from various bending and torsion loads were compared with analysis from a comparable NASTRAN model.

Chordwise and spanwise strain plots indicated that the sandwich skins carry the bending loads, whereas the reinforced areas at the leading and trailing edges act as shear webs. Good correlation between the experimental strains and NASTRAN analysis was obtained.
Effects of Processing Variables on the Quality of Co-cured Sandwich Panels
Authors: Jouin P , Pollock D , Rudisill E
Published: March 2009

This paper summarizes basic studies conducted to compare the effects of various processes and materials on the quality of co-cured honeycomb sandwich panels with carbon-epoxy facings. Manipulation of the vacuum-pressure-temperature schedules of those processes resulted in improved facing surface quality, compaction, and sealing. The mechanical properties of those panels also improved.
Image Enhancement Techniques for Ultrasonic NDE Applications
Authors: Steiner KV
Published: March 2009

Ultrasonic nondestructive evaluation (NDE) methods are reliable in the inspection and certification of composite structures. Complex structures are scanned by sophisticated automated multi-axis robotic systems. The acquired data are processed to generate images based on peak-amplitude or time-of-flight data. Digitizing of the ultrasonic information has opened the door to powerful computer graphics image enhancement techniques.

Image enhancement techniques can be applied such that critical information is highlighted and defects detected in the structure are classified. Used properly, image enhancement of digitized data dramatically improves the interpretability of ultrasonic information. A wide variety of image enhancement techniques, applicable in particular to ultrasonic NDE, are discussed. In addition, a new method of interpreting ultrasonic data by working from digitized full-volume waveform information is presented. This work, combined with statistical analysis methods, enables the operator to perform complete post-scan evaluation.
Stress Field Sensitivity of a Composite Patch Repair as a Result of Varying Patch Thickness
Authors: Siener MP
Published: March 2009

The desired method for repair of composite airframe structures is by joining with an adhesive(-like) material. The available choices of structurally efficient joint configurations are limited. Most of the commonly used joint configurations would result in repairs that would be either impractical, because of the long adherend overlap lengths required to sustain the design load, or unsafe, because a shortened lap length would limit the load-carrying capability of the joint. Single lap joint configurations based on a variety of patch material thicknesses and stiffnesses are investigated for elastic response and strength capability. The section stiffness of the patch material is kept constant in the direction of the first principal stress, as the number of plies is decreased. The average modulus of the patch adherend is increased by reorienting the plies in the laminate. This is done to demonstrate the possibility of increasing the average joint failure shear stress and the accompanying load transfer efficiency by increasing the stiffness of the adherends. Stress analyses of these configurations are carried out and compared to the results from testing the described configurations.

Experimental data show that it may be necessary to incorporate the nonlinear adhesive behavior into the model to account for the extensional response of the adherends. Also, it may be necessary to model each composite ply to predict the extent of incompatibility of the adhesive bondline and the adjacent composite material. The data also demonstrate that the failure of a composite joint depends on the strength of bondline-contacting interfacial plies, as well as the usual factors considered when estimating joint strength.
Alkyl Polyglycosides: Versatile, Biodegradable Surfactants for the Agricultural Industry
Authors: Aleksejczyk RA
Published: March 2009

Alkyl polyglycosides, a new class of nonionic surfactants, meet the challenges of the agricultural industry by being biodegradable and effective. Their physical properties make them superior surfactants for many applications in a wide range of conditions. Alkyl polyglycosides have excellent aqueous solubility and are stable in the presence of high levels of electrolytes. In addition, they are non-gelling and insensitive to temperature changes due to the lack of a cloud point. These unique solubility properties coupled with their compatibility with anionic, cationic and other nonionic surfactants, make it easy to formulate concentrated or dilute products. Alkyl polyglycoside surfactants are environmentally safe and have excellent toxicity and biodegradability profiles. Alkyl polyglycoside surfactants offer the agricultural industry a new biodegradable raw material with a broad range of properties and advantages.
N-Alkyl Pyrrolidone Requirement for Stable Water-Based Microemulsions
Authors: Narayanan KS , Chaudhuri RK
Published: March 2009

Stable, efficacious microemulsions of carbaryl and a number of pyrethroids (D-Allethrin, Permethrin and tetramethrin), alone or as complex mixtures, both with and without piperonyl butoxide as a synergist, have been developed (patents pending). These active ingredients were microemulsified in a system comprised of: (A) an optimized solvent system in which certain C-1 to C-8 alkyl pyrrolidones were necessary components; (B) an optimized anionic and/or nonionic surfactant system; and (C) water @ ⩾ 85%(W/W). The system is uniquely thermodynamically stable, has low toxicity and is biodegradable, and may have universal applicability with minor modifications of the ratio of its components. The complex microemulsion system of pyrethroids has very low turbidity (⩽20 NTU at 10–25°C), and is thermally stable (45°C, 6 months). Turbidity increased with temperature (900 NTU at 45°C), but became clear when cooled to ambient temperature. A model is proposed that explains the role of the N-alkyl pyrrolidones in achieving stable microemulsion formulations.
Characterizing the Fire Safety of Liquid Pesticide Formulations by Using ASTM D56 Tag Closed Cup Flash Point Method
Authors: Namnath JS
Published: March 2009

Building codes in the United States use the letter and intent of model codes issued by the National Fire Protection Association (NFPA). The most recent NFPA codes restrict warehousing of flammable and combustible liquids contained in plastic. To meet these new requirements, formulations are developed to have a higher flash point, incorporate water as a a major ingredient, or are converted to a non-liquid form.

NFPA flammability classification for liquid pesticides is largely based on results of ASTM D56 Tag Closed Cup Flash Point Method.

This study used ASTM D56 to determine flash points of liquid pesticide formulations of varying composition and water content.

In mixtures of combustible and flammable aromatic solvents the flash points were unaffected by relatively high fractions of flammable aromatic content. In other systems where the formulation had considerable water content and a small amount of aromatic solvent the flash points were found to be close to that of the solvent.

This study concludes flash points of complex formulations cannot be assumed to be that of the lowest flash component. Systems must be tested individually for accurate results.
Culigel® Controlled-Release and Pest-Management Systems
Authors: Levy R , Nichols MA , Miller TW
Published: March 2009

Culigel® Systems encompass novel controlled-release and water-management technology for pest-management applications in aquatic and terrestrial environments. Culigel® technology is based on nontoxic and degradable acrylamide and acrylate superabsorbent polymers that are formulated to entrap/encapsulate one or more bioactive agents used in pest-management applications, and then release them at controlled rates when activated by water. Bioactive agents encapsulated within Culigel® matrices are protected from environmental degradation or loss due to sunlight, volatilization, oxidation, microbial attack, run-off or drainage. Controlled release of mosquitocides from Culigel® granules is regulated by one or more inert dispersants that are admixed in the pesticide formulation to accelerate or slow the release of a liquid or solid bioactive agent from the microporous structure of the granular matrices. Release profiles of organophosphate larvicides, growth regulators, and larvicidal bacilli can be tailored to specific pest-control requirements by altering the type and/or concentration of inerts such as surfactants, emulsifiers, wetting agents, alcohols or salts used in the formulation. Culigel® polymers alone can also be used to physically control immature mosquitoes.
Container Design and ‘Glug’
Authors: Omilinsky BA , Lindsay AD
Published: March 2009

Under the mandate of FIFRA '88, the EPA was to promulgate regulations to “facilitate the safe use of containers…”. The task placed before the Agency was to determine whether and to what extent quantification of the discontinuous flow of liquid from a container orifice (glugglng) was possible. The use of a test fixture — data acquisition — computer link-up was determined to be an effective method that correlates with observed glugging.
The Influence of Paraffinic Oil and Nonionic Surfactant on the Foliar Activity of an Aryloxyphenoxypropionate Herbicide
Authors: Keeney FN , Noveroske RL
Published: March 2009

Formulation design criteria used in the development of emulsifiable concentrate compositions containing built-in adjuvants for XRD-492-methyl are discussed. Foliar applications of radiolabelled XRD-492-methyl were made on Setaria faberi (giant foxtail) and Avena fauta (wild oats) to characterize foliar retention, uptake, and basipetal transport of 14C-activity. On the basis of 14C-activity basipetal (downward) transport data, POLYGLYCOL 26-2 was the most effective nonionic surfactant studied and in combination with paraffinic oil, a weight ratio of 2:1 paraffinic oil: POLYGLYCOL 26-2 appeared near optimum. A total adjuvant concentration in the final composition of 60 wt % in conjunction with an active ingredient concentration of 30–120 g ae/ha provided a minimum adjuvant concentration in 187 L/ha total spray volume of 0.2% (w/v) paraffinie oil and 0.1% (w/v) nonionic surfactant when the use rate (g ae/ha) was the same as the active ingredient concentration (g ae/L).
Adjuvants to Reduce Drift from Handgun Spray Applications
Authors: Salyani M , Cromwell RP
Published: March 2009

The off-target drift deposits from handgun applications of two spray mixtures (one with an invert emulsion oil and one with a polymeric adjuvant) were compared to that of water, all containing a fluorescent dye tracer. Drift deposit samplers consisting of mylar sheets and air sampler filters were positioned at several locations downwind and around the line of spray application. Weather data were recorded by a weather station and the amounts of the tracer dye deposit on the targets were measured with a fluorometer.

Spray mixtures containing the adjuvants produced lower drift deposits, on both mylar sheets and filter papers, as compared to water only sprays. The use of invert emulsion oil (Visko-Rhap) resulted in the lowest drift deposits from handgun applications.
Evaluation of Fumed-Silica Insulation for a Thermal Conductivity Standard Reference Material
Authors: Rennex BG , Somers TA , Faison TK , Zarr RR
Published: March 2009

Standard Reference Materials (SRMs) used for thermal conductivity measurements are required by industry, academic, and government laboratories for calibrating heat-flux-meter apparatus or checking the accuracy of guarded-hot-plate apparatus. New thermal conductivity SRMs are sought to improve the accuracy and extend the operational range of these apparatus. An advisory panel recommended the development of a low thermal conductivity SRM having approximately the same thermal conductivity as blown fluorocarbon foams, suitable for a temperature range of -175 to 900°C. Fumed-silica insulation was recommended by the advisory panel as the most suitable material.

The National Bureau of Standards (NBS) examined four lots of fumed-silica insulation and recommended one candidate for further development as a low thermal conductivity SRM. The four lots of fumed-silica insulation were examined for their relative handleability, material uniformity, variability of thermal conductivity measurements, and effect of heat treatment on the measured thermal conductivity of the materials. Thermal conductivity measurements were conducted using the NBS 1-m Guarded Hot Plate for each lot of fumed-silica insulation at a mean specimen temperature of 24°C. Analysis of the thermal conductivity data was performed using the NBS statistical analysis program, Dataplot.
Radiant Heat Transfer in Extremely Low Density Fibrous Assemblies
Authors: Dent RW , Skelton J , Donovan JG
Published: March 2009

In very low density insulating assemblies, heat transfer occurs mainly by gas phase conduction, by convention, and by radiation. Many attempts have been made to analyze the parameters that control the radiant component of this heat transfer using electromagnetic theory based on the Maxwell equations. Extensive solutions are available in the literature for spheres but few results have been calculated for cylinders (which would model fibrous insulations), although the relevant equations have been given by Van de Hulst and by Larkin and Churchill. Larkin and Churchill give appropriate values for “real” refractive indices only, with zero absorption.

We have now obtained complete “complex” solutions as functions of fiber diameter and the fiber optical properties of refractive index and absorption coefficient (or dielectric constant). These solutions allow a full understanding of the roles of scattering and absorption in radiant energy transfer and show how these can be optimized for various materials as a function of wave-length (or temperature).

Once the radiant heat transfer is minimized for single isolated cylinders, we consider how this translates to a low density assembly of many such cylinders or fibers. The results show that radiant heat transfer can be minimized by the selection of an optimum fiber diameter and that this optimum differs for each material and for different absorption coefficients (as these affect the real and imaginary parts of the refractive index which determine the heat transfer).
Variation of Insulating Properties of Closed-Cell Foam Insulation
Authors: Ostrogorsky AG , Glicksman LR
Published: March 2009

Heat is transferred through closed-cell foam insulation by conduction through the solid polymer making up the cell structure, conduction through the low conductivity gas (blowing agent) inside the cells, and radiation. The effective thermal conductivity of closed-cell foam panels changes with the foam age due to diffusion of air components into the foam and diffusion of the blowing agent out from the foam. The change in the composition and thermal conductivity of the gas mixture was modeled as a function of the aging time. The change in the composition is computed by solving the transient diffusion equations for each gas species in the foam. The thermal conductivity of the gas mixture is computed from an empirical correlation proposed by Lindsay and Bromley.

A computer program was developed to numerically solve the governing equations. The effective diffusion coefficients of the air components and the blowing agent are the main code inputs. The numerical prediction of the change of the effective conductivity of foam panels for a given age is within 6% or better of the conductivity obtained in long-term tests under three different thermal environments.
Foam Insulation Aging: Historical Perspective and Outstanding Problems
Authors: Zwolinski LM
Published: March 2009

Rigid polyurethane foam originated in the World War II era. This material, the reaction product of polyisocyanates and hydroxyl-terminated polyols, was originally expanded by in situ generation of carbon dioxide during the polyurethane polymerization process. A major improvement in the insulation value of polyurethane foam was effected in the early 1950s by the development of technology to use chlorofluorocarbons (CFCs) as the blowing agent.

This paper presents a historical perspective on the development of rigid polyurethane foam as a superior insulation material. The role of CFC expansion agent will be examined with a review of the early concerns of aging of foam and the accompanying change in insulating property. The effects of blowing agent diffusion, humidity during foam aging, and the aging environment gas on the thermal conductivity of cellular material are detailed. Early attempts to explain heat transfer through rigid cellular structures in terms of conduction, convection and radiation factors are cited.

Attention is focused on problems outstanding to a complete understanding of foam aging. These factors include test methodology, the role of gas diffusion, polymer distribution in a cellular structure, effects of barrier materials, in-service moisture influences, foam structure features, and total insulation-containing structural design.
Long-Term R-Values and Thermal Testing Requirements for Rigid Insulating Foams
Authors: Hagan JR , Miller RG
Published: March 2009

This paper presents the results of two experimental studies. The first was a continuation of a 5-year aging study on foil-faced polyisocyanurate thermal insulation boards. These boards were retested in the guarded hot box and represent 11-year aged data. The results indicated excellent agreement with the plateaued R-values established on the 5-year aged samples.

The second effort is an ongoing correlation study between the large-scale guarded hot box and small-scale heat flow meter tests using permeable faced polyisocyanurate foam thermal insulation boards. Thicknesses tested ranged from 2.5 to 8.1 cm (1 to 3.2 in.). The results to date show that, in general, with proper sampling of large-scale boards, good agreement can be expected between guarded hot box and heat flow meter test results.
A Survey of Window U-Value Measurements in Sweden (1977–1987)
Authors: Staelens P
Published: March 2009

At the Swedish National Testing Institute (SP) window thermal transmittance (U-value) measurements are carried out in a Guarded Hot Box (GHB). It is shown that the GHB meets the requirements of the relevant Swedish Standard (SS 024212,13) and International Standard Draft Proposal (ISO/DP 8990). The SS 024213 measurement routines are discussed.

A survey of measurement results acquired during the last ten years shows the continuous improvement of the U-value of windows produced in Sweden as well as the increasing importance of additional panes and improved sealed glazing units.

By way of comparative Guarded Hot Plate (GHP) and GHB measurements on sealed glazing units it is shown that the GHP method should be examined thoroughly and its results handled with care in order to prevent misinterpretation by, for instance, the client. It is further noted that the GHB technique, although commonly used, is not completely investigated and that on the level of standardization much work is yet unfinished.
Heat Transfer Characteristics of a Recently Developed Lightweight Structural Concrete
Authors: Van Geem MG
Published: March 2009

A lightweight structural concrete was developed for use in exterior walls of low-rise residential and commercial buildings. The lightweight concrete has a unit weight of 800 kg/m3 (50 pcf), a compressive strength of 13.8 MPa (2000 psi), and a thermal conductivity of 0.23 W/m · K (1.6 Btu · in./h · ft2 · °F). Lightweight concretes have not been previously developed with this combination of low density and moderate strength. The most commonly used concrete, normal weight concrete, has a unit weight of approximately 2320 kg/m3 (145 pcf), a compressive strength in the range of 17 to 41 MPa (2500 to 6000 psi), and a thermal conductivity of 1.7 to 2.3 W/m · K (12 to 16 Btu · in./h · ft2 · °F).

The portland cement concrete developed for this project can be used to combine structural, thermal insulation, and heat storage capacity functions of exterior walls in one element. For many climates this concrete can be used without additional insulation as a complete wall system in lowrise buildings.

Heat transfer characteristics of two 200-mm (8-in.)-thick, full-size wall assemblies were evaluated using a calibrated hot box (ASTM C 976). One test specimen, designated Wall L, was a 200mm (8-in.)-thick wall constructed entirely of the newly developed lightweight structural concrete. The second specimen, designated Wall S, was the same as the first except for a 150-mm (6-in.)-high normal weight concrete strip running horizontally across the wall at midheight. The horizontal strip simulates a floor slab extending through an exterior wall.

Overall thermal resistances of Walls L and S, respectively, are 0.92 and 0.83 m2 · K/W (5.2 and 4.7 h · ft2 · °F/Btu) at 24°C (75°F). Thermal resistance of Wall S is 11% less than that for Wall L.

Tests under dynamic temperature conditions provide a measure of thermal response for selected temperature ranges. Dynamic response includes heat storage capacity as well as heat transmission characteristics of the wall assembly. Results from a 24-h period, sol-air temperature cycle showed that heat storage capacity of the low density concrete delayed heat flow through the test specimen. Average thermal lag for the 200-mm (8-in.)-thick lightweight concrete wall was 6 h.

Thermal and physical properties of the lightweight concrete were also measured on small-scale specimens. Concrete thermal conductivity, thermal diffusivity, specific heat, compressive strength, flexural strength, splitting tensile strength, shear strength, modulus of elasticity, drying shrinkage, and freeze/thaw resistance were determined.

Laboratory test results provide information on the thermal and physical performance of the new lightweight concrete.
Transient Coupled Conduction and Radiation Heat Transfer Through Ceiling Fiberglass/Gypsum Board Composite
Authors: Yeh HY , Roux JA
Published: March 2009

The heat transfer phenomenon in a fiberglass insulation and gypsum board (sheetrock) composite was investigated numerically. Heat transfer through the fiberglass insulation was taken to occur by coupled conduction and volumetric radiation. The fiberglass insulation was considered as a radiatively absorbing, emitting, and scattering medium. Heat transfer within the gypsum board was taken to be by conduction only. Measured (transient) temperatures at the top of the fiberglass insulation and on the bottom of the gypsum board were used as boundary condition information in obtaining a numerical solution. These temperatures were measured in a residential attic for summer and winter climatic conditions. For purposes of minimizing heat loss in winter and heat gain in summer, two different configurations of fiberglass insulation were studied. One configuration was a standard R-19 [15 cm (6 in.) thick] fiberglass batt; the other configuration was a standard R-19 fiberglass batt with a foil radiant barrier installed on top of the insulation. It was found that the batt with the foil radiant barrier reduced the heat gain in summer by about 45% and reduced the heat loss in winter by about 13%.
Spectral Radiative Properties and Apparent Thermal Conductivity of Expanded Polystyrene Foam Insulation
Authors: Yajnik SJ , Roux JA
Published: March 2009

Heat transfer in foam insulations is primarily due to conduction and radiation. In order to predict the heat transfer in expanded polystyrene foams the determination of reliable spectral radiative properties is important since radiation accounts for up to 27% of the overall heat transfer at moderate temperatures (250 to 350 K). Most of the previous work done on the determination of the spectral radiative properties of foam insulations employed direct transmission measurements and Beer's law to invert the extinction coefficients. This paper utilizes directional-hemispherical reflectance data in the wavelength range from 4 to 20 μm to invert the spectral radiative properties of a standard reference material, namely 20.7 kg/m3 expanded polystyrene foam insulation. Apparent thermal conductivity values are predicted using the inverted radiative properties. The non-linear least squares method was used to invert the spectral radiative scattering and absorption coefficients from the experimental reflectance data and a numerical model.
Computer Modeling of Climates
Authors: Cash CG
Published: March 2009

The mathematical study of many dynamic responses of building materials and constructions to climatic variations has been hampered by the lack of a suitable way to model climatic components such as temperature, precipitation, humidity, wind, solar radiation, and cloud cover. It was noticed by the author that a curve called the “companion to the cycloid” seems to be similar in shape to ambient temperature versus time plots. This was the start of the work reported in this paper because, if a successful model of the temperature cycles could be developed, we would have a powerful tool to help us in our understanding of the thermal behavior of materials and systems.

This paper presents methods for the mathematical modeling of the ambient air temperature at any location where statistical atmospheric data are available. The model was checked by comparing the calculated air temperatures with the actual air temperature data at six diverse locations in the continental United States. In addition, the actual hourly air temperatures (recorded at three-hour intervals) were compared with the calculated hourly air temperatures from the model for a six-year period at one location.

The model was expanded, with data from the literature, to model the temperature of white, gray, and black roof surfaces. These calculated surface temperatures are used to illustrate the utility of the model in estimating the sliding potential of several bituminous roofs.

The usefulness of the minimum temperature and the temperature loading parts of the model has been demonstrated by the work reported in this paper. The validity of the surface temperature part of the work is yet to be established.

Finding the proper curve shape for the thermal model opens up many lines of investigation for studying building materials as dynamic components. Other studies currently being performed include the migration of bitumen through the felts within the roofing membrane and the displacement of one-ply systems in response to the normal thermal cycles. Future studies are not limited to roofing; the model can be applied wherever the effects of temperature cycles are important.

The preliminary look at the sliding potential of bituminous built-up roofing membranes reported in this paper may be the start of a study to provide rational limits for the maximum slope that should be permitted for each class of bitumen, instead of using timeworn standards that may not be appropriate.
Factors Influencing Consumer Insulation Activities
Authors: Meeks CB
Published: March 2009

Using a sample of 37 687 single family homeowners from the 1980 Annual Housing Survey, this study applied discriminant analysis to determine which variables influence presence, addition, and cost of insulation. Housing units with insulation were more likely to have storm doors or windows, be newer, more expensive, be located in the Northcentral region rather than the South, and have an attached fan and electric or oil heat rather than natural gas. An increase in the age of the head and presence of a child under 6 years old as well as length of occupancy were more highly associated with housing without insulation.

The addition of insulation was more likely in older homes, homes located in regions other than the South, homes heated with oil, liquid petroleum gas, or wood rather than natural gas, and homes with storm doors or windows and an attached fan. While presence of a child under 6 years old increased the probability, length of occupancy had a negative impact.

Using these variables as discrimators, 74.2% of the households with insulation were correctly classified, while 60.5% of the households who added insulation were correctly classified. Expenditures on insulation varied with region, length of occupancy, age and value of the house, and presence of an attached fan. Thus this study provides a base for identifying households which will undertake insulation activities.
Review of ASTM Guide for Removable Insulation Covers (C 1094)
Authors: Hart G
Published: March 2009

With a need for periodic inspection or access to many hot insulated surfaces, removable/reuseable insulation covers have been found to be a good solution. These covers reduce the heat loss on surfaces such as valves, flanges, pumps, compressors, and piping where otherwise a permanent, non-reuseable type of insulation might be added. The use of removable covers can reduce the long-term cost of gaining access to the hot surfaces that need periodic inspection.

There are a number of different performance requirements encountered by removable insulation covers on hot surfaces. In general, the covers should insulate effectively, be capable of being easily removed and replaced, and last a certain period of time. An impediment to their durability is the conditions to which the blankets are exposed: high service temperature, leaking chemicals, sun and rain, physical abuse, and fire, among others. The selection of appropriate materials to meet the performance requirements of a particular job can be a difficult and complex task. Such a selection is generally addressed with specifications.

As as first step in developing removable insulation specifications, ASTM Committee C-16 on Thermal Insulation formed a task group to develop a standard guide. This document, which was balloted before Committee C-16 in late 1987 and received Society approval as ASTM C 1094 in 1988, identifies the performance issues faced by removable covers and their constituent materials. Being a guide, it does not recommend particular materials or even performance values. Rather, it recommends appropriate test methods, as well as general design and construction issues, that should be addressed by a specification. The use of ASTM C 1094 in developing removable cover specifications should ultimately improve the performance and quality of those covers.
New Developments in Test Technology for ASTM C 692 (Preproduction Corrosion Test for Insulation To Be Used on Austenitic Stainless Steel)
Authors: Whitaker TE , Whorlow KM , Hutto FB
Published: March 2009

Significant improvements have been made in the test procedures used in ASTM C 692 which deal with preproduction testing of wieking-type insulation for use on austenitic stainless steel. A drip procedure which literally turns the apparatus upside down has been found to be more reproducible as well as more realistic in terms of how insulation is actually contaminated in a realuse situation. The new procedure employs a steam-heated pipe to heat the coupons and thus provides far greater temperature uniformity than previously. The drip method controls the amount of liquid applied to each coupon to ± 10%, a much closer control than was possible with the previous wicking method. Correlations between the old and new procedures are provided. In addition to improvements in the test protocol, procedures for the metal qualification test have been vastly improved.
An Automated High-Temperature Guarded-Hot-Plate Apparatus for Measuring Apparent Thermal Conductivity of Insulations Between 300 and 750 K
Authors: Hust JG , Filla BJ , Hurley JA , Smith DR
Published: March 2009

An automated guarded-hot-plate apparatus was designed and built to meet the requirements of ASTM standard test method C 177 for measuring the thermal transmission properties of thermal insulation. The apparatus is controlled by a scientific desktop computer. Measurements with this apparatus can be performed at temperatures from 300 to 750 K in environments of different gases at pressures ranging from atmospheric pressure to roughing-pump vacuum. A novel design for a thermocouple device is used; this device more accurately senses the average temperature over the surface of each heater plate. An improved algorithm for the control sequence provides more stable heater powers and specimen temperatures. Initially the algorithm brings the system rapidly to a temperature setpoint with minimal overshoot. It also permits highly sensitive control of the plate temperatures in later phases of the measurement sequence when thermal stability of the specimen boundaries is very important in measuring the thermal conductivity with high precision. Overall uncertainties of thermal conductivities at atmospheric pressure are 2% at 300 K and 3% at 750 K.
Skid Resistance and Road-Surface Texture
Authors: Augustin H
Published: March 2009

The most important factor resulting from the investigation of the effects of road-surface texture characteristics on skid resistance is the technological consequences with a view to the composition of the wearing course. In the course of this work, qualitative data were obtained and evaluated, which shall later be supplemented by quantitative data, about the coefficient of friction measured with the locked wheel on the one hand and through tracings of the surfaces of cores and laboratory samples on the other hand. The tracings were carried out with a device that has a measuring accuracy of ±5 μm and a step length of 12.5 μm. To investigate the time-dependent changes of the road-surface texture under traffic, tests were carried out with a polishing simulator. Through the tracing of selected profiles and the statistical evaluation of the results before and after polishing, comparisons can be made with other existing systems for the measurement of the surface texture as well as prescriptions for new technological demands on materials for the construction of wearing courses. As a result of these investigations, the polishing test according to the British Standard Polished Stone Value (PSV) has been made obligatory for Austria.
The Influence of Polishing Resistance of Sand on Skid Resistance of Asphalt Concrete
Authors: Dames J
Published: March 2009

For 20 years, the Wehner/Schulze polishing machine at Berlin Technical University has been used as a testing system for analyzing the relationship between the polishing resistance of mineral aggregates used in road construction and the skid resistance of road surfaces used by traffic. The results obtained suggest that real traffic conditions have been successfully simulated and reproduced. The machine is described with reference to an actual test on the influence of the polishing resistance of sand on the skid resistance of asphalt layers.
The Introduction of a Skidding-Resistance Policy in Great Britain
Authors: Gargett T
Published: March 2009

Research associated with skidding resistance has been ongoing at the Transport and Road Research Laboratory (TRRL) for over 50 years, and in 1979 a draft “Standard” based on that research was prepared by the Department of Transport for implementation on the National trunk road network. However, the Standard was not issued because not enough was known about the existing levels of skidding resistance, and with the information then available it was not possible to demonstrate the cost-effectiveness of introducing the policy.

In an effort to provide the necessary information, the Department planned a National Skidding Resistance Survey (NSRS) based on the Sideway-force Coefficient Routine Investigation Machine (SCRIM), and during 1982 survey was undertaken on a short (approximately 10-km lengths) sample basis to represent the network nationwide and to provide an adequate number of samples of the many different categories of site that are encountered on a road system. Altogether a representative sample of about 1000 km was taken forward for further analysis. The sample was broken down into short subsections and each allocated to a site category such as traffic light approach, nonevent open road, motorway, bend, major junction, minor junction, dual carriageway, and single carriageway. Average and minimum skidding-resistance values were determined for each subsection and all injury accidents, each defined by type (dry no-skid, dry skid, wet no-skid, wet skid), were allocated to the subsection of their occurrence.

Analysis of the data demonstrated that very different skidding resistance/accident relationships existed between the various categories of site. Based on the findings, a policy was developed that would not only save accidents but also could be shown to be highly cost-effective. The paper briefly summarizes the findings of the NSRS and outlines the general principles (including skidding resistance values) of new skidding-resistance policy for in-service roads.
The Use of Fuzzy-Sets Mathematics for Analysis of Pavement Skid Resistance
Authors: Huihua X , Henry JJ
Published: March 2009

The physical interaction between roadway surface and vehicle tires has been widely investigated. Roadway conditions, traffic characteristics, environmental factors, and driver habits all play important roles in skid resistance and safety characteristics of pavements. It is difficult, however, to use quantitative statements to describe these uncertain factors, and the poor correlation between pavement performance and these factors makes it impossible to predict skid-resistance properties with regression analysis. To evaluate pavement skid resistance, a new methodology has been introduced which uses fuzzy-sets mathematics. The skid performance of pavement sections can be grouped by fuzzy cluster analysis of the data obtained from sand-patch and British pendulum number testing, as well as skid numbers measured on test sections with blank and ribbed test tires. A computer model which predicts locations that have a high accident potential can be established from the fuzzy cluster results. These results can also be used to predict seasonal variations in pavement skid resistance. The principle discussed here can be valuable in all types of pavement-condition evaluations. This paper presents the state of the art in using fuzzy cluster analysis for evaluating pavement skid resistance, first describing the objectives and the scope of possible applications of this methodology, and then giving the calculation procedures and the results of a case study using this technique. Recommendations for future pavement-skid-resistance research are outlined.
Predicting the Skid Resistance of Bituminous Pavements Through Accelerated Laboratory Testing of Aggregates
Authors: Diringer KT , Barros RT
Published: March 2009

The goal of this study was to correlate the results of a laboratory test procedure measuring aggregate polish resistance with skid resistance in bituminous pavements. This correlation would be instrumental in identifying skid-resistant aggregates and would create the potential for assuring lifelong-skid-resistant bituminous pavements.

This study was conducted in two phases. The first estimated the empirical relationship between aggregate microtexture and cumulative polishing using a modification of the ASTM standards: Recommended Practice for Accelerated Polishing of Aggregates Using the British Wheel (D 3319-83) and Standard Method for Measuring Surface Frictional Properties Using the British Pendulum Tester (E 303-83). An exponential model was developed which realistically approximates the minimum polish value observed with the theoretical asymptote of the polishing rate curve. The magnitude of this asymptote, PV, correlated well with New Jersey's skid-resistance experience with specific aggregate types and was subsequently used in the study's second phase.

In the second phase of this study, a more detailed relationship between PV and long-term minimum skid resistance was sought. Experiments were conducted to evaluate polish values of aggregates and skid resistance of bituminous pavements composed of these aggregates and to collect environmental data on selected skid test sites over a period of one year. This information was used to normalize the skid resistance of a bituminous pavement in terms of the aggregate's polish value and cyclical environmental factors.

Because further refinement is needed, a tentative acceptance limit for aggregate prequalification may be identified using this relationship. Possible values for this acceptance limit may range from PV = 25 to PV = 32, depending upon the factors one chooses to include in this consideration.

Additional research is required to check and refine the models developed. This paper concludes with a detailed description of the work to be accomplished in order to finalize this analysis and implement a statistical specification for the prequalification of surface course aggregates based on polish resistance.
A Closed-Loop Calibration Procedure for a British Pendulum Tester
Authors: Kulakowski BT , Henry JJ , Lin C
Published: March 2009

Considerable concern among the users of the British pendulum tester has resulted from the lack of agreement among devices. One of the sources of the inconsistency appears to be a complex, cumbersome, and ineffective calibration procedure. In this paper, a new closed-loop calibration procedure is proposed. The method uses an aluminum alloy surface as the calibration standard. The tester is calibrated by adjusting the slider spring tension until the result obtained on the standard surface falls within prescribed limits. The pendulum arm was redesigned to allow for easy adjustment of the spring tension. The proposed calibration procedure is simple enough to be conducted daily or before each new series of measurements, as necessary. The accuracy of the results obtained with the new procedure is evaluated. The results of the laboratory experiments as well as the results of the computer simulation of the British pendulum tester are presented.
Evaluating the Polishing Properties of Aggregates and Bituminous Pavement Surfaces by Means of the Penn State Reciprocating Polishing Machine
Authors: Nitta N , Saito K , Isozaki S
Published: March 2009

In this study, the polishing properties of coarse aggregates and bituminous pavement mixtures were investigated by means of the Penn State Reciprocating Polishing Machine. The test results were evaluated by BPN5000, which is the measured British Pendulum Number (BPN) after 5000 polishing passes of a rubber pad using alumina (35 μm) abrasive. Aggregate mineral hardness was measured by the Shore Hardness Testing Machine.

Polishing tests for eleven aggregate samples were performed and the results were compared with the results of Shore hardness tests. The results suggested that an average of Shore hardness and its coefficient of variation (CV) are both significant factors for evaluating the polish susceptibility of coarse aggregate. Based on these results, polishing rate, τ, defined as a measure of polish susceptibility, was successively related with the above two factors in the multiple linear regression form which can be used to predict polish susceptibility of coarse aggregate in the laboratory.

Another series of polishing tests was performed to determine the effects of asphalt binder components and the coarse aggregates on the polishing properties of bituminous mixtures. The results suggested that the most important factor affecting polishing levels of a mixture is the exposed area of aggregate in the specimen surface. An attempt was made to relate BPN5000 of various mix designs with an exposure ratio, Er, defined as a measure of exposed area of aggregate, in the linear relation that can be used to estimate the polishing level of bituminous mix designs in the laboratory by measuring only Er.
A Numerical Analysis of the Friction Mechanism of Grooved Road Surfaces
Authors: Purushothaman N , Heaton BS , Moore ID
Published: March 2009

Longitudinal or transverse grooving is a form of treatment used on concrete pavements to improve skid resistance. Reports in the literature have speculated that longitudinal grooving provides extra microtexture on the surface and hence improved skid resistance and directional stability; transverse grooves, on the other hand, provide better drainage and an additional component of hysteretic friction because their texture distorts the tire rubber. Although many experimental studies of the influence of grooves on skid resistance have been reported, very little has been done to explain theoretically the nature of the frictional mechanism of the grooves. In this paper, a three-dimensional viscoelastic finite-element procedure developed to analyze the sliding of rubber over equally spaced transverse grooves is described. From the numerical analysis and friction values measured in the laboratory using the British Pendulum Tester, a friction mechanism for a grooved road surface is proposed.
Dynamic Behavior of a Vehicle on a Rutted Road
Authors: Nakatsuji T , Kaku T , Fujiwara T , Hagiwara T , Onodera Y
Published: March 2009

Wheel ruts on paved roads affect the maneuverability of a vehicle and sometimes trigger fatal accidents. At present, however, not enough is known about the cause of this unstable maneuverability on a rutted road. It is the purpose of this paper to provide some information on the dynamic behavior of a vehicle running on a rutted road. In order to evaluate the stability and controllability of a vehicle on a rutted road, we performed various running tests both on a rutted road and on a flat road.

Based on analyses using root-mean-squared (rms) values and the Developing Spectrum, the following conclusions were obtained: (1) RMS values for the vehicular motion on a rutted road are much greater than those on a flat road; (2) low-frequency contents below 1 Hz play an important role in the behavior of the vehicle on a rutted road; (3) visual guidance by ruts occasionally leads to stable straight runnings on a rutted road; and (4) the severer the lane-changing conditions, the larger the interaction between sprung mass and unsprung masses.