bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermographic Inspection of the Installation Quality of Retrofitted Wall Insulation
Authors: Tsongas GA , Ball TJ
Published: December 2008

Infrared thermographic scans of the walls of 79 homes in Spokane, Washington, were made during the winter of 1983 as a means of observing the installation quality of retrofitted wall insulation. A special attempt was made to determine quantitatively the amount of void area that is typical in insulated walls since it can have a significant impact on thermal performance. Valid results were obtained for 30 of the test homes in this study, and the average uninsulated or void area was 9%, with a range of 1 to 35%. This result is in excellent agreement with those from other studies. For a 9% uninsulated area, estimates of the increase in heat loss relative to a fully insulated wall vary from a low of about 9% to as high as about 40%.

As suggested by the wide range in results, some of the retrofit wall insulation jobs were excellent and some were extremely poor. The newer installations were generally poorer. The important point is that it is clear from these results that wall insulation can be properly installed with little or no void area. Improved quality control on the part of the installers is certainly possible and needed. The fact that the average installation quality is relatively poor and the range in results is very large indicates that some kind of inspection program is advisable.

During this thermographic study, an assessment was also made of blown-in wall insulation installation problems. A number were observed, most of which could be eliminated with proper care and attention on the part of the installers. In addition, an effort was also made to locate high heat loss areas. One notable finding is that often the exposed portions of heated basement walls were uninsulated and therefore exhibited relatively high heat loss.
Formaldehyde Emissions from Selected Fibrous Glass Insulation Products
Authors: Matthews TG , Westley RR
Published: December 2008

The formaldehyde (CH2O) emission potential of fibrous glass insulation acquired from the three largest manufacturers in the United States has been investigated. Screening measurements of unfaced and kraft-faced R-19, foil-faced R-11, and 25.4-mm (1-in.) unfaced insulation made with a formaldehyde surface emission monitor (FSEM) demonstrate low interproduct and intermanufacturer variation in CH2O emission rates. The FSEM screening data and environmental chamber measurements of unfaced R-19 insulation taken at 23°C and 50% relative humidity both indicate CH2O emission rates of 0.02 ± 0.01 mg/m2 h after one to three months of product conditioning in atmospheres of low CH2O concentration. Threefold to fourfold increases in CH2O emissions were measured in environmental chamber tests taken at 38°C and 68% relative humidity, simulating potential seasonal exposures in attic and wall cavities adjacent to indoor compartments. However, a two-compartment, diffusion model describing the potential impact of attic insulation at 38°C and 68% relative humidity on indoor CH2O concentrations indicates a maximum increment of 0.03 mg/m3 (0.02 ppm).
Effects of Moisture on the Thermal Performance of Spray-Applied Insulation Systems
Authors: Benner SM , Modi D , Larson DC
Published: December 2008

The absorption of moisture in insulation systems can produce a degradation of the thermal performance of these systems. These effects have been studied with both laboratory and field testing methods in fiberglass and cellulose spray-applied insulation systems. In the laboratory, transient thermal resistance and moisture gain of horizontal, 25-cm-square, 5-cm-thick specimens have been measured. The upper metal substrate surfaces of the specimens were maintained at 10°C, and the bottom free surfaces were exposed to a flow of air at 30°C and 10 to 50% relative humidities. Moisture gain was measured by periodic weighing of the specimens, and the thermal resistance was calculated from thermocouple and heat-flow sensor readings. The fiberglass and cellulose materials gained as much as 5 and 8% moisture by volume, respectively, when exposed to air at 50% relative humidity; much lower moisture gains were observed at lower air humidity levels. The process of vapor flow toward the substrate surfaces contributed significantly to the apparent thermal conductivity. Field measurements of thermal resistances were made on horizontal 1.2-m-square, 5-cm-thick specimens. The corrugated metal substrates were exposed to outdoor ambient conditions while the bottom free insulation surfaces were exposed to a steady flow of indoor air. Field measurements were made under both summer and winter conditions, and no moisture contribution to the thermal conductivity was noted.
Material Degradation of Thermal Insulating Mineral Fibers
Authors: Low NMP
Published: December 2008

Inorganic mineral fibers of the slag wool and rock wool type and of the glass fiber type were found to exhibit physical disintegration and morphological modifications on the fiber surface when these fibrous products were exposed to environments in which an excessive water medium and heating at temperatures up to 100°C were maintained for a period of several months. The physical disintegration transformed the fine, threadlike fibers into small segments and granules. Scanning electron microscopic examinations showed that test specimens of several slag-rock fibers displayed a rough, eroded fiber surface after the fibers had been immersed in water and heated to temperatures below 60°C for about three months, while similar fibers displayed the development of a reticular network structure, or “honeycomb morphology,” on the fiber surface after they had been immersed in water and heated to temperatures between 85° and 100°C for 14 days. Analyses of the water solution and of the disintegrated fibers suggest that these modifications of the fibrous products are caused by chemical leaching and hydration processes. Thermal conductivity measurements showed that the disintegrated fibers have thermal insulating values about 15% lower than those of normal, threadlike fibers.
Performance of a Group of Well-Insulated Solar Houses in the United Kingdom
Authors: Alderson JV , Guy A , Justin B , Shaw G
Published: December 2008

The monitoring of 14 single-story, one-bedroom senior citizens' houses in the northwest region of the United Kingdom is described. Nine of the 14 dwellings were built with very high levels of insulation (in comparison with the then existing 1976 building regulations) and with a form of Trombe wall to provide passive solar gains. The remaining five buildings, of the same internal layout as the others, were insulated only to the minimum specified standards and contained no special solar features. This group was used as a control for comparative purposes. The houses were wholly electrically heated using an off-peak low-tariff-storage heating system. Some 250 sensors, mainly resistance thermometers, were distributed within and on various parts of the structure of the dwellings for monitoring structural thermal behavior. Also, a local weather station was installed on site for climatic measurements. These were interfaced by means of an on-site data logger and land transmission line to a remote control computer at Pilkington Brothers, Research & Development Laboratories some 30 km (20 miles) away. Data were collected every hour, excluding the inevitable breakdowns, for a period of some three years. The resulting energy savings associated with the various insulation and solar measures were determined and used to provide estimates of cost-effectiveness. The most effective measures were extra ceiling insulation, cavity wall insulation, and double glazing.
How the Plastic Behavior of Asphalt Mixtures Influences Pavement Life
Authors: Yandell WO
Published: December 2008

It seems from the author's theoretical and applied research that uncertainties in pavement life prediction could be reduced by paying attention to the plastic behavior of its component materials. By ensuring that the relationship between the plastic behavior of the asphaltic concrete relative to that of the underlying layers (relative plastic behavior) is adjusted to an appropriate value, pavement life will be maximized. The sensitivity analysis reported in this paper gives an insight into the effect of relative plastic behavior on pavement life. The sensitivity analysis makes extensive use of the mechano-lattice stress-strain analysis of elastoplastic-layered media since it is able to detect the buildup of residual stresses and strains. These can have the effect of either increasing or decreasing pavement life.

It is therefore hoped that the highway engineer will be able to make use of this information to prolong pavement life. This he could do by designing the plastic behavior of the asphaltic concrete in the light of existing plastic behavior of the base and subgrade. Alternately the plastic behavior of the base and or the subgrade could be modified in the light of the plastic behavior of the asphaltic concrete. The plastic behavior of the asphaltic concrete may be controlled by modifying the rheological properties of the asphalt or of the asphaltic concrete mix.
Off-Line Process Monitoring of Coal-Derived Liquid Fuels by Computer-Assisted Low-Voltage Mass Spectrometry
Authors: Taghizadeh K , Davis BH , Windig W , Meuzelaar HLC
Published: December 2008

Compositional changes of Coal-Derived Liquids (CDLs) during hydrotreatment on fixed bed catalysts can be investigated by low-voltage (12 eV) mass spectrometry (MS) in combination with multivariate analysis without chromatographic pre-separation. Low-voltage (12 eV) MS data were obtained and compared under two different inlet conditions; (1) MS inlet at ambient temperatures and (2) with the MS inlet preheated to about 200°C. The major trend found in both data sets by Factor analysis was the hydrotreatment effect, namely, hydroaromatic (hydrotreater product) versus aromatic (hydrotreater feed) compounds. A second “time + temperature” trend that reflected the aging of the catalyst as well as the temperature of the hydrotreater reactor was only obtained under ambient inlet temperature conditions. Numerically extracted spectra along the second trend show that more of the low molecular weight components were found early in the process and also at lower reactor temperatures; whereas more of the higher molecular weight components, primarily alkyl substituted polynuclear aromatics, were obtained later in the process and at higher temperatures of the hydrotreater.
Stress-Intensity Factors for Small Surface and Corner Cracks in Plates
Authors: Raju IS , Atluri SN , Newman JC
Published: December 2008

Three-dimensional finite-element and finite-element-alternating methods were used to obtain the stress-intensity factors for small surface and corner cracked plates subjected to remote tension and bending loads. The crack-depth-to-crack-length ratios (a/c) ranged from 0.2 to 1, the crack-depth-to-plate-thickness ratios (a/t) from 0.05 to 0.2. The performance of the finite-element alternating method was studied on these crack configurations. A study of the computational effort involved in the finite-element-alternating method showed that several crack configurations can be analyzed with a single rectangular mesh idealization, whereas the conventional finite-element method requires a different mesh for each configuration. The stress-intensity factors obtained with the finite-element-alternating method agreed well (within 5%) with those calculated from the finite-element method with singularity elements.

The stress-intensity factors calculated from the empirical equations proposed by Newman and Raju were generally within 5% of those calculated by the finite-element method. The stress-intensity factors given herein should be useful in predicting crack-growth rates and fracture strengths of surface- and corner-cracked components.
Effect of Void Nucleation on Fracture Toughness of High-Strength Austenitic Steels
Authors: Purtscher PT , Reed RP , Read DT
Published: December 2008

The fracture of seven austenitic stainless steels with varying nickel and nitrogen contents were studied at 4 K. Smooth, 6-mm-diameter tension specimens and 22-mm-thick compact specimens were used. Nitrogen content controlled the yield strength and influenced fracture toughness by its effect on yield strength. Increasing the nickel content increased the fracture toughness at a constant nitrogen content. Observations of the fracture surfaces and polished cross sections through the fracture surfaces of test specimens showed that nucleation controlled the dimpled rupture fracture process. A critical stress criterion for nucleation that depends on both the applied stress and strain was developed and applied to the fracture toughness test. This fracture criterion explained the increase in fracture toughness with increasing nickel and the decrease in fracture toughness with increasing yield strength for strengths over 600 MPa.
Gaseous-Environment Fatigue Crack Propagation Behavior of a Low-Alloy Steel
Authors: Liaw PK , Leax TR , Donald JK
Published: December 2008

Fatigue crack growth behavior of 4340 steel was investigated in gaseous environments: laboratory air, hydrogen, and helium. No significant effect of specimen orientation on the rates of fatigue crack propagation was observed. In each environment, increasing load ratio decreased the threshold stress-intensity range (ΔKth). The effect of load ratio on ΔKth in the air environment was, however, much more significant than that in wet hydrogen and dry environments (dry hydrogen and dry helium). At low load ratios (≲ 0.5), the values of ΔKth in the air environment were larger than those in dry environments. The ΔKth values in wet hydrogen were in between those in air and dry environments. At a high load ratio of 0.8, ΔKth was, however, insensitive to test environment.

The effects of load ratio and environment on fatigue crack growth rate properties are discussed in light of crack closure and hydrogen embrittlement mechanisms. While the effects of roughness-induced crack closure and hydrogen embrittlement on crack growth rates were found to be negligible, oxide-induced crack closure governed the kinetics of gaseous-environment, near-threshold crack propagation behavior. However, thick-oxide deposits in wet hydrogen did not cause high levels of crack closure.
The Crack Velocity-KI Relationship for AISI 4340 in Seawater Under Fixed and Rising Displacement
Authors: Mayville RA , Warren TJ , Hilton PD
Published: December 2008

An experimental study was conducted to determine if the type of loading, excluding cyclic loading, has an effect on the crack velocity/stress-intensity relationship for environmentally assisted cracking. Compact tension specimens made of AISI 4340, σ() = 1095 MPa (159 ksi), were tested in synthetic seawater under constant load, constant crack mouth opening displacement (CMOD), constant stroke rate (rising displacement) ranging over four orders of magnitude, and dual stroke rate. The results show that when crack growth is assisted by the environment the same a-KI curve is obtained for each type of loading within the bounds of data scatter. These observations are supported by calculations which show that the cracktip opening displacement rate, a measure of crack-tip strain rate, is insensitive to the different types of loading for this system.
Fracture-Mechanics Approach to Tribology Problems
Authors: Murakami Y , Kaneta M
Published: December 2008

Two tribology problems are studied analytically from the viewpoint of fracture mechanics. One is an inclined semicircular surface crack under Hertzian contact loading and the other is an elliptical crack embedded parallel to the surface under Hertzian contact loading.

The behavior of crack opening/closure for a surface crack formed on lubricated rolling/sliding line-contact surface is analyzed theoretically on the basis of fracture mechanics. The crack opening displacement is controlled mainly by surface traction, contact pressure, and oil hydraulic pressure. Both the direction and the magnitude of the surface traction govern the oil seepage into the crack. The oil hydraulic pressure on crack faces is induced by two types of mechanism depending on the movement of contact pressure: the contact pressure transmitted directly by the oil to the crack faces and the oil blocking phenomenon caused by closure of mouth of crack. It was concluded by the analytical results that the oil seepage into a surface crack is the crucial factor which causes the pitting phenomena in rolling/sliding contact fatigue. From this point of view, the reason why pitting phenomena are more frequently observed on the follower surface than on the driver surface can be clearly explained.

The variations of three-dimensional, mixed-mode stress-intensity factors for an embedded elliptical crack under a Hertzian contact pressure moving over the surface are analyzed. The crack opening occurs near the leading crack tip as well as near the trailing crack tip during one pass of contact load. This crack opening behavior was confirmed by the experimental measurements. The directions of crack extension are also discussed.
Growth, Fracture, and Nondestructive Evaluation of Hydride Blisters in Zr-2.5 Nb Pressure Tubes
Authors: Leger M , Moan GD , Wallace AC , Watson NJ
Published: December 2008

Rupture of a cold-worked Zircaloy-2 pressure tube in Pickering Unit 2 in 1983 occurred when a crack developed from an array of hydride blisters. These had formed on the outside surface of the pressure tube where it contacted the surrounding calandria tube. Fol-lowing this event, a comprehensive research program was initiated by Ontario Hydro. Its objective was to determine the consequences of pressure tube-calandria tube contact for channels in other reactors with Zr-2.5 Nb pressure tubes. The purpose of this paper is to present some of the results that have been obtained in the areas of blister growth, fracture, and nondestructive evaluation and to show how these results may be applied to Canada Deuterium Uranium (CANDU) reactor inspection.

Blisters were grown both on small specimens and on pressurized tubes. Blisters were ob-served to grow by gradual precipitation of hydride platelets throughout a volume that also increased with time. Blister growth rates increased rapidly with increasing average temperature. The hydride distribution in the blisters has been observed to be highly variable.

Four-point bending fracture tests were carried out on the small specimen blisters. These fracture tests indicate that blister size is a key parameter in determining the stress required to crack the blister with larger blisters cracking at lower applied stresses. This trend is shown to be consistent with previous finite-element modelling, which incorporated hydride plasticity.

Two of the pressurized tubes were inspected with a specially designed ultrasonic head, and responses were correlated with metallographic information. The ultrasonic inspection system was capable of detecting cracks as small as 0.15 mm deep in small blisters. This gives some expectation that inspection will be able to identify blistered tubes.
Internal Hydriding in Irradiated Defected Zircaloy Fuel Rods
Authors: Clayton JC
Published: December 2008

Internal hydriding of Zircaloy cladding is a persistent cause of cladding failures. It occurs in the fuel rods of water-cooled nuclear power reactors that have a small cladding defect. This report summarizes the experimental findings, causes, and mechanisms of internal hydriding in defected Zircaloy-clad fuel rods. Irradiation test data on the different types of defected fuel rods, intentionally fabricated defected and in-pile operationally defected rods, are compared. Significant factors affecting internal hydriding in defected Zircaloy-clad fuel rods (defect hole size, internal and external sources of hydrogen, Zircaloy cladding surface properties, nickel alloy contamination of Zircaloy, the effect of heat flux, and fluence) are discussed. Pertinent in-pile and out-of-pile test results from Bettis and other laboratories are used as a data base in constructing a qualitative model that explains hydrogen generation and distribution in Zircaloy cladding of defected water-cooled reactor fuel rods.
Electron Microscopy Study of Oxide Films Formed on Zircaloy-2 in Superheated Steam
Authors: Zhou B-X
Published: December 2008

Electron microscope techniques were used to investigate black and white oxide films, formed before and after the oxidation transition, on Zircaloy-2 in superheated steam at 673 and 773 K. The nodular corrosion appearing on black oxide films during oxidation transition has been also investigated. A compressive stress gradient distributed through the thickness of black oxide films was measured to be ∼500 MPa/μm in films with a thickness of 1.2 (μm decreasing to ∼60 MPa/μm with an increase in film thickness to 2.1 μm when nodular corrosion appears. Monoclinic, cubic, and tetragonal lattice structures in black oxide films formed both at 673 and 773 K have been identified. The proportion of cubic and tetragonal phases decreases with the increase of temperature and turns into an exclusively monoclinic lattice structure in white oxide films after oxidation transition. The grain size in black oxide films is extremely fine (<50 nm), and grain contrast is indistinct. The high internal stress in black oxide films induced an imperfect crystal structure. It was observed from a high resolution lattice image that the oxide crystals consist of mosaics ∼20 nm in size. The larger spacing on (100) and (010) planes in some places might be associated with clusters of tin atoms. Pores (<10 nm) existing on triple grain boundaries in the white oxide films have been observed. Small areas in black oxide films, which are 3 to 4 times more than the average thickness, are considered to be the nuclei of nodular corrosion. The oxide/metal interface at nodules are characterized by the protrusion, which have the appearance of cauliflower, with small semispherical bumps overlapping one another, and ripple marks on small bumps. These are characteristics that might occur because nodules grow much faster than the surrounding oxide. The model for the formation of nodular corrosion previously proposed by the author is discussed further in light of results obtained in the present work.
Magnetic Study of Zircaloy
Authors: Miyake C , Takamiya T
Published: December 2008

Although the β-phase has been reported to be a supersaturated solid solution with a small amount of elements, such as iron, chromium, nickel, and so forth, it was found that the phase of Zircaloy-4 after heat treatments above 830°C quenching and 1030°C annealing is in a superparamagnetic state which contains particles of Zr(Fe1-xCrx)2 so small (10 to 20 Å) that they can not be detected by usual methods. The β-phase of Zircaloy-2 may be in a similar state to Zircaloy-4 but can not be called a superparamagnetic state because of nonmagnetism of responsible precipitates. In order to give a deeper understanding of “nodular corrosion,” magnetic measurements of susceptibility and magnetization were carried out on Zircaloy-2 and -4 before and after heat treatments at 0.1 to 1 T from temperature of liquid nitrogen to room temperature. Magnetization curves at temperature of liquid nitrogen for Zircaloy-4 correspond closely to the calculated Langevin function. After heat treatments above 900°C, magnetization for Zircaloy-4 increases more than three times. This means that the amount of small particles of ferromagnetic precipitates is increased by heat treatments.
Link Between Stress Corrosion and Corrosion-Fatigue Behavior of Zircaloy in an Iodine Environment
Authors: Schuster I , Lemaignan C
Published: December 2008

Three types of recrystallized Zircaloy-4 plates have been studied at room temperature in a methyl alcohol solution of iodine (iodine concentration = 10-3) and in dry air as a reference medium. Crack growth rates have been measured using double cantilever beam (DCB) and center notched (CN) specimens, depending on plate thickness. Fatigue life was obtained on smooth tensile type specimens.

Experimental data show that a corrosion fatigue phenomenon exists for Zircaloy in an iodine methyl alcohol solution; it is characterized by the following results: For fatigue life, a reduction in numbers of cycles to failure has been observed at intermediate stress levels, about a factor of 8, while there was no reduction of the fatigue strength. For crack growth rate, an increase has been found, by a factor of about 4, which had slight frequency and orientation dependence.

Extensive scanning electron microscope (SEM) fractography showed that the mechanism of corrosion fatigue of Zircaloy is rather unique: in contrast to classical corrosion fatigue, for which the increase in crack growth rate is due to the chemical enhancement of crack opening along the entire crack front, leading to wider striations, it was found in Zr-4 that the fracture surface consists of grains fractured by pseudo-cleavage as seen during stress corrosion cracking (SCC) crack growth, and other grains fractured by fatigue with striation spacings similar to those obtained in dry air at the same Delta K. For the initiation step, it was found that only intergranular cracking occurred on the free surface, until the stress intensity factor reached the threshold level for SCC or dry fatigue crack propagation, or both, at which point corrosion-fatigue started.
Stress Versus Strain Rate Characteristics of Zircaloy Cladding Tubes Subjected to Various Deformation Paths
Authors: Suzuki H , Okubo T
Published: December 2008

Load relaxation properties of unirradiated Zircaloy nuclear fuel claddings were measured at 648 K. Deformation paths preceding the relaxation were altered in order to study the factors affecting relaxation properties. The histories chosen were (1) constant strain rate tensile deformation, (2) constant load creep deformation, and (3) biaxial followed by uniaxial creep. Stress versus time records were obtained from the relaxation runs. Stress versus strain rate curves were further derived and effects of prior strain rate, strain, transient deformation and strain hardening on relaxation properties were discussed. It was found from the experimental results that after strain hardening and transient deformation saturates, the strain rate just prior to relaxation has a major effect on the stress versus strain rate characteristics. This finding holds both for the relaxation after tension and creep. Existing models could not describe these findings.
Effects of Microstructural Factors on Irradiation Growth in Zirconium-Niobium Alloys
Authors: Sadaoka N , Fuse M
Published: December 2008

The irradiation growth mechanism of Zr-Nb alloys has been evaluated on the basis of a growth model in which point defect parameters obtained by molecular dynamics are used.

In the proposed growth model the effects of an acceleration of interstitial flow to the grain boundary are considered. This phenomenon is caused by specific microstructures in the Zr-Nb alloys. Experimental irradiation growth data for specimens with various microstructures were analyzed with the model. The calculated results indicated that the growth rate of Zr-Nb alloys, which became either positive or negative depending on the microstructures, could be simulated by this model adjusting the interstitial in-flow acceleration factor. Further negative growth rate was attributed to the increase of interstitial in-flow to the grain boundaries with specific orientations.
Principal Stresses Derived from Self-Boring Pressuremeter Tests in Soft Clay
Authors: Benoit J , Clough GW
Published: December 2008

Careful evaluation of the in-situ lateral stress is important for many marine applications. Advanced versions of the self-boring pressuremeter (SBPM) allow assessment of these insitu horizontal stresses in three different directions. Full advantage of the multiple measurements is best achieved by using a micro-computer data acquisition system. Such a system is described in this paper along with the lateral stress results obtained in a series of 32 tests in soft clay.
A Theoretical Study of Pore Pressure Generation and Dissipation Around the Pressuremeter
Authors: Baguelin FJ , Frank RA , Nahra R
Published: December 2008

Results of finite element analyses of self-boring pressuremeter tests in theoretical two-phase soils are presented. In particular, pore pressures generated during an initial small strain expansion stage and their dissipation during a subsequent consolidation stage are analysed for different pressuremeter lengths. It is shown that the basic results of the reference expansion test are not affected by partial drainage. Pore pressure measurements during volume holding tests are proven to yield satisfactory values of radial coefficient of consolidation using the elastic plane strain solution of Randolph and Wroth (1979), even for the shortest probes. The self-boring pressuremeter thus provides, for offshore practice, interesting basic soil parameters measured in-situ, besides the limit expansion pressure for direct design of deep or shallow foundations.
Relating Undrained Triaxial and Pressuremeter Stress-Strain Characteristics by Using Multi-Yield Surface Model Parameters
Authors: Kauschinger JL
Published: December 2008

Multi-yield surface model parameters, which define the stiffness (Hi), size (k(i)), and location (α1(i)) of a nest of yield surfaces were fitted to triaxial compression and extension data for nine fine grained soils [1,2]. Each set of model parameters were used in a computer program to calculate the total stresses (σrr,σzz,σϑϑ) and strains (εϑϑ, εrr) for an idealized load/unload pressuremeter stress path. The pressuremeter stress and strain data for all nine soils were utilized as the bassis for developing an empirical procedure which could be used to extract multi-yield surface model parameters from shear stress-strain data, (σrr − σϑϑ) versus εγγ. The empirical procedure was used to extract values of Hi, k(i), and αi(i) for each soil from the corresponding pressuremeter stress-strain data. The nine sets of model parameters fitted to (σrr − σϑϑ) versus εrr data where specified as input for a computer program which were then used to calculate the corresponding load/unload triaxial compression and extension stress-strain data, (σyy-σxx) versus εyy.
Determination of Properties of Sand from Self-Boring Pressuremeter Tests
Authors: Robertson PK , Hughes JMO
Published: December 2008

The self-boring pressuremeter test is ideally suitable for determining in-situ engineering properties of sand. A new method for the determination of the friction angle is presented that accounts for the non-linear volume change behaviour of loose sands. The determination of shear modulus from small unloading-reloading cycles is discussed. A method is presented that allows the shear modulus values to be normalized with respect to stress level. A rational method is also presented to allow the ‘elastic’ shear modulus measured from small unloading-reloading cycles to be applied to engineering design problems where the loading may induce strains larger than the ‘elastic’ level.
Analysis and Verification of Louisiana Pile Foundation Design Based on Pressuremeter Results
Authors: Davidson RR , Bodine DG
Published: December 2008

The Menard pressuremeter was utilized as one element of a comprehensive soil property characterization of medium to stiff, plastic, Pleistocene clays on which the pile foundations for a proposed coal-fired power plant would be supported. Pressuremeter testing was supplemented by drilling, sampling and laboratory testing. Various design methods were utilized to predict the ultimate capacity and load-deformation behavior of the pile foundations under axial and lateral loads. Analytical predictions were verified by a program of full-scale instrumented pile load testing on various types of piles including hel-cor corrugated straight-shaft, monotube, step-taper, precast concrete and pipe piles. Five axial tension and compression load tests and one lateral load test were conducted. The field and laboratory testing program confirmed that the pressuremeter provided accurate properties of the clay and that reliable predictions of axial and lateral pile capacity and deformation can be made using these properties.
Application of Pressuremeter Testing to Assess Lateral Pile Response in Clays
Authors: Kay S , Griffiths DV , Kolk HJ
Published: December 2008

Typical lateral load magnitudes encountered on land and offshore are compared. The effect of pile deflection and stiffness response on jacket performance is discussed. The limitations of current design methods are noted. Alternative design procedures are given, using site specific pressuremeter load-deformation data and a quasi three-dimensional non-linear finite element method. Comparisons are made between the observed and computed behaviour of lateral load tests on small diameter piles in clay for which pressuremeter data are available. The problem of extrapolation to larger diameter single piles, and the behaviour of pile groups, is discussed.
Use of Gelling Clays to Stabilize Agricultural Pesticide Suspensions and Emulsions in Aqueous Systems
Authors: Sawyer EW
Published: December 2008

Pesticides are often supplied as suspension or emulsion concentrates in water systems and even more often are applied in aqueous media at desired field concentrations (tank mixes) to obtain uniform spreads at desired rates. The key to success in these applications is “uniformity,” so that after deposition, pesticides exhibit uniform activity throughout the treatment areas. A well-proven technique for obtaining uniformity in concentrates and field strength blends is that of stabilizing with gelling clays. In this presentation, methods of incorporating the clays into the suspensions and emulsions are discussed. Correlations are made between incorporation techniques, processing equipment available, and the optimum stabilities achievable. Rheological characteristics desired in stable suspensions and emulsions are described and compared with those resulting from clay incorporation. The clay gel structure and the resultant gel strengths and viscosities from the clay crystals plus other contributing particulate materials in the continuous phase gels are discussed.
The Relative Erosivity of Coal-Oil, Coal-Water, and Petroleum Coke-Oil Slurries
Authors: Lee Y-H , Clark HM
Published: December 2008

The relative erosivity (defined as the ratio of the rate of mass loss from a target specimen tested in one slurry and the rate of mass loss in another slurry) for coal-water, coal-oil, and petroleum coke-oil slurries has been determined using pot testers with a rotating flat-plate specimen of either mild steel or 304 stainless steel with a tip speed of 18.3 m/s. Pittsburgh No. 8 seam coal and Whiting medium sulfur coke, both ground to passing 200 mesh, were used together with high flash distillate fuel oil. Slurry viscosity was measured before and after testing, and surface damage was examined using the scanning electron microscope. The effects of slurry concentration (solids loading), velocity, and target material were noted. Evidence of erosion-corrosion was observed for slurries with added stabilizers and for water-based slurries. The erosivity increased in the order coke-oil, coal-oil, coal-water and with increasing solids loading up to about 50% after which a decrease was observed. Comments on problems of erosivity measurement using pot testers are included.
The Validity of Fuel Recycling During Erosivity Testing Using Coal-Water Liquid Fuels
Authors: Sedman KG , Thornley JC , Gilders RD , Hoey GR
Published: December 2008

A coal and water fuel was recycled repeatedly through an erosion test loop. The effects of this on the fuel's erosiveness were studied. This was done to determine the feasibility of erosion testing using continuously recycled coal-water fuel. The erosiveness of the coal-water slurry was observed not to be a monotonic function of the number of cycles but was observed to rise to a peak and then decrease. The initial increase in the erosiveness of the slurry was correlated with an increasing liberation of large angular pyrite grains, whereas the subsequent decrease in erosiveness was correlated with the comminution and rounding of the grains of solid matter and with increasing viscosity.
Comparison Between Laboratory Characterization and Field Performance of Steel Mud Pump Liners Coated with CM 500L, a Tungsten-Carbon Alloy
Authors: Bhat DG , DeKay YR
Published: December 2008

A coating of CM 500L (a tungsten-carbon alloy), deposited by a proprietary chemical vapor deposition (CVD) process on a steel mud pump liner, has been developed to give excellent wear resistance against slurry abrasion. The Miller Slurry Abrasivity Test was modified to simulate, as closely as possible, the conditions encountered in the field application. The modified Miller test was used successfully to compare the wear resistance of the coating with the microstructure. This comparison was found to be useful in the development of the coating process, permitting an optimization of the properties of the coating/substrate system for a predictable and acceptable field performance. The modified test procedure is shown to give results which can be used to predict the service life of CM 500L-coated steel mud pump liners with a much greater accuracy than with the conventional procedure.
Jet-in-Slit and Vibratory Methods for Slurry Erosion-Corrosion Tests of Materials
Authors: Oka Y , Matsumura M , Yamawaki M , Sakai M
Published: December 2008

Slurry erosion-corrosion tests were conducted on metallic materials of practical use by two kinds of testing apparatuses. One is a vibratory apparatus which uses a magnetostriction vibratory unit commonly used for the accelerated cavitation testing of materials. The other is a jet-in-slit apparatus by which a jet of slurry impinges on the test surface. The test results obtained by each apparatus showed a good agreement in the order of merit of the materials. The test results of the jet-in-slit apparatus agreed with the actual service performance of the material in relative magnitude of damage rates.

By making a comparison of the erosion-corrosion parameters between the testing apparatuses and the actual service conditions in the field, the testing conditions required for quantitative assessment of erosion-corrosion damage were discussed.
Infrared Microscopy: A Single-Fiber Technique
Authors: Chase DB
Published: December 2008

The advantages and limitations of Fourier transform infrared spectrophotometry (FT-IR) microscopy are discussed. Use of a single aperture at an image plane leads to drastic reductions in photometric accuracy in the spectra of single fibers. Improved performance can be achieved by using physical aperturing. The polarization properties of the microscope have been determined and infrared dichroic spectra of single fibers are shown.
Dorsiflexion of the Human Ankle as it Relates to Ski Boot Design in Downhill Skiing
Authors: Shealy JE , Miller DA
Published: December 2008

In alpine skiing, the ski boot is an integral part of the ski boot-binding system. The ski boot protects the ankle from excessive dorsiflexion during forward falls, because the ski boot is levered out of the heel binding. A ski boot designer needs to know what the ranges of dorsiflexion are for human ankles so that the allowable forward flex built into the ski boot will not exceed some specified level. That specified level should be such that a large part of the population will not exceed a safe level of dorsiflexion. The stiffening of the ankle by voluntary contraction of the muscles that control the ankle joint cannot be relied on because the reaction time to contract the muscles will be greater than the time available to the skier under many circumstances. This study looks at the maximum voluntary dorsiflexion of a group of people (n = 63) similar to a skiing population. The anatomical and biomechanical posture of the subjects was intended to represent typical skiing situations, therefore, the subjects were measured in a weight-bearing, flexed knee, upright posture. The age, gender, height, weight, and skiing experience of the subjects were recorded as independent variables. The maximum voluntary dorsiflexion of the ankle was the dependent variable. Ten subjects were measured while the knee was kept in a straight or extended posture. The analysis indicates that there is no statistically significant relationship between dorsiflexion and any of the independent variables. The mean dorsiflexion was 42.7°, the fifth percentile value was 28.5 and the ninety-fifth percentile value was 56.7°. The straight knee posture reduces the effective dorsiflexion by 8.5°. Current standards permit as much as 40 to 45° dorsiflexion. The implications are that current standards are excessive; a reasonable limit would be something under 30°. Such a limit is consistent with the maximum dorsiflexion found in most current ski boots.
Measurements of the Forces Needed to Take Off Classic and Rear Entry Ski Boots
Authors: Binet M-H , Montillet B , Delouche G , Thomas M
Published: December 2008

Because of concern with the difficulties encountered when removing rear entry ski boots from patients with lower limb injuries, an investigation was undertaken to determine if there are significant differences between the forces necessary to remove a rear entry boot and those necessary to take off a normal entry boot.

This laboratory study used an articulated foot with an ankle joint. The angles of the ankle's joint were measured, and the pulling forces necessary to remove the foot from various models of usual and rear entry ski boots were recorded.

Records were kept of several different people attempting to remove the boots. It was found that while it was possible to remove normal entry boots from the dummy's foot using reasonable force and without disturbing the foot's position, this was not the case with rear entry boots. In fact, according to the several different candidates, either extra forces were required or the position of the ankle joint had to be altered.

Practice and training play a great part in this removal. It has been proven that a doctor trained in the methods of removing boots from the injured skier uses a lower pulling force than an engineer not familiar with such methods.

Removing the boot without disturbing the ankle joint and using only reasonable force should be added to the existing standards concerning ski boots presently set by the industry.
Measurement of Strength and Loading Variables on the Knee During Alpine Skiing
Authors: Maxwell SM , Hull ML
Published: December 2008

This study focuses on the prevention of knee injuries during snow skiing. To develop a technology of knee injury prevention, both the strength and loading on the knee during skiing activity must be known. This paper reports measurements of variables influencing both knee strength and loading of the joint. The strength variables measured included the degree of activity in six muscles crossing the knee, the knee flexion angle, and the force along the tibia shaft. Transducers included surface electrodes to monitor electromyogram signals indicating the degree of muscle activity and a goniometer to measure both hip and knee flexion angles. The complete loading on the knee was derived from a dynamometer, which measured the six load components at the boot-dynamometer interface. The transducer data were acquired and stored by a compact, battery-powered digital data acquisition-control system.

Three male subjects of similar physical size (nominal was 1.8 m and 75 kg) and skiing ability (advanced intermediate to expert) were tested under similar conditions. Each subject skied a total of four slalom runs—one snowplow and three parallel. The total time of each test was 21 s. Example data plots from different types of runs are presented and discussed. Based on observations from the data, necessary performance features for ski bindings offering improved protection from knee ligamentous injuries are defined.
Axial Rotation of the Lower Limb Under Torsional Loading: II. Parameter Identification of a Dynamic System Model
Authors: Johnson C , Hull ML
Published: December 2008

In Part I of this two-part article, experiments that measured the response of the lower limb to dynamic, transient torsional loading applied at the boot/foot were described. Test variables included rotation direction, weight bearing, and joint flexion. For one of the three subjects tested, two approaches were explored for specifying parameters (that is, inertia, damping, stiffness) of a three-degree-of-freedom dynamic system model which best duplicated the measured response. One approach involved identification of linear parameters by means of optimization; the other approach entailed estimation. Parameter estimates, which included nonlinear, asymmetric stiffness functions, were derived from the literature. For both approaches, the efficacy of parameters was evaluated in terms of the resulting model's ability to duplicate the measured joint axial rotation. The optimization was undertaken to identify parameter dependence on test variables. Results indicate that, to a degree, parameter values are influenced by test variables. Results also indicate that the nonlinear, estimated model better approximates the experimental data than the linear, identified model.

In addition to identifying parameters of a three-degree-of-freedom model, parameters were also identified for a single-degree-of-freedom model where the motion variable was intended to indicate the rotation of the in vivo knee. It is concluded that the simpler model offers good accuracy in predicting both magnitude and time of occurrence of peak knee axial rotations. Model motion fails to track the measured knee rotation subsequent to the peak, however.
Metacarpophalangeal Sprain of the Thumb in Downhill Skiers: Ergonomic Study
Authors: Ledoux X , Ledoux A , Drouet N
Published: December 2008

Sprain of the thumb metacarpophalangeal (MCP) joint is a frequent and serious injury in downhill skiers. A prospective study of 119 cases during the 1984-1985 winter season was carried out to determine the sprain mechanism and its correlation with the skier's ability, the type of ski pole, and the injury.

Four basic mechanisms were found to be involved. 1. Thumb dislocation by the strap when the skier's hand slid down the pole. 2. Impact of the abducted, antepulsed, and extended thumb in the snow, the hand moving forward, seen when the hand was ejected from the upper end of the pole. The design of the pole handle and the way it was gripped gave the hand a dangerous position with the thumb out stretched perpendicular to the palm. The injury would result from the thumb being stopped by the snow and the hand sliding forward. 3. In some falls, the hand rotated around the insertion of the strap, giving a contusion of the ulnar aspect of the MCP joint. 4. The thumb end could get caught in the snow when the falling skier tried to recover his balance with hand closed on the pole handle. It was concluded that: (1) the pole strap was a risk factor of unequal importance in competitors and the others, (2) “safety clips” were inefficient, (3) pole handles that surround the hand were dangerous, (4) during the fall the hand must be prevented from being ejected with the thumb abducted, and (5) some parts of existing pole handles were dangerous.

The characteristics of an ergonomic downhill ski pole handle are suggested. The corresponding prototype is demonstrated.