bluuebunny/crossref_metadata_2025 huggingface dataset:
Ball Standards Relevant to Risk of Head Injury
Authors: Heald JH , Pass DA
Published: March 2009

Several baseball and softball physical properties relate directly or indirectly to the risk of head injury, namely size, weight, hardness, and liveliness. Rule book specifications for the official game balls in baseball and Softball specify the size and weight. Ball liveliness is sometimes specified. This study has evaluated the effects of ball hardness and liveliness on the risk of head injury in impact studies with humanoid head models, rigid head forms, and actual cadaver impact tests. The Severity Index (SI) and Head Injury Criteria (HIC) were both measured over a wide range of ball hardness and impact speeds. The risk of head injury was determined using the Prasad-Mertz risk curves. The results reveal a very strong relationship between ball hardness and head injury risk, ranging from 80% risk at 28.6 m/s (60 mph) for popular hard baseballs and softballs, down to 1% risk for softer balls now being used in some youth league programs. The cadaver impact tests confirmed that the humanoid head model and Severity Index injury criteria are well suited for the prediction of head injury risk for highly focal (concentrated in small area) blows from baseballs and softballs to the side of the unprotected head. Field test injury statistics show that the use of softer type baseballs in youth league play can reduce the incidence of ball impact injuries by about 70%.
Comparative Performance at Low Temperature of APP Modified Bituminous Membranes after Artificial and Natural Weathering
Authors: Cogneau P
Published: March 2009

Comparative performance at low temperature of APP modified bituminous membranes after artificial and natural weathering is described. For many years accelerated test methods have been developed to study the behavior of the roofing membranes. The objective is to analyze the correlation between samples obtained after heating for 28 days at 80°C and 6 months at 70°C and samples obtained from roofs in Sweden, Norway, Belgium, France and Spain. The correlation between the natural and accelerated weathering results reveals that climatic conditions play an important role in modifying the cold performance characteristics of the finish product. However, cold adhesive or torched application methods also have a significant influence on the results.
Thermally Induced Loads in Single Ply Membranes
Authors: Turenne RG , Stenman HK , Mech MN , Dutt O
Published: March 2009

Thermally induced loads in single ply, non-adhered membranes can exert considerable influence on their performance in cold weather. Accurate measurements, however, are difficult to obtain because of the composite nature of the materials. An apparatus was designed and constructed at NRCC that can test four specimens simultaneously for measuring induced loads. The environmental chamber is fitted with four sets of mini-grips and load cells. It is cooled by liquid nitrogen and controlled by a PID controller. The data are stored in a micro computer. Samples of non-reinforced EPDM and reinforced PVC were tested. Different testing protocols were used in order to determine which would provide the most reliable results. It was found that a faster rate of cooling tends to give lower values of load. Cooling in steps gave more consistent average values than lowering the temperature at a constant rate.
Monitoring Biocorrosion and Biofilms in Industrial Waters: A Practical Approach
Authors: Videla HA , Blanchi F , Freitas MMS , Canales CG , Wilkes JF
Published: March 2009

This paper describes a practical approach to the assessment of biotic and abiotic processes at the metal/solution interface, introducing a nonconventional multipurpose sampling device that can be used in a conventional side-stream corrosion rack. The complete monitoring program for biofilms and corrosion in water-using systems includes parallel field and laboratory measurements, in addition to the sampler exposures. This device can simplify collection of samples for biofilm and corrosion product analyses, facilitate field and laboratory studies for biocide selection, and provide a useful source of samples for assessing corrosion and biofouling effects in the system. Two practical cases, involving an industrial cooling water system and a secondary oil recovery water injection line, are briefly described to illustrate the effectiveness of the monitoring program.
Corrosion Resistance of Several Conductive Caulks and Sealants from Marine Field Tests and Laboratory Studies with Marine, Mixed Communities Containing Sulfate-Reducing Bacteria (SRB)
Authors: Jones-Meehan J , Vasanth KL , Conrad RK , Fernandez M , Little BJ , Ray RI
Published: March 2009

Due to seawater intrusion and moisture accumulation, corrosion of antenna foundations/ship's super-structure has been observed and was attributed to galvanic corrosion of the aluminum with the silver-based conductive caulk used for electromagnetic interference/ electromagnetic pulse (EMI/EMP) conductivity between the antennas and the ship's super structure. Several conductive caulks and sealants were field tested and evaluated to determine if the environment would degrade their performance, for the prevention of seawater intrusion, and to prevent potential failures due to corrosion. A nickel-based conductive caulk with a corrosion inhibitor (PRC 1764) performed well in all of the field tests over a period of 15 months. Because of the excellent corrosion resistance, adequate EMI/EMP and shielding characteristics, the nickel-loaded caulk with a corrosion inhibitor has been recommended for antenna applications. Among the sealants, GE RTV 157, GE RTV 167 and Product Research Corporation ProSeal 870 polysulfide performed well. GE RTV 157 is already in use for topside applications and its use is being continued.

Three conductive caulks (PRC 1764, PI 8500, PI 8505) were applied to 4140 steel coupons. Caulked coupons were exposed to five mixed, microbial cultures in the laboratory for 15 months. At the end of the exposure period, environmental scanning electron microscopy (ESEM) analyses were used to demonstrate that bacteria including sulfate-reducing bacteria (SRB) were found under the conductive caulks. In laboratory testing, there was water and bacterial intrusion which resulted in corrosion of the steel under the conductive caulk. The laboratory caulked samples were not covered with a sealant such as RTV as described previously for the field test samples.
Bench-Scale Predictions of Mattress and Upholstered Chair Fires: Similarities and Differences
Authors: Babrauskas V
Published: March 2009

The life safety hazard issues associated with flaming fires of mattress and up- holstered furniture are explored. It is shown that full-scale heat release rate (HRR) is the dominant variable which needs to be controlled. This can be determined directly by full-scale measurement. In many cases, full-scale tests are not convenient to conduct. Thus, it is desirable that bench-scale procedures be available which can be used to predict some of the important features of the full-scale test. Such procedures have been developed at NIST for upholstered furniture during several prior studies. In the present work, differences between the behavior of mattresses and of upholstered furniture are explored. Mattresses and upholstered chairs are soft goods which are constructed in a somewhat similar way: both use padding foams or battings, covered by upholstery fabric. There are differences in construction, however. Mattresses are flat, whereas upholstered chairs normally have seats, backs, and side arms. Also, an upholstered chair is constructed normally on a wood frame, whereas a mattress has no structural components, or else has steel innersprings. The quantitative knowledge of mattress behavior is still not as advanced as that for upholstered furniture. Nonetheless, based on a recent set of tests, the behavior of mattress fires can be quantified initially. Especially, data are now available to predict whether or not a particular mattress construction will lead to a propagating fire. Similarly as for upholstered furniture, such a limit value can be used to determine whether certain regulatory pass/fail criteria are met. The relationship obtained is incomplete, however, because the known roles of ignition source power level (that is, kilowatts output) and geometrical configuration are not yet quantified. Also, there is not yet a detailed explanation for differences between the observed relationships for mattresses and for uphol- stered chairs. Thus, future work will need to be done to address and further quantify these effects.
The Incidence, Types, and Circumstances of Injuries to Ice Hockey Players at the Bantam Level (14 to 15 Years Old)
Authors: Bernard D , Trudel P , Marcotte G , Boileau R
Published: March 2009

The objective of this investigation was to determine the incidence, types, and circumstances of injuries that occurred during the 1987/1988 and 1988/1989 hockey seasons. Five hockey leagues, three in the Québec region and two in the Outaouais region, were studied, and over 300 games were observed. Phase 1 consisted of establishing anthropometric (height and weight) and biomechanical (force of impact and maximal skating speed) profiles for each player. Phase 2 consisted of recording the circumstances surrounding each injury. This was accomplished through observers at games as well as through interviews with players after games or, in case of injuries requiring medical intervention in hospitals, through follow-up telephone conversations with seriously injured players. In all cases, information regarding diagnosis, causes, and circumstances surrounding the injuries was recorded on a recording form.

Important variations were found in the height and weight of players, with differences in range reaching 41 cm (16.4 in.) and 47.7 kg (105 lb), respectively. A 357% difference in the force of impact during body checking between the weakest and the strongest player was also observed. In terms of injuries, body checking caused 46.2% of all minor injuries, whereas the stick was responsible for 21%. Contusions were the most frequent type of injuries, whereas major injuries consisted of fractures and sprains. Body checking was identified as the cause of 75% of all major physical trauma recorded during both seasons. Coaches appeared not to be aware of most minor physical impairments of their players.
Stress Intensity Factor Solutions for Surface Cracks in Flat Plates Subjected to Nonuniform Stresses
Authors: Raju IS , Mettu SR , Shivakumar V
Published: March 2009

The case of a surface crack in a flat plate has received a lot of attention from the fracture mechanics community because of its practical applicability as an idealization of a flaw in structures. Among all the solutions available, those of Raju and Newman seem to be the most accepted and cover the widest range of geometric parameters. These solutions are, however, known only for the cases of tensile and bending loads, and include the effect of finite width using an empirical equation. Residual stresses and more complex forms of loading lead to nonlinear stress distributions across the thickness in real structures. Attempts were made by a few researchers to provide solutions for arbitrary loading using the weight-function and other methods, but a comprehensive treatment of these solutions is not available. The objective of the present work is to provide complete solutions including the effect of finite width using direct tabular inter polation of the finite-element results and to demonstrate the accuracy of a weight-function approach for computing stress intensity factors for a cracked plate subject to arbitrary stresses across the thickness. The reference solutions used in the weight-function scheme were obtained using the three-dimensional finite-element method (FEM). The full range of geometric parameters such as the crack-length-to-width ratio 2c/W, the crack-depth-to-thickness ratio a/t, and the aspect ratio a/c was covered so that accurate interpolation and extrapolation could be made for any given geometry. Piecewise cubic Hermite interpolation was used to compute the quantities corresponding to intermediate values of the geometric parameters. The new solution was compared with the earlier Newman-Raju equation. The new solution in tabular form was then used directly in the weight-function method. The stress intensity factor solution developed here was incorporated into the fatigue crack growth program NASA/FLAGRO, which is widely used by the aerospace community.
Elemental Analysis of Waste Oils by Inductively Coupled Plasma Mass Spectrometry
Authors: Williams MC
Published: March 2009

Environmental regulations specify the analysis of recycled oil for arsenic, cadmium, chromium, lead, and total halogens. Waste oils for disposal must be analyzed for arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver. Inductively coupled plasma mass spectrometry (ICP-MS) is a multielement technique with sufficient sensitivity to determine most metals and some nonmetals at the parts-per-billion level. Direct aspiration of the sample after dilution in a suitable solvent eliminates the tedious and potentially dangerous acid digestion process and the loss of volatile elements. The heat generated in the plasma and the addition of oxygen in the gas streams aid the breakdown of complexes of metals and the destruction of the organic matrix. The detection limits in a multielement analytical batch for elements of high mass [>80 atomic mass units (amu)] approach 5 to 50 μg/m3 for undiluted samples. Elements of lower mass suffer from isobaric or polyatomic interferences, which degrade detection limits.
Fatigue Strength Reduction Imposed by Porosity in a Fiberglass Composite
Authors: Dill CW , Tipton SM , Glaessgen EH , Branscum KD
Published: March 2009

Porosity, defined as voids in the matrix material, is a recurring anomaly in fiberglass and more advanced composite laminates. Although a variety of dependable nondestructive testing (NDT) methods are available for detecting porosity, reliable analytical techniques for assessing the fatigue strength reduction imposed by porosity are not currently available. Instead, manufacturers and analysts have historically relied on simple “rule of thumb” strength reduction factors based on monotonic tension tests, a typical reduction being 20%.

With an increasing emphasis on the effects of age and fatigue on high time aircraft, the question arises as to the adequacy of static strength tests alone to assess the effects of porosity. This paper discusses the results of a testing program in which porous and nonporous [0,90]s fiberglass specimens are cycled in zero to maximum (R = 0) loading over life ranges from a few hundred to a few million cycles. The degree of porosity is estimated from visual examination of the edges of each specimen. Flat specimens approximately 2.8 mm thick were prepared by laser cutting with the edges then sanded to remove the heat-affected region. For comparison, several specimens were also milled using a template. Results of the tests are presented in terms of maximum stress versus number of cycles to complete separation. The data indicate that fatigue strength reduction can be significantly greater than 20% for lower fatigue lives and close to 20% at lives of a few million cycles. If the voids are assumed to constitute stress concentration factors that accelerate the breakdown of the matrix material, then a fatigue strength reduction factor of about 1.5 to 1.2 may be inferred from the data. This compares favorably with the results of a finite element analysis on a typical internal void.
Total System Approach to Predict Shelf Life of Packaged Food Products
Authors: Gyeszly SW
Published: March 2009

A total system approach should be used to simulate the shelf life of packaged food products. The main advantage of modelling the product-packaging-distribution system is in helping to make proper decisions during product and packaging development.
Extended Laboratory Testing for Two Structural Glazing Silicone Sealants
Authors: O'Connor TF , Panek JR
Published: March 2009

The owner of an eighty story building was concerned that insufficient extended laboratory durability testing information was available for two silicone structural glazing sealants proposed for use on the new building curtain wall. A two phase laboratory testing program was conducted to resolve these concerns.

Phase I involved testing for durometer and weight loss after extended heat aging by ASTM C661 and C792, cyclic movement after extended exposure in a weatherometer by ASTM C719, and adhesion-in-peel after extended water immersion by ASTM C794. Also, the pull-off strength of the organic coating, that the structural sealants were adhered to, was tested by ASTM D4541. Phase II used glazed components of the curtain wall for mock-up testing to destruction, to determine the ultimate strength of the structural silicone sealant joint by ASTM E330.

Phase I testing indicated that the extended laboratory exposures did not result in any detrimental changes to the properties of the sealants. Also, the pull-off strength of the organic coating exceeded the strength of the structural sealants. Phase II testing indicated that the ultimate strengths of the structural sealants exceeded manufacturer's published strengths.
New Tests for Adhesion of Silicone Sealants
Authors: Gutowski VS , Russell L , Cerra A
Published: March 2009

It has been widely accepted that the ASTM C-794 peel test is suitable for determining adhesion between the sealants and substrates used in curtain wall construction. However, it is shown in this paper that this test has certain deficiencies which may allow the acceptance of some materials which in fact have poor initial adhesion and long-term durability.

The influence of the specimen's geometry, sealant type, sealant thickness, cross-head speed (test rate), etc, on the resultant failure mode and quantitative results are discussed in detail.

Finally, two novel adhesion tests are proposed and discussed, i.e.: (a) ‘thin’ peel specimen test (b) ‘thin’ lap-shear specimen test.

Comparative results, obtained using a range of common commercially available sealants, show that the proposed tests have significant advantages over the accepted ASTM C-794 test as well as the DIN 52455 and ISO/DIS 9047 tests.
Use of the Constrained Blister Test to Study Sealant Adhesion
Authors: Klosowski JM , Dent SJ
Published: March 2009

An attempt was made to modify the constrained blister test as designed and reported by Dr. David A. Dillard of Virginia Polytech. (VPI) and independently by Dr. A. (Sam) Moet of Case-Western Reserve Univ. to apply to sealants. The test device is detailed and modifications of the device to make it applicable to mullions and samples collected from the field are explained. Variables such as sealant thickness, distance between sealant and the constraining plate and the rate of pressure were also studied. The data from the constrained blister is compared to the peel test and the lap shear test. Lastly the validity of the test modifications as indicated are discussed.
The Influence of Gloss Level in Polyester-Powder Coatings on the Adhesion of Silicone Sealants
Authors: Gutowski VWS , Cerra A , Russell L
Published: March 2009

It has been frequently observed that the strength of adhesion between silicone sealants and polymer-coated substrates depends on the coating's gloss level.

The study described in this paper reveals that there seems to be a relationship between the gloss and the coating's surface properties as determined by the non-dispersive, γn-d, component of the total surface energy. It is shown that gloss increase is associated with an increase in the substrate γn-d. The exact pattern of this relationship cannot yet be established due to the narrow range of experimental data. Experiments carried out with several commercially available silicone sealants show that the higher the coating's gloss level, the stronger the adhesive bond between the sealant and the substrate. This finding is shown to be consistent with the earlier proposed mechanism of adhesion, according to which an increase in the value of the non-dispersive component of the substrate total surface energy leads to increased bond strength to the point where adhesive forces become stronger than the cohesive strength of the bulk sealant.
Difficult Sealant Joints
Authors: Nicastro DH
Published: March 2009

Many premature sealant failures occur in joints which differ from the “archetype” -- the common parallel-sided, uniform, panel-to-panel expansion joint, with an hour-glass sealant profile. Parameters are discussed for obtaining good long-term performance from non-classical types of weatherseal joints. The conditions which are addressed include problems with substrate surface profile, intrinsic properties of substrates, joint shape, and dimensions. Also presented is a summary of the considerations in preventing premature sealant failure which are common to all types of exterior weatherseal joints.
Factors Governing the Life-Expectancy of Dual-Sealed Insulating Glass Units
Authors: Wolf AT , Waters LJ
Published: March 2009

The water-vapor permeability of the secondary insulating glass sealant plays only a subordinate role in the life-expectancy of a dual-sealed insulating glass unit, since the resistance of the edge-seal to water-vapor diffusion is determined almost exclusively by the low water-vapor permeability of the polyisobutene (PIB) primary seal. On the other hand, great importance must be attached to the viscoelastic properties of the secondary insulating glass sealants, particularly to their tensile stress behavior and their elastic recovery, as these properties affect the ability of the primary seal to function.
Fraction of the Global Normal Irradiance Incident from the Northern Part of a Clear Sky
Authors: Pernisz UC , Klosowski JM
Published: March 2009

The luminous flux received from a clear blue sky at the north side of a building was determined relative to the global normal illuminance with a commercial photometer using a hemispherical diffusor. Measurements with narrow band interference filters were also made to obtain information on the ratio of these quantities in the violet and blue parts of the visible spectrum. It was found that the blue sky provides 6.3% of direct sunlight at a wavelength of 370 nm. In comparison, a value of 4.7% was found for the luminous flux (not spectrally resolved).

It is concluded that materials which degrade principally by absorption of UV light will last approximately 15 times longer on the north side of a building than when fully deployed on a southern exposure.
Estimation of Fatigue Propagation Life in Resistance Spot Welds
Authors: Sheppard SD
Published: March 2009

The main objective of this research is to develop a model of fatigue crack propagation in resistance spot welded joints. An important feature of this development is that the model should be usable by designers considering fatigue response of structures containing multiple welds. This objective is achieved by examining the stress state around a load bearing resistance spot weld. A general expression for the structural stress around the weld is formulated that is dependent only upon the loading immediately surrounding the weld and is therefore independent of specimen design.

In previous work [1], it was found that structural stress could be successfully used to estimate life for crack initiation and growth to a length of 0.25 mm in resistance spot welds (RSW), and that this period represents less than 30% of the total life in as-welded joints. It is important to note that estimation of this period is highly dependent on fatigue related material properties.

In the current work, structural stress is related to crack propagation life through linear elastic fracture mechanics. Life estimates are made using the resulting relationship between structural stress and life. These estimates are compared with experimentally measured lives of welds in HSLA steel. A variety of specimen configurations are considered (e.g., tensile-shear, coach peel) in a number of conditions (e.g., as-welded, pre-stressed). Estimations are all within a factor of three of measured lives.

This approach to life estimation uses simple finite element representations of the weld connection to calculate structural stress. It is therefore appropriate for use by designers/analysts making life estimations based on finite element representations of structures containing multiple spot welds.
A Reverse Plasticity Criterion for Specifying Optimal Proof Load Levels
Authors: Tipton SM , Sorem JR
Published: March 2009

It is well known that the fatigue strength of certain engineering components can be enhanced by the application of overloads. Extended fatigue life can occur when components with stress gradients at critical locations (e.g., bending or the presence of a stress concentration, or both) are service loaded positively in one direction following an overload in the same direction. Localized plasticity can result in residual compressive stresses that combine with the applied service stress history to enhance fatigue life.

For a component with a stress concentration (notch), guidelines are presented for specifying an “optimal” overload level based on the elastically calculated severity of the notch and the axial stress-strain behavior of the material, characterized by a Ramberg-Osgood relation. An algorithm is presented based on standard notch strain analysis techniques (Neuber's Rule and the strain energy density approach) and the concept of a reverse plasticity criterion. Use of the algorithm is demonstrated by generating examples of design curves for engineering steels. One version of the algorithm, based on a Neuber analysis, suggests that the optimal overload level is a function of only the yield strength of the material and independent of the strain hardening exponent. The results presented in this paper approximate situations where notch root constraint is small or negligible. However, the approach can be extended to account for multiaxial constraint on notch root deformation. Although the algorithm and criterion attempt to maximize the local compressive stress, supplemental analyses are required to assure that fracture or gross plastic deformation, or both, are avoided. Limitations to the approach are discussed and modifications are suggested with regards to the Bauschinger effect. The approach does not attempt to address the maintainability of the residual stress during subsequent fatigue loading and experimental data for direct comparison to the approach do not currently exist.
Fabrication of Zr-2.5Nb Pressure Tubes to Minimize the Harmful Effects of Trace Elements
Authors: Theaker JR , Choubey R , Moan GD , Aldridge SA , Davis L , Graham RA , Coleman CE
Published: March 2009

Trace elements can reduce the fracture resistance of Zr-2.5Nb pressure tubes. The effects of hydrogen as hydrides and oxygen as an alloy-strengthening agent are well known, but the contributions of carbon, phosphorus, chlorine, and segregated oxygen have only recently been recognized. Carbides and phosphides are brittle particles, while chlorine segregates to form planes of weakness that produce fissures on the fracture face of test specimens. A high density of fissures is associated with low toughness. With long hold times in the (α + β) region, oxygen partitions into the α-grains; such grains are hard and, if they survive fabrication, may reduce the toughness of the finished tube. Through a cooperative program involving AECL and the manufacturers, a series of manufacturing innovations and controls has been introduced that minimizes these harmful effects.

Hydrogen is present in the zirconium sponge as water, can be absorbed at each stage of tube fabrication, and needs to be carefully controlled, particularly during ingot breakdown and subsequent forging. Hydrogen concentrations in finished tubes have been reduced by a factor of three through the optimization of manufacturing processes and the implementation of new technology. Multiple vacuum arc melting, use of selected raw materials, and intermediate ingot surface conditioning have resulted in much improved fracture toughness through the reduction of chlorine and phosphorus concentrations. Optimum distribution of oxygen may be achieved through changes to the extrusion process cycle. An understanding of the Zr-2.5Nb-C phase diagram, particularly the solubility of carbon at low concentrations, has resulted in the specification of a lower carbon concentration.
Corrosion Behavior of Zircaloy-4 Cladding with Varying Tin Content in High-Temperature Pressurized Water Reactors
Authors: Garde AM , Pati SR , Krammen MA , Smith GP , Endter RK
Published: March 2009

Fuel rods clad with Zircaloy-4 with varying tin contents (1.33 to 1.58% Sn) and annealing parameters (1.0 to 4.1 × 1017 h with Q/R = 40 000°K) were irradiated in demonstration fuel assemblies in a high-temperature pressurized water reactor (PWR) to burnups in excess of 35 giga watt days per metric ton of uranium (GWd/MTU). The same cladding variants were subjected to long-term static water autoclave tests at 633°K of duration greater than 1100 days. Production fuel rods fabricated with low-tin (1.33 Sn) and high-tin (1.55 Sn) Zircaloy-4 cladding were also irradiated in regular fuel assemblies in two high-temperature PWRs to burnups up to 48 GWd/MTU. Poolside cladding oxide thickness measurements were conducted on 167 high-tin rods and 67 low-tin rods during refueling outages. The measured, circumferentially averaged, peak cladding oxide thickness values ranged from 3 to 113 μm. At high burnups, the oxide thickness on low-tin cladding was 30 to 40% lower than that on high-tin cladding. The long-term autoclave results also showed the beneficial effect of lower tin level on the corrosion rate, although to a lower degree than in PWRs. The 633 K water autoclave test appears to rank the corrosion resistance of the investigated Zircaloy-4 variants in the same order as in PWRs. Hydrogen analysis results indicate that tin level does not influence the hydrogen uptake of autoclave-tested samples. The observed in-PWR influence of tin level on the Zircaloy-4 cladding corrosion rate was incorporated in the ESCORE clad corrosion model by adjusting the pre-exponential term in the post-transition corrosion rate equation.

A corrosion rate acceleration at high burnups may be related to either hydride precipitation at the metal oxide interface or to degradation of the oxide thermal conductivity. The observed effect of tin on the uniform corrosion resistance of Zircaloy-4 in high temperature water is consistent with the corrosion mechanism that assumes the migration of 02- anion vacancies through the oxygen deficient zirconia to be the rate-controlling process. It is postulated that lower tin level in Zircaloy-4 decreases the vacancy concentration in the oxide and, thereby, increases the corrosion resistance. It may be possible to further improve the corrosion resistance of low-tin Zircaloy-4 by optimizing the nitrogen and tin concentrations in Zircaloy.
Clay Soil Heave Caused by Lime-Sulfate Reactions
Authors: Mitchell JK , Dermatas D
Published: March 2009

Reactions between lime, alumina released from clay during pozzolanic reactions, and sulfates present in some soils (causing the formation of the highly expansive crystalline mineral ettringite) have been responsible for the deterioration and ultimate failure, by expansion, of several lime stabilization projects.

The mechanisms for these reactions were hypothesized, and a laboratory research program using lime-treated artificial soil samples of compacted kaolinite-sand and montmorillonite-sand mixtures, incorporating known amounts of sulfates, was designed and undertaken. The strength, swelling, compositional, and micromorphological characteristics of the treated samples were determined following different curing times and soaking conditions.

Ettringite formation was evidenced in all lime-treated samples, whenever sulfates were present. A non-expansive monosulfate calcium-aluminum-hydrate forms first in the high alumina content lime-treated kaolinite-sand mixes. The monosulfate converts to an expansive trisulfate form (ettringite), after a period of a few months. Conversely, ettringite starts to form at the early curing stages (after a few days) in the low alumina lime-treated montmorillonite-sand mixes.

It was found that the amount of heave following ettringite hydration and growth is a function of the amount and rate of release of alumina into solution. The amount and type of sulfates present is also a factor influencing the quantity and crystal morphology of ettringite formed. Moreover, temperature and humidity fluctuations were also found to play an important role in the overall ettringite-related heave mechanism, as they affect reaction rates, solubilities of species, and the overall stability fields of a soil system's components.

Continuing research will extend the results reported here to a more quantitative specification of conditions leading to deleterious reactions in lime stabilization applications. Concurrently, treatment methods that may prevent such adverse reactions are being explored.
Some Results from Ongoing Research on Road Roughness
Authors: Hegmon RR
Published: March 2009

Road roughness can be described by two dimensional profiles in the direction of travel. These profiles are used for driving actuators for vehicle testing and dynamic computer simulations. Road roughness affects primarily ride quality and dynamic wheel loads. The effects of dynamic wheel loads on the stresses in the pavement and subsequent effect on pavement life is the subject of current research at the FHWA (Federal Highway Administration).

This paper presents a review of the extensive work done over the years in the Pavement Division of the Office of Research of FHWA and some recent results on road roughness profiling and on pavement response to dynamic loads. Current and planned work is described in some detail. The current interest is on the interactions between rough pavements and heavy trucks. Field and laboratory measurements, and computer simulations to predict the interaction forces are discussed. Distribution of strains and deflections under passing truck wheels are shown for different test conditions.
Pavement Damage as Related to Tires, Pressures, Axle Loads, and Configurations
Authors: Sebaaly PE
Published: March 2009

Dual radial tires and wide base radial single tires were tested in the laboratory under three levels of inflation pressures and axial loads. The measured characteristics of the tires were gross contact area, net area, tire deflection, and contact pressures. The distributions of contact pressures were used in a theoretical analysis to evaluate the flexible pavement performance related parameter. The response of two flexible pavement structures was investigated in terms of the tensile strains at the bottom of the asphalt layer. In the second phase of this research, two full scale pavement sections were instrumented using strain gages to measure the strains at the bottom of the asphalt concrete layer. The data analysis presented in this paper shows the effect of varying the tire type, tire inflation pressure, and axle load and configuration on the response of flexible pavements. The results of the two studies showed that the wide base single tires are more damaging than the dual tires under all combinations of the test variables.
Test Methods and Applications for Slurry Erosion — A Review
Authors: Clark HM
Published: March 2009

The contribution of laboratory tests to understanding the rate and distribution of erosion by slurries in industrial hardware is reviewed. The unifying principle that erosion rate must depend on the rate of dissipation of particle kinetic energy on the target is emphasized. The application of laboratory test results to wear in centrifugal pumps and to slurry pipelines is evaluated and it is noted that reliable, quantitative information on mass removal as a function of the rate of particle impact or the motion of particles in an abrasive bed is required. Laboratory erosion tests have been widely used to determine material rankings and to examine the effect of some experimental variables, but have not yielded information on the frequency and velocity of particle impact. Such information is now available through suspension flow modelling of laboratory test geometries. This approach allows the prediction of changes in erosion rate with changes in test variables and hence can provide the required quantitative data for industrial application. The need for further laboratory work to understand the energetics of material removal by sliding particle beds is emphasized.
A Stratified Air Model for Simulation of Attic Thermal Performance
Authors: Parker DS , Fairey PW , Gu L
Published: March 2009

An improved computer simulation model for attics has been developed. The model accounts for detailed radiation, buoyancy and wind driven air flows and thermal stratification within the attic airspace. Through comparison with measured data, the paper examines the relative importance of the various modeling parameters and assumptions upon simulation accuracy. Stratification of the attic air was found to be a critical modeling characteristic which is typically ignored in building energy simulations. Both model and measurement results show that air stratification increases significantly when low-emittance surfaces are included.
Thermal Performance of HCFC-22 Blown Extruded Polystyrene Insulation
Authors: Yarbrough DW , Graves RS , Christian JE
Published: March 2009

A closed-cell foamboard insulation containing chlorodifluoromethane (HCFC-22) has been monitored in the laboratory and in the field for about three years. Experimental data for this developmental extruded polystyrene insulation has been obtained in two laboratories using three apparatuses. A correlation of apparent thermal conductivity with time gives the thermal resistivity of the two-inch-thick unfaced foamboards to within 3% with 95% confidence. A thermal resistivity of 30.2 m∙K/W (4.36 ft2∙h∙°F/Btu∙in) was calculated from the correlation for time equal 180 days after manufacture. Based on three years of data, the predicted thermal resistivity is 27.6 m∙K/W (3.98 ft2∙h∙°F/Btu∙in) as time since manufacture becomes large. Field measurements confirm the decrease with time of the thermal resistivity that was observed in the laboratory.

A three-dimensional model for heat transfer through foamboard was used to predict thermal resistivity as a function of time. A comparison of the experimental results with the model shows a radiative contribution to the total heat flux of about 30%. A one-dimensional model was used to show the effect of initial foamgas pressure and thickness on thermal performance.
Experimental Test Results of Interior Vs. Exterior Insulation in Extremely Hot Climates
Authors: Al-Mofeez I , Woods PK
Published: March 2009

Three room-sized building modules were constructed in Elhasa, Saudi Arabia during the summer of 1988. These test modules were identical except for the manner in which they were insulated. One had no insulation, another had insulation on the exterior surface of the exterior walls, and a third had insulation on the inside surface of the exterior walls. Hypotheses were developed and tested based upon an equation expressing the anticipated relationship of lifecycle costs among these three test modules. The equation is: Lifecycle cost (E) < Lifecycle cost (I) < Lifecycle cost (U); where (E) is exterior insulated condition, (I) is interior insulated condition, and (U) is uninsulated condition.

To estimate present worth and equipment size, MRT field measurements were used to fine tune an hour-by-hour energy simulation program called ENERCALC. The thermal characteristics of the buildings were entered along with the annual weather data for the site of the experiment. The buildings' annual heat gains and losses, peak heat gains and losses, summer hourly air-conditioning demand profile, and the present worth of each building were then compared. The comparison indicated that the life-cycle cost of the externally insulated building was the lowest among the three buildings.
Gas-Filled Panel High-Performance Thermal Insulation
Authors: Griffith BT , Arasteh D , Selkowitz S
Published: March 2009

This paper introduces a new high performance non-CFC based insulating material with primary applications for refrigerator/freezer and building walls. Characteristics of these gas-filled panels, projected and experimental thermal performance levels, cost estimates, and manufacturing/installation issues for this material are discussed. Independent testing of prototypes has yielded R-values of 36 m-K/W (5.2 hr-ft2-F/Btu-in) for air filled panels, 49.3 m-K/W (7.1 hr-ft2-F/Btu-in) for argon filled panels, and 86.8 m-K/W (12.5 hr-ft2-F/Btu-in) for krypton filled panels. Target R-values values are 36 m-K/W (5.2 hr-ft2-F/Btu-in), 55 m-K/W (8 hr-ft2-F/Btu-in), and 105 m-K/W (15 hr-ft2-F/Btu-in) for air, argon, and krypton filled panels, respectively. Manufacturing costs depend strongly on gas-fill and structural requirements and are estimated at 42 to 850 $/m3 (0.10 to 2.00 $/ft2-in). This insulation system can be fabricated using commercially available materials and equipment.
Aerogel — A High Performance Insulating Material at 0.1 Bar
Authors: Hunt AJ , Jantzen CA , Cao W
Published: March 2009

Silica aerogel is a low-density, transparent and porous solid that achieves vacuum-like insulating performance at a very modest vacuum (0.1 bar). Research is under way to further improve the thermal performance of this already highly insulating material by reducing the internal radiative heat transfer. The thermal resistance of aerogel is increased by adding infrared absorbing compounds to reduce the radiative heat transfer within the aerogel. Aerogel samples were prepared and their infrared transmission spectra were measured. After suitable materials and preparation methods were evaluated, an evacuated aerogel panel was prepared for thermal conductivity measurements. The measurements performed on this panel demonstrated significant increases in thermal performance over similar panels without opacification agents. Enhanced aerogel insulation has the potential to displace the current use of chlorofluorocarbons (CFCs) in refrigerator, and other appliances, thereby reducing the CFC damage to the ozone layer while producing significant gains in energy efficiency.
Field Performance, Hydrolysis and Durability of Urea Formaldehyde Foam Insulation in Australian Dwellings
Authors: Brown SK
Published: March 2009

Durability and field performances of urea formaldehyde foam insulation (UFFI) in Australian dwellings and the physical and chemical properties important to these performance have been investigated by a combination of field inspections and product sampling, a postal survey of building problems and occupant complaints, formaldehyde gas concentration measurements and laboratory assessment of product behaviour. Products gathered in the field exhibited large differences in physical and chemical properties and stability. Ill effects have been reported to Health Departments by occupants in 0.2% of installations and were typical of those known to result from exposure to formaldehyde gas, showed strong association to building occupancy and may have been associated with poorly formulated and unstable products. Laboratory assessment of commercial products showed that all products hydrolysed, lost strength and emitted more formaldehyde gas under high humidity conditions. However, only products with high acidity exhibited dimensional instability, some exhibiting linear shrinkage of more than 30% after only short periods of exposure to high humidity.
Experience with J Testing of Type 304/308 Stainless Steel Weldment
Authors: Graham SM , Lloyd WR , Reuter WG
Published: March 2009

Crack initiation toughness tests were conducted using the J-integral as a fracture characterizing parameter according to the ASTM Test Method for JIc, a Measure of Fracture Toughness (E 813-87). The specimens were made from a weldment of Type 304 stainless steel (SS) base metal and Type 308 SS weld metal, and were fabricated such that the crack initiation toughness (JIc) of the weld metal could be measured. A peculiar feature of all of the tests was that crack growth occurred in an inverse tunneling mode. The provisional initiation toughnesses (JQ) calculated from the test results were determined to be invalid because the validation requirements on change in crack front curvature and on accuracy of the predicted crack extension were not met. The accuracy of the predicted extensions was improved by applying correction factors to the last measured compliances to account for crack front curvature, plastic deformation, friction, and indentation. The excessive change in crack front curvature was caused by the transition from tunneling growth during fatigue precracking (before the specimens were side grooved) to inverse tunneling during slow stable crack growth. Crack growth by inverse tunneling indicates a constraint condition at the root of the side-grooves that is more severe than in the center. If this is the case, the measured initiation toughness should be a valid indication of the lower bound for high constraint.
Low-Frequency Shear Wave Logging in Unconsolidated Formations for Geotechnical Applications
Authors: Kaneko F , Kanemori T , Tonouchi K
Published: March 2009

There are four kinds of methods used in low-frequency shear wave logging. They are the downhole method, uphole method, cross-hole method, and suspension PS logging. Among these methods, the downhole method is commonly used in Japan. Hundreds of shear wave measurements using the downhole method have been carried out since it was established in the 1970s.

Suspension PS logging is a recently developed method in which a nonsymmetric seismic source and two receivers are built into a single probe. Source-to-receiver spacing is 2 and 3 m and the logging frequency ranges from 100 to 1000 Hz. Shear waves generated by the seismic source in the probe are detected with the receivers installed 1 m apart, and the shear wave velocity is calculated from the difference of the arrival time between the two receivers. Because the distance between the two receivers is fixed in the probe and the shear wave source produces a repeatable signal, velocity values obtained by suspension PS logging have less errorsxompared with the other methods.

Shear wave velocity measurements have important applications in earthquake engineering. In this paper, shear wave velocity measurements are shown to give a useful indication of soil liquefaction potential and shear moduli that can be used to predict the amplitude of surface soil motions during earthquakes.