bluuebunny/crossref_metadata_2025 huggingface dataset:
Facilitating Cold Climate Pavement Drainage Using Geosynthetics
Authors: Raymond GP , Bathurst RJ
Published: April 2008

Good highway drainage has been recognized for many centuries. The theoretical concepts are simple and the technology applicable to highways built today (1999) is widely available in the technical literature. It is widely understood that efficient drainage is essential to good highway performance independent of aggregate compacted density or aggregate stability. While the theoretical concepts are simple they are often not effective in cold climates. Indeed, for cold climates, these simple concepts are shown by field excavations described herein to be lacking in a number of aspects. Based on field excavations and performance of some selected Ontario highway locations, involving both clay and sand subgrades, recommendations are presented for the design detailing, selection and installation of geosynthetic edge drains. Installation at the investigated sites was by various techniques that included: ploughed-in-place, trench excavation, and mechanical trencher and boot. All excavated edge drains were installed as retrofits either at the time of the original pavement construction or several years later. The retrofits used the existing excavated/displaced shoulder granular material as backfill. Frost action, despite what was considered good drainage practice at the time of installation, is shown to have had a major effect on field performance.
Development of a Performance-Based Specification (QC/QA) for Highway Edge Drains in Kentucky
Authors: Fleckenstein LJ , Allen DL
Published: April 2008

The Kentucky Department of Highways (DOH) has been trying to remove water from its pavements since the early 1970s. Aggregate-filled trenches were used to remove water in the early 70s and perforated pipe edge drains were introduced in the mid-1970s. These systems remained relatively unchanged until the late 1980s. In 1987, after a number of localized pavement failures throughout Kentucky, the Kentucky Transportation Center (KTC) and the Kentucky DOH started evaluating the effectiveness and performance of these edge drain systems. It was found that most of the panel edge drains were significantly damaged during installation and that approximately 50% of the outlet pipes were crushed and/or the headwalls were clogged. As a result of these findings, several design changes were made in 1989. Research conducted between 1989 and 1991 indicated that the performance of the system had improved but failures still existed. In 1997, after the completion of an in-depth research study on the performance and construction of these systems the Kentucky DOH required that all edge drain outlets be inspected with a pipeline inspection camera. The contractor was made responsible for inspecting and repairing his own work. This was the early stages of a quality control (QC) program for edge drains in Kentucky. The camera inspections decreased the number of edge drain outlet failures from approximately 20% to approximately 3% to 5%. Of the 3% to 5% found damaged, the contractor was responsible for complete repairs. Current failure rates for mainlines are approximately 2%. At this time only 1/3 of the mainline is being inspected (headwall to approximately 150 ft into the mainline). In May 1998, the Kentucky DOH established a mission to incorporate quality into their construction projects by transitioning, where possible, from method specifications to QC/QA, performance related, warranty, and other innovative specifications for the year 2000. In 1998, a team was formed to evaluate the current edge drain specification and make recommendations and revisions towards a full fledged QC/QA specification. This paper discusses the historical performance of edge drains in Kentucky and the recent changes in the specification.
Influence of Test Apparatus on the Measurement of Transmissivity of Geosynthetic Drains
Authors: Chew S-H , Wong S-F , Teoh T-L , Karunaratne G-P , Tan S-A
Published: April 2008

The transmissivity of geosynthetic drains differs significantly under different test conditions. Test conditions can vary in terms of confining medium, the length of the specimen, and the direction of flow and properties of the fluid. This paper presents the findings on the determination of transmissivity of two prefabricated vertical drains and a geonet obtained using two different test apparatus. The first apparatus, in accordance with ASTM, comprises two stiff platens which press directly against a 300-mm-long specimen placed horizontally between two foam rubber layers. The second apparatus involves the use of compressed air which acts as the confining medium on a specimen enclosed in an elastic membrane. Flow of de-aired water for this setup is vertically upward. This paper seeks to compare objectively the differences in the performance of these two drainage testing apparatus for planar geosynthetic drainage products. A comparative study of the transmissivity of the prefabricated vertical drains and geonet under different test conditions is also presented.
Sampling and Analysis of Beryllium at JET: Policy Cost and Impact
Authors: Campling D , Patel B
Published: April 2008

This paper describes the sampling and analysis of beryllium at the Joint European Torus (JET) fusion facility. The current policy requiring 100 % personal air sampling (PAS) and taking many surface contamination smears generates 40,000 samples per year. Sample processing, analysis, and the quality assurance (QA) program are described. Costs are summarized to derive a cost per sample of ≈£4.2 ($8). This is economical but as 99.8 % of PAS measurements are < 2μg/m3 and the aggregated costs are high, reviewing the policy is justified. The disadvantages of the present strategy, the options for a change of policy, and the role that an accredited real-time analysis instrument could play are discussed. Retrospective analysis affects the machine operating time; a quicker technique would have a significant impact on improving experimental time. The project's experience is that turnaround times of 2–6 h can be routinely achieved for large numbers of samples.
Shadow Corrosion Mechanism of Zircaloy
Authors: Lysell G , Nystrand A-C , Ullberg M
Published: April 2008

The mechanism of Zircaloy shadow corrosion was studied theoretically and experimentally. The theoretical study showed shadow corrosion, with a few exceptions, to be remarkably consistent with a galvanic corrosion mechanism. The exceptions may be explained as radiation effects. An experiment was therefore devised to test the galvanic hypothesis, based on the fact that galvanic corrosion requires a closed current loop. Three pieces of Zircaloy cladding with stainless steel counter electrodes were exposed in-pile. Two of the claddings were galvanically coupled to the counters. The third cladding was well insulated by fitting it to a 100 mm sapphire tube. The claddings were irradiated together in oxidizing water chemistry for one reactor period. The galvanically coupled claddings developed shadow corrosion, but not the well insulated cladding.
TEM Examinations of the Metal-Oxide Interface of Zirconium Based Alloys Irradiated in a Pressurized Water Reactor
Authors: Abolhassani S , Restani R , Rebac T , Groeschel F , Hoffelner W , Bart G , Goll W , Aeschbach F
Published: April 2008

Metal-oxide interfaces of three different materials irradiated in a pressurized water reactor have been analyzed by TEM and AEM. Standard Zircaloy-4. low-tin Zircaloy-4. and Zr-2.5%Nb were used for this study. The microstructure of the material on the two sides of the metal-oxide interface, the geometry of the interface, the distribution of different alloying elements, and the oxygen profile have been examined in each material. Results of the examinations showed that the three materials had different microstructure and oxygen distribution on the two sides of the metal-oxide interface. In particular, the following parameters were noticed: a) the geometry of the interface seems to be of a different nature in the case of Zr-2.5%Nb alloy. Unlike the Zircaloy-4 alloys, which show an undulated interface, this material has a “jigsaw” type interface. This point is discussed, and its role on the oxidation is considered, b) Hydrides are observed and analyzed in the vicinity of the interface in the case of low-tin Zircaloy-4, and it is shown that they can have an influence on the occurrence of cracks in this material, c) The origins of stress are discussed, and it is shown that it can have different sources. The crystal structure of the oxides is mainly monoclinic. A tetragonal oxide is observed at some regions, in particular in the standard Zircaloy-4.
Mechanical Properties of Zircaloy-4 PWR Fuel Cladding with Burnup 54-64MWd/kgU and Implications for RIA Behavior
Authors: Desquines J , Cazalis B , Bernaudat C , Poussard C , Averty X , Yvon P
Published: April 2008

The PROMETRA material testing program is a support program related to the study of high burnup fuel rod behavior under Reactivity Initiated Accidents (RIA) and to the interpretation of the CABRI REP-Na RIA test results. Hoop and axial tensile tests have been performed on fresh and irradiated Zircaloy-4 cladding alloy first at CEA Grenoble hot labs and now at CEA Saclay in order to assess the cladding mechanical behavior during RIA transients. Efforts have been continuously carried out in order to improve the prototipicallity of the tests for RIA studies involving new specimens and new testing techniques. The corrosion level of irradiated specimens reached up to 130 μm of oxide layer thickness. The influence of in-pile oxide layer spallation has also been addressed. High strain-rate material properties of irradiated Zircaloy-4 and the consequences of hydride embrittlement can be derived from the PROMETRA program.
Metallurgical Attachment of a Porous Tantalum Foam to a Titanium Substrate for Orthopedic Applications
Authors: Medlin DJ , Scrafton J , Shetty R
Published: April 2008

A porous tantalum foam (Trabecular Metal™) has been successfully attached to a titanium substrate for an orthopedic acetabular cup application by two different methods: sintered powder processing and diffusion bond processing. A metallurgical evaluation of the interfaces between the tantalum foam and the titanium substrates has been performed, as well as long-term corrosion immersion tests to evaluate the susceptibility of the materials and design to crevice corrosion attack. The sintered powder attachment method used sprayed titanium powder at the interface between the tantalum foam and the titanium substrate. The assembly is sintered at high temperature to form a metallurgical bond between the sintered titanium powder and the titanium substrate and a predominately mechanical interlock between the sintered powder and the tantalum foam. The diffusion bond attachment process used time, pressure, and temperature to form a metallurgical bond between the tantalum foam and the titanium substrate by solid state diffusion. Both methods formed acceptable bond strengths with no evidence of corrosion attack from the corrosion immersion tests.
Mechanical Properties of Cast Ti-Fe-0-N Alloys
Authors: Koike M , Guo Q , Brezner M , Fujii H , Okabe T
Published: April 2008

A recent addition to existing titanium alloys is the Super-TIX™ series (Nippon Steel Corp., Japan), which has intermediate strength between the strengths of CP Ti and Ti-6A1-4V as a result of balancing the Fe, O, and N concentrations. Two alloys in this series were investigated: Ti-l%Fe-0.35%O-0.01%N (Super-TIX800™; LN) and Ti-l%Fe-0.3%O-0.04%N (Super-TIX800N™; HN). These alloys were arc-melted and cast using an investment casting method, and their mechanical properties were examined. The yield strength (∼600 MPa) and tensile strength (∼680 MPa) were approximately 33 and 29° higher, respectively, than the corresponding strength of cast CP Ti (ASTM Grade 2). Their percent elongation was somewhat (but not significantly) higher (2–3 %) than that of Ti-6A-4V. On the other hand, the elongation of CP Ti was approximately 7 %. The moduli of elasticity of the alloys ranged from 100–120 GPa. These Ti-Fe-O-N alloys exhibit higher uniaxial yield and tensile strengths than CP Ti, which is currently used for dental applications.
Corrosion Resistance, Mechanical Properties, Fatigue Properties, and Tissue Response of Ti-15Zr-4Nb-4Ta Alloy
Authors: Okazaki Y , Gotoh E
Published: April 2008

Ti, Zr, Nb, and Ta are biocompatible elements. A Ti-15Zr-4Ta-4Nb alloy for medical implants is being developed. In terms of in vitro cytocompatibility, the new bone tissue response to the Ti-15Zr-4Ta-4Nb alloy determined through rat tibia implantation was equal to or better than that to the Ti-6A1-4V alloy. An acceptable level of biological response can be expected when this alloy is used appropriately because it consists of biocompatible elements and has excellent biocompatibility, corrosion resistance, microstructure, and mechanical and fatigue properties. Therefore, the Ti-15Zr-4Ta-4Nb alloy with a low metal release rate is considered advantageous for long-term surgical implants.
Corrosion of Modular Titanium Alloy Stems in Cementless Hip Replacement
Authors: Urban RM , Gilbert JL , Jacobs JJ
Published: April 2008

Severe, localized corrosion of titanium-alloy femoral stems has been reported for specific designs of hip prostheses intended for fixation using acrylic cement. The purpose of the present study was to examine the possibility that corrosion might also occur when titanium-alloy stems are inserted without cement, but the body of the stem is modular in design. Fourteen (7 primary and 7 revision) cementless, modular-body, titanium-6 % aluminum-4 % vanadium alloy femoral stems of similar design were removed at revision surgery after 2 to 108 months in situ. The reason for removal was unexplained pain (4), femoral or acetabular loosening (4), infection (3), recurrent dislocation (2), or component malposition (1). The devices and, in selected cases, tissue from the joint psuedocapsule were studied with the use of light and scanning electron microscopy. Fretting corrosion products were characterized using energy dispersive x-ray analysis, selected area diffraction, and micro-Raman spectroscopy. Damage at the modular body connections was absent in 3 stems, mild in 6, moderate in 4, and severe in 1. The surface damage was characterized predominately by fretting scars and by pitting and etching. Thick deposits of mixed titanium oxides were found adherent to the stem at the sites of corrosion and as 0.01 to 200 micrometer particles within histiocytes and multinucleated giant cells in the joint pseudocapsule. Fretting corrosion at the modular-body junctions of titanium-alloy femoral stems can generate solid degradation products, adding to the particulate biu-den of the periprosthetic tissues and potentially accelerating bearing-surface wear by a third-body mechanism. Both of these features can potentiate the development and progression of osteolysis. In addition, fretting corrosion can increase the potential for structural failure of the device. These findings stress the importance of the design of modular junctions to minimize corrosion and the generation of corrosion products.
Influence of Exposure Conditions on Bacterial Adhesion to Zirconium Alloys
Authors: Yamokoski EA , Buczynski BW , Stojilovic N , Seabolt JW , Bloe LM , Foster R , Zito N , Kory MM , Steiner RP , Ramsier RD
Published: April 2008

In this paper we combine surface analytical techniques (X-ray photoelectron spectroscopy, X-ray diffraction, infrared reflection absorption spectroscopy, optical and electron microscopy) with viable counts and statistical ANOVA methods to determine the propensity for biological adhesion on zirconium alloy surfaces. We compare the adhesion of laboratory and clinical strains of Staphylococcus aureus. Staphylococcus epidermidis, and Pseudomonas aeruginosa to Zircaloy-2 and Zircadyne-705 materials. Thermal oxidation of the alloys prior to exposure to biological species is also investigated. We present data for 72-h incubation of bacteria and alloys in both shaken and stationary environments. The results of our statistical analysis and experimental observations are relevant to the use of zirconium-based materials for biomedical applications.
Behavior of Irradiated Type 316 Stainless Steels under Low- Strain-Rate Tensile Conditions
Authors: Yoshitake T , Yamagata I , Akasaka N , Nakamura Y , Tsai H , Cole J , Allen T
Published: April 2008

The effects of lower strain rate on the tensile behavior of 12 % cold-worked type 316 stainless steels irradiated in the EBR-II reactor under low-dose-rate and moderate temperature conditions were investigated. Tensile tests were carried out at a strain rate of 1 × 10-7/s. Post-test fractography and microstructural characterization were also performed. Irradiation temperature and dose appeared to have the greatest effect on hardening and ductility loss, whereas dose rate appeared to have less apparent effects. In conjunction with earlier work performed on the same material at a strain rate of 1 × 10-3/s, there was no significant effect of strain rate on tensile behavior under the irradiation conditions examined. For fracture behavior, the material after irradiation exhibited typical ductile fracture during both high and low-strain-rate tests.
Low Strain-Rate Microstructural Deformation Behavior in 316 Stainless Steel Irradiated in EBR-II
Authors: Cole JI , Allen TR , Tsai H , Yoshitake T , Yamagata I , Akasaka N , Nakamura Y
Published: April 2008

In order to better understand the influence of the radiation-induced defect microstructures on changes in stainless steel deformation behavior, the microstructures of irradiated 12 % cold-worked 316 stainless steel were examined following slow-strain-rate tensile testing. Tensile samples were fabricated from two hexagonal ducts that were irradiated in the outer rows of the Experimental Breeder Reactor. The samples were irradiated at temperatures ranging from approximately 383 to 443°C and doses up to approximately 41 displacements per atom. The tensile tests were conducted at a strain rate of 1 × 10-7 s-1 and test temperature of ∼430°C. Transmission electron microscopy was employed to quantify the defect microstructures of three pairs of samples, each pair having been exposed to similar irradiation conditions. One sample of each pair was taken from the gauge section of a tested tensile sample, and the other was untested. The influence of the defect microstructure on the deformation and fracture behavior is evaluated and results are discussed in light of current theories of deformation behavior in irradiated metals.
Neutron Flux Effect on the Irradiation Hardening of Type 304 Stainless Steel
Authors: Torimaru T , Kodama M , Tanaka S , Nakamura T , Asano K , Kumagai K
Published: April 2008

In order to investigate the neutron flux effect on the irradiation hardening of type 304 stainless steel, microstructure observation, tensile test, and micro Vickers hardness test were performed on the type 304 stainless steel irradiated to 1.6 × 1024-1.4 × 1026 n/m2 in LWRs, (flux 3.4 × 1015-5.6 × 1017 n/m2/s). The tensile test was carried out in air at 288°C, and the hardness test was also carried out in air, but at room temperature. The amount of irradiation hardening increased with increasing neutron flux. The amount of irradiation hardening was proportional to the 0.25th power of neutron flux. Dislocation loop density increased with increasing neutron flux, and mean diameter had hardly any dependence on neutron flux. From the above, the neutron flux dependence of dislocation loop density could be said to be the main factor controlling irradiation hardening under LWR irradiation conditions. The amount of irradiation hardening of type 304 stainless steel used in LWR is expected to be lower than the predicted amount from higher flux irradiated materials.
Modeling the Effects of Oversize Solute Additions on Radiation-Induced Segregation in Austenitic Stainless Steels
Authors: Hackett MJ , Was GS , Simonen EP
Published: April 2008

Oversize solute additions to stainless steels hold promise for reducing radiation-induced segregation (RIS), possibly delaying the onset and severity of irradiation-assisted stress-corrosion cracking (IASCC). The Modified Inverse Kirkendall (MIK) model for RIS in austenitic stainless steels was adapted to include the effects of defect trapping, which is expected to be caused by oversized solutes, on RIS. The model accounts for the sensitivity of RIS to both dose rate and temperature. Model results show that the primary contribution to the reduction in RIS occurs through vacancy trapping and recombination with migrating interstitials, requiring strong solute binding energies on the order of 1.0 eV. The maximum reduction in RIS due to defect trapping increases with dose rate and temperature. The general trends of the model are consistent with experimental data from proton and neutron irradiations.
Extrapolation of Fracture Toughness Data for HT9 Irradiated at 360–390°C
Authors: Gelles DS , Kurtz RJ
Published: April 2008

Following irradiation in the FFTF-AC01 test at 360°C to 5.5 x 1022 n/cm2, two HT9 samples tested at 30°C were measured to have fracture toughness levels of 28.2 and 31.9 MPa m1/2, respectively, whereas a third identical specimen tested at 205°C gave 126 MPa m1/2. Based on testing of notched tensile specimens from the same irradiation test, the low toughness was a result of brittle fracture. A similar low level of toughness has also been demonstrated in HT9 following irradiation at 250°C, and therefore such behavior is reproducible. Using ASTM Standard E 1921-02, which characterizes the fracture toughness of ferritic steels that experience onset of cleavage cracking at instabilities, it is shown that these data can be analyzed by a Master Curve approach, and that the trend of the fracture toughness over a wider range of temperatures can be estimated. Master Curve analysis demonstrates that toughness will remain low over a wide range of temperatures near 30°C, but will degrade only slightly when temperatures drop to -10°C.
Radiation- and Thermally-Induced Phosphorus Inter-Granular Segregation in Pressure Vessel Steels
Authors: Lu Z , Faulkner RG , Jones RB , Flewitt PEJ
Published: April 2008

A survey of neutron- and thermally-induced phosphorus inter-granular segregation behavior in C-Mn welds, LWR plates, LWR HAZ materials, and VVER steels is described in this paper. The materials were irradiated up to doses of 0.13 dpa (fast neutron energy > 1 MeV), with dose rates ranging from 1.75 × 10-8 dpa/s to 10-12 dpa/s, at temperatures between 190°C and 400°C. Irradiation-induced P inter-granular segregation has been found in LWR and VVER materials at high doses (generally 10–130 mdpa) but is absent in all Magnox C-Mn submerged-arc welds at lower doses (1.5–13 mdpa). The dose sensitivity of the irradiation-induced P monolayer coverage depends on the material examined, being highest for VVER plates and weld, lower for the LWR materials, and zero for the C-Mn welds. There are high initial P segregations (arising from pre-heat-treatment) in C-Mn weld and LWR HAZ materials and low initial P segregation in LWR and VVER steels. Comparisons of the experimental data with model predictions are made. The amount of phosphorus segregation is shown via site competition models to be related to free carbon concentration. The model results show a good agreement with experimental measurements.
Creep-Fatigue Behavior in High Strength Copper Alloys
Authors: Li M , Stubbins JF
Published: April 2008

Copper alloys are found to experience a stress relaxation during holds at maximum tension and maximum compression during cyclic loading patterns. This stress relaxation response has an effect on fatigue life by reducing the numbers of cycles to failure, particularly in the high cycle fatigue, long life regime. The stress relaxation behavior is found even for room temperature loading conditions, well below the temperature regime normally associated with creep and stress relaxation. It is suggested that the creep and stress relaxation deformation modes during hold periods is predominantly through primary creep process.
Dynamic Modulus Testing of Thin Pavement Cores
Authors: Pellinen TK , Xiao S , Raval SY
Published: April 2008

A novel method of testing thin surface cores using the dynamic (complex) modulus test is proposed that utilizes composite mechanics theory. Rectangular specimens are sawed from the round surface layer cores, and the sawed blocks are simply stacked horizontally without bonding. Two hydrostone caps are made to provide flat and smooth loading ends, as well as to restrain the blocks from moving during loading. Two Linear Vertical Differential Transformers are attached 180° apart to the flat uniform side of the horizontally stacked cores to obtain the strain response without measuring over the joint of the cores. The advantage of this approach over the diametral loading mode, used for resilient modulus testing, is that it provides homogenous testing conditions, which gives direct access to stress and strain and, therefore, constitutive equations.
Obtaining Creep Compliance Parameters Accurately from Static or Cyclic Creep Tests
Authors: Kim J , Roque R , Birgisson B
Published: April 2008

Obtaining creep compliance parameters that accurately represent the creep response of asphalt mixtures is critical for proper evaluation of the thermal cracking performance, as well as load induced cracking performance of asphalt pavements. A power law, which uses three parameters to describe the creep compliance curve, is commonly used for asphalt mixtures. However, the specific values of the parameters obtained can depend on both the testing and the data interpretation methods used. Different testing methods (for example, static versus cyclic creep) offer different advantages and disadvantages related to complexity in testing, as well as in the sensitivity of the data obtained from each test to the compliance parameters of interest. In general, cyclic creep tests provide greater sensitivity and accuracy at shorter loading times, while static creep tests are more accurate and reliable for the determination of the long-term creep response.
The Importance of Integrating Flashing and the Water Resistive Barrier in the Exterior Wall Systems of Residential Buildings
Authors: Dorin L
Published: April 2008

Building science studies have recognized the importance of the proper installation of flashing and its integration with the water resistive barriers as very important to the success of a wall assembly. The roll of flashing is to direct water away from the opening to the water resistive barrier, which in turn directs the water to the exit point in the wall. The integration of these two elements and the quality of their installation is ultimately important to the success of the wall system. It is equally important to select products, which perform as intended after installation. Extensive testing has been conducted on local and methods completely fail to perform the required function of preventing water leakage. Conclusions are that it is important to follow E 2112 in installing flashing and integrating it with the water resistive barrier (WRB). It is equally important that a WRB is used. Each element of the installation is important. If the flashing is perfect, but the WRB lets water through, then there are potential problems.
Elastic-Plastic Finite Element Stress Analysis of Two-Dimensional Rolling Contact
Authors: Jiang Y , Chang J , Xu B
Published: April 2008

Cyclic plastic deformation is a major cause of failure in rolling elements. Previous work reveals that a cyclic plasticity theory plays a critical role in the elastic-plastic stress analysis of rolling contact. In this paper, a recently developed cyclic plasticity model is integrated into a commercially available finite element package. The plasticity model is characterized by its ability to describe general cyclic stress-strain phenomena that occur in rolling contact. The finite element model with the implementation of the plasticity theory is used to simulate the elastic-plastic stresses for line rolling contact. The normal contact pressure is idealized as the Hertzian distribution and the tangential force is assumed to be proportional to the normal pressure. Detailed stress and strain histories as well as residual stresses and plastic flow are obtained for repeated rolling. It is found that the residual stresses stabilize after a limited number of rolling passes but the plastic flow persists. The rate of plastic flow decreases with increasing number of rolling passes.
Root Cause Analysis to Identify Hydraulic Failure Modes
Authors: Reichel J , Wahl M
Published: April 2008

Different tribological systems work under different conditions in axial piston pumps, vane pumps, or radial piston motors. Root cause analysis procedures are used to identify the failure modes discovering typical performance limits of hydraulic fluids and fluid power components. Therefore, pump lubrication and operation requirements, preferably existing in pump manufacturer specifications, must be determined. Hydraulic fluid performance standards are developed in International Standards ISO 11158, “Specifications for mineral oils hydraulic fluids (H)“, ISO 12922, “Specifications for fire-resistant fluids (HF)” and ISO/DIS 15380 “Specifications for environmentally acceptable hydraulic fluids (HE)”. All these standards represent minimum requirements. Fire-resistant and environmentally acceptable fluids show the most different performances in comparison to mineral oil based fluids. Fluid and components properties should be in good balance. The performance of different hydraulic fluids and various pumps has been predicted using small—and large—scale bench tests. Performance limits on fluids and pumps were finally tested together, followed by root cause analysis to identify hydraulic failure modes. Finally, fluid additives or component modifications led to high system performances and optimized fluid power applications. This paper describes important failure modes, reasons for fluid-depending material damages and rolling contact fatigue failures in roller bearings for hydraulic systems which are significant for the components life span. The report is focused on both useful fluid and appropriate pumps. Results from hydraulic pump tests with new steel quality for roller bearings are useful for optimized tribological systems, aqueous or non aqueous hydraulic fluids and new applications in fluid power industries.
Analysis of Failure Modes of a Military Hydraulic Fluid: MIL-H-46170
Authors: Mowery RB , Purdy EM
Published: April 2008

The Army replaces the hydraulic fluids in its vehicles annually. A feasibility investigation to determine if used military hydraulic fluid could be reused was conducted.

Samples of used fluid from military vehicles were collected, analyzed to determine the physical and chemical properties, and compared against specification requirements for new fluid. These fluids were then purified and retested to determine the failure modes. Results showed that the ability to control foaming was the only property that significantly suffered. Restoring the foaming resistance, and removing water and particulate contamination returns the fluid to full specification performance. Adding anti-foaming additive in the field is highly impractical because it is needed in such a low concentration.

Virgin fluid is sufficiently robust in anti-foaming agent, that mixing one part of virgin fluid to three parts of purified, used fluid would bring the mixture back to full specification performance.
Piston Pump Failures In Various Type Hydraulic Fluids
Authors: Ohkawa S , Konishi A , Hatano H , Voss D
Published: April 2008

Instead of an engine oil SAE10w, various hydraulic fluids recently have been introduced into hydraulic systems of construction equipment which generate 35 MPa and more oil pressure. An antiwear hydraulic oil VG46 became a main fluid of Japanese hydraulic excavators. A biodegradable hydraulic fluid is spreading from Central Europe to the world. A synthetic fire-resistant hydraulic fluid also became popular in the world. When those different types of hydraulic fluids were used in the construction equipment, many field pump failures were found. Thus we have investigated the various hydraulic fluids, that have caused pump failures in the field, using a Komatsu HPV35+35 pump test. The HPV35+35 test could reproduce all the field pump failures. The mechanisms of the pump failures are discussed.
Effect of Pump Inlet Conditions on Hydraulic Pump Cavitation: A Review
Authors: Bishop RJ , Totten GE
Published: April 2008

This paper provides an overview of hydraulic fluid impact on the inlet condition and cavitation potential. A clear understanding of physical properties is vital to properly evaluate their effect on lubrication and cavitation. Proper hydraulic system design is critical for optimal operation and to eliminate cavitation as a root cause of wear. The importance of proper inlet conditions on hydraulic system performance is reviewed. The effect of physical properties, including vapor pressure, viscosity, density and bulk modulus on cavitation, as well as the idea of a pump-specific critical cavitation number is also discussed.
The Influence of Surface Topography and Environment on the Fatigue Life of a Hydraulic Motor
Authors: Scott W
Published: April 2008

Investigations into fatigue failure of the cam rings of hydraulic motors revealed a characteristic ripple superimposed on the surface profile. It was also found that the incidence of failure coincided with sites having high humidity.

This paper shows how reduced fatigue life under these conditions may be estimated.
Rust Inhibitor Contamination-Related Problems in Military Aircraft Hydraulic Systems
Authors: Sharma SK , Snyder CE , Gschwender LJ , Liang JC , Schreiber BF
Published: April 2008

Stuck servovalves were observed during pre-flight checks in some aircraft using MIL-PRF-83282 hydraulic fluid. Analysis of hydraulic fluid samples and stuck valves as described in the paper provided a link between valve failures and barium dinonylnaphthalene sulfonate (BSN) content of the hydraulic fluid. The BSN contamination was traced to residual MIL-PRF-6083 preservative fluid that had not been drained from components before installation on the aircraft. The hypothesis was validated by laboratory tribological experiments using a reciprocating tribometer and grazing angle microscope Fourier transform infrared spectroscopy. Corrective actions included reemphasizing procedures to drain MIL-PRF-6083 from components and establishing a 10 ppm maximum limit for barium in new MIL-PRF-83282.

Since the corrective actions were taken, no valves have locked up, further validation that the preservative fluid, MIL-PRF-6083, as a contaminant in the operational aircraft, is the root cause of the valve lockups. The recommended corrective actions were: 1) removing and cleaning the hydraulic valves; 2) assuring that the barium content of the aircraft hydraulic fluid does not exceed 15 ppm.

Other factors besides the presence of BSN which contributed to the valve-sticking problem included: the elevated hydraulic fluid temperature, the valve design and materials, and the duty cycle. The simplest and most cost-effective solution to the problem was limiting the amount of BSN in the aircraft hydraulic system. Other aircraft hydraulic systems problems perceived to be caused by BSN contamination are discussed.
Viscoelastic Model of Anisotropic Flywheels
Authors: Emerson RP , Bakis CE
Published: April 2008

A theoretical model for plane-stress, anisotropic, multiple-concentric-ring rotors subjected to time-variable spinning, press-fit, and thermal loads is presented. The problem solution is based on a mechanics of materials approach with a linear viscoelastic constitutive law and Schapery's quasi-elastic solution technique. The model accounts for the effects of temperature on the material creep properties by including time-shifting. Simulations of the stresses and strains in flywheel rotors under realistic non-isothermal load histories are given.
A Study of Time-dependent and Anisotropic Effects on the Deformation Response of Two Flywheel Designs
Authors: Saleeb AF , Arnold SM , Al-Zoubi NR
Published: April 2008

The influence of material time dependency and anisotropy in the context of two specific flywheel designs -preload and multi-directional composite (MDC)- is investigated. In particular, we focus on the following aspects: 1) geometric constraints, 2) material constraints, 3) loading type, and 4) the fundamental character of the time-dependent response, i.e., reversible or irreversible. The bulk of the results presented were obtained using a composite (PMC IM7/8552 @135° C) material system. The material was characterized using a general multimechanism hereditary (viscoelastoplastic) model. As a general conclusion, the results have clearly shown that both the preload and the MDC rotor designs are significantly affected by time-dependent material behavior, which may impact the state of rotor balance and potentially reduce its operating life. In view of the results of the parametric studies and predictions made in the present study, the need for actual experimentation focusing on the time-dependent behavior of full-scale flywheel rotors is self-evident.
Materials and Durability Characterization of Composite Wrap Systems Using NOL Ring Tests
Authors: Karbhari VM , Zhang J , Wu L , Reynaud D
Published: April 2008

A variety of composite systems, incorporating glass, carbon, and aramid fibers, and fabricated through the use of wet winding, wet layup, prepreg winding, resin infusion, or adhesive bonding of prefabricated shell sections, is being used as jackets for the seismic retrofit of columns. In the case of circular columns, the use of flat coupons for system and durability characterization does not accurately replicate field-level aspects as well as the interaction of materials and structural configuration. A jacket used for seismic retrofit is designed to confine concrete and prevent excessive dilation. NOL-ring burst tests are seen to provide a good simulation of the actual structural and load configuration for the application and are proposed as a means of characterization and durability evaluation. The paper describes results of a characterization program on four different systems, including results after laboratory and field exposure.
Interfacial Contact Behavior of CFRP-Metal Couples
Authors: Al-Mayah A , Soudki K , Plumtree A
Published: April 2008

The contact pressure and shear stress on the surface of a carbon fiber reinforced polymer (CFRP) rod in contact with an aluminum alloy counterface of two different hardnesses were studied. The main objective was to investigate the effect of high contact pressures on the sliding behavior of the couple. The shear stress was related to the sliding distance. A modified coefficient of friction was introduced and found to express correctly the decrease in shear stress with increase in contact pressure. In addition, the effect of clamping load on the compressive displacement of the rod and sleeve was investigated. The relationship was found to be nonlinear, with the sleeve hardness having a minimal effect.
Fatigue Life of SCS-6/Timetal® 834 at Room Temperature and 600°C: Experiments and Modeling
Authors: Peters PWM , Zeng W , Hemptenmacher J , Xia Z
Published: April 2008

Fatigue of the titanium matrix composite (TMC) SCS6/Timetal 834 has been investigated at room temperature and 600°C. Whereas the room temperature behavior is mainly influenced by fatigue crack formation and growth, this is not the case for fatigue at 600°C. The runout specimens did not show any crack, whereas runout specimens tested at room temperature showed multiple transverse cracks with a characteristic distance. The main reason for the lack of cracks was found to be the result of stress relaxation of the matrix. This effect is strong due to the fact that the first 105 cycle are performed at a low frequency (0.25 Hz).

In the second part of this work attention is focused on modeling the most important damage mechanism under room temperature conditions. Initial computation of crack growth rates in TMC, assuming interfacial friction being the only stress transfer mechanism (i.e., bond strength is considered to be zero), proved to be unrealistically high. For that reason in the present work crack growth rates are calculated considering a fiber/matrix bond strength and friction in case the bond breaks. In this case three dimensional finite element models deliver more accurate crack growth rates.
Sports Activity after Total Knee Arthroplasty
Authors: Yamagishi T , Suzuki H , Shizuka M , Kikuchi T
Published: April 2008

In this study, patients who played sports after undergoing a total knee arthroplasty (TKA) were functionally analyzed and their degree of satisfaction was surveyed. The study group consisted of seven men and four women (out of a group of 89 total knee arthroplasties). They were evaluated by the Tegner (1) activity score and the Japanese Orthopaedic Association (JOA) score (2). The mean age of the patients was 68 years (range: 47 to 76) at surgery and the mean follow-up period was 26.4 months (range: 11 to 60). Wright Advantim uncemented knee prostheses with a stem and posterior stabilizer or Wright Advance uncemented knee systems (Wright Medical, USA) were used. All operations were performed using a medial subvastus approach by the senior author (TY). The mean preoperative JOA score was 67.3 and it improved to 87.3 at follow-up. The mean Tegner score improved from 1.5 to 4 points after the operation in those patients who returned to sports. At follow-up, none of the patients demonstrated polyethylene wear, showed signs of loosening or required revision surgery. Once strength, mobility, and coordination recovered, patients were successfully allowed to return to low-impact activity such as downhill skiing, jogging, hiking, and mountaineering. It is too early to determine the effect of these increased activities on polyethylene wear and loosening.
Motorist conquest in big cities: The case of Budapest
Authors: Erhart Sz.
Published: April 2008

Economic growth requires well functioning transport systems. The paper deals with the problems associated with ever-increasing car use and traffic jams in Budapest. Car scarcity was the major problem that impeded car use two decades ago which has transformed into road scarcity since then. Road capacity is limited in the Hungarian capital, only the public transport can help to satisfy medium run travel demand of residents. As motorisation and car use grow congestion related time loss, petrol and pollution costs put a heavy burden on Budapest. International experience shows that restrictions on cars can mitigate congestion. In many large cities introduction of road pricing in central areas has become one of the most successful traffic management solutions. Experience in London and Stockholm confirms that citizens support car use restrictions even if they are placed on car use.
Inflation targeting in Hungary: A case study
Authors: Erdős T.
Published: April 2008

In the present article the author examines how to develop economic and monetary policy in order to efficiently apply inflation targeting. In Hungary, an inflation targeting system has been applied since 2001. As a result of the current monetary policy, consumer price level must regularly be kept stable at least in a mid-term approach in the middle but possibly also in the long run, or else it should be rising slowly, two per cent per year, at the most. Should the monetary authority have to deal with an already existing fast inflation rate, a considerable reduction of the rate of inflation must be aimed at year by year. Once monetary policy succeeds in bringing down inflation, the low rate achieved must permanently be secured. However, it is not sure that monetary policy has to prefer inflation targeting under any circumstances whatsoever.This policy has a favourable effect only if two substantial preconditions are given: public finances are near the equilibrium and nominal wages are regularly adjusted to the growth rate of GDP. Otherwise, inflation targeting may also have harmful effects such as excessive overvaluation of the national currency, excess of domestic use over GNP, increase of domestic and external debt, decreasing trend of the savings and investment rate, lower economic growth potential.
Price competition vs. quality competition: The role of one-way trade
Authors: Bojnec Š. , Fertő I.
Published: April 2008

This paper investigates trade balances and unit values focusing on Hungarian-Slovenian bilateral agri-food trade flows to distinguish types of one-way and two-way trade flows, categories of price competition and categories of quality competition. We combine Gehlhar — Pick’s (GP) (2002) procedure of four trade categories with knowledge from literature on intra-industry trade (IIT) to disentangle one-way trade, which can be significant when trade between two countries is imbalanced, from two-way matched trade flows with unit values as proxies for price. By comparing the empirical results obtained using the additional categories of one-way trade and disentangled IIT types in two-way matched trade by product was found that GP’s two price and two quality competition categories and IIT types complement each other. The decomposition of GP non-price competition categories on quality competition and one-way trade illustrates that one-way trade is the most significant component of agri-food trade between Hungary and Slovenia, a finding relevant for agri-food trade of several small countries. One-way trade cannot be associated by the simultaneous export and import unit values by the product, but by some other factors of trade specialisation and comparative trade advantages of relevance for public policy makers and private business.
A Disordered Copper-Palladium Alloy Used as a Cathode Material
Authors: Poizot By Philippe , Laffont-Dantras Lydia , Simonet Jacques
Published: April 2008

A novel method of forming a palladised copper (Cu/Pd) interface of well defined structure is described. The CuPd alloy is straightforwardly obtained by immersing a copper substrate in acidic solutions of palladium salts. Depending on the composition of the salt/acid solution, the copper surface is virtually instantly covered with a CuPd deposit. With nitric and sulfuric acid solutions and the corresponding Pd(II)-based salt, the deposit is composed of nanoparticles of disordered CuPd alloy dispersed at the copper interface. The alloy-modified surface was successfully used as an efficient promoter of bond cleavage reactions, especially those of carbon–iodide and carbon–bromide bonds in alkyl halides. The catalytic activity is specifically characterised by a very large shift in potential as between the use of a regular glassy carbon surface and the palladised copper interface. With alkyl halides (RBr and RI), the shift toward less cathodic potentials is so large that it enables the one-electron cleavage of C–I and C–Br bonds. This method should enable the heterogeneous generation of free alkyl radicals as transients in electrochemical reactions. These novel cathodic materials could also be of considerable interest for the disposal of halogenated waste.
Safer, Faster and Cleaner Reactions Using Encapsulated Metal Catalysts and Microwave Heating
Authors: Pitts By M. R.
Published: April 2008

The combination of focused microwave heating and encapsulated metal promoters (EnCatTM) offers a safer, cleaner and more cost-effective solution to a wide range of catalyst-mediated reactions, some of which are not widely accessible to the bench chemist due to high hazard ratings. These include the palladium-catalysed Sonogashira cross-coupling, palladium-catalysed transfer hydrogenation, platinum-mediated hydrogenation and osmium tetroxide-catalysed dihydroxylation.