bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Fastener Flexibility on the Prediction of Load Transfer and Fatigue Life for Multiple-Row Joints
Authors: Huth H 
Published: December 2008

An improvement of the accuracy of fatigue life prediction methods used for multiple-row riveted or bolted joints can be expected only if the rivet load distribution is considered during design and fatigue analysis. To calculate the individual load transfer and the bypassing load the fastener flexibility must be taken into account. Semiempirical formulas for the calculation of fastener flexibility existing in the literature turn out to be not exact or at least not applicable for a wider range of joint geometries. This unsatisfactory situation was the reason for performing an extensive experimental investigation during which fastener flexibilities for a wide range of joints of practical interest were determined.
The effects of primary joint parameters, such as the plate material, clamping length, and diameter and material of the fastener, as well as the effects of secondary parameters, such as the clamping force, condition of the faying surfaces, and fit and type of head of the fastener, were investigated through specific variations. For this purpose load-deformation measurements under quasi-static and flight-by-flight loading conditions were performed using single- and double-shear specimens with known load transfer.
A formula for fastener flexibility, valid for riveted and bolted metallic and graphite/epoxy joints, was derived from the test results and proved to be significantly superior to those found in the literature. This formula for load transfer calculations of multiple-row fatigue loaded joints was used to predict accurately the measured values of load transfer. This improvement also leads to a better fatigue life prediction. The load transfer measurements showed a quasi-linear relationship between the applied load and the total load transfer which was little affected by fatigue loading, although the load transferred by bearing was not constant. By measuring bearing loads and local strains close to fastener holes in a multiple-row joint the author shows that with increasing friction the bearing stress and the local strains decreased. The redistribution of loads or the changes in the mechanisms of load transfer result in a relief of the fatigue critical location. Since these changes of the local stress situation cannot be predicted, the application of fatigue life prediction methods on the basis of local strains must lead to inaccurate results.
Strength and Lifetime of Bolted Laminates
Authors: Ramkumar RL , Tossavainen EW 
Published: December 2008

An extensive experimental program was conducted to investigate the effects of various parameters on the strength and lifetime of bolted laminates. The tested joint specimens were composite-to-metal joints where a single fastener transferred the load from one plate to the other. The various test variables were the bolted plate geometry, laminate lay-ups, stacking sequences and thicknesses, fastener material, diameter, fastener head type (protruding or countersunk), fastener torque, joint configuration (single lap or double lap), load type (tensile or compressive under static and fatigue loading conditions), and test environment conditions (room or ambient temperature and dry; elevated temperature and wet). All the laminates were fabricated using AS1/3501-6 graphite/epoxy prepreg material.
Static tests reproduced the general trends reported in the literature for the effects of plate edge distance and plate width on the strengths of laminates and the corresponding failure modes. Constant-amplitude fatigue tests were conducted at a frequency of 10 Hz, maintaining a constant minimum-to-maximum cyclic load ratio. The effect of the maximum cyclic load amplitude, as a fraction of the corresponding static strength, on the number of cycles to failure was recorded. Hysteresis plots, hole diameter, and fastener torque loss measurements were also obtained during fatigue. The obtained results complement data available in the literature.
The Development and Field Service History of Ford Automotive Aluminum Radiators
Authors: Barkley JM , Wiggle RR , Winterbottom WL 
Published: December 2008

A major program was launched by Ford Motor Company in 1976 to develop lightweight and durable aluminum heat exchangers. This program resulted in the identification of two radiator designs: a brazed flat tube design for maximum efficiency and weight savings and a mechanically assembled design with superior mechanical durability at a reduced facilities investment. Both designs have plastic tanks mechanically crimped to the header and an epoxy coating added to the air side of the header to insure mechanical integrity and leak-free tube-to-header joints.
Heat exchanger development testing of both brazed and mechanically assembled aluminum radiators ranged from simple laboratory glassware tests to controlled fleet and limited production field tests. A key element of this development program was the tracking and retrieval of radiators from two large-scale field trials. Radiators from these trials were analyzed metallographically for internal and external corrosion. Only 3 of 150 mechanically assembled aluminum radiators analyzed showed significant corrosion. For these three samples, high chloride levels (&gt;100 ppm), low glycol concentrations (&lt;30%), and very low inhibitor levels were found. Significant internal corrosion in prototype vacuum brazed aluminum radiators was found to be related to tubes clad with AA7072 and the use of a AA6951 header material. Subsequent production level radiators with no sacrificial clad on the tube interior surfaces and a AA3005 header material showed very little corrosion. External corrosion was noted on tube surfaces for some vacuum brazed radiators retrieved from areas near the seacoast or where large amounts of deicing salts are used.
In general, projections made on the basis of the retrieval studies indicated that the aluminum radiators have comparable or better durability than current production copper/brass radiators. Copper/brass radiators appear to be more susceptible to field performance degradation because of external fin-to-tube solder corrosion after several years in service. Although material and design improvements have led to a marked improvement in the corrosion resistance of both copper/brass and aluminum radiators, further effort is required to attain a “corrosion proof” system. Current investigations involve improving clad/core alloys, external coatings, gasket materials, header designs, and braze processes.
U.S. Army Antifreeze after 50 Years
Authors: Jordan CB 
Published: December 2008

In the early 1930s, the U.S. Army became involved in the research and development of automotive antifreeze/coolants. This effort was justified because military requirements for antifreeze/coolants are more severe than those usually encountered in normal civilian operation. The tactical and operational deployment of military vehicles results in exposure to extreme climatic operating conditions and unusual storage situations. Nearly every conceivable cooling system design is utilized in military vehicles. Because of the need for antifreeze/coolants that will perform in all of these environments, the development of Army antifreeze specifications through the years centered around a single universal material that would be compatible with all situations. The aim for maximum efficiency, simplified logistics, and safety has been maintained.
Technical activities for the past 50 years demonstrate the Army's willingness and ability to assume its share of responsibility for coolants. Army contributions and expertise are recognized by associates in government and industry. This paper highlights stages of technological progress made toward the development of coolants through the years.
Use of the Disk Bend Test to Assess Irradiation Performance of Structural Alloys
Authors: Hamilton ML , Huang FH 
Published: December 2008

The disk bend test has been a valuable technique for rapid evaluation of the ductility of a large number of alloys under consideration for use as structural materials in the breeder and fusion reactor programs. The test employs the 3-mm-diameter, 0.3-mm-thick microscopy and density disk specimen, conserving valuable experimental volume in the limited reactor space available.
The test involves bending the disk symmetrically about the center, producing a simple, axisymmetric stress state. Experimental results are in agreement with a theoretical analysis of the bend configuration. The advantages and limitations of the technique are discussed.
The test has shown that commercial precipitation-strengthened alloys and the Path B alloys of the U.S. Fusion Program exhibit unacceptably low ductilities following irradiation. This was demonstrated for a number of alloys, in a variety of thermomechanical conditions, including cold worked, cold worked and aged, and solution treated and aged.
Comparison of Mechanical Properties in Thin Specimens of Stainless Steel with Bulk Material Behavior
Authors: Rickerby DG , Fenici P , Jung P , Piatti G , Schiller P 
Published: December 2008

Simulation of neutron damage by means of light ions produced by a charged particle accelerator requires the use of specimens having a relatively small irradiated area in order to obtain a high displacement damage rate. The irradiated zone must also be thin (∼ 20 to 200 µm typically) to ensure homogeneity of the damage and to avoid excessive specimen heating due to absorption of beam energy.
To gauge the effect of very thin specimens on the mechanical behavior of Type 316 stainless steel, three series of comparative tests have been performed: tension tests on miniature specimens of 2 mm width, thermal creep tests using this same type of specimen, and fatigue crack growth measurements in 8-mm-wide notched specimens. Experimental results for thin, reduced-size specimens have been compared both with those for rather thicker specimens of the same design and with published data for specimens of standard dimensions.
Tension tests on the miniaturized specimens in the temperature range of 297 to 1123 K indicated little dependence of the yield stress and the ultimate tensile stress on thickness, while elongation to fracture tended to decrease with decreasing thickness. A negligible influence of thickness on thermal creep behavior was observed for tests carried out in vacuo. Fatigue crack growth rate and number of cycles to crack initiation were found to be similar in both thin and thick specimens.
A Miniaturized Mechanical Testing System for Small-Scale Specimen Testing
Authors: Hannula S-P , Wanagel J , Li C-Y 
Published: December 2008

In this paper a miniaturized mechanical testing system designed for multiple testing modes is described. The main testing modes include (1) constant displacement rate testing in uniaxial tensile, compressive, and cyclic loading; (2) load relaxation testing; and (3) indentation hardness testing with a controlled displacement rate or displacement (load relaxation) with an indentation probe size as small as a few micrometers in diameter. The system, originally developed for testing materials and interconnecting structures for microelectronic components, is designed so that tests in different modes can be performed with only minor modifications. For room temperature testing, the temperature stability of the system is better than 0.1°C. The maximum loading capacity and displacement range are ∼ 100 N and 5 cm, respectively, and the smallest displacements that can be controlled are ∼ 0.01 µm.
The capabilities of the testing system in different testing modes are demonstrated. Tensile and load relaxation test results of thin wires (&lt;0.1 mm in diameter) with an accuracy comparable to bulk specimen results are presented. Also reported are results from indentation load relaxation tests with indentation depths applicable to irradiated material testing. Correlations between the mechanical properties of miniaturized specimens and bulk properties are discussed.
Use of Subsize Fatigue Specimens for Reactor Irradiation Testing
Authors: Liu KC , Grossbeck ML 
Published: December 2008

This paper demonstrates use of subsize fatigue specimens for testing highly irradiated specimens to generate reliable information for alloy development and structural design applications. Essential specimen design features needed to accomplish irradiation and stable cyclic fatigue loading at elevated temperature and in high vacuum are discussed in detail.
As examples, test results are presented for Type 316 stainless steel tested at 430 and 550°C. Comparisons are made between data generated from full-size and subsize specimens tested at 430°C with total strain ranges as high as 2% without buckling; results indicated a good reliability of the specimens and testing methods.
Experience in Subsized Specimen Testing
Authors: McConnell P , Sheckherd JW , Perrin JS , Wullaert RA 
Published: December 2008

Several techniques are reviewed for obtaining fracture toughness, impact energy, or flow data from subsized specimens. These specimens are useful when there is insufficient material or space (e.g., reactor vessel surveillance programs) for larger, more conventionally sized specimens. Such specimens are useful in other situations where, because of the structural configuration, it is appropriate to use small specimens (e.g., fusion first wall structures). The data obtained from these specimens may be (1) correlated with actual structural response or the response of larger specimens, (2) compared with test results on similar sized specimens (useful in tracking shifts in material behavior), or (3) used to provide input to fracture models.
Techniques for testing specimens of compact-tension, Charpy V-notch, and compression specimen geometries are described. Comparison is made with results from larger specimens in terms of ASTM validity criteria where possible.
Some of the specimens had been machined to substandard size from an ample amount of source material. For example, compact-tension specimens as small as 3 mm thick tested with valid fracture toughness results are discussed. Miniature Charpy specimens of similar size are also reviewed.
Other standard size specimens have been constructed from very small pieces of a limited volume of material. This approach may be useful to nuclear reactor surveillance programs. Rebuilt Charpy specimens consist of a crack tip region comprised of the original specimen to which two end tabs have been attached. The crack tip region of a compact-tension specimen is constructed from broken Charpy bars which are press-fit into a second piece of material with compact-tension shaped geometry. Results of testing these specimens are compared with those obtained from the original specimens of similar size.
Al3Li Precipitate Modification in an Al-Li-Zr Alloy
Authors: Gayle FW , Vander Sande JB 
Published: December 2008

An Al-2.34Li-1.07Zr (weight percent) alloy was produced using rapid solidification processing in an attempt to modify the δ′ (Al3Li) precipitate found in the Al-Li binary system to a complex Al3(Li,Zr) phase. Such a modification is expected to increase fracture toughness and ductility by decreasing shear localization, which is a major drawback in Al-Li alloys. A novel microstructure is presented in which a zirconium-rich phase present as fine spheres or discontinuously precipitated rods (with diameters of 6 to 20 nm) is subsequently enveloped by δ′ during aging at 190°C.
Electron diffraction effects, energy-dispersive X-ray analysis in scanning transmission electron microscopy, and preliminary electron energy loss spectroscopy results indicate that the precipitate phase stable at 500°C is Al3(Lix,Zr1−x), where x appears to be 0.45 to 0.8. This is in contrast to the Al-Li and Al-Zr binary systems, in which the equilibrium phases at 500°C for these solute levels are aluminum solid solution and Al3Zr in an aluminum matrix, respectively. The alloy shows longitudinal strength-ductility combinations which are significantly better than those of a low-zirconium control alloy and which compare quite favorably with those of other Al-Li alloys.
Effective Method for Degassing Evaluation of Aluminum PM Alloys
Authors: Kirchoff SD , Adkins JY , Griffith WM , Martorell IA 
Published: December 2008

Current U.S. Air Force programs are using aluminum powder metallurgy (PM) to extend the use of aluminum in both airframe and engine applications. The benefits of aluminum PM over conventional ingot metallurgy (IM) processing include enhanced mechanical properties resulting from a very homogeneous microstructure, extension of solid solubility limits, formation of metastable phases, and decreased grain size. During processing of the aluminum powder into a final product or into a workable preform, degassing is desirable to facilitate the breakup of the oxide skin and to disperse it. Also, the undesirable hydroxides that form must be removed to optimize mechanical properties. Although degassing has been frequently studied, evaluation techniques for degassing efficiency have been neglected.
This program deals with the development of an effective and rapid method of evaluating degassing in aluminum products. Several methods, including ultrasonic inspection, density measurements, mass spectroscopy, and optical metallography, have been studied and evaluated using 7091 alloy small laboratory compacts. The times and temperatures of degassing were varied in such a way as to ensure that both adequate and poor degassing conditions were obtained. Each method of evaluation is discussed.
Aquatic Monitoring: A Rationale for Obtaining and Interpreting Aquatic Ecosystem Chemical Exposure Data
Authors: Adams WJ , Hoogheem TJ , Michael PR 
Published: December 2008

Aquatic hazard evaluation of chemicals requires sound data on both exposure and toxicity so that judgment can be made on the adequacy of the margin of environmental safety. Experience obtained through three years of national aquatic monitoring indicates that chemical monitoring programs need to include the following basic components if the data are to be credible, useful, and consistent with the state-of-the-art results: (1) a rationale for site selection; (2) a logical set of criteria for selection of sample types—that is, water, sediment or biota—based upon the physical-chemical and toxicological properties of the chemical of interest; (3) an appropriate cost-effective statistical design; (4) a team with a demonstrated capability for obtaining noncontaminated samples; (5) a top-notch analytical laboratory with experienced personnel, appropriate instrumentation, and fully validated and tested methods; (6) exacting quality-assurance and quality-control measures in all aspects of the program, including sample collection, sample storage, and analyte determination; (7) an analytical limit of detection for environmental samples low enough to provide meaningful comparisons of biological effects and environmental exposure data; and (8) the capability to assess the monitoring data consistent with state-of-the-art aquatic hazard assessment techniques.
Using the above-mentioned components of an aquatic monitoring program, cumylphenyl diphenyl phosphate (CPDPP), a component of an industrial hydraulic fluid, was monitored in 1982 at 24 sites located across the continental United States. Assessment of the hazard of CPDPP for sites where detectable levels were observed was performed by calculating the margin of safety between environmental water concentration and acute and chronic toxicological effects for aquatic organisms inhabiting the water column and sediments. A new approach for assessing chemical concentrations on sediment is proposed. The technique consists of calculating sediment interstitial water concentration of CPDPP and comparing these values with toxicological effect concentrations observed in the laboratory for sediment-dwelling organisms.
Concentrations of CPDPP in the environment ranged from &lt; 0.1 to 0.2 μg/L in surface water and from &lt; 100 to 200 μg/kg in sediment. Positive identification of CPDPP occurred in only 12 out of 85 surface water samples and 3 out of 53 sediment samples. CPDPP safety margins were determined to be typically a factor of 10 or greater for the most sensitive water column organism (lake trout) and 390 or greater for a typical sediment dwelling organism. These margins of safety provide evidence that CPDPP at its current use level has a low potential to affect aquatic organisms.
Rationale and Sampling Designs for Freshwater Mussels Unionidae in Streams, Large Rivers, Impoundments, and Lakes
Authors: Isom BG , Gooch C 
Published: December 2008

Historically, the rationale for sampling freshwater mussels was almost entirely for purposes of taxonomy, natural history surveys, and conservation and propagation efforts following a decline of the pearl button industry in the early 1900s.
The concept of quantitative sampling of freshwater mussels is almost unknown in historical literature. Except for some proprietary or unpublished quantitative studies, the first study designed primarily to quantitatively sample freshwater mussels was by Scruggs [1] followed by Isom [2], Bates [3], Isom [4], and Dennis and Bates [5]. An earlier concept paper on “Quantitative sampling of mollusks and crustaceans” can be found in Wurtz [6].
This paper describes quantitative sampling methods for freshwater mussels within the context of varied study objectives, for example water pollution surveys. An example of a quantitative site-specific mussel study on the Cumberland River, Tennessee, is included. Difficulties with this study's design and application are discussed in some detail, along with site-specific studies on Kentucky Reservoir, Tennessee River, and Clinch River, Tennessee.
Species Selection for Vascular Graft Evaluation
Authors: Didisheim P 
Published: December 2008

Similarities and differences between human and several other mammalian species are reviewed with respect to hematologic parameters and the histologic response to implanted prosthetic vascular grafts. No species is clearly more similar to man than any other with regard to all aspects reviewed. For this reason it is suggested that species selection for vascular graft evaluation be based on practical considerations such as ease of handling and of surgical and anesthetic technique and the cost of purchase and maintenance of the animal. Based on these criteria, the dog appears to be the species of choice.
In vitro tests of platelet deposition and fibrinogen adsorption to expanded polytetrafluoroethylene (EPTFE) and woven Dacron® during simulated arterial flow was predictive of results reported following implantation of these materials as small diameter vascular grafts in animals and man. These methods may therefore be useful as in vitro screens of new prosthetic vascular materials.
With five materials tested, ranking of the intensity of the blood-material response in vitro was the same or similar among three species—human, canine, and porcine—despite the major pathophysiological differences among these species. These observations suggest that, for in vitro hemocompatibility testing, species selection based on apparent similarity to man is neither necessary nor likely to yield more clinically relevant data. There is no compelling evidence at present that data derived from vascular implant studies with the baboon are more relevant to human use than data obtained from studies with the dog.
Following vascular graft implantation, thromboembolism was seen more often in the dog while calcification was observed with greater frequency in the pig. Because of such species specificities in the nature of the response, it may be advisable to evaluate grafts in more than one species, specifically the dog and pig. It may also be useful to study the effect on vascular graft patency and other responses, of diseases in the host that simulate those that commonly exist in human candidates for graft implantation.