bluuebunny/crossref_metadata_2025 huggingface dataset:
Production and Economic Consequences When Machining Glass Ceramic
Authors: Turker EG , Stanislao J , Richman MH
Published: May 2009

Experimental data was obtained characterizing the machinability behavior of glass ceramic material (K2O-MgF2-MgO-SiO2). To determine how this material can be processed under production conditions an economic model was developed using Taylor's equations. A machining parameter was ultimately established with a minimum cost per unit while achieving a maximum production rate.
Load-Time Attenuation During Instrumented Charpy Impact Testing
Authors: Rack HJ
Published: May 2009

The uses and limitations of procedures designed to characterize and correct for load-time attenuation occurring during dynamic impact testing are described. The importance of wave form, time to maximum load, and load decay time are considered. It is shown that, within certain bounds, wave form attenuation calibration procedures can be used as a means of correcting data which contains excess filtering.
A Note on Pseudo-Acoustic Emission Sources
Authors: Egle DM , Brown AE
Published: May 2009

This paper describes an experimental comparison of the stress waves generated by three sources of simulated acoustic emission events: a piezoelectric generator, an electric spark, and a pulsed laser. The stress waves produced by the electric spark indicate that the stress generating mechanism is the thermally excited pressure pulse in the air surrounding the spark. Each of the sources is shown to be capable of producing stress waves of less than 1-μs duration, but the piezoelectric generator appears to be the most advantageous technique.
Fracture Energy and Crack Tunnelling
Authors: Johnson FA , Radon JC
Published: May 2009

Instrumented impact testing has been used to measure the dynamic fracture-initiation toughness of some precipitation hardened aluminum alloys. The results of these tests have been calculated by the energy method GIc = ω/ηA and by the K calibration formula. The difference in origin and interpretation between the initiation toughness GIc = ω/ηA and specific fracture energy ω/A has been considered.

Double-cantilever beam (DCB) specimens of these alloys have been used to measure point values of fracture toughness by the compliance method and average propagation toughness by the specific surface energy method. Fracture propagation is of the semistable type in these non-rate-sensitive alloys, and the toughness values are found to be similar by both methods. An exception is when crack tunnelling develops during crack propagation in thick DCB specimens. Then KIc from the surface energy method tends to be lower than that from the compliance method.
X-Ray Residual Stress Calibration Data of Certain Ferrous and Nonferrous Alloys
Authors: Ranganathan BN , Wert JJ , Clotfelter WN
Published: May 2009

Data pertaining to X-ray residual stress standards of certain ferrous and nonferrous alloys have been presented. These standards which have been obtained using conventional X-ray diffraction techniques will be employed in conducting field-type residual stress measurements in the shuttle program by using automatic servo-controlled systems.
Converting Fatigue Loading Spectra for Flight-by-Flight Testing of Aircraft and Helicopter Components
Authors: Ekvall JC , Young L
Published: May 2009

Fatigue tests conducted on structural components of flight vehicles are generally required to demonstrate compliance with contract and military specifications. The results of these tests provide assurance to the customer that the structure will have an acceptably low probability of fatigue crack occurrence during service and that the cracks that do develop in service will propagate slowly enough to allow detection and repair. This overview presentation describes how to convert fatigue service loading spectra into fatigue test spectra to meet the requirements for full-scale fatigue testing of aircraft and helicopter components.
Constancy of the Tensile Test Machine Stiffness
Authors: Fortes MA , Proença JG
Published: May 2009

A method is presented for determining the current value of the stiffness of a tensile machine during uniaxial loading tests. The method is based on stress relaxation tests and on the measurement of the slopes of the load-time curve at the moment when the crosshead speed is changed from zero to some finite value. This method has shown that the stiffness can be taken as a constant within fairly wide ranges of the load level, crosshead speed, and specimen dimensions.
Unusual Potential Drop During the Application of the Electrical Potential Method in a Fracture Mechanics Test
Authors: Bachmann V , Munz D
Published: May 2009

The application of the electrical potential method during a fracture mechanics test can give rise to a potential drop if the maximum load during fatigue precracking is exceeded. The effect is only observed if the fatigue fracture surface is very rough. The reason is a contact of the fatigue fracture surface caused by a lateral deformation in the direction of the crack front.
Nomograph for Determining Corrosion Rate in Wire Coil Tests
Authors: Zanker A
Published: May 2009

A nomograph has been devised that will allow a rapid solution to the equation outlined in the ASTM Test for Corrosivity of Water in the Absence of Heat Transfer (Weight Loss Methods) (D 2688-70). Test procedures are described, and instructions for the use of the nomograph are provided.
Statistical Interpretation of Strength Tests of Masonry Units for Structural Applications
Authors: Brown RH , Grogan JC
Published: May 2009

The acceptance criteria for both brick and concrete block masonry units are reviewed and compared to those of concrete. Modifications in the acceptance criteria for masonry units are recommended which limit the amount by which the strength of any masonry unit may fall below the specified value. Probabilistic methods are used to develop equations which provide uniform, reliable compliance with both the existing and recommended acceptance criteria. It is shown that the producer of masonry units who exercises high standards of quality control is rewarded with a higher design strength. The producer who conducts more than minimum testing is similarly rewarded.
Sulfur- and Polymer-Impregnated Brick and Block Prisms
Authors: Chen WF , Mehta HC , Slutter RG
Published: May 2009

To enhance significantly both the strength and durability of concrete and other related building materials, the technique of polymer impregnation has received a wide-spread recognition in recent years. The price of oil-based monomers, however, due to shortage of oil, prevents a large-scale use of this technique. The objective of this paper was to demonstrate the applicability of sulfur as an attractive substitute to monomers for impregnation. It was demonstrated that sulfur impregnation of building block and brick units and prisms, carried out at atmospheric pressure using a simple process developed in the laboratory, could give equivalent relative strength increase compared to polymethyl methacrylate-impregnated units and prisms. Sulfur impregnation showed greater than 90% reduction in water absorption and virtually no acid attack. This suggests possible application of treated masonry to sewage pipes and culverts, to acid treatment vessels and pump beds, and to enhance the strength and durability of low-quality masonry.
Correlating Models and Prediction of Erosion Resistance to Cavitation and Drop Impact
Authors: Veerabhadra Rao P , Syamala Rao BC , Lakshmana Rao NS
Published: May 2009

Using venturi and rotating disk data, correlations are established between volume loss rates obtained from different stages of volume loss-time curves and various single and multiple material properties. The significance of correlations and relationships is judged from various statistical parameters computed. The analysis indicates that during the initial and development phases hardness and shock compression ratio play a predominant role, and once the erosion develops modified resilience and tensile strength significantly influence the erosion phenomenon. For the correlations involving volume loss taken from the initial and development phases the statistical parameters exhibit considerable variation, while in the developed phase their variation is insignificant. Analyses of extensive erosion data from the authors' laboratory and from other laboratories indicate that groupings of properties like ultimate resilience × hardness (UH) and tensile strength × hardness (T,H) or groupings such as UHE and UHT, exhibit best correlations. Several equations are proposed to predict erosion rates of various materials tested in different laboratories.
Development of a Method to Measure Wear on Resilient Flooring
Authors: Irwin WE
Published: May 2009

Interlaboratory and intralaboratory reproducibility has been shown for a method to measure wear on resilient flooring. The work was done by the ASTM F06.33 Task Group on Abrasion and Wear, using a loose-grit feeding device as an attachment on the Taber abraser. Otto F. V. Frick, National Institute for Material Testing, Stockholm, Sweden, developed the original feeding device, now called the Frick-Taber Attachment. This prototype feeder was modified and subsequently manufactured in sufficient quantity to carry out this program. The coefficients of variation of volume loss between six cooperating laboratories using five different resilient floorings were found to be no greater than 20%. Within any one laboratory, the coefficients of variation were approximately 10% or less. A ranking of equivalent flooring materials according to the wear expected from wear tests reported in the literature corresponds with the loss results found in this effort. The F06.33 Task Group has concluded that the technique has sufficient precision to be recommended as a method to measure wear on resilient flooring.
A New Stable Nickel-Base Thermocouple
Authors: Starr CD , Wang TP
Published: May 2009

The change in magnitude and direction of electromotive force (EMF) and the accompanying structural changes of nickel-chromium (Ni-Cr), nickel-silicon (Ni-Si), and nickel-silicon-magnesium (Ni-Si-Mg) alloy thermoelements at 1800°F (982°C) in air were studied in comparison with a standard type K thermocouple of the same size. The Ni-Cr versus Ni-Si-Mg couple changes only +200 µV versus +600 µV for the Type K couple after 21 200 hours at that temperature. The EMF changes of K+ and the Ni-Cr alloy are attributed to the simultaneous oxidation of Cr and Si and to the increase in oxygen. The EMF change of K- is caused by the preferential oxidation of silicon, aluminum, manganese, and iron and to the increase in oxygen. The EMF changes of Ni-Si and Ni-Si-Mg are caused by the preferential oxidation of Si and to the increase in oxygen. The presence of magnesium increases the stability of the Ni-Si system by blocking the reaction of silicon and oxygen.
The Effects of Temperature and Relative Humidity on Static Strength of Hydrated Portland Cement
Authors: Barrick JE , Krokosky EM
Published: May 2009

This paper delineates the effects of temperature and relative humidity on static strength (fatigue) of hydrated portland cement mortar. An experimental program involving the static loading of small cement-sand beams at varying conditions of temperature and relative humidity was undertaken to obtain information on the time required for fracture. This data was analyzed with a statistical procedure developed for truncated, lognormal distributions. The results are presented as cumulative probability distributions. A stress-corrosion mechanism dependent on the presence of calcium hydroxide is postulated as a result of this study.
Mechanical Properties at Elevated Temperature of CuBath® Electroplated Copper for Multilayer Boards
Authors: Fox A
Published: May 2009

Differential thermal expansion in plated through holes (PTHs) of multilayer boards (MLBs), due to soldering or to changes in ambient temperature, produces thermal strains and possibly failure of the electroplated copper. In addition, repeated thermal cycling may produce mechanical ratcheting.

A first requirement for the design of PTHs is a knowledge of the mechanical properties at elevated temperature of the electroplated copper, potentially the weakest link in the structure. To provide such information, the creep, creep-rupture, stress relaxation, and monotonic tensile properties for CuBath® copper, electroplated under controlled laboratory conditions, were studied as a function of temperature and thickness. In addition, strain ratcheting at elevated temperature was determined from repeated stress relaxation tests. The material studied was found to exhibit adequate localized ductility for the design requirements of our MLBs, although, as is generally the case for electroplated copper, its final elongation after fracture was lower than that for wrought, annealed copper.
Influence of Calcium Chloride on the Drying Shrinkage of Alite Paste
Authors: Berger RL , Kung JH , Young JF
Published: May 2009

The drying shrinkage at 55% relative humidity of alite pastes with and without 1% calcium chloride (CaCl2) at equal degrees of hydration was investigated. CaCl2 increases drying shrinkage at all levels of hydration studied. However, the difference in drying shrinkage of pastes with and without 1% CaCl2 decreased with increased hydration. Shrinkage of pastes with CaCl2 decreased with increasing hydration (40 to 75%), whereas shrinkage of pastes without CaCl2 increased with increasing hydration (43 to 62%). A larger weight loss during drying was noted in pastes without CaCl2. Reference is made to the relationship between the observed shrinkage in alite pastes and differences in the pore size distributions of tricalcium silicate pastes with and without CaCl2.
Base Stabilization Using Pelletized Blast Furnace Slag
Authors: Emery JJ , Kim CS , Cotsworth RP
Published: May 2009

Laboratory studies on the use of fine-grained, self-cementing pelletized blast furnace slag in stabilized base construction are presented. The slag chemistry is such that the finer portions of ground pelletized slag show cementing properties. A satisfactory stabilized base mix composed of 70% crusher run blast furnace slag and 30% ground pelletized slag has been developed, and the critical level of minus No. 200 fines has been established. The ground pelletized slag is readily produced, even from moist pellets, using an intensive mixer with a high speed rotor that grinds the slag. The strength development of the ground pelletized slag is not very sensitive to the glass content but is highly dependent on the quantity and Blaine fineness of the minus No. 200 fines in the ground slag. A procedure for the determination of glass content is given. The use of ground pelletized blast furnace slag offers a viable alternative to the use of asphaltic or portland cements in many cases, with an attendant saving in energy resource requirements.
Remolding Stresses and Directional Strength Behavior of an Illitic Clay
Authors: Khera RP
Published: May 2009

The cause and the nature of anisotropy in a cohesive soil was investigated by direct shear and triaxial compression tests. Samples formed under hydrostatic stress showed isotropic shear strength and pore pressure behavior as well as the lack of bias in soil fabric. When the samples from the same clay were molded under one-dimensional consolidation stress, the pore pressure was observed to be isotropic, but the effective stress shear strength was not. Also, these samples had oriented soil structure. The anisotropic strength resulted from the sample stress history and not from the stresses existing prior to shearing. The ratio between the pore pressure at failure and the mean consolidation pressure during remolding, as well as the inclination of the failure plane to the specimen axis, were observed to be essentially constant for all specimens.
Machining Glass Ceramic in Dry and Wet Environments
Authors: Stanislao J , Turker EG , Richman MH
Published: May 2009

Glass ceramic (K2O-MgF2-MgO-SiO2) was found to have relatively good machinability that is restricted within a very limited range of machine settings. The microstructure of glass ceramic has had significant influence on the machining capabilities. Tool geometry, tool composition, and the machining environment influenced cutting forces, workpiece surface quality, and tool life.
An Evaluation of a Proposed Test Method for Determining the Maximum Dry Density of Dense Graded Aggregate
Authors: Roberts FL
Published: May 2009

A unique compaction test method similar to ASTM Test for Moisture-Density Relations of Soils, Using 10-lb (4.5-kg) Rammer and 18-in. (457-mm) Drop (D 1557-70) was developed and evaluated in the course of a National Cooperative Highway Research Program study of density standards for field compaction of granular base and subbases conducted at Clemson University. The new test method, called the Marshall Hammer Compaction Test, utilizes a standard 1/30 ft3 (944.64 cm3) mold as specified in ASTM Test D 1557-70, Method C, but the 10-lb (4.53-kg) Marshall hammer is substituted for the 10-lb (4.53-kg) Proctor hammer. Also, forty blows for each of the five layers are used to provide a total compaction effort of 90 000 ft-lbs/ft3 (4362.6 kN·m/m3) for the new test.

Laboratory density tests were performed using ASTM Test D 1557-70, Marshall hammer, and a combination procedure to determine the effects of additional energy and confinement on density produced. Four materials were tested with these procedures, and the densities were compared. Gradation tests were also performed to determine the extent of the degradation produced by the additional compaction energy. The laboratory densities were compared with densities obtained from full-scale prototype test pit constructions using the same materials.

Results from this study showed that the Marshall hammer procedure produced densities that were on the average 3 lb/ft3 (48 kg/m3) higher than those produced using ASTM Test D 1557-70. A comparison of the laboratory densities with the field densities showed that ASTM Test D 1557-70 obtained maximum dry density results which were 96.7% of the test pit densities while the Marshall hammer procedure obtained 99.0%. If a specification of 98% of maximum field compaction is required, as in some control-strip, compaction-control procedures, then the Marshall hammer procedure would provide an adequate target density at a specification level of 100% or less.
Local Strain Behavior Prior to Fatigue Crack Nucleation
Authors: Quesnel DJ , Meshii M
Published: May 2009

The local strain behavior of cold-rolled HSLA (niobium) steel was investigated in the vicinity of a circular hole for first loading, first unloading, and in the unloaded state after 50 000 and 82 000 cycles by determining εθ as a function of distance from an 0.02-in. (508-μm) circular notch by direct comparison of optical micrographs at approximately ×1000. This technique allows changes in length to be determined to ±0.15 μm which, over a 100-μm gage length, corresponds to an engineering strain resolution of ±0.15%. The resolution is sufficiently high to allow local strain distributions, as calculated from elasticity and plasticity theory, to be compared with the experimental data. A pseudo-plastic solution was developed from the plane stress solution by considering A. E. Green's three-dimensional solution and Neuber's relation between stress and strain concentrations. The monotonic deformation law obeyed by cold-rolled niobium steel was experimentally determined and combined with the pseudo-plasticity result to obtain a quantitative prediction of the local strain behavior on first loading. Experimentally obtained strain behaviors for first loading provide good agreement with the pseudo-plasticity result for each of the strain levels investigated. The strain distribution measured after the first unloading demonstrated that a compressive residual stress is generated during the first cycle. The strain distribution developed by repeated tension loading is also presented and discussed.
A Definition of Drawability and Its Relation to Deformation in the Drawing of Square Cups
Authors: Hsu TC , Lee SY
Published: May 2009

Drawability is first distinguished from stretchability and the relative amounts of drawing and stretching in any particular forming operation are quantitatively defined. The generalized definition of drawability is based on the definition of the boundary of the product, with which a quantitative definition of draw-in is established. Drawability is then defined as the maximum draw-in at the completion of the cup. It is shown, both theoretically and experimentally, that the draw-in is maximized by choosing the right size, shape, and orientation of the blank to match a particular shape and size of the cup and the boundary. The definition of drawability, hitherto associated with the drawing of round cups, as the Swift test, is generalized to include cups of all shapes. The drawability index so determined can be used not only to compare two materials in the same process, as can be done in the Swift test, but also to compare two processes using the same material, which has hitherto been impossible.
Methods for Determining the Strength of Brittle Materials in Compressive Stress States
Authors: Adams M , Sines G
Published: May 2009

Testing techniques capable of stressing brittle materials in any biaxial compressive stress state have been developed. The design of the specimen, the test devices, and the testing procedures are described in detail. Test results obtained with these techniques, which define the compressive biaxial failure envelope for WESGO AL-995 alumina, are presented. The general problems inherent in the compression testing of very strong brittle materials are discussed.
Monitoring Crack Extension in Fracture Toughness Tests by Ultrasonics
Authors: Klima SJ , Fisher DM , Buzzard RJ
Published: May 2009

An ultrasonic method was used to observe the onset of crack extension and to monitor continued crack growth in fracture toughness specimens during three-point bend tests. A 20-MHz transducer was used with commercially available equipment to detect average crack extension less than 0.09 mm. The material tested was a 300-grade maraging steel in the annealed condition. A crack extension resistance curve was developed to demonstrate the usefulness of the ultrasonic method for minimizing the number of tests required to generate such curves.
Alignment Problems in the Tensile Test
Authors: Christ BW , Swanson SR
Published: May 2009

Uniaxial tensile testing is a method used throughout the world to measure the strength and ductility of materials. An important aspect of uniaxial tensile testing which often goes unrecognized is test system alignment. Poor alignment can significantly influence test results at small strains, especially the fracture strengths of materials in a brittle state. The purpose of this review paper is to enable a reader to identify sources of misalignment, recognize the effects of misalignment on tests results, evaluate the extreme surface bending strains and stresses, and become acquainted with some techniques for reducing misalignments to within tolerable limits. Numerous references are made to the literature which describes how misalignment may be influenced by couplings in the loading train and by specimen design. A quantitative assessment of the devices and techniques discussed in this literature is made in those cases where sufficient data have been provided. The literature surveyed indicates that misalignment in carefully designed and precisely machined testing systems ranges between 3 and 15% bending. The need for reporting the misalignment at which a given test result is obtained is pointed out.
Structural Tests of Aerodynamic Surfaces: A Systems Approach to Analysis and Design
Authors: Goldenberg K
Published: May 2009

One of the primary tasks in structural ground testing of aerodynamic surfaces is to resolve complex, curvilinear pressure fields into applied test loads. A systems approach is presented which optimally performs this analysis and integrates it with major subsequent phases of the engineering operation: specifically, correlation of actual/theoretical shear and moment curves, selection of loading pad geometry, test fixture analysis, and graphical display of the results. Computer programs are available to calculate these results rapidly using curve fitting and statistical methods modified for test data evaluation.
Evaluation of Intergranular Corrosion in Stainless Steel
Authors: Loginow AW
Published: May 2009

Specimens of Type 304 austenitic stainless steel with carbon contents of 0.017, 0.024, 0.046, and 0.059% were subjected to intergranular corrosion tests in acidified copper sulfate solutions with and without additions of metallic copper. In the annealed condition the steels were not attacked by either of the test environments. After a sensitizing heat treatment, both test procedures showed essentially the same behavior; intergranular corrosion occurred only on steels with 0.046 and 0.059% carbon.

Of the visual, metallographic, and scanning electron microscope methods of examining test specimens, the latter produces a superior permanent record. Tactile examination proved to be a simple method of determining intergranular attack on specimens bent after exposure to the test solutions. Evaluation of the examination methods led to a proposed sequence for examining specimens, from a low-sensitivity visual examination to a high-sensitivity examination with a scanning electron microscope. Limitations of the test methods are discussed.
Correlation of Strength of Cement Mortar Cured by 28-Day Standard and Accelerated Methods
Authors: Chriss S
Published: May 2009

Based on the results of an experimental preliminary investigation, two correlations are presented between the standard 28-day strengths of 2-in. (50.8-mm) portland cement mortar cube specimens and the strengths of companion specimens cured under standard conditions for 1 day, and then subjected to accelerated curing for 1, 2, and 3 days in a water bath at 95°C. The proposed correlations, although by no means conclusive, seem to indicate that a unified approach to prediction of standard 28-day strengths may be possible without resorting to development of individual “standard curing-accelerated curing” relationships for each kind of cement of different quality.
Prediction of Fatigue Life of Plain Concrete Beams from Fracture Tests
Authors: Ramsamooj DV
Published: May 2009

A mathematical model, based on the principles of fracture mechanics, is proposed for the prediction of the flexural fatigue life of plain concrete beams. The model predictions are compared with about 400 experimental data from four separate collections, published earlier, covering materials with wide ranges of compressive strengths, 20 Mpa to 44.8 MPa, stress range ratios (minimum/maximum bending stress) of 0 to 0.75, and flexing frequencies of 1 to 20 Hz. There is good agreement between the model and the regression lines fitted to the experimental data.
Relevant Errors Associated with Tension Testing of Metals
Authors: Tomesani L
Published: May 2009

The problems of properly evaluating the tensile properties of metals are examined. In particular, we estimate the errors introduced by the use of simplified relationships that do not consider the change in specimen volume during the test, and by ordinary regression analysis performed with only one uncertainty-affected variable. Typical values of these errors on different materials are computed by means of tension tests on cylindrical specimens.
Stress Correction for Removal of Material in X-Ray Stress Determination
Authors: Kang ZQ , Li JB , Wang ZG
Published: May 2009

To determine residual stresses in a (flat) plate or bar with a rectangular cross-section by X-ray diffraction after removal of material, we can sectionally approximate the measured stress curve with depth using power series, then consequently evaluate the additional stresses created by removal, and finally obtain the true stress distribution with depth before the layers were removed. Formulas to evaluate corrections for stress have been derived. Two examples demonstrate that power series with few terms can provide us with an approximation good enough for the measured stress curve, and that the influence of the approximation on the corrective result is far less than that of the errors arising from the X-ray stress determination itself.
Preparation of Stainless Steel Adherends for Adhesive Bonding
Authors: Gaskin GB , Pilla GJ , Brown SR
Published: May 2009

Adhesively bonded stainless steel aircraft components often fail prematurely at the adhesive/adherend interface. This failure results from exposure of the adhesively bonded joint to various mechanical and thermal stresses, as well as the exposure to hostile environments. Currently, there is not a single, reliable preparation for adhesive bonding that is universally employed for all classes of stainless steel.

This study was conducted to evaluate several existing stainless steel prebonding processes, to determine the significant process factors contributing to the adhesive/stainless steel interfacial performance, and to develop a single reliable prebond preparation for stainless steels. Several surface pretreatments were evaluated with various classes of stainless steel. Wedge crack extension test results of moisture conditioned test specimens show that a newly developed pretreatment process yields the most stable passivation surface for various classes of stainless steel.
Enforcement of International Regulations
Authors: Osmus LA
Published: May 2009

Disastrous incidents in international aviation in 1985 prompted the U.S. Congress to pass legislation, The International Security and Development Cooperation Act, to deter crimes against civil aviation. It requires that the Federal Aviation Administration (FAA) assess international airports serving as last points of departure into the United States.

The implementation of this law, through the Foreign Airport Assessment Program, yields benefits for both the United States and the host governments assessed. It provides for an exchange between the U.S. government and foreign governments on how to strengthen security procedures: a mechanisms for international airports to obtain technical assistance, training, and equipment for the United States; and a way to regulate foreign air carriers.
Regulation: Perception and Reality
Authors: Laird DR
Published: May 2009

Since the onset of the screening of passengers and their carry-on baggage in 1973 to combat hijackings, the number of hijackings in the United States has been brought to zero. A team effort by the carriers and the Federal Aviation Administration (FAA) played a significant role in the elimination of the problem.

Technology developed in the 1970s for airport passenger screening is being pushed beyond its limits in an attempt to detect improvised explosive devices. As we wait for the next generation of technology to appear, we are forced to rely on a combination of overlapping and expensive procedures designed to find the “needle in the haystack.”

A solution may be the blending of present technologies to meet the threat in aviation today. We must not find ourselves in the situation where the cost of the technologies is not justified in relation to risk. The public will surely be a barometer in this evolving and sensitive process.
Australian System for Aviation Security Identification Cards and Associated Personnel Background Checking
Authors: Turner R
Published: May 2009

A description is given of the Australian system for aviation security identification cards which authorize persons to be in restricted areas of airports. Considerations in associated background checking of personnel applying for the cards are outlined.
Reconciling Passenger Facilitation and Security
Authors: Joy TJC
Published: May 2009

An appropriate balance must be achieved between the efficient movement of passengers through airports and security. Some practical aspects of airport operations to obtain such a balance are discussed.
Security Technologies and Techniques: Airport Security Systems
Authors: Bouisser J-F
Published: May 2009

A description of pertinent text and figures from the revised Chapter 6, “Technologies and Techniques of Security,” of the ICAO security manual is provided.
The Role/Responsibility of the Freight Forwarder
Authors: Koch A
Published: May 2009

Security measures related to the handling of air cargo are outlined, and the responsibilities of policing authorities, airports and airlines, and freight handlers are made clear, within the context of Danish law and the Danish Civil Aviation Administration.
The Need to Harmonize Cargo Security Rules
Authors: Forbes D
Published: May 2009

The International Civil Aviation Organization (ICAO) has not been able to influence world governments sufficiently to bring about universal support for Annex 17 security measures governing air cargo. The industry, notably the indirect carriers, view government regulatory plans as unrealistic and unconvincing, because of inconsistencies and extremes in the application of Annex 17 principles. The resultant lack of progress could be countered by uniting government and industry within the middle ground of compromise, and by providing ICAO with the machinery to help administrations introduce harmonized practices.
International Aviation Security Research and Development
Authors: Polski PA
Published: May 2009

A discussion of the research and development activities with the U.S. Federal Aviation Administration (FAA) related to aviation security, based on the principles of (1) denying access; (2) weapons/explosives detection; (3) human factors; and (4) aircraft hardening, is presented.
Reaching Consensus on Technical Standards through ICAO: The Work of Ad Hoc Group of Specialists on the Detection of Explosives
Authors: Cartwright N
Published: May 2009

The ICAO Ad Hoc Group of Specialists on the Detection of Explosives was responsible for the preparation and monitoring of the technical annex for the recently signed International Convention on the Marking of Plastic Explosives for the Purposes of Detection. It is also currently developing protocols and standards for the testing and evaluation of explosives detection equipment Under the umbrella of ICAO the group has developed an approach that has very successfully dealt with the challenge of consensus building in this specialized area of new technology and rapidly evolving capability.
Development of Trace Explosive Detection Standards
Authors: Elias L
Published: May 2009

The lask of defining detection standards for trace explosive detectors, similar to those used with bulk detectors, is not straightforward. Difficulty arises because the relation between the mass of concealed explosive within a package and the quantity of telltale vapor or other trace residue around the exterior of the package is not predictable. Nevertheless, it is possible to formulate meaningful test procedures that can be used to quantify detector performance in terms of minimum detectable trace levels. Such test procedures, outlined here, could be useful in establishing detection criteria for evaluation or certification purposes.
Selection and Use of Explosives Detection Devices to Check Hand-Held Luggage
Authors: Hnatnicky S
Published: May 2009

A comparison of four explosives detection devices of use in airport security for the checking of carry-on luggage is presented.
Determining the Potential Drop Calibration of a Fatigue Crack Growth Specimen Subject to Limited Experimental Observations
Authors: McKeighan PC , Smith DJ
Published: May 2009

Six separate calibration techniques are applied to potential drop (PD) and crack length data from 23 experimental datasets. Five of the techniques use limited experimental input gained during precracking and after test completion to derive the coefficients associated with the calibrations. The datasets include SE(B) and M(T) specimens, fatigue crack growth (FCG) tests and foil analog simulations as well as various aluminum alloys and steel. A comparison of the calibration techniques is undertaken in terms of crack length and the subsequent effect on stress intensity factor errors. The best calibration techniques using two PD and crack length data pairs are the two-point modified and post-test corrected Johnson's equation. Using these methods, 21 of the 23 tests satisfy a criterion based on an acceptable ±2% mean variation in stress intensity factor. If a statistical assessment of the data is made, only 30 to 35% of the tests satisfy this criterion. Finally, the crack length prediction errors that result from the different calibrations can typically cause a 15 to 30% variation in FCG rate da/dN at a given ΔK level. This difference is found to be primarily due to errors in the ΔK calculation.
A Fractographic Technique for the Estimation of Initiation Fracture Toughness JIc for Ductile Materials
Authors: Srinivas M , Kamat SV , Rao PR
Published: May 2009

A single specimen fractographic technique based on critical stretch zone width measurements is suggested for the estimation of fracture toughness (JIc) for highly ductile materials. The salient feature of this technique is that it overcomes the problem of fatigue precracking and is able to predict the fracture toughness of a material using a blunt notch specimen. Fracture toughness tests on commercially pure Armco iron, nickel, and aluminum as well as Al-Mn based austenitic stainless steel and En28 steel were carried out to validate the method.
Deducing Crack History in an Aged Boiler Tube from Fracture Surface Topography
Authors: Kobayashi T , Shockey DA , Ogundele G , McNabb DD , Sidey D
Published: May 2009

A new fractographic technique, FRActure Surface Topography Analysis (FRASTA), was applied to a crack in a boiler tube of a fossil-fired power plant in an attempt to determine when in its 22-year service history the crack initiated and the rate at which it grew. By comparing the topographies of the conjugate crack surfaces, we estimated that the crack nucleated about 68 000 h after onset of service and experienced several periods of accelerated and decelerated growth with rates ranging from 5 × 10 to 9.5 × 10 mm/h. These findings correlated roughly with chemical cleanings and startup/shutdown cycles. A similar analysis of a corrosion fatigue specimen tested under controlled conditions in the laboratory provided results consistent with measured values.

These results suggest that fractography can be used to extract valuable information on cracking kinetics in aged systems and thereby, lead to new ways to predict, monitor, and extend component life.
A Suggested Test Procedure to Measure Mixed Mode I–III Fracture Toughness of Brittle Materials
Authors: Kumar AM , Hirth JP , Hoagland R , Feng X
Published: May 2009

This article describes a test procedure to measure mixed mode I–III fracture toughness. The traditional compact tension specimen geometry is modified to include an angled crack slot. This angle is varied to produce various mode I/mode III ratios. A further modification to the specimen design involving two crack fronts in a triple “pantleg” configuration that can produce near-mode III loading at the crack tip is also described. Together, these two specimens can be used to test the entire spectrum of combined mode I–III. Results of mixed mode fracture tests on 2034 aluminum alloys using these specimens are presented. A three-dimensional (3-D) finite element model of the modified compact specimen to validate the analytical procedure is also described. Angular correction factors for the mixed mode case are also presented. The results indicate the feasibility of developing a new standard test method to measure mixed mode fracture toughness in macroscopically brittle metallic materials.
Numerical Assessment of the Dynamic Tension Test Using the Split Hopkinson Bar
Authors: Rodríguez J , Navarro C , Sánchez-Gálvez V
Published: May 2009

An experimental and numerical analysis of tension tests in the Hopkinson bar is made to assess the suitability of this method to characterize materials in tensile conditions at strain rates about 1000/s. The stress and strain fields that appear in the specimen are analyzed by the finite element method. This mathematical simulation of the test allows a check of the hypotheses normally used in obtaining results: equilibrium situation and uniform strain distribution in the specimen. The simulation process also provides some criteria to design the experimental setup and the specimen geometry for the best agreement with the ideal situation. Finally, because of the usual assumption regarding the uniformity of the strain distribution in the specimen may not be valid, some corrections are suggested to obtain reliable material properties from direct test results in different situations.
Radial Basis Function Network Learns Ceramic Processing and Predicts Related Strength and Density
Authors: Cios KJ , Baaklini GY , Vary A , Tjia RE
Published: May 2009

Radial basis function (RBF) neural networks were trained using the data from 273 Si3N4 modulus of rupture (MOR) bars that were tested at room temperature and 135 MOR bars that were tested at 1370°C. Milling time, sintering time, and sintering gas pressure were the processing parameters used as the input features. Flexural strength and density were the outputs by which the RBF networks were assessed. The “nodes at data points” method was used to set the hidden layer centers and output layer training used the gradient descent method. The RBF network predicted strength with an average error of less than 12% and density with an average error of less than 2%. Further, the RBF network demonstrated a potential for optimizing and accelerating the development and processing of emerging ceramic materials.
Bond Tests of Fiberglass-Reinforced Plastic Bars in Concrete
Authors: Larralde J , Silva-Rodriguez R , Burdette J , Harris B
Published: May 2009

Fiberglass Reinforced Plastic (FRP) bars for concrete reinforcement have been commercially available for several years. The main advantage of such bar relative to the conventional steel reinforcing bars is their resistance to corrosion. The reinforced plastic bars are slightly different from the conventional steel bars both geometrically and mechanically. Thus, research is needed to understand their behavior and to be able to use them in concrete reinforcement with adequate reliability. Bond strength of reinforced plastic bars in concrete is one of the mechanical and behavioral differences with the steel bars. This paper presents the results of pullout and beam tests conducted to determine the bond stress-slip behavior of FRP bars in concrete.
Estimation of Young's Modulus and of Hardness by Ultra-Low Load Hardness Tests with a Vickers Indenter
Authors: Trindade AC , Cavaleiro A , Fernandes JV
Published: May 2009

The evaluation of the elastic-plastic properties of a material by using an ultra-low load hardness test requires a geometrical calibration that must take into account the imperfect form of the diamond indenter. In the present work, the Vickers indenter offset of the microindentation equipment was estimated using differently heat-treated steel samples. To this end, the dimensions of the indentations have been evaluated by two different methods: optical measurement of the diagonals and direct measurement of the penetration depth during the test. The elastic-plastic properties are then calculated from the analysis of the penetration depth/indentation load curves. The Young's modulus values determined for the different high-speed steel samples were very similar and close to the literature value for steel if the appropriate corrections are performed. The hardness values decrease when the determination procedure includes the geometrical correction of the indenter offset, and still further when using the total correction obtained by means of optical measurements of the indenter diagonal. Variation of the hardness values with the applied load is much less when the corrections are carried out.
An Excitation System for Dynamic Testing of Large Structures
Authors: Salawu OS , Williams C
Published: May 2009

The service behavior and real performance of engineering materials and systems are best evaluated using data obtained from prototype or full-scale testing, or both. For large engineering structures composed of materials such as concrete, with variable properties, data from such tests are invaluable. Full-scale forced vibration testing is a useful tool for obtaining information on the condition of structural systems. As compared to ambient vibration testing, forced vibration testing can provide more accurate estimates of damping capacity and yield data from which better system identification of structural parameters is possible. However, full-scale forced vibration field testing is much more difficult to achieve when compared with laboratory tests on prototypes. The (large) size of the structure usually means special excitation systems are required. The development and performance characteristics of such an excitation system is described in the article. The system consists of an hydraulic actuator, mounted within a purpose built frame, two pumps, an electronic control unit, and a personal computer. It can be used to induce vertical excitation of highway bridges, long-span floor slabs, and similar structures.
Modeling Wood in Transverse Compression
Authors: Pellicane PJ , Bodig J , Mrema AL
Published: May 2009

A plane-stress, Finite element model has been developed to predict the stress distribution in wood members subject to perpendicular-to-grain compression. This model exploits linearstrain, isoparametric triangular elements used in sufficient number to achieve a convergent solution. Model verification was achieved through comparison of numerically obtained deformation predictions with corresponding experimental data obtained from actual test specimens. Twenty-seven specimens were instrumented to determine their deformations at numerous locations. Test materials were sampled from three logs (two eagelemann spruce, one western hemlock). Specimens were fabricated with three widely different orthotropic ratios, three geometries (length/depth ratios), and three loading geometries (uniformly distributed load across the estire length, one-half length, and one-quarter length). In total, 377 experimental measurements on 27 specimens were compared to finite element predictions. The results showed that on average the model predicted local deformation to within 5%.
Inconsistencies between CTOD andJCalculations
Authors: Wilson CD , Landes JD
Published: May 2009

Crack-tip opening displacement (CTOD) determined using the plastic hinge model included in the ASTM E 1290 (Test Method for Crack-Tip Opening Displacement (CTOD) Fracture Toughness Measurement) is inconsistent with CTOD determined using the ASTM E 813 (Test Method for JIc. Measure of Fracture Toughness) combined with an equation relating J to CTOD. The plastic hinge model is also inconsistent with the EPRI handbook estimation scheme. The plastic hinge model is highly inaccurate for hardening materials. To explore these inconsistencies, the EPRI scheme was used to generate theoretical load-displacement curves of a compact tension (CT) specimen for a wide range of materials and crack sizes. An alternate equation, derived for a power law hardening material, is shown to be consistent with both the ASTM E 813 and the EPRI handbook estimation scheme. The alternate equation accounts for nonlinearities in the relationship between CTOD and plastic load-line displacements. Differences between the alternate equation and the EPRI scheme are discussed. Experimental results demonstrate the inaccuracy of the plastic hinge model and the accuracy of the power law model.