bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of Linear Expansion in Bricks Due to Freezing
Authors: Davison JI , Sereda PJ
Published: February 2009

A linear extensometer is described that can be used to measure expansions resulting from freezing in saturated porous inorganic building materials. Typical freezing curves illustrate reversible and irreversible expansions. The procedure may have application as a simple test method for assessing the durability of bricks or other porous inorganic building materials.
Use of Pelletized Slag in Concrete Masonry Units
Authors: Cotsworth RP
Published: February 2009

This paper contains a brief description of the slag pelletizer and the external pressures which led to its development. Pelletized expanded slag is an improved lightweight aggregate for the concrete masonry market. When compared to the earlier lightweight slag aggregates, the improvement manifests itself by a 20% reduction in cement contents for equal compressive strength masonry units. In addition, the water absorption of the masonry is reduced, the green strength is increased, and the visual properties of color and texture are improved. Research work and field trials indicate that the latent hydraulic property of the slag is available in the manufacture of block and brick masonry to further reduce added cementitious binder contents and thereby conserve energy. This can be accomplished by partially grinding the slag at a block plant to produce a self-cementing aggregate. It was also shown that slag fines may be partially replaced or extended by silica flour under some conditions of use.
Surface-Crack Shape Change in Bending Fatigue Using an Inexpensive Resonant Fatiguing Apparatus
Authors: Pierce WS , Shannon JL
Published: February 2009

An inexpensive device for producing surface cracks of controlled size and shape is described along with results of its use which show how the shape of the surface crack changes as it grows in bending fatigue from a variety of crack starter shapes. The growth pattern for any crack is uniquely defined by the crack starter configuration and appears to be independent of alloy. Shape changes are substantial and all growth curves tend toward a common growth curve. Circular cracks tend to become elliptical with an associated increase in stress intensity factor. This increase accelerates the crack growth rate and proximity to the critical flaw size. Through-cracks produced by the extension of a surface crack in a bending stress field will have length ten times the section thickness. The results demonstrate the necessity of taking into account changing crack shape in the calculation of structural life when bending is a significant component of the stress field.
Phase Extraction and Analysis in Superalloys—Second Summary of Investigations by ASTM Subcommittee E04.91
Authors: Donachie MJ
Published: February 2009

Additional phase identification procedures for superalloys have been evaluated. Reproducibility of results has been assessed and some tentative procedures for extraction of powdered metals and for the separation of extracted carbide and Laves phases have been evaluated. A definite procedure has been established to minimize errors in the identification of X-ray diffraction patterns of superalloy phases. The need for integrated use of analytical techniques to identify phases and characterize alloys by combined extraction, optical, electron optical, microprobe, and X-ray diffraction techniques has been recognized.
Displacement Coefficients Along the Inner Boundaries of Radially Cracked Ring Segments Subject to Forces and Couples
Authors: Gross B
Published: February 2009

Displacement results of plane boundary collocation analysis are given for various locations on the inner boundaries of radially cracked ring segments (C-shaped specimens) subject to two complementary types of loading. Results are presented for ratios of outer to inner radius Ro/Ri in the range of 1.1 to 2.5 and ratios in the range of 1.1 to 2.5 and ratios a/W in the range 0.1 to 0.8, where a is the crack length for a specimen of wall thickness W. By combination of these results the resultant displacement coefficient Δ or the corresponding influence coefficient E'BV/P can be obtained for any practical load line location of a pinloaded specimen.
Low Energy Impact Behavior of Composite Panels
Authors: Aleszka JC
Published: February 2009

Current results of an experimental study to determine the resistance of eight-ply AS/3501-5 graphite/epoxy, [±45 deg/0 deg/90 deg]s, to impact loadings incurred during ground handling and routine maintenance of aircraft are presented. The impact loading was simulated by dropping a 249-g (8 troy oz) cylindrical weight with a hemispherical head through a guide tube onto the panels. The configuration of the drop weight head was designed to simulate a blunt instrument while the total weight approximated that of a typical hand tool. This technique, which enabled up to 3.6 J (2.7 ft-lb) to be imparted to the panels, was found to be more versatile and informative than the conventional ball drop test.

Specimen response was monitored by strain gages attached to the drop weight and interfaced with an instrumentation system to provide load-time and energy-time records. These records were correlated with visible damage in the panels. The load and absorbed energy corresponding to incipient and full penetration damage were independent of impact velocity in the range studied.
Evaluation of Cushion Dynamic Properties by Impedance Measurements
Authors: Nassar EM
Published: February 2009

A method is proposed for the evaluation of cushions in dynamic environments. With the mechanical impedance technique the cushion properties are determined in terms of equivalent distributions of stiffness, damping, and mass parameters. Test results on a specific material show that these parameters may be considered of constant magnitude within limited ranges of frequencies and input levels. The equivalent cushion parameters are presented in dimensionless form as functions of the geometry and the input levels. The results warrant future tests at broader ranges of input and geometrical variables for further development of the method.
A Summary and Comparison ofJEstimation Procedures
Authors: Chipperfield CG
Published: February 2009

The various methods available for estimating the value of the J integral for standard fracture toughness specimens are summarized and compared theoretically and on the basis of available experimental data. Tentative recommendations are made as to which particular methods of analysis should be included in the posttest evaluations of J.
Marine Atmosphere Stress Corrosion Tests on Precracked Specimens from High-Strength Aluminum Alloys: Effect of Corrosion-Product Wedging
Authors: Dorward RC , Hasse KR , Helfrich WJ
Published: February 2009

Stress corrosion tests on precracked double-cantilever beam specimens from 2000- and 7000-series aluminum alloys have been in progress for up to seven years at a marine-atmosphere exposure site near Daytona Beach, Fla. One of the most significant results of these tests concerns the effects of specimen self-loading (because of exfoliation and corrosion-product wedging) on the relative crack growth resistance of different alloys. Self-loading is apparently affected by copper content but is not limited to copper-bearing alloys. Copper-free alloy 7039-T64, for example, showed self-loading effects after 3 to 4 years' exposure. Naturally aged 2XXX alloys and peak-aged, copper-containing 7XXX alloys were most sensitive to self-loading, usually showing the effects within six months. However, cracks in 7075-T73, a stress corrosion resistant alloy, also continued to propagate at rates that were not insignificant after several years' exposure, whereas alloy 2024-T851 appeared more resistant to corrosion-product wedging than 7075-T73.
Design and Performance of a Deadweight Standard Rockwell Hardness Testing Machine
Authors: Barbato G , Desogus S , Levi R
Published: February 2009

The design principles and main features of a deadweight standard hardness testing machine developed at the Instituto di Metrologia “G. Colonnetti” are described. Vickers and Brinell tests with deadweights ranging from 10 to 187.5 kg may be performed on the machine, which is built mainly for Rockwell A, B, and C scales.
Procedures for the Reduction and Testing of Bias
Authors: Visman J
Published: February 2009

The detection of bias depends on the precision of the sampling procedure that is employed to measure it. The significance of detected bias is therefore a relative matter; nonperformance of the bias test gives a one-sided answer only as smaller bias may exist. In fact, all measurements can be said generally to produce answers that are to some degree affected by systematic error. In this paper three different aspects are treated as starting points for formulating a standard method for bias: (1) the conditions under which bias occurs in the sampling of broken coal and factors that contribute to its control, (2) the means whereby bias can be reduced, and (3) the discussion of two procedures for the testing of bias. Attention is drawn to the terminology and the definitions that are related to the reduction and testing of bias, with special reference to the need for finding a common terminology in which the basic principles of probability are anchored down for public use regardless of the field of endeavor to which it is to be applied.
Acute Fish Toxicity and Absorption Tests of an Experimental Detergent Builder, Trisodium Carboxymethyloxysuccinate
Authors: Newsome CS , How MJ
Published: February 2009

Trisodium carboxymethyloxysuccinate (NaCMOS) is a new sequestering agent being evaluated as a builder in detergents. It contains neither phosphorus nor nitrogen and is readily and completely biodegraded in aerobic and anaerobic environments. The concentration of NaCMOS lethal to 50% of a batch of fish over 96 h (TLm96) in static tests is 2.9 g/litre and 2.3 g/litre for goldfish (Carassius auratus) and rainbow trout (Salmo gairdneri), respectively, in hard water (300 mg hardness/litre as calcium carbonate). These concentrations are 2300 to 160 000 times greater than the predicted concentrations that could occur in the aquatic environment from the use of NaCMOS as a detergent builder. The highly polar character of NaCMOS indicates that it would not be bioconcentrated; this is consistent with the results of absorption tests using 14C-labeled NaCMOS and goldfish. The results support the environmental acceptability of NaCMOS.
Fracture Modes and Acoustic Emission of Composite Materials
Authors: Rotem A , Altus E
Published: February 2009

Unidirectional fibrous composite material laminae are the construction material of a laminate. Four failure modes can occur in this material, and the identification of these modes is as important as the identification of onset of fracture. Acoustic emission (AE) pulses, generated by the change in the stress field resulting from cracking in a material, have a unique pattern of amplitude distribution that depends only on the mode of fracture and the type of material. By using a tapered double-cantilever beam as grips for the unidirectional lamina, a crack with a constant stress intensity factor was induced, thus eliminating the factor of the stress level. Placing the lamina in different directions relative to the grips imposed a different failure mode. By plotting the log of the relative number of AE pulses above some level versus the log of the relative level, a single constant coefficient can be measured for each material and mode of fracture. The AE energy is proportional to the energy released by the cracking; this proportionality depends on the medium where the AE waves have to travel, and not on the cracking mode.
Sampling and Analysis of Atmospheric Sulfur Dioxide with the Lead Dioxide Plate (Huey Plate)
Authors: Levadie B
Published: February 2009

The performance characteristics of the lead dioxide (Huey) plate for sampling sulfur dioxide are evaluated, and a method for determining sulfur dioxide as precipitated barium sulfate by weighing on an electrobalance is described. The data produced by exposing Huey plates over a two-year period are presented. A direct relationship between the concentration of sulfur dioxide in the ambient atmosphere as determined by continuous automatic monitoring and the mass loading of lead sulfate on the Huey plate has been confirmed. The correlation coefficient for the relationship was 0.90.
A Tower Extensometer
Authors: Findley WN , Lepper JK
Published: February 2009

A self-contained extensometer is described for rapid and highly accurate tension testing of several samples of rigid plastics over the entire range from zero load through fracture. The instrument has high sensitivity and linearity; negligible friction, backlash, and dead zone; a construction that permits installation after the specimen is located in the machine and that permits leaving the instrument on during fracture; and a design that averages the strain of the specimen. The instrument may also be used on metals whose hardness is significantly less than that of the gage points.
A Simple and Sensitive Method of Monitoring Crack and Load in Compact Fracture Mechanics Specimens Using Strain Gages
Authors: Deans WF , Richards CE
Published: February 2009

The calibrated strain on the back face (the face opposite that from which the slot is machined) of compact tension (CT) and T-type wedge-opening-loading (WOL) specimens provides a method for measuring crack length when the load is known or for measuring load when the crack length is known. The method is simple, reliable, sensitive, and inexpensive. A good correlation was achieved between strain measurements on a CT specimen and values computed from a two-dimensional finite element analysis. The method has good potential for developing into a more sensitive crack length measurement technique than has previously been achieved.

Calibration tables and graphs are reproduced that describe the relationship between crack length, back-face strain, and load for CT and T-type WOL specimens of any size and thickness and for any linear elastic material.

The method has several advantages over the closely related crack opening displacement (COD) technique for some test situations and these are described. In particular, the back-face strain increases linearly with crack length for constant stress intensity conditions except for very deep cracks in CT specimens. The overall characteristics render the technique ideal for incorporation into computerized/automated crack growth testing.

For constant back-face strain, the stress intensity was shown to decrease with increase in crack length for both CT and T-type WOL specimens. This decrease is more pronounced than for corresponding constant COD testing and this provides a good technique for obtaining threshold fatigue or stress corrosion conditions.
The Influence of Bulk-Solution-Chemistry Conditions on Marine Corrosion Fatigue Crack Growth Rate
Authors: Bogar FD , Crooker TW
Published: February 2009

An exploratory study has been conducted to determine the influence of bulk-solution-chemistry conditions on corrosion fatigue crack growth rate in high strength alloys. Various solutions commonly employed in studies relating to marine corrosion were evaluated for their relative severity in crack growth rate tests. Related aspects involving aeration and applied cathodic potential were included. The results indicate that bulk-solution-chemistry conditions can influence measured values of corrosion fatigue crack growth rate by as much as a factor of three; however, the relative severity of various solutions can vary, depending on alloy composition.
Use of the Double Torsion Method to Study Crack Propagation in an Adhesive Layer
Authors: French RH , Raj R
Published: February 2009

The double torsion technique offers a simple method of studying crack propagation in adhesive layers. The method has been applied successfully to obtain crack-velocity versus crack-extension-force curves for fracture in bonds constructed from an epoxy and a nylon-impregnated adhesive. The thickness of the adhesive layer is found to have a significant effect on the fracture behavior.
Cohesive Bond Strength Prediction for Adhesive Joints
Authors: Flynn PL
Published: February 2009

An analytical study was carried out to derive the acoustic spectral response of an attenuating bond line. A similar effort was done to relate the time-base response of an attenuating bond line to the material properties of the adhesive. In this study, resonance separation, ultrasonic amplitude ratio, and resonance depth were related to the acoustic impedance, attenuation, and sound velocity of the adhesive layer.

Experimental verification of the derived correlations was provided by systematically varying the properties of Chemlok 304, a two-part paste adhesive, by mixing the adhesive in a range of proportions. Single overlap shear specimens were made with these adhesive mixtures and the adhesive properties were measured in situ with high frequency broadband ultrasonics. The ultrasonic data were reduced to yield the sound velocity, density, and attenuation coefficients of the adhesive mixtures. The specimens were tensile-tested to determine joint strength and stiffness. The strength and stiffness of the bonded joints correlated well with the ultrasonic amplitude ratio, sound velocity, attenuation coefficient, and resonance depth.
Laboratory Testing of Asphalt Concrete for Porous Pavements
Authors: Woelfl GA , Wei IW , Faulstich CN , Litwack HS
Published: February 2009

Laboratory testing was conducted to determine the effects of aggregate gradation and asphalt content on the stability and permeability of open-graded asphalt concrete. Test results indicate that permeability increases and stability decreases as the aggregate gradation becomes more open-graded, that is, includes less of the smaller sized particles. Also, permeability decreases as asphalt content increases whereas maximum stability occurs at an optimum asphalt content. Open-graded asphalt concrete was installed in the field for a porous pavement parking lot. The pavement has been serviceable for over two years, including exposure to winter conditions.
RCurve and Fracture Toughness of Thin Sheet Materials
Authors: Schwalbe K-H , Setz W
Published: February 2009

Crack growth resistance R curve tests were done on center-cracked panels of three aluminum alloys. Two methods for the measurement of crack length were compared: the compliance method and the potential method. The latter gives more consistent results. It was found that the stress intensity serves as a correlation parameter for crack growth up to a limiting value of the net section stress that is equal to 0.9 times the yield strength. The fracture stress can be accurately predicted by the R curve concept.
Some Aspects of Fatigue Crack Closure in Two Contrasting Titanium Alloys
Authors: Halliday MD , Beevers CJ
Published: February 2009

Fatigue crack growth at intermediate rates was measured in compact tension specimens of the microstructurally contrasting alloys Ti-6Al-4V (Imperial Metal Industries, Ltd. [IMI] titanium 318) and Ti-6Al-5Zr-0.5Mo-0.25Si (IMI titanium 685). Sinusoidal loading was used with a ratio of minimum load to maximum load R of 0.1. The incidence of crack closure was examined during fatigue with both direct current potential drop and crack-opening-displacement (COD) methods; COD was found to be more reliable for closure measurement than potential drop. In contract to the fine-grained IMI 318, the coarse-structured IMI 685 showed substantial load transfer across the crack faces during fatigue and this was attributed to mismatch of the fracture faces. It was shown that the large differences in crack growth rate between the two alloys could be substantially accounted for by an effective stress intensity factor range concept. Marked reductions in growth rate produced by variable amplitude loading of the IMI 318 could not be explained in terms of crack closure.
The Effects of Stress Dwells and Varying Mean Strain on Crack Growth During Thermal Mechanical Fatigue
Authors: Gemma AE , Ashland FX , Masci RM
Published: February 2009

Two types of test were used to evaluate the effects of creep and thermomechanical fatigue (TMF) on the crack growth rates of two nickel-base superalloys: directionally solidified MAR-M200 + hafnium and conventionally cast B-1900 + hafnium. In the test type designated simulated creep/TMF, the mean strain was incremented by a fixed amount at the maximum cycle temperature of each 20th TMF cycle. For the test type designated as creep/TMF, a constant stress was imposed at the maximum temperature for a fixed time period of each 20th TMF cycle. The crack growth rates for both test types were generally higher than the average rates of the baseline data from pure TMF tests. The fracture surfaces of the simulated creep/TMF specimens showed a considerable amount of plane stress behavior, that is, changes in crack planes and growth along steep angular planes. On the other hand, the fracture surfaces of the creep/TMF specimens were more typical of crack growth under plane strain conditions. A strong correlation was found for both alloys between baseline primary creep rates and cumulative creep rates of the interaction test specimens.
Fatigue Crack Growth Rate Data Acquisition System for Linear and Nonlinear Fracture Mechanics Applications
Authors: Ruschau JJ
Published: February 2009

A computer-based, automated data acquisition system was developed for determining fatigue crack growth rate data for both linear and nonlinear fracture mechanics testing. The system hardware used was a Hewlett Packard (HP) 9825A desktop computer equipped with an HP 6940B multiprogrammer.

For linear elastic fracture mechanics (LEFM) testing, the crack growth rate da/dN is presented as a function of the stress intensity factor range ΔK. Compliance relationships are used to monitor crack length which is then used to calculate the stress intensity range.

For nonlinear fracture mechanics (NLFM) testing, the crack growth rate is related to the rate of potential energy change, or ΔJ. Compliance techniques are also used to monitor crack extension.

The results of both analysis methods obtained with the acquisition system for aluminum alloys 2124-T851 and 7075-T73 (Unified Numbering System [UNS] A92124 and A97075) are in excellent agreement with results obtained using the more conventional visual and analytical methods. The automated system is superior from a point of speed and consistency and possesses the accuracy required for valid crack growth testing. Furthermore, the system requires no personal supervision or special specimen preparation and thus would be available for obtaining fatigue crack growth results from test specimens that are subjected to adverse environments which preclude the use of visual measurements.
Determination of Crack Tip Energy Dissipation and Elastic-Plastic Fracture Toughness Parameter with Ductile Crack Extension
Authors: Shoji T
Published: February 2009

In order to evaluate the elastic-plastic fracture toughness parameter of nuclear pressure vessel steel, SA533B-C1 1 (Unified Numbering System [UNS] K12539), near and beyond general yielding, a newly developed technique for large plastic strain measurement, that is, the recrystallziation-etch technique, was applied to compact tension and three-point bend specimens with a crack length/specimen width of 0.6 that were tested to draw resistance curves for stable crack extension. Based on the results reported previously that the equivalent plastic strain distribution around the blunted crack tip could be measured by means of the recrystallization-etch technique, the plastic energy dissipation or work done within an intense strain region at the crack tip accompanying ductile crack extension was measured experimentally. Furthermore, the size and loading condition effects on this crack tip energy dissipation rate were examined in comparison with other candidate parameters for crack extension criteria in the presence of large scale plasticity. The size of the intense strain region could be regarded as equal to the process zone size where the fracture is taking place. Formation and extension characteristics of this zone were discussed from a view point of elastic-plastic fracture toughness parameters including the relationships with existing fracture toughness parameters such as crack opening displacement and J integral.
An Evaluation of a Load-Line Extensometer for Elastic-Plastic Fracture Toughness Testing
Authors: Williams JA , Carlson KW
Published: February 2009

A load-line extensometer using linear variable differential transformer (LVDT) displacement transducers was developed and evaluated for use in multispecimen and single specimen J value versus crack growth (J-R) curve testing. The LVDT extensometer accuracy and repeatability was compared with that of clip gage extensometers commonly used in fracture toughness evaluatons. Data on load versus displacement and J value versus crack growth for ASTM A533, Grade B, Class 1 (Unified Numbering System [UNS] K12539) steel obtained by using both extensometers were also compared.
Residual Stress Profile in Machined Parts
Authors: Israeli A , Papiar R
Published: February 2009

The processes of machining precision parts have to be planned to result in low residual stresses, and a fast and reliable method is required to determine such stresses. A system was developed to meet this need. This system is based on continuous etching of a cylindrical specimen. Changes in specimen length are monitored as a function of etching time. The residual stress is then calculated with the Bauer and Heyn equation. Residual stress profiles caused by single point turning of 4340 steel (Unified Numbering System [UNS] G 43400) and maraging 300 steel specimens were evaluated by this procedure. This profile provides stress distribution in depth below the machined surface at various turning feeds, and it is used to define a residual tensile force. It is shown that an increase of feed increases the depth of the residual stressed layer and also increases the residual tensile forces. The ratio of residual tensile force to tool force as a function of the turning feed has a minimum.
Magnetic Properties of Iron and Low Carbon Steel for Soft Magnet Applications
Authors: Stokes JL
Published: February 2009

An investigation was conducted to assess the relative merits of five soft magnet materials proposed as alternatives to ARMCO Electromagnet Iron (EMI), which is no longer available. Four irons and an SAE J403 (1005) (Unified Numbering System [UNS] G10050) steel were considered. When annealed in 94% nitrogen-6% hydrogen at 843°C (1550°F) for 4 h and aged at 100°C (212°F) for 400 h, two of the irons were found to be equivalent to EMI with regard to both coercive force and magnetic stability. A third iron exhibited similar magnetic properties after annealing but required a higher annealing temperature to reduce the coercive force to an acceptable value. The fourth iron and the 1005 steel met the coercive force requirement after annealing at 843°C (1550°F) in 94% nitrogen-6% hydrogen, but suffered significant increases in coercive force during aging at 100°C (212°F).
Erosion Behavior of Polystyrene
Authors: Thai CM , Tsuda K , Hojo H
Published: February 2009

Erosion tests of polystyrene were made by impingement of glass beads at various attack angles and impact velocities. Two erosion damage peaks near the angles of 20 and 50°, which have never been observed on other materials, were found. In the erosion process near the peak of 50°, a characteristic ring-like damage pattern on the surface was recognized. To explain the experimental results, a new erosion mechanism based on the initiation and propagation of transverse cracks beneath the surface at the tip of longitudinal cracks was introduced. And by this mechanism, the erosion rate could be given by R = ρhS*/Mo where h, S*, and Mo are the factors describing the characteristics of the ring-like damage pattern and ρ is the density of material. The theoretical values agreed quite well with the experimental ones.
Isochronous Relaxation Curves for Type 304 Stainless Steel After Monotonic and Cyclic Strain
Authors: Swindeman RW
Published: February 2009

Relaxation tests to 100 h were performed on Type 304 stainless steel in the temperature range 480 to 650°C and were used to develop isochronous relaxation curves. Behavior after monotonic and cyclic strain was compared. Relaxation differed only slightly as a consequence of the type of previous strain, provided that plastic flow preceded the relaxation period. We observed that the short-time relaxation behavior did not manifest strong heat-to-heat variation.
Acoustic Emission Monitoring of Weldments
Authors: Hopwood T , Havens JH
Published: February 2009

Weld tests were performed on low-carbon and high-strength, low-alloy steel weldments. The weldments were monitored with an acoustic emission detector during both the “in-process” and the “in-cooling” phases of the welding operation. Artificial defects were induced in several of the welds to promote cracking. Some high-strength weldments were designed to produce welds subject to high restraint. Nondestructive and destructive evaluation of the completed weldments revealed that high acoustic emission activity during in-cooling could be correlated with embedded defects and cold-cracking. Copious emission activity was also detected from unflawed weldments. Acoustic emissions were detected in high-strength steel weldments for periods up to 265 h. However, there was no clear relation between the duration of acoustic emission activity and cracking. On a per-electrode-deposited basis, high-stressed welds produced more emissions than low-stressed welds.
A Phenomenological Description of the Acoustic Emission Response in Several Polycrystalline Materials
Authors: St. Lawrence W
Published: February 2009

The pattern of acoustic emission response in snow subjected to constant deformation rates is examined. The structural character of snow is discussed and an equation that describes the pattern of the acoustic emission response is derived. Comparison between the predicted acoustic response and experimental data is made and the agreement is shown to be excellent. The acoustic emission response for 7075-T6 aluminum and iron-3% silicon subjected to constant rates of deformation is also considered. The acoustic emission equation derived for snow represents the response in these materials. It is suggested that the internal fracture concept used to develop the model for snow may also apply to other densely packed polycrystalline materials.
Environmental Testing Under Random Loading
Authors: Dodds CJ
Published: February 2009

A data reduction and analysis technique is presented for describing a multivariate nonstationary random process, representing a multiaxial stress distribution, by stationary techniques. An accurate simulation of this stress environment is achieved in the laboratory by using an iterative “deconvolution” technique to derive a series of excitation signals that will be used for fatigue testing.
Determination of the Fracture-Energy Criterion JIc of Two Steels by Static and Dynamic Testing
Authors: Nguyen-Duy P , Phélippeau G
Published: February 2009

The fracture energy criterion JIc was determined on two carbon-manganese steels, SA-516-70 and SA-105-B, from a single specimen. A graphic method is proposed for verifying the validity of measured values of JIc. Static JIc and dynamic JIcD experiments on precracked Charpy V-notch specimens at ambient temperature enabled the observation of the effect of loading rate on the value of JIc. For these two steels, the effect of side grooves was detected only in dynamic testing. For SA-516-70 steel, JIcD > JIc, while JIcD > JIc for SA-105-B steel, because of transition temperature fracture behavior. For SA-516-70, static testing was performed on three-point bend specimens of different dimensions to determine the effect of geometrical parameters on the value of JIc. A ligament 1-cm long is the lower limit for the determination of JIc.
A New Load-Transmitting Medium to Measure Strength of Brittle Materials
Authors: Erdei CK
Published: February 2009

A testing apparatus based on the principle of a new load-transmitting medium developed by the author is presented in this paper. Instead of solid bearing platens, “Lamina Pack” bearing platens are used in a compression test to overcome the shortcomings of current testing techniques. Data obtained in past investigations of nonmetallic brittle materials demonstrated that machines using solid bearing platens in contact with the specimen cause significant lateral restraint to the specimen and severe disturbances to the specified stress state, resulting in misleading apparent strength measurements. Previous attempts to replace testing machines with solid bearing platens have failed as the machines proposed do not have sufficient load capacity to measure the compressive strength under combined stresses of most of the brittle materials of engineering use. The apparatus exerts no appreciable lateral restraint to the specimen and has a high load-transmitting capacity. Strain measurements on specimens subjected to uniaxial compression applied by lamina platens show uniform deformation and indicate that the specified stress state (purely normal stresses applied to the boundaries of the specimen) has been closely approached.
High-Speed Sampling Cutters and Their Effect on Bias
Authors: Bluck WV , Hanson R , Huntington FR
Published: February 2009

Currently, in the United States, systems used to obtain a gross sample of flowable bulk material on a conveyor belt generally use a cross-chute sampler. With higher tonnage material handling systems, it would be advantageous to employ higher cutter speeds to keep the size of the gross sample collected within practical limits. Current cross-chute sample cutters are somewhat limited to cutter speeds in the range of 30 to 61 cm/s (12 to 24 in./s), primarily because of mechanical and structural limitations. Swing-arm-type samplers have features that permit higher cutter speeds, which reduce the quantity of primary increment taken. This paper presents the results of a test program for swing-arm samplers operating at cutter speeds up to 122 cm/s (48 in./s) and determines the parameters of control that must be considered to stay within acceptable statistical limits for bias.
An Optical Comparator for Evaluation of Fine Sieves
Authors: Bareket N , Poluianov EW , Mancini FP
Published: February 2009

An optical comparator for testing the compliance of fine sieves with existing standards was designed and built. It is a portable, low-cost instrument, featuring a range of magnification from ×8 to ×270 and scanning capabilities over a 30-cm-diameter surface. The design principles are discussed and test results regarding the accuracy and speed of operation are presented.
Crack Initiation, Slow Crack Growth, and Unstable Propagation of Ductile Fracture in Mild Steels in a Laboratory Experiment
Authors: Ogasawara M , Kuriyama Y , Tamano T , Mimura H , Yanagimoto S
Published: February 2009

A laboratory test for the unstable ductile fracture of mild steels was developed. A shear crack was initiated from a very deep notch. Some devices such as “pipe tabs” were used to reduce the stiffness of the system enough to allow the shear crack to continue to grow in an unstable manner. Four kinds of pipe materials were tested, and three of them with low ductility showed unstable ductile fracture. The fracture toughness for the onset of unstable fracture in these steels was evaluated and correlated successfully to upper shelf energy in the Charpy test.

A slow crack growth test was performed with a high stiffness tensile system, ductile crack growth resistance R curves being obtained experimentally. A model of ductile crack growth was proposed by the modification of the Dugdale model, elastic/perfectly plastic crack analysis, by which R curves were finely described. Critical energy release rate 𝒢 values for the onset of unstable ductile crack propagation were shown to compare well with the values estimated from the R curves. Thus, ductile crack growth, both slow and rapid, is well characterized by the values of notch ductility.
Evaluation of Assembly Stresses of Automotive Leaf Springs by Acoustic Emission
Authors: Baram JC , Eckhaus S , Rosen M
Published: February 2009

The acoustic emission Kaiser effect is used to evaluate the quantitative state of stress of leaf springs used in the automotive industry. Changes in curvature radii or in yield stress caused by thermal or mechanical treatment of the leaves are accurately assessed by a bend test procedure. The computation of the assembly stresses of the springs can be made knowing the actual yield stress of each leaf, thus enabling optimal design. The technique may be applicable to the reuse of discarded leaf springs subjected to mechanical deformation.
Similarities in Different Experiments of Erosion Caused by Cavitation and Liquid Impingement
Authors: Veerabhadra Rao P , Syamala Rao BC
Published: February 2009

Correlations of erosion resistances of materials tested in different equipment are reported. Analysis of the authors' data from rotating disk and venturi equipment indicates that there exists a good correlation between the erosion resistances of materials tested at different intensities. The study indicates that time effects on erosion are important in correlations of this type. The erosion resistances of materials tested in two different devices exhibit good correlations indicating a quantitative similarity between different forms of erosion. The investigations also show that the prediction of erosion resistances of materials in a field device may be made with the data from a laboratory device which may not fully reproduce the flow conditions in the field. These conclusions are also checked with data reported from other laboratories.
The Measurement of Absorbed Charpy Impact Energy Using a Vertical Drop Tower
Authors: Server WL , Henderson GR
Published: February 2009

Standard Charpy calibration specimens designed for verification of pendulum impact machines have been tested on a vertical drop tower impact machine. Two different test techniques (optical velocity measurement and integrated digital load-time response) for measuring the fracture energy of these specimens have produced equivalent sets of data which match the range of expected pendulum machine results. The more flexible vertical drop tower machine can therefore be used to measure Charpy impact energies with the same reliability as the conventional pendulum machines.
Application of the Electrical Potential Method to Crack Length Measurements Using Johnson's Formula
Authors: Schwalbe K-H , Hellmann D
Published: February 2009

The applicability of Johnson's equation for the potential drop to three specimen geometries is demonstrated. In addition, some remarks are made concerning the influence of crack length and specimen width on the resolution of the potential method.
Damping in Turbine Blade Alloys
Authors: Wolfenden A
Published: February 2009

Measurements of the damping capacity Q−1 of candidate turbine blade alloys for the Wairakei, New Zealand geothermal power station and other future power stations are reported. The techniques used were the piezoelectric ultrasonic composite oscillator technique (PUCOT) at 40 or 80 kHz and stress levels 70 kPa to 37 MPa and the vibrating reed technique (VRT) at 321 Hz and stress levels 32 to 177 MPa. Specimen materials investigated were Ti-6A1-4V, 26Cr-1Mo steel, Firth-Vickers (United Kingdom) FV520B steel, 15Cr-Mo steel, and 410 (Unified Numbering System [UNS] S41000) stainless steel. The results include Young's modulus and the stress and strain amplitude dependences of Q−1. The frequency dependence of Q−1 was found to be only a few tens of percent, much smaller than the predicted dependence. Of the two techniques, it was shown that the VRT is more suited to damping measurements at the operational stress levels for turbine blades. The PUCOT, VRT, and high stress cyclic stress-strain data were plotted on a universal curve of damping energy versus stress. The plot covers 14 orders of magnitude in damping energy and five orders in stress.
Damping and Metals Characterization
Authors: Weissmann GF
Published: February 2009

Damping and internal friction have been used extensively in studies concerned with microstructural and macrostructural changes of crystalline materials and with the mechanism causing inelastic deformations. Damping has seldom been used for metals characterization on an engineering level. Some possible reasons are discussed. The energy dissipation of strongly amplitude-dependent metals is determined best by measuring the work per cycle required to maintain a constant kinetic energy for a specimen subjected to bending or torsional vibrations. A mathematical relationship between the kinetic energy and the work per cycle is proposed and compared with experimentally determined data. An excellent correlation has been obtained. Three experimentally determined constants classify the behavior of metals in the range most important for engineering applications.
Laser Evaluation of Cutting Angle and Surface Finish in Scalpel Blades
Authors: Shetty D
Published: February 2009

A simple inexpensive technique to assess the sharpness of scalpel blades by laser diffraction is presented. Two of the factors that contribute to edge sharpness such as cutting angle and grinding finish of the side faces are evaluated by optical transformation techniques. One could therefore arrive at an optimum set of values of the above two factors which would in turn lead to the production of sharper blades.
Dynamic Fracture Toughness and Fatigue Crack Growth Rate Properties of ASME SA508 CL 3 and SA508 CL 3a Base and Heat-Affected-Zone Materials
Authors: Logsdon WA
Published: February 2009

Dynamic fracture toughness tests were performed on ASME SA508 Cl 3 and Cl 3a base and heat-affected-zone (HAZ) materials. Linear elastic results of dynamic iniation fracture toughness obtained under fast or rapidly applied loading rates KId were obtained at low temperatures while J-integral techniques were used to evaluate dynamic fracture toughness over the transition and upper shelf temperature ranges. Loading rates in terms of stress intensity factor rate ˙K averaged 5.35 × 104 MPa · m1/2/s (4.83 × 104 ksi · in.1/2/s). Tension, Charpy impact, drop weight nil-ductility transition (NDT), and room temperature, air environment fatigue crack growth rate (FCGR) tests were also performed. From a dynamic fracture toughness as well as FCGR standpoint, SA508 Cl 3a steel can be considered as an acceptable alternative to the more commonly used SA508 Cl 2a pressure vessel steel, especially for structural applications in which underclad cracking is a potential problem.
The Effect of Self Stresses on High Cycle Fatigue
Authors: Fuchs HO
Published: February 2009

It now seems to be understood that self stresses (residual stresses) increase or decrease fatigue life mainly by preventing, delaying, or accelerating the growth of cracks. The action of self stresses is currently being related to fracture mechanics. The fact that the effect of self stresses is far stronger at notches than in smooth push pull specimens, or in other smooth specimens, is gaining more and more recognition. In current publications this fact is modeled by considering not only the local surface stresses, but also the distribution of load stresses and self stresses below the surface of the specimen or part.
A Constant Stress Tensile Creep Machine for Very Low Stresses
Authors: Yavari P , Langdon TG
Published: February 2009

A simple constant stress tensile creep machine is described for use at very low stress levels. The initial mechanical advantage of the machine is 3:8 and the minimum feasible load is about 1.8 N. Some typical creep results are presented for an aluminum-5% magnesium alloy with measured steady-state strain rates down to about 10−9 s−1. It is demonstrated that the results obtained from this machine coincide with data from a normal creep machine at high stress levels, but the stress marking the experimental lower limit is reduced by more than one order of magnitude.
A Compressive Creep Machine
Authors: Findley WN
Published: February 2009

A deadweight loading machine for creep tests in compression is described. The machine was designed to minimize buckling and friction. A four-bar linkage was used to guide the movable crosshead. Strain was measured by a single differential transformer. The specimen consisted of a thin-walled tube heated internally by a quartz tube lamp. An example is given of creep of 2618-T61 aluminum in compression.
Impurity Variations in Electrolytic Cathode Copper
Authors: Medrick DS , Teague JE
Published: February 2009

This work was conducted to evaluate the effects of segregated impurities (particularly sulfur) in various locations of a randomly selected electrolytic cathode on the fabricability of wires drawn from spikes cast with copper from these regions of the cathode. Results were analyzed by the different performance levels achieved with copper fabricated from these cathode regions. Another aspect of this work was an investigation of a 340 200-kg (750 000-lb) copper lot consisting of a 154 700-kg (341 000-lb) section of sheared cathodes (top and bottom 102-mm [4-in.] wide strip sheared off each cathode) and a comparison 185 500-kg (409 000-lb) section of unsheared regular cathodes for reference purposes. This split lot was fabricated into magnet wires, and the results between these two sections were compared as to performance levels obtained in the finished wire products.
Sampling of Electrorefined Copper Cathodes
Authors: Tuddenham WM , Dangerfield AD , McMillan BB
Published: February 2009

Problems involved in the sampling of electrorefined cathode production in a typical refinery are examined. Items discussed include: nonhomogeneity in single cathodes, nonhomogeneity among cathodes from the same electrolytic cell, nonhomogeneity among cathodes from single production lots, and limitations of visual examination in predicting cathode quality. Ordinary sampling procedures involving one or two cathodes are shown to be totally inadequate for obtaining true measures of the average impurity contents from a shipping lot. Suggestions for sampling frequency drawn from the experience of the study are presented.
Strength Reduction in Thin Aluminum Alloy Sheets by Laser Irradiation
Authors: Clark G , de Morton ME
Published: February 2009

In order to assess the extent of the damage produced in thin metallic sheets by high-energy laser radiation, the residual tensile strength of small-scale 7075-T6 alumimum alloy specimens has been measured after laser irradiation and cooling. The effect of applied loads during irradiation upon residual strength is found to be small for all loading levels except those approaching the elastic limit. In addition, the use of an equivalent hole size parameter to describe the extent of laser damage and to compare the strength-reducing effects of various irradiation parameters is proposed.
Application of Accelerated Weathering Test to Glass-Fiber Reinforced Polyester Sheets of Improved Surface Durability
Authors: Yamasaki RS , Blaga A
Published: February 2009

An accelerated weathering test has been applied to three types of commercial glass-fiber reinforced polyester (GRP), the durability of which has been improved by the application of various surface finishes. The nature and rate of induced surface degradation were monitored throughout the exposure period by scanning electron microscopy and, where possible, compared with those produced by horizontal outdoor exposure at Ottawa, Canada. Acrylic-lacquer-coated GRP underwent six types of surface damage leading to exposure and surface microcracking of the GRP substrate. The first three types of damage produced by artificial weathering were similar to those induced so far after six years of outdoor weathering, resulting in an acceleration factor of 6. Gel-coated GRP sustained surface microcracking as for outdoor exposure with an acceleration factor of 9. Poly(vinyl fluoride)-laminated (PVF) GRP underwent five types of damage, resulting in delamination of PVF and surface microcracking of the unprotected GRP resin. The first two types of damage have been verified to date after six years of outdoor exposure and were accelerated by a factor of 5.