bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparison of Methods for Determining the Shear Properties of Glass/Resin Unidirectional Composites
Authors: Loveless HS , Ellis JH
Published: February 2009

This paper describes and compares three methods of test for determining the interfacial adhesive strength of the glass/resin bond in reinforced plastic (RP) unidirectional composites. Measurement of the shear properties of these materials is of fundamental importance to the fiberglass manufacturer developing optimum sizing systems for the surface treatment of glass fibers used as plastics reinforcements. A new test, developed explicitly for the shear strength determination of pultruded cylindrical composites, is described and data obtained thereby are compared with similar results obtained by torsional and short-beam methods. Unlike this new notched-rod test, both the latter tests may occasionally give tensile rather than shear failures, thus rendering their usefulness questionable, since the shear strength of the composite has not been measured under such circumstances.

Contrary to earlier work of other researchers, the current experiments suggest that the shear strength of the RP composite may exceed that of the resin matrix when the bond at the glass/resin interface has been optimized.
Application of an Optical Heterodyne Interferometer to the Inspection of Surfaces
Authors: Lavan MJ , Van Damme GE , Cadwallender WK , DeYoung TF
Published: February 2009

The application of a high accuracy, wide bandwidth optical heterodyne interferometer to the inspection of surfaces is described and sample data are given. The data format should make the system particularly suitable for automatic inspection systems.
Nondestructive Evaluation of Strength Degradation in Glass-Reinforced Plastics as a Result of Environmental Effects
Authors: Meron M , Bar-Cohen Y , Ishai O
Published: February 2009

Destructive and nondestructive tests were conducted on glass-reinforced plastic specimens after degradation by immersion in hot water for various periods. Ultrasonic attenuation was found to correlate well with normalized residual strength data obtained from destructive tests.
Standards for In-Vitro and In-Vivo Comparison and Qualification of Bioabsorbable Polymers
Authors: Wade CWR , Hegyeli AF , Kulkarni RK
Published: February 2009

The bioabsorbable polymers poly(DL-lactic acid), poly-(isobutyl 2-cyanoacrylate), and poly(methyl 2-cyanoacrylate) have been evaluated comparatively in organ and cell cultures in vitro and in rat muscle tissues in vivo. Effects of the polymers on cell ultra-structure in organ cultures, on cell surface characteristics, and cell population doubling times in cell cultures have been correlated with hemorrhage, fibrosis, and necrosis. This correlation has been used to establish three cytotoxicity points (highly, moderately, and minimally toxic) for characterization or prediction of the in vivo behavior of absorbable polymers. As a result of these findings, and because these polymers are readily available, easily characterized, and have long shelf lives, they can be used as reference standards for testing and qualification of bioabsorbable materials.
Evaluation of Filter/Separators and Centrifuges for Effects on Properties of Steam Turbine Lubricating Oils
Authors: Taylor JW
Published: February 2009

A study was undertaken to determine the feasibility of using filter/separators in a bypass water-removal system for steam turbine lubricating oils. Twelve steam turbine oils were investigated in reduced-scale, 0.946 litre/min (0.25 gal/min), 500-h filter/separator experiments for effectiveness of water removal, effects of oil additives on performance of the filter/separator, and detrimental effects of filter/separators on oil properties. When effects on additives in the oil were indicated, restoration of the additives by adding up to 10% new oil was tried. Parallel investigations in a laboratory model continuous centrifuge were also conducted for comparison with the results obtained in the filter/separator investigations.

Satisfactory water removal effectiveness in filter/separators was demonstrated. Interactions of water-oil additives was encountered in varying degrees in eight of the twleve oils evaluated. Four of these oils were considered unsuitable for use unless reformulated. Since similar effects on oil additives may be encountered in either filter/separators or centrifuges, it is indicated that each oil should be evaluated for water-oil additive interactions to establish their suitability for use with water removal devices.
A Servo-Controlled Hydraulic Hot-Torsion Machine for Hot Working Studies
Authors: Fulop S , Cadien KC , Luton MJ , McQueen HJ
Published: February 2009

A closed loop servo-controlled hydraulic hot-torsion testing machine is described that is capable of applying a maximum of 100 revolutions of twist at velocities up to 15 revolutions/s with a maximum torque of 110 N·m. When a test specimen measuring 25 by 6 mm is used, these factors correspond to a maximum surface strain of 80, a shear strain rate of 12 s−1, and a shear stress of 1800 MPa. The motor displacement is programmed with the aid of a digital function generator and either torque or rotary displacement may be used for feedback control. The test pieces are held between a hydraulic motor and a fixed torque cell by superalloy loading members mounted in self-aligning chucks. They are heated by a radiant furnace and are enclosed in a transparent quartz tube that is flushed with argon during testing. By flooding the tube with water at the completion of a test, the specimen may be quenched to permit the study of the microstructures developed during hot deformation as well as the effect of various holding times on the deformation structures.

The capability of the machine is illustrated by results obtained on specimens of Waspaloy® tested at temperatures between 20 and 1093°C at strain rates in the range 0.03 to 7 s−1. The flow curves generated during these tests and the relationship between stress, strain rate, and temperature are discussed.
Three-Point Bending at Large Deflections
Authors: Theocaris PS , Paipetis SA , Paolinelis S
Published: February 2009

A complete investigation of three-point bending at large deflections was attempted with the view of applying it as a test method for the determination of the effective modulus of elasticity of materials. A general solution of the problem was attempted by considering friction forces at the supports, axial forces along the beams tested at large deflections, and the effect of finite depth. The solution was carried out for homogeneous, perfectly elastic materials with equal tensile and compressive moduli under the assumption that plane sections remain plane at large deflections and that no appreciable effect of shear or stress concentrations at the position of load application exists. The effect of roller supports of finite radius was also considered. The results obtained by the present theory provide sufficient data for the design of a bending test under any given conditions or accuracy required.
Delayed Yielding of a Plane Stress Viscoelastic Dugdale Model
Authors: DasGupta A , Brinson HF
Published: February 2009

The purpose of this investigation is to characterize the delayed yielding and fracture phenomena in a viscoelastic ductile polymer where crack growth is associated with the formation and growth of a plastic zone at the tip of the crack. This investigation deals with the time before catastrophic failure occurs in front of the crack tip. The bulk material is considered viscoelastic as well as rate dependent and is modeled by a modified Bingham model used by Brinson. The yielded material in the crazed region is modeled by the viscoelastic-plastic model of Crochét. Our theoretical solution has been adapted to a plane stress polycarbonate Dugdale model to facilitate a simple experimental verification. Such results could be useful in predicting lifetime, reliability, and failure criteria in structural members made from viscoelastic-plastic materials.
A Mathematical Model for the Determination of the Breakage Distribution in Batch Grinding
Authors: Tomlinson PN , Venter RD , de Malherbe R , Lees L
Published: February 2009

A mathematical model analogous to the rate of decay of radioactive materials has been developed to describe the unit operation of comminution. The model provides a useful theoretical base from which the fraction by weight on screens of different sizes can be determined after defined periods of grinding.
Studies on the Characteristics of Erosion with Plain Jets and Jets with Cavitation Inducers
Authors: Syamala Rao BC , Janakiram KS
Published: February 2009

Experimental investigations made on the characteristics of erosion resulting from the impingement of liquid jets is reported. Experiments were conducted for several plain jets of 4- to 12-mm diameter and jets with cavitation inducers of four diameter ratios in a velocity range of 5 to 45 m/s. A detailed dimensional analysis of the several parameters governing liquid impingement erosion is presented. The erosion rate-time curves for impingement by jets with cavitation inducers did not show the incubation and accumulation zones significantly. The normalized erosion rate increased with jet velocity and approached a constant value at higher jet velocities. The erosion rate decreased rapidly and then remained approximately constant with an increase in caviation number. The erosion rate increased faster with frequency of impingement than with increase in jet velocity. A maximum value in peak erosion rate occurred around angles of impingement of 25 to 40 deg.
Development of Light- and Water-Exposure Apparatus
Authors: Suga S
Published: February 2009

Several developments designed to solve the problems found in the operation of light- and water-exposure apparatus of enclosed carbon arc type, open flame carbon arc type, and xenon arc type are described. The life of carbon rods was lengthened from 20 to 48 h in an enclosed carbon arc lamp and from 20 to 60 h in an open flame carbon arc lamp. In a xenon lamp the rate of the decrease in radiation output was reduced, doubling the life of the lamp. An automatic system for light intensity control in a xenon arc maintained a constant level of intensity throughout the test period, and an automatic system for black-panel temperature control made it possible to minimize the variation of temperature to within ±1°C. These developments increase the usefulness in operational procedure and improve the reproducibility of the test.
Fracture Toughness of Stretched Acrylic Plastic
Authors: Sutton SA
Published: February 2009

This paper presents the method and results of a parametric study of instability toughness, as measured by the plane-strain KIc and plane-stress Kc fracture toughness of a multiaxially stretched acrylic plastic. A large number of computer-controlled tests were conducted with the compact tension specimen under high compliance loading/load control. These tests reveal the significant effects on Kc and KIc of a wide range of loading rates, specimen thicknesses, and specimen geometry. A direct and immediate application of the results is the recommendation of a new fracture toughness acceptance test for these materials.
The “Instantaneous” Effect of Internal Moisture Conditions on the Strength of Glass-Fiber-Reinforced Plastics
Authors: Ishai O , Arnon U
Published: February 2009

Glass-fiber-reinforced laminates composed of two different commercial epoxy resin matrix formulations, a “medium-temperature” system and a “high-temperature” system, were tested in tension after immersion in hot water. Tests were carried out both in the “as-is” wet condition and after drying. The internal moisture condition was found to have a significant effect on the tensile strength. Dried specimens of the medium-temperature resin were stronger than their wet counterparts. The reverse was the case with specimens based on the high-temperature resin.
A Composite Grip Design for Elimination of Extraneous Noise During Acoustic Emission Testing
Authors: Wood WE , Dilipkumar DD
Published: February 2009

A major problem in acoustic emission analysis during dynamic loading is the noise generated by the test system itself. A composite grip assembly, designed on the principle of rapid attenuation of sound waves when they pass through multiple interfaces, can reduce the background noise by almost two orders of magnitude. This allows a maximum amount of information to be obtained through acoustic emission analysis.
Infrared Techniques for the Evaluation of Silicon Carbide Heat-Exchanger Tubing
Authors: Deininger WD , Kupperman DS
Published: February 2009

The potential application of infrared techniques to detect flaws and measure heat transport in silicon carbide heat-exchanger tubing is discussed. Axial heat-flow patterns were monitored with a commercially available infrared camera. Computer modeling was used to help establish the relationship between temperature distributions and the various thermal parameters. The experimental data and computer-modeling predictions were in fair agreement. These tests indicated that thermography may be a useful nondestructive-evaluation technique for rapid assessment of thermal-heat-transport properties in silicon carbide heat-exchanger tubing.
Constant-Pressure Liquid Filtration: Mathematical Models for Fast Plugging of the Filter Medium
Authors: Johnston PR , Beals DL
Published: February 2009

While four different, classical, mathematical expressions exist to describe the rate at which flow decreases during constant-pressure, liquid filtration, none describes the situation in which the flow rate drops very fast, such as in rapidly plugging operations. Presented here are three additional expressions which do.
Effects of Stress Ratio on Fatigue Crack Growth Rates in X70 Pipeline Steel in Air and Saltwater
Authors: Vosikovsky O
Published: February 2009

Fatigue crack growth rates in an X70 pipeline steel were measured over a wide range of stress intensities in laboratory air and in 3.5% sodium chloride solution under free corrosion and cathodic (coupled to zinc) potentials. The effects of stress ratio in all these environments and of cyclic frequency in the sodium chloride solution were studied. The results are compared with fatigue crack growth rates measured previously in lower strength X65 steel. The stress ratio strongly influences the fatigue crack growth thresholds and close-to-threshold growth rates. With increasing stress intensity range, the stress ratio effect decreases similarly in both air and aqueous environments. The lower cyclic frequency enhances corrosion fatigue crack growth rates at intermediate stress intensity ranges, as was observed earlier in X65 steel.
Performance of Chevron-Notch Short Bar Specimen in Determining the Fracture Toughness of Silicon Nitride and Aluminum Oxide
Authors: Munz D , Bubsey RT , Shannon JL
Published: February 2009

Ease of preparation and testing are advantages unique to the chevron-notch specimen used for the determination of the plane strain fracture toughness of extremely brittle materials. During testing, a crack develops at the notch tip and extends stably as the load is increased. For a given specimen and notch configuration, maximum load always occurs at the same relative crack length independent of the material. Fracture toughness is determined from the maximum load with no need for crack length measurement. Chevron notch acuity is relatively unimportant since a crack is produced during specimen loading. In this paper, the authors use their previously determined stress intensity factor relationship for the chevron-notch short bar specimen to examine the performance of that specimen in determining the plane strain fracture toughness of silicon nitride and aluminum oxide.
Stress Relaxation in Bending of Copper Beryllium Alloy Strip
Authors: Fox A
Published: February 2009

The stress-relaxation behavior of two copper beryllium alloys in strip form, Copper Alloy UNS No. C17000 and C17200, was studied in the temperature range 23 to 232°C (73 to 450°F). The behavior of mill-hardened material is compared to that of material having been fully precipitation heat-treated. Analysis of the data indicates that stress relaxation is a function of test temperature, prior cold work, and the subsequent aging treatment. At temperatures of 177°C (350°F) and above, the stress relaxation of the mill-hardened alloys appears to be affected by simultaneous aging at the test temperature. In addition to stress-relaxation data the alloys studied are characterized by their tensile and bending properties as well as electrical conductivity.
Erosion and Cavity Characteristics in Rotating Components
Authors: Veerabhadra Rao P , Syamala Rao BC , Lakshmana Rao NS
Published: February 2009

An investigation of the initiation and growth of erosion and of the effect of velocity and pressure on erosion in a rotating disk is presented. Also, the role of an intervening noncavitating period on erosion is studied. The results indicate that at high intensities the peak rate of erosion decreases with increases in pressure. The erosion rate/time curves obtained for metallic materials are explained by the eroded particle distribution and the cavity size. The average size of the eroded particles decreased when pressure and tensile strength of the material were increased. The erosion rate peaked after an intervening noncavitating period. The use of the rate of erosion, defined as an average over the entire test duration, in the equation governing the theory of erosion resulted in reasonably good correlations. The correlations reveal that it is possible to predict the length, width, and area of a cavity when the cavitation parameter σ is known. The normalized width of a cavity may be estimated if its normalized length is known.
Results of an ASTM Cooperative Test Program on theJIc Determination of HY130 Steel
Authors: Clarke GA , Landes JD , Begley JA
Published: February 2009

A cooperative test program to evaluate testing procedures for the determination of JIc was organized under the auspices of ASTM. The material tested in this program was HY130 steel. A total of 21 laboratories in five different countries participated in this testing program. Although considerable scatter was found in the JIc results from various laboratories much of the scatter was attributed to material properties variations.

From the results of this program a recommended testing procedure was developed by a working group formed by the ASTM Task Group on Elastic-Plastic Fracture, E24.01.09. The data from the cooperative test program is presented along with the reasoning for developing the recommended JIc test procedure.
MeasuringJIc, and the Resistance to Crack Growth After Initiation
Authors: Early PW , Burns SJ
Published: February 2009

A ductile fracture toughness (JIc) test that uses fracture specimens with finite differences in crack area is reviewed. Experimental results are given for Ti-6Al-4V, A471 Ni-Cr-Mo-V rotor steel, and 4140 high strength steel. Resistance to further crack propagation after initiation is discussed in terms of the tearing modulus, which is equal to dJ/dA, A being the crack area. A useful expression for the tearing modulus is given.
A Hot Compression Testing Apparatus for the Study of Isothermal Forging
Authors: Immarigeon J-PA , Kandeil AY , Wallace W , de Malherbe MC
Published: February 2009

An apparatus for uniaxial compression testing has been developed to simulate isothermal forging conditions. The system is capable of applying 100-kN loads at temperatures up to 1200 ± 3°C in a controlled environment and at constant true strain rates between 10−5/s and 1/s. The apparatus is described and its performance discussed. To illustrate its use, results on the flow behavior of nickelbase superalloy compacts and composites are presented that demonstrate the importance of proper control of the testing parameters. The difference in flow strength of the two materials under identical testing conditions is discussed.
Development of a Chronic Toxicity Test Using Chironomus riparius and the Sublethal Effects of Trisodium Carboxymethyloxysuccinate
Authors: Lee CM , Fullard JF , Huntington E
Published: February 2009

The preliminary development of a 24- to 34-day life-cycle test using the freshwater midge Chironomus riparius is described. The method allows the determination of the sublethal effects of a toxicant on the survival of each life stage, overall growth of the larval stages, egg production, and hatchability of the F1 generation eggs. Trisodium carboxymethyloxysuccinate (Na3CMOS), a potential partial replacement for phosphates in fabric washing powders, is used to demonstrate the method.

There was no effect on survival from stage to stage or overall survival from the egg to the fourth larval instar at up to 92 mg/L Na3CMOS. There were no effects on growth or egg production at ≤92 mg/L Na3CMOS or on hatchability of the F1 eggs at ≤42 mg/L Na3CMOS. None of the F1 generation eggs hatched in 92 mg/L Na3CMOS. The number of adults produced clearly decreased with increasing concentration >12 mg/L Na3CMOS but, in this preliminary work the data did not permit statistical verification of the threshold of effect.

This method has been shown to be sensitive enough to identify sublethal effects of toxicants and shows considerable promise as a method for hazard evaluation. Limited evidence suggests that the test species C. riparius has a sensitivity to toxicants of a similar order to other commonly used test organisms.
Room Temperature Capacitance and Dissipation Factor Measurement of Chip Capacitors—An Interlaboratory Evaluation
Authors: Lo WC
Published: February 2009

An interlaboratory test on room temperature measurement of unencapsulated multilayer ceramic capacitors (commonly known as chip capacitors) was conducted under the sponsorship of ASTM Committee F01 on Electronics. Results show that a well-defined method of test is needed to get agreement among mesurements of capacitance and dissipation factors for this type of capacitor.
Fatigue Life Prediction of Welded Components Based on Fracture Mechanics
Authors: El Haddad MH , Topper TH , Smith IFC
Published: February 2009

An elastic-plastic fracture mechanics solution for fatigue cracks initiating from weld toes is introduced that admits plasticity by replacing the conventional stress term with a strain term. It accounts for the propagation of very short cracks by the introduction of an effective crack length equal to the actual length increased by an amount l0, where l0 is a constant characteristic of the material and material condition. Consideration is also given to the effect of mean stress and crack front shape on an intensity factor derived from this solution. Crack growth results for cracks in both elastic and plastic strain fields of welded specimens, when interpreted in terms of the intensity factor, show excellent agreement with elastic long crack data. This intensity factor, when combined with a propagation model that includes all stages of crack growth, also successfully predicts the entire life of butt- and fillet-welded specimens for two steels. The threshold stress corresponding to the failure of butt-welded specimens is equal to the smooth specimen fatigue limit stress divided by the elastic stress concentration factor. However, for fillet welds, the stress level corresponding to failure is higher than the fatigue limit stress divided by the elastic stress concentration factor. At stresses between these two stress levels, cracks start at fillet-weld toes but do not propagate to failure.
A Proposed Standard Round Compact Specimen for Plane Strain Fracture Toughness Testing
Authors: Underwood JH , Newman JC , Seeley RR
Published: February 2009

A round, disk-shaped specimen is proposed as a standard test specimen for addition to ASTM Test for Plane-Strain Fracture Toughness of Metallic Materials (E 399-78a). The specimen is diametrically cracked, and it is loaded in the same general way as the existing standard compact specimen. Tests and analyses were performed to verify that the proposed round compact specimen and associated stress intensity factor K solution are appropriate for a standard plane strain fracture toughness test. The use of the round compact specimen for other fracture tests is described.
A Wide Range Stress Intensity Factor Expression for the C-Shaped Specimen
Authors: Kapp JA , Newman JC , Underwood JH
Published: February 2009

A new expression has been developed to calculate the stress intensity factor K for the C-shaped specimen over a wider range of specimen parameters, namely, crack depth to width ratio a/W, load eccentricity X/W, and radii ratio r1/r2, than had previously been available. The rationale for the expression was to use known K solutions for short and deep cracks to develop a nondimensional form of K. This nondimensional form of K approaches the correct limiting values as a/W goes to both zero and one. Numerical K results from previous work were then nondimensionalized to this form and the dependence of K on a/W was determined by multivariable linear regression. The final expression agrees with the numerical K solutions within ±1.0% for 0.45 ≤ a/W ≤ 0.55 for all r1/r2 and X/W of either 0 or 0.5; within ±1.5% for 0.2 ≤ a/W ≤ 1 for all r1/r2 and X/W equal to 0 or 0.5; and within ±3% for 0.2 ≤ a/W ≤ 1 for all r1/r2 and 0 ≤ X/W ≤ 1. The accuracy of this expression will allow expanded use of the C-shaped specimen for crack growth resistance curve determination and fatigue crack growth rate testing.
Vibrations in Compact Specimens During Crack Arrest Testing
Authors: Rahka K
Published: February 2009

Measurements of loading arm behavior on compact tension type, transversely wedge-loaded crack arrest specimens have been made. A crack-opening measurement point close to the crack initiation site was selected in addition to face or load-line position. Conclusions concerning acceleration, vibration, and damping behavior of the specimen arms were reached and differences in the behavior of two alternative specimen types are indicated. The influence of fracture morphology on specimen behavior is reported in detail. Suggestions for further work to clarify crack run-arrest behavior of tentative test specimens are presented.
Vibratory Horn Cavitation Erosion Comparisons
Authors: Hammitt FG , Okada T
Published: February 2009

Results of tests of vibratory horn cavitation erosion conducted at Fukui University, Fukui, Japan, and the University of Michigan, Ann Arbor, are compared. The tests were primarily for mild carbon steels (equivalent to Type 1018). The results from Fukui University for various other materials are also included. The maximum mean depth of penetration rate (MDPRmax) varies approximately as horn amplitude to the 1.5 power, and there are strong increases in MDPRmax for increased specimen diameter. There are also strong effects of horn frequency.
Effect of Specimen Shape and Cyclic Loading on Tension Tests of Two Epoxy Resins
Authors: Findley WN , Reed RM
Published: February 2009

Cyclic load experiments are reported for two epoxies, one containing rubber particles. With and without interruptions during unloading, the experiments were performed on an Instron machine at a constant rate of head motion using an averaging extensometer capable of strain to fracture and having no dead zone. Results of interrupted unloading tests show the effect of elasticity of the portion of the specimen outside the gage length on the observed stress-strain curves.
A Procedure for Strain-Controlled High-Cycle Fatigue Testing at Elevated Temperatures
Authors: Majumdar S , Raske DT , Burke WF
Published: February 2009

A procedure for conducting high-cycle fatigue tests under indirect axial strain control is presented. Stroke control is maintained throughout the tests. However, the frequency of cycling is periodically reduced so that the axial strain can be measured directly, and the stroke signal is adjusted to correct any drift in the axial strain signal. Tests have been conducted to demonstrate the viability of such a procedure.
Effect of Understressing and Coaxing on the Fatigue Limit of a Transverse Butt-Welded Joint
Authors: Lawnicki JJ , Cutler VC
Published: February 2009

A test program was developed to compare both the effects of thermal stress relief and “understressing” and “coaxing” techniques on the predetermined fatigue limits of selected weldments. Approximately 100 specimens were cut from 1025 welded plate and reduced to a finished size of 6.35 mm (0.25 in.) thick by 31.75 mm (1.25 in.) wide by 279.4 mm (11 in.) long. A 6.35-mm (0.25-in.) diameter hole was drilled in the weld to control the failure location. The specimens were subjected to fully reversed bending at selected stress increments until failure occurred. The results indicated that understressing and coaxing produced a marked increase in the effective fatigue limit for all specimens with the most significant increase observed in the specimens that had no thermal stress relief of the weldments. One of the practical applications might be in a case in which a controlled break-in period for welded components is feasible and thermal stress relieving is not.
Chevron V-Notched Bend Specimen for KIc Measurement of Brittle Materials
Authors: Shih TT
Published: February 2009

A chevron V-notched bend specimen is proposed for plane-strain fracture toughness KIc testing of brittle materials. This specimen has the following distinctive advantages over more conventional toughness specimens: (1) the simple geometry can easily be machined, (2) no fatigue precracking is required, (3) no crack length measurements are required (KIc can be calculated from knowledge of the peak load alone), and (4) the test can easily be conducted at elevated temperatures. The proposed specimen was calibrated with a 7079-T6 aluminum alloy of known fracture toughness. Subsequently, the fracture toughness of the ceramic material Pyroceram® 9606 was determined with the same specimen design. The reproducibility of KIc values was found to be excellent: 2.64 MPa·m1/2 ± 3% (2.39 ksi·in.1/2 ± 3%). The proposed specimen design is also recommended as an inexpensive toughness screening test for other structural materials. The chevron V-notch crack starter used in the bend bar specimen is also recommended for use in other specimen designs to improve the capability for both fatigue and stress corrosion threshold testing. In view of the tremendous cost- and time-saving potential associated with the chevron V-notch design, it is recommended that a detailed finite element analysis be performed on this configuration to further substantiate the applied stress and stress intensity conditions.
Early Assessment of Concrete Quality by Accelerating Compressive Strength Development with Heat (Results of ASTM's Cooperative Test Program)
Authors: Wills MH
Published: February 2009

Rapid concrete construction practices have led to increasing pressure to assess the quality of concrete at a very early age. Therefore, a cooperative test program was conducted among nine laboratories to evaluate several existing test procedures involving the use of either hot water, boiling water, or the heat of hydration of portland cement to provide heat necessary to accelerate the compressive strength development of concrete. Depending upon which procedure was employed, the amount of acceleration ranged from 1.1 to 2.5 times the strength developed after the same period of moist curing. Statistical analyses of the data justified adoption of a standard method that can be used to judge the quality of concrete soon after mixing. This method involves three procedures of accelerated curing which are limited to concrete made with the same materials and tested by the same laboratory. It has been designated ASTM C 684-74 (Making, Accelerated Curing, and Testing of Concrete Compression Test Specimens). Use of it, under the conditions stated therein, results in as reliable an evaluation of the quality of the concrete at one or two days of age as compared to that measured at 28 days of age according to ASTM C 31-69 (Making and Curing Concrete Test Specimens in the Field).
Holographic Interferometry for Measuring Swelling of Hardened Concrete
Authors: Goldberg JL , O'Toole KM , Roper H
Published: February 2009

Holographic interferometry is used to study the deformation of one surface of a concrete test specimen while water is allowed to diffuse into the body of the material. The potential of this new approach for examining the dynamic behavior of swelling concrete is demonstrated by applying the technique to two hardened concrete test specimens made with different aggregate materials.
Freezing and Thawing Tests and Theories of Frost Damage
Authors: Blachère JR , Young JE
Published: February 2009

Cyclic freezing and thawing tests on structural clay materials are reported. These results and those of recent studies on the freezing of water in consolidated porous materials and the theories of frost damage are used to discuss the mechanisms of pressure generation and relief mechanism. It is concluded that the major mechanisms of stress generation and relief during the freezing of water in porous materials may be different for small or large cooling rates, and that it is probable that freezing and thawing tests can be accelerated, although it should be done with great caution.
Mechanisms of Acceleration by Calcium Chloride: A Review
Authors: Skalny J , Maycock JN
Published: February 2009

Calcium chloride (CaCl2) is a well-known accelerator of the hydration of concrete. Its activity is very complex, and a meaningful mechanistic interpretation requires an assessment of the effect of CaCl2 on each of the individual clinker mineral components. This paper reviews the considerable literature associated with hydration acceleration of calcium silicates, aluminates, and ferrites in the presence of CaCl2. It attempts to cover all of the most meaningful data and observed effects and to relate these effects to various proposed mechanisms. Where appropriate, the reviewed work is critiqued, and suggestions for potentially important new fields of research are offered.
Simulating Rain Impact Damage to Supersonic Missile Radomes
Authors: Smith DG , Kinslow R
Published: February 2009

A test simulating the rain impact damage to two ceramic missile radomes traveling at supersonic speeds is described. A water-jet gun has been developed which fires a short burst of water at speeds up to 5000 ft/s (1524 m/s). This gun was used to simulate the impact of raindrops on the radomes. Equations are given relating the crater volume and area of a single jet impact to the energy of the jet. Then equations are given which express the cumulative damage as a function of impact angle, drop size distribution, velocity, and rain field length and intensity. A computer code has been written to solve these equations. The computer code gave results that agreed well with an actual rocket sled test. The code was used to predict the damage for a new set of conditions, and the water-jet gun was used on full-scale radomes to simulate the predicted rain impact damage.
A New Technique for the Study of Cement Hydration by Scanning Electron Microscopy
Authors: Taylor DH
Published: February 2009

A new scanning electron microscopy technique is described which permits the study of cement hydration in greater detail than by other methods. Its chief advantages are (1) high sensitivity to early stages of hydration; (2) ability to detect amorphous as well as crystalline phases; and (3) ability to distinguish the behavior of individual components (cement or aggregate) of concrete during hydration. Examples of results obtained by this technique are presented.
Static and Impact Behavior of Graphite/Epoxy Composite Laminates Containing Third-Phase Reinforcement Materials
Authors: Adams DF , Perry JL
Published: February 2009

A series of graphite/epoxy composite laminates containing four different types of third-phase reinforcement materials were fabricated, incorporating an anisotropic ply lay-up pattern. Both thick and thin laminates were used. Static tensile, flexure, and short beam shear specimens and Charpy impact specimens were tested, the latter with an instrumented impact tester. The fracture surfaces of the static flexure and the Charpy impact specimens were then examined in detail with a scanning electron microscope. Observed similarities and differences between the static flexure and impact fracture characteristics of a given composite were noted and referred to the corresponding energies absorbed to failure. Similar comparisons were made between the various material combinations.
Economic and Performance Aspects of Increasing Insulation on the Temperature of Built-Up Roofing Membranes
Authors: Cash CG , Gumpertz WH
Published: February 2009

The energy crisis has raised demands for a substantial increase in the insulation of roofing systems, and calculations in this paper confirm that the financially most favorable insulation has a thermal resistance much higher than that of presently used systems. Objections have been raised to the increase in the thermal resistance of roofs on the basis that this will result in a substantial increase of the temperature range to which membranes are subjected, with resultant increase of membrane cracking from temperature movement. We have made a number of calculations to check on the justification of such concerns.

The results of our work, based on a number of simplifying assumptions, show that increasing the thermal resistance of insulation, over presently prevailing standards, does not significantly enlarge the thermal range to which roofing membranes are presently subjected. This applies both to changes in the ambient temperature and to solar radiation. Insulation thickness should therefore be based on considerations of economy and energy conservation, but there are still unresolved problems of decreasing impact resistance and lateral stability.
Reliability of Whittemore Gage Length Measurements
Authors: Ashton HE
Published: February 2009

A large number of measurements on a nickel-steel alloy bar and on brass inserts in the bar were taken to determine if wear was taking place in the alloy standard or in the Whittemore gage. Microscopic examination was used to confirm the dimensional results. It was concluded that neither the gage nor the brass exhibited significant changes in readings but that the alloy showed a change after 1500 readings. It is proposed that for long-term studies an alloy bar with hardened steel inserts should be used. The precision of measurements made with the gage was estimated from the large set of results.
Properties of Florida-Oolite Concrete
Authors: Collins JJ , Hsu TTC
Published: February 2009

An experimental study of the mechanical properties of Florida-oolite concrete and oolite aggregates is presented. The properties of Florida-oolite concrete determined were strength, modulus of elasticity, creep, and shrinkage. The properties determined for oolite aggregates were strength, modulus of elasticity, unit weight, specific gravity, absorption, and percentage of voids. The modulus of elasticity and the creep coefficient of concrete were found to be significantly less than the values predicted by the standard American Concrete Institute equations. In addition, the effects of prestress and heat curing on the properties of Florida-oolite concrete are discussed.
A Short-Time, High Temperature Mechanical Testing Facility
Authors: Marion RH
Published: February 2009

Design and performance details are given for a facility developed to obtain the mechanical properties of materials under high heating rate or transient temperature conditions and medium strain rates. The system uses self-resistance heating and is applicable to materials possessing electrical resistivities ranging from that of aluminum to that of graphite. Heating rates as high as 2000 K/s in graphite are attained under controlled conditions. Methods of measuring temperature and the effects of expected temperature distributions are discussed. A method for measuring strain during transient temperature conditions to 3000 K is described. Finally, results are presented for the stress-strain behavior of Type 316 stainless steel and ATJ(S) graphite obtained for heating times of few seconds.
Volume Fraction Determination in Cast Superalloys and Directionally Solidified Eutectic Alloys by a New Manual Point Count Practice
Authors: Andrews CW
Published: February 2009

Volume fraction of a constituent or phase was estimated in six specimens of conventional and directionally solidifed eutectic alloys in accordance with ASTM Recommended Practice for Determining Volume Fraction by Systematic Manual Point Count (E 562–76). Volume fractions determined ranged from 0.086 to 0.36, and with one exception the 95% relative confidence limits were approximately 10% of the determined volume fractions. Since the confidence limit of 10%, which had been arbitrarily chosen previously, was achieved in all but one case, this application of Recommended Practice E 562-76 was considered successful.
Load-Displacement Measurement and Work Determination in Three-Point Bend Tests of Notched or Precracked Specimens
Authors: Buzzard RJ , Fisher DM
Published: February 2009

Suggestions for testing of notched or cracked three-point bend specimens are presented that (1) correct displacement measurement errors resulting from misalignment between the load applicator and specimen; (2) account for coincidental strains not associated with the work of crack extension; (3) simplify record analysis and processing; and (4) extend displacement gage range without sacrifice of sensitivity or accuracy. These testing details are particularly applicable to procedures in which the crack extension force J1 is determined from the work done on the specimen.
A New Method of Test for Flexural Fatigue of Plastics
Authors: Gauvin R , Trotignon J-P
Published: February 2009

The flexural fatigue resistance of plastics as determined by ASTM Test for Flexural Fatigue of Plastics by Constant-Amplitude-of-Force (D 671-71) employs a technique that permits the testing of only a single specimen at a time. By contrast, the test based on constant-amplitude-of-deflection of the specimen proposed in this paper accommodates up to 16 specimens simultaneously, thereby substantially reducing the time required for the test. Constant-amplitude-of-deflection of the specimen is effected by rotation of its builtin end. Experimental data are presented that show that both methods give substantially comparable results for nylon 6/6 and acetal homopolymer. A brief description of the apparatus required for the new test is also given.
Threshold Corrosion Fatigue Crack Growth in Steels
Authors: Tu LKL , Seth BB
Published: February 2009

The threshold stress intensity factor range ΔKth of three steels was studied in air and steam. Constant load and constant crack opening displacement (COD) tests were conducted by using tension-tension sinusoidal wave function loading. The COD tests were controlled by a high frequency clip-on strain gage. Crack growth rate was measured by both optical and COD compliance techniques and verified by metallographic examination of the broken specimens. The ΔKth value was determined as the asymptote to the best-fit data below a crack growth rate of 2.5 × 10−8 cm/cycle. The ΔKth values were higher in steam than in air. Crack growth rates in air and steam generally crossover or merge in the range of 2.5 × 10−6 to 2.5 × 10−7 cm/cycle; below this range the growth rate is lower in steam than in air. The higher values in steam tests were explained by environmentally assisted crack branching and corrosion products formed at the crack tip after long-time testing at growth rates of less than one lattice spacing per cycle of loading.
Comparison of Equivalent Energy and Energy Per Unit Area (¯W/A) Data with Valid Fracture Toughness Data for Iron, Aluminum, and Titanium Alloys
Authors: Witzke WR , Stephens JR
Published: February 2009

Small specimens cut from large test specimens that had provided valid plane strain fracture toughness value KIc measurements were tested in slow bending at 25 and −196°C. The resulting load deflection curves were interpreted by the equivalent energy technique and two variations of the energy per unit area technique. The small specimen fracture toughness values resulting from all three methods produced good correlations with the valid, large specimen KIc values for the two test temperatures. For screening purposes the subsize specimen tests were considered to provide a relatively simple and reasonable estimate of the KIc of a material.
“PARS”—A Portable X-Ray Analyzer for Residual Stresses
Authors: James M , Cohen JB
Published: February 2009

The design, operation, and testing of a 7 to 11-kg hand-held X-ray device for measuring residual stresses are described. The instrument is based on a miniature X-ray tube and generator and a position-sensitive detector. No motion of the detector is needed to record a peak, eliminating the expensive and heavy gearing characteristic of a conventional diffractometer; the only mechanical motion during a measurement is one change of the orientation of the device to the object. An entirely portable instrument is therefore available for use in the plant or in the field. Tests are reported in which the stress is measured to ±40 MPa (± 6 ksi) or better in 4 to 20 s, depending on the specimen.
Measuring the Thermal Expansion of Solids with Strain Gages
Authors: Poore MW , Kesterson KF
Published: February 2009

A technique was developed to measure the thermal expansion of solids in the temperature range from −50 to 175°C. The technique uses strain gages to measure expansion and Type J (iron/constantan) thermocouples to measure temperature. Measurements were made on pure platinum and on copper and tungsten standard reference materials obtained from the National Bureau of Standards. Results were compared with the certified values of expansion. The maximum difference between measurements made in this study and the certified values was 0.26 × 10−6/°C for the mean coefficients and 0.40 × 10−6/°C for the instantaneous coefficients. The standard deviation of the measurements of the mean coefficients was 0.11 × 10−6/°C.
Comparison of Stress Corrosion Cracking Properties of Several Aircraft Structural Alloys
Authors: Ryder JT , Krupp WE , Pettit DE , Hoeppner DW
Published: February 2009

Sustained load subcritical flaw growth characteristics of five alloys of interest to aircraft designers were investigated. The aluminum alloy (2024-T851) and steel alloy (18Ni-maraging) were studied in 3.5% sodium chloride solution and high humidity air environments while two of the titanium alloys, Ti-6Al-4V (recrystallized annealed) and Ti-6A1-6V-2Sn (solution-treated and overaged), were also investigated in these environments plus sump tank water. The Ti-6Al-4V (beta) alloy was tested in 3.5% sodium chloride solution. Wide differences between the alloys were noted not only in their cracking rates but also in their responses to similar loads and environments. Specimen thickness was found to have an important effect on stress corrosion susceptibility of the titanium alloys. Many coupons of specific titanium alloys had significant subsurface crack growth without visible surface growth. For these alloys, no precise threshold for stress corrosion cracking could be defined.
An Indirect Tensile Test for Masonry Units
Authors: Borchelt JG , Brown RH
Published: February 2009

The failure of masonry in laboratory testing of walls and prisms and certain aspects of grouted construction is often the result of tensile splitting. These tensile stresses arise from differences in modulus of elasticity and Poisson's ratio between the masonry unit and mortar or grout. Since tensile splitting is so prevalent in masonry construction, a better means of evaluating the tensile strength of masonry units is needed. A splitting tensile test is proposed as a means of measuring tensile strength of masonry units. Splitting strength is compared to standard strength tests for 14 clay units and 14 concrete block units. Uniform failure modes and strengths support the adoption of a splitting test as a standard of masonry unit strength.