bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite Strain and the 0.01 Percent Offset Yield Strength
Authors: Wonsiewicz BC , Hart RR
Published: February 2009

The validity of the stress at 0.01 percent offset as an approximation to the elastic limit was evaluated for a high-strength material, textured copper-beryllium CA-172. Specimens were loaded in uniaxial tension and precise determinations were made of the load-extension diagram. In loading to a strain of 0.85 percent, offsets of ∼0.02 percent were observed with insignificant permanent strain (<5 × 10−5) remaining on release of the load. Permanent strain of 0.01 percent occurred only after an offset of 0.05 percent and a strain of 1 percent. The nonlinearities observed correspond to previously reported higher-order elastic effects in copper. A priori corrections to the offset strength for elastic nonlinearities are impractical since the nonlinearities depend on both the higher-order elastic constants of the material and the preferred orientation. The limitations of the offset yield strengths are discussed and the suggestion made that dynamic energy absorption techniques be considered to measure the onset of plastic flow; that is, plastic strains of about 0.01 percent.
Comparison of Bending and Tension Tests in Creep of Sheet Metal
Authors: Duncan JL , Ragab AR
Published: February 2009

A technique is presented for obtaining creep data for thin sheets using a test in which the whole sheet is arranged as a cantilever loaded by its own weight. A theory is given for deriving creep parameters from measured deflection rates in two tests. A stress-strain rate curve is derived from a number of tests using the skeletal point method. Tensile and bending tests were performed on superplastic eutectoid Zn-Al sheet at room temperature which demonstrated the applicability of the bending test to obtain creep properties of superplastic alloys. Erratum to this paper appears in 2(1).
A Test Procedure for Determining the Resilient Properties of Granular Materials
Authors: Kalcheff IV , Hicks RG
Published: February 2009

The resilient response of highway materials has generally been considered to be a function of intensity, number, duration, and frequency of the stresses to which it has been subjected. To date, little research has been conducted to show the effects of these factors on the response of paving materials and from what has been done, the observed behavior varies from material to material.

The purpose of this investigation was to better define the effect of stress repetitions, load duration, frequency, and sequence on the resilient response of several crushed stone materials. Tests were carried out at two levels of density and moisture condition using a conventional triaxial cell. Repeated axial compressive stresses, as well as static ones, were applied under conditions of constant confining pressures. The resulting axial strains were measured.

Results from the tests indicated that the number of stress repetitions and stress sequence had little effect on the resilient behavior of granular materials. There was no evidence of a change in resilient behavior with changes in load duration or frequency. The significance of these findings is that the resilient response determined after 150 to 200 repetitions will provide a reasonable indication of resilient properties for a material subjected to a complex stress history. Findings also indicate that the response to stresses of different intensities can be measured in any sequence on a single sample. Furthermore, the response can be determined using either static or dynamic triaxial load tests.

Test procedures are formulated to provide the practicing engineer with a simple procedure for determining an estimate of the resilient properties of granular materials.
A Mathematical Description of the Elevated Temperature Flow Behavior of Type 304 Stainless Steel at High Strain Rates
Authors: Steichen JM
Published: February 2009

A mathematical description of the true stress-true strain tensile behavior of annealed Type 304 stainless steel has been completed for tests at strain rates from 3 × 10−5 to 1 × 102 s−1 and temperatures from 600 to 1600°F (316 to 871°C). This description provides an accurate method for predicting deformation behavior within this temperature and strain rate region. It formulates a means of describing materials properties which can be readily factored into design, performance, and safety analyses of structural components.
The Influence of Loading Variables on Environment-Enhanced Fatigue Crack Growth in High Strength Steels
Authors: Miller GA , Hudak SJ , Wei RP
Published: February 2009

An experimental program was carried out to further determine the range of applicability of the superposition model, proposed by Wei and Landes, for estimating the effects of cyclic loading variables and chemical environment on fatigue crack growth. AISI 4340 steel, tempered at 200°F and 500°F, and RQ360A steel were used in this investigation. The influences of frequency, stress ratio, and cyclic-load waveform were examined. The results showed that the superposition model provides correct estimates of the trend and the order of magnitude for the influences of these variables within the applicable range (that is, for Kmax > KIsee) provided that steady-state crack growth data are used. Data on the AISI 4340 steel suggest the presence of some synergistic effect of fatigue and environmental attack. Modification of this model will be needed to incorporate this effect and to improve the accuracy of predictions.

Environment can affect fatigue-crack growth at K levels below KIsee. Data obtained on the RQ360A steel (below KIsee) indicate that the environmental effect can depend on frequency and cycli-cload waveform. These results are in agreement with published results on highly alloyed steels. Further basic studies will be needed to clarify these effects and to develop viable prediction procedures.

Nonsteady-state crack growth in fatigue was observed. This stage of crack growth would occur at the start of testing and following test interruptions. This phenomenon must be recognized, and be taken into consideration in data acquisition and subsequent utilization.
Mechanical Sampling with Stopped-Belt Accuracy
Authors: Ellis JJ
Published: February 2009

“Stopped-belt” samples are considered to be the standard of accuracy for mechanical sampling systems. Theoretically, stopped-belt samples do not disturb the stream of material in a manner deterimental to the obtaining of a true cross section of material from a stream of material. This paper explores the factors that create bias as a result of disturbing the stream flow. It outlines tests that can be performed on the material to be sampled and provides guidelines for the designing and operating of sampling systems that will enable them to obtain samples in a manner comparable to stopped-belt cuts. It is desirable to have sampling systems that are free of bias, provide samples that have a high degree of accuracy, and that are economical to own and operate.
Vibratory Cavitation Tests at 200-kPa (2-Bar) Suppression Pressure
Authors: Zhou Y , Hammitt FG
Published: February 2009

Cavitation erosion of 1100-0 and 2024-T-4 aluminum, 1018 carbon steel, 316 stainless steel, and 3% carbon cast iron was measured in tap water by vibratory horn at 200-kPa (2-bar) suppression pressure, at various temperatures and amplitudes. Erosion rate (MDPR) and incubation period (IP) were computed according both to total specimen area and to actual area eroded. Maximum damage depth penetration rate DmPR was also measured. Actual eroded area and maximum damage depth penetration rate are also presented. These are of substantial practical interest, since maximum damage depth Dm is often the best criterion to indicate failure. Incubation period IP is also considered to have more precise meaning if calculated according to actual eroded area. Temperature effects upon MDPR are reported. According to the test data at 200-kPa (2-bar) psv (where psv = p − pv, where p = static pressure and pv = vapor pressure) as well as the previous data at 100-kPa (1-bar) psv and some pertinent literature, MDPRmax occurs in the range 60 to 70°C (140 to 160°F). A new nondimensional damage depth parameter C = Dm/MDP, where MDP is the mean depth of penetration, has been defined. C versus horn amplitude is found to be an approximately exponential function for the ferrous alloys, but insufficient data is yet available to define similar trends for the aluminums. Scanning electron microscope photomicrographs of eroded surfaces of five materials tested show the pitted honeycombed surfaces, somewhat different for the different materials.
Accuracy and Precision of Crack Length Measurements Using a Compliance Technique
Authors: Hewitt RL
Published: February 2009

A compliance crack measurement technique has been implemented in a computer-controlled fatigue crack growth rate test written to conform to the ASTM Test for Constant-Load-Amplitude Fatigue Crack Growth Rates Above 10−8 m/cycle (E 647). The use of a “correction” factor in the compliance expression is discussed and relevant details of the computer implementation are provided. Possible sources of error in the technique have been investigated and the relative precision and absolute accuracy determined using 12.6-mm-thick compact tension specimens of 2024 T351 (Unified Numbering System [UNS] A92024) aluminum having widths of 51 mm. The relative precision of individual measurements using standard fixtures was found to be about 0.05 mm, but this can be reduced to as little as 0.01 mm by averaging over 20 measurements. For most crack lengths, the calculated lengths were within 0.25 mm of the average physical crack lengths measured from profiles on fractured specimens.
Cross-Linking of Polyfluoroolefin Copolymers
Authors: Hudlicky M
Published: February 2009

After a short survey of the development of fluorinated elastomers, curing of fluorinated copolymers is described. The discussion includes the main cross-linking agents such as diamines, Schiff bases, dithiols, bisphenols, peroxides, and irradiation, and the modes of action of the agents on copolymers of vinylidene fluoride, chlorotrifluoroethylenes, perfluoropropylene, and perfluoro (methyl vinyl ether). For better understanding the chemistry of cross-linking of fluoro polymers, properties and chemical reactivity of simple polyfluoro compounds are thoroughly discussed with special emphasis on the differences in chemical behavior of polyfluoro derivatives and their parent compounds. Reactions utilized in cross-linking such as addition, displacement, elimination, and isomerizations are exemplified on simple fluorinated compounds, and potential uses of some of them for new types of cross-linking are pointed out.
Ethylene-Propylene-Diene Monomer (EPDM) and Fluorocarbon (FKM) Elastomers in the Geothermal Environment
Authors: Harwood HJ
Published: February 2009

Thermal and hydrolytic processes that are likely to occur when hydrocarbon and fluorocarbon elastomers are subjected to geothermal conditions are discussed. Polyhydrocarbon backbones have good chemical resistance, but many cross-links present in cured polyhydrocarbons can be hydrolyzed under geothermal conditions. Perfluorinated elastomers have excellent thermal and hydrolytic stability, although they are potentially susceptible to hydrolytic degradation. The cross-links present in cured perfluorocarbon elastomers are probably also susceptible to hydrolysis under severe conditions. It seems that improvements can be made in geothermal seals if they can be cured by processes that yield chemically stable cross-links.
Analysis of an Internally Radially Cracked Ring Segment Subject to Three-Point Radial Loading
Authors: Gross B , Srawley JE
Published: February 2009

The boundary collocation method was used to generate Mode I stress intensity and crack mouth-opening displacement coefficients for internally radially cracked ring sements (arc bend specimens) subjected to three-point radial loading. Numerical results were obtained for ring segment outer-to-inner radius ratios Ro/Ri ranging from 1.10 to 2.50 and crack length to segment width ratios a/W ranging from 0.1 to 0.8. Stress intensity and crack mouth displacement coefficients were found to depend on the ratios Ro/Ri and a/W as well as the included angle between the directions of the reaction forces.
Temperature Effect on Rheological Properties of Cattle Manure Slurry
Authors: Chen Y-R , Shetler EL
Published: February 2009

A constant temperature rotational viscometer was fabricated for studying temperature effect on rheological properties of beef cattle manure slurries having total solids concentrations (TS) ranging from 2.5 to 19.3%. The rheological properties of the slurries had shear rates ranging from ∼ 20 to 200 s−1 and temperatures ranging from 14 to 64°C. In this shear rate range, it was found that the power-law equation could be used to describe the slurry's shear stress and shear rate relationship. Apparent viscosity of the slurry was found to decrease as temperature increased, and increase as TS increased. Equations to express the apparent viscosity as a function of TS and absolute temperature were given. The activation energy (Andrade's equation) of the beef cattle manure slurries was found to be 13.8 kJ/mol.
Safety Considerations for Photographic Film in the X-Ray Screening of Air Travelers' Luggage
Authors: McIninch VG
Published: February 2009

The use of X-rays in the screening of passengers' luggage and similar packages entering airport secure areas requires consideration of the possible effect on contents therein. Among commonly carried items, the possibility of damage to photographic film is a great concern to the traveling public. This paper presents a study of the possible effects on conventional camera films plus results of some practical tests and a summary of passengers' experiences as reported to a major photofinishing and film manufacturing organization. Also included are results of measurements on the sensitivity of several commonly used films to low-level X-ray exposure. To protect unprocessed film from significant effect, it is recommended that individual X-ray inspection exposures be kept below 1 mR, and that no more than 5 mR be permitted to accumulate from multiple inspections. An explanation of these limits is given, and recommendations to the traveler for protecting the film against excessive X-ray exposure are briefly discussed.
Use of X-Ray Diffraction with the Gaussian Curve Method to Evaluate the Hardening in Quenched Steels
Authors: Kurita M , Ihara I , Shinbo M , Koguchi H
Published: February 2009

An X-ray diffraction line will broaden considerably when steels transform to martensite on quenching. Slack quenched steels contain a mixed martensite and fine pearlite structure which produces an anomalous diffraction line profile with a sharp peak superimposed on a broad base. The sharpness of the diffraction line peak can be measured by using a constant of the Gaussian curve fitted to the peak. This constant (denoted GCP) for completely hardened steels increases with increasing carbon content up to 0.7 wt% carbon. At higher carbon contents, the GCP becomes almost constant. Also, the GCP increases with increasing hardness along a single curve independently of carbon content. The GCP for the slack quenched steels is smaller than that for the completely hardened steels. Extent of hardening of the slack quenched steels having a sharp diffraction line peak can be evaluated rapidly and nondestructively by comparing their GCP value with that for the completely hardened steels.
Fracture Mechanics Evaluation of Irradiation Embrittlement in Reactor Vessel Steels Based on the Rate Process Concept
Authors: Nogata F , Takahashi H
Published: February 2009

A new evaluation procedure for the critical fracture toughness (KIc, KId) from Charpy-V impact absorbed energy is presented. The strain-rate/temperature effect on the cleavage-controlled fracture toughness transition is first explained by applying the concept of a stress-dependent rate process for fracture initiation. The expression described in terms of the Charpy-V energy ratio, Cv-us/Cv, for fracture toughness under a constant strain rate is newly derived. The feasibility of the new procedure for evaluating the irradiation embrittlement of reactor pressure vessel steel, such as SA533B-1, is here verified utilizing the data for both unirradiated and irradiated materials in the literature. Another method for the determination of coefficients in the new expression from the Cv-fitting curve is also presented.
Determination of Fracture Toughness by CTOD Resistance Curve Method
Authors: Putatunda SK
Published: February 2009

Fracture toughness δi of AISI 4340 steel in the hardened and tempered condition has been determined by the multiple-specimen CTOD (crack tip opening displacement) resistance curve method. This fracture toughness δi value has been compared with the JIc fracture toughness also obtained by the multiple-specimen JR curve technique. The investigation also examines the effect of specimen size, thickness, and width on δi and δR curve behavior. The effect of these parameters on the constraint factor m in the J-δ relationship has also been examined. Compact tension specimens with TL orientation were used. All specimens satisfied ASTM E 813 standard size requirements.

This investigation demonstrates that Jδi values obtained by the CTOD resistance curve method are similar to JIc values obtained from the J-integral resistance curve method. The specimen thickness has no significant influence on δi or δR curve behavior. On the other hand, specimen width has a distinct influence on constraint factor m and δR curve behavior.
Determination of Fracture Toughness for Brittle Nonmetallic Materials at the Subcritical Crack Growth Stage
Authors: Naumenko VP
Published: February 2009

In addition to the KIc characteristics of such brittle materials as glass-like and ceramic ones, it is proposed to determine the values of KIo and KIi, corresponding to the crack onset and the beginning of the accelerated stage of its subcritical growth. An experimental method has been developed: to grow a given edge crack in a flat specimen, to determine the values of KIo and KIi by loading this specimen in transverse compression and then, in the course of eccentric tension (wedging) of the same specimen, to evaluate the KIc characteristics. The validity of the KIo, KIi and KIc values obtained for glass and polymethyl methacrylate (PMMA) is confirmed by their comparison with the data published.
Interpretive Report on the Sensitization of Type 304 Stainless Steel
Authors: Loria EA
Published: February 2009

When Type 304 stainless steel is sensitized by a thermal treatment in the range of 400 to 850°C, intergranular attack will occur upon subsequent exposure to certain media. Interest in the sensitization behavior of Type 304 has been rekindled by the recurrent problem of pipe cracking in boiling water reactors, and the subject is of major importance to the electric power utility industry. In many practical situations, such as welding, sensitization is best studied by continuous cooling through the sensitizing temperature range wherein the variables are the peak temperature reached and the cooling rate in contrast to temperature and time of the isothermal hold which has been the customary practice. This report will focus on the importance of continuous cooling sensitization in certain heats of Type 304 with changing section size. A review of the test methods that assess intergranular corrosion and the effort to quantify degree of sensitization upon Jominy testing of bar, strip, and pin specimens or Gleeble-type testing of small rods will be presented. The major influence of carbon content and the effects of other elements will be discussed along with material remedies and suggestions for future work.
Analysis of Service Failures in Thermoplastic Pressure Piping Water Systems
Authors: Reinhart FW , Furno FJ
Published: February 2009

Investigators into failures of installed thermoplastic water piping systems often do not have sufficient knowledge of the types or classes of failure and their causes to make a proper analysis of problems in this area because of the newness of thermoplastic piping. The authors, who have had extensive detailed and long-term experience in this field (40 and 28 years respectively), decided it would be helpful to users, manufacturers, installers, piping engineers, code officials, and other interested parties if a concise treatment of this topic was presented.

The types or classes of failure found in thermoplastic water piping systems are burst, damaged pipe and/or fittings, and leaking joints. The causes of these failures are improper system design, overpressurization, use of materials not intended for manufacture of piping components, non-standard materials, contaminated materials, improper manufacture, improper handling, faulty installation, poor joints, and the installed system being damaged by third parties. These topics are discussed in detail. A list of publications that describe procedures and recommendations to reduce failures in service is given.
Direct Modeling of Concrete Block Masonry Under Shear and In-Plane Tension
Authors: Hamid AA , Abboud BE
Published: February 2009

A better understanding of the complex behavior of masonry structures is necessary to embrace the more appropriate concept of ultimate strength design. Owing to the prohibitive cost of full-scale testing of masonry systems, a more economical method utilizing direct modeling techniques is proposed. It is the objective of this study to evaluate the use of direct modeling of ungrouted and grouted block masonry under shear and in-plane tension. A total of 62 quarter-scale model shear and tension specimens were tested, and the results were compared with similar prototype test results. The study includes the effect of mortar strength, grout strength, and load orientation on the assemblage mode of failure and ultimate strength. Correlations between model and prototype results are performed. Excellent correlations were obtained for mode of failure and the overall effects of different parameters. It is concluded that direct modeling is feasible and is capable of predicting the behavior of masonry. Deviations from prototype strength results were observed that are attributed to size effect of aggregate, imperfections in unit geometry, and higher strength values of model blocks.
A Better Way to Present Results from a Least-Squares Fit to Experimental Data: An Example from Microhardness Testing
Authors: Sargent PM
Published: February 2009

Fitting a straight line to data using the least-squares method is very often the method of choice when presenting experimental results. When there are a number of sets of data, each with its fitted line, it can be difficult at first to appreciate the meaning of the results. Also, parameters calculated from least-squares fits are often quoted without estimates of accuracy, even when the original data contain considerable scatter.

A method is described here that aids the assimilation of a number of least-squares fits and takes full account of estimates of accuracy.
Investigation of DynamicJId for Alloy Steel Weldments Using the Split Hopkinson Bar
Authors: Bassim MN , Bayoumi MR , Hsu TR , Matthews JR
Published: February 2009

The fracture toughness parameter JId, under dynamic loading conditions, was determined for weldments of HY80 and QT28 alloy steels using a split Hopkinson bar technique. JId was obtained for the fusion zone, the heat-affected zone, and the base metal for these steels as a function of temperature in the range of −80 to 25°C and at loading rates of ˙K = 106 MPa√m s−1. Wedge loaded compact tension specimens were loaded in a split Hopkinson bar. The onset of stable crack growth was determined by using a strain gage that was attached ahead of a fatigue crack. The results show that, at −80°C, fracture with limited stable crack growth takes place, while for all other testing conditions considerable ductility precedes fracture of these alloys.
An Ultrasonic Method for Determining Axial Stress in Bolts
Authors: Johnson GC , Holt AC , Cunningham B
Published: February 2009

An ultrasonic technique for determining the axial stress within a bolt was developed and experimentally verified. The technique uses time-of-flight measurements of both shear and longitudinal waves propagating along the axis of a bolt along with the material parameters to calculate the stress acting on the bolt. One significant advantage of the technique is that an independent measurement of neither the original nor present length is required. Experimental results suggest that the method may be usable for fasteners which have experienced a small amount of plastic deformation.
Bibliography on Clean Glass: Supplement I
Authors: Campbell DE , Adams PB
Published: February 2009

This bibliography supplements an earlier bibliography on clean glass(Journal of testing and Evaluation, Vol. 5, No. 1, Jan. 1977, pp. 53–57) by extending coverage of the literature from 1973 through 1984. Coupled with the recommendations included in ASTM Practice for Designing a Process for Cleaning Technical Glasses (C912), the list of references, organized into five categories for ready access, should provide a useful up-to-date base for rationally designing a cleaning process.
Reference Samples for the Evaluation of Salmonella Isolation Methods
Authors: Beckers HJ
Published: February 2009

Reference samples consist of gelatin capsules containing 0.2 g of spray-dried milk inoculated with Salmonella. These reference samples enable each laboratory to test individually the performance of Salmonella isolation methods and to study the effects of foods and its competitive flora on the isolation of Salmonella. The reference samples have also been found useful in collaborative studies testing the reproducibility of methods. It is recommended to evaluate the performance of Salmonella isolation methods with reference samples.
Cyclic Stress and Diametral Strain Response During High Strain Amplitude Fatigue of a 1Cr-1.3Mo-0.3V Bainitic Rotor Steel at Elevated Temperature—Part II
Authors: Rahka KA , Laird C
Published: February 2009

Tests of a Cr-Mo-V rotor steel have been carried out at 550°C using continuous cycling and cycling with tensile dwells. A special feature of these tests was that they were carried out in control by the axial total strain but that diametral strain was simultaneously measured. Comparison of the diametral and axial strain ranges showed that “Poisson's ratio” initially increased but subsequently declined steadily with accumulating cycles. While these results do not challenge the traditional view of Poisson's ratio which is defined for homogeneous material, they indicate that numerical values of the ratio must be used with caution. The results on diametral strain response are carefully analyzed and defended as a true material response; they indicate that the ratio of diametral to axial strain is sensitive to the accumulated fatigue damage of the specimen in a rather unpredictable fashion.
A Computerized Test System for Thermal-Mechanical Fatigue Crack Growth
Authors: Marchand N , Pelloux RM
Published: February 2009

A computerized testing system to measure fatigue crack growth under thermal-mechanical fatigue conditions is described. Built around a servohydraulic machine, the system is capable of a push-pull test under stress- or strain-controlled conditions in the temperature range of 25 to 1050°C. Temperature and mechanical strain are independently controlled by the closed-loop system to simulate complex inservice strain-temperature relationship.

A d-c electrical potential method is used to measure crack growth rates. The correction procedure of the potential signal to take into account powerline and RF-induced noises and thermal changes is described. It is shown that the potential drop technique can be used for physical mechanism studies and for modelling crack tip processes.
A Method for Determining Conservative Fatigue Threshold While Avoiding Crack Closure
Authors: Matsuoka S , Takeuchi E , Kosuge M , Shimodaira M , Ohta A , Nishijima S
Published: February 2009

The low-rate fatigue properties of a mild steel are obtained on small compact-type (CT) specimens while avoiding crack closure. These properties are similar to those of butt-welded joints obtained at a much lower stress ratio in the range −1 to 0.5. This is a result of the existence of tensile residual stress at the crack tip of the welded joint which prevents crack closure even at low stress ratios. It is concluded that the most conservative fatigue crack propagation properties, including fatigue threshold values, can be easily obtained by confirming that the results are the same for CT specimens tested at different terminal stress ratios using a ΔK decreasing method which avoids crack closure.
A Suggested Role of Combustion Toxicity in Fire Risk Assessment
Authors: Alexeeff GV , Packham SC
Published: February 2009

At least 17 test methods have been developed to examine the acute toxicity of thermal decomposition products produced in fires. However, a consensus has not been reached on a method of integrating this information into a fire risk assessment. This paper suggests a fire risk assessment methodology with the goal of improving risk management and reducing future fire deaths. Following hazard identification, four steps are presented: (1) calculation of the probability that a material will be present in a fire, (2) estimation of smoke concentrations in specific fire scenarios, (3) determination of the qualitative and quantitative nature of toxic effects of smokes, and (4) estimation of the likelihood of the toxic injury resulting to humans based on correlations between animal models and humans. A concentration-time product is used in estimating exposure, since recent reports indicate it is likely to be the most appropriate method for comparing the toxicity of smokes with each other and to pure gases.
Linear Elastic Fracture Mechanics Applied to an Adhesive Spar—Wingskin Joint
Authors: Gradin PA , Nilsson S
Published: February 2009

When utilizing adhesive bonding in structures where a failure might have serious consequences, one is generally interested in the possibility of determining the sensitivity of the bond strength to certain types of bond imperfections. It is well known that most adhesive bonds will contain defects such as voids, regions with no or poor bonding, and microcracks. When such defects are located in regions with alternating stresses of sufficiently high amplitude, they might grow to form macrocracks.

To investigate how the static strength of an adhesive spar—wingskin joint is affected by the presence of two straight edge cracks in the interface between the adhesive and the spar flange and located symmetrically with respect to the spar center line, experiments were performed for different crack sizes. Specimens were loaded by a tensile force acting along the spar center line in order to simulate the effect of fuel pressure. To find out whether the usual linear elastic fracture mechanics (LEFM) assumption of a critical elastic energy release rate value at onset of fracture applied in this case also, the elastic energy release rate was calculated analytically by use of a simple beam model and numerically by use of the finite element method (FEM).

The following conclusions were drawn for the specific geometry considered:

1. For crack lengths below 4 mm, the joint was critical with respect to interlaminar separation in the spar flange.

2. For crack lengths above 4 mm, the joint was critical with respect to debonding.

3. The critical energy release rate was approximately constant for crack lengths in the interval of 4 to 15 mm. The influence of the radius in the connection between the spar web and spar flange and the elasticity modulus of the elastic insert in the same region was investigated numerically. From this it was concluded that:

4. For cracks larger than about 10 mm the joint will become more crack sensitive with increasing radius, whereas it will be almost unaffected by changes in the insert elasticity modulus.
A Method for Obtaining Conservative S-N Data for Welded Structures
Authors: Nakamura H , Nishijima S , Ohta A , Maeda Y , Uchino K , Kohno T , Toyomasu K , Soya I
Published: February 2009

A method of fatigue testing is proposed to simulate the behavior of large-sized welded structures having high tensile residual stresses by means of ordinary small width specimens containing a low level of residual stresses. The method involves the varying of the stress range from test to test while always maintaining the maximum stress at the yield strength of base metal. The results obtained by the proposed method agreed with those for slit welded joints containing high tensile residual stresses fatigued at constant amplitude at a stress ratio of zero. However, the fatigue strength of small width welded specimens as determined by the proposed method was lower than that obtained by the conventional method at a stress ratio of zero. It is emphasized that the proposed method is effective in obtaining conservative S-N data to be used for design of welded structures, where local fluctuating stresses were considered to pulsate downwards from tensile yield strength regardless of the applied stress ratio. It was also found that in the presence of a high tensile residual stress the grinding of the toe of welds which contain no undercut was not effective in improving the fatigue strength of welded joints.
Effect of Nonmetallic Inclusions on Some Ductility Parameters of Hot-Rolled Steel Sheet
Authors: Pretnar B , Yebuah RAN
Published: February 2009

Nonmetallic inclusions have detrimental effects on ductility parameters such as elongation and reduction in area obtained in tension testing. Moreover, inclusions elongated in the rolling direction cause distinct anisotropy of these parameters.

This paper gives a demonstration of how this anisotropy can be utilized to assess the effect of elongated inclusions on the ductility of steel sheet. Other factors (e.g., sheet thickness and steel strength) that also influence the ductility are eliminated by taking the difference between the values of the ductility parameters in the longitudinal (rolling) and the transverse directions. Replicate tests and methods of mathematical statistics are employed in estimating the sensitivity of the different ductility parameters to nonmetallic inclusions. Tension specimens with special forms (twice perforated and V-notched specimens) have been devised to increase the sensitivity of the ductility parameters. Reduction in area is found to be a much more discriminating parameter than elongation at fracture.
Impact Testing of Flexible Polyurethane Foams
Authors: Shestopal VO , Chilcott B
Published: February 2009

Methods of obtaining information on dynamic properties of flexible foams from a limited number of impact tests are considered. The test procedure is based on measuring acceleration and displacement during the entire impact (not only maximum values as required in current standards). Interpretation of the results uses two theoretical approaches: stress-strain relationships and similarity considerations. Each approach has its own advantages. The developed algorithm, applied presently to four commercial packaging foams, allows the plotting of cushioning diagrams and predicts the shape of time-impact dependence for an arbitrary drop height and foam thickness. Properties of composite cushioning structures can be calculated.
Liquid Filtration: Examples of the Effects of Temperature, Viscosity, and Liquid Flow Rate
Authors: Johnston PR
Published: February 2009

On filtering particles of silica or iron oxide from water with filter paper, or a cartridge built of rayon fibers, the filtration efficiency, E, of 1 to 10 μm particles changed from 0.4 to 0.999 with changes in temperature, viscosity, and liquid flow rate. Variations in temperature and in viscosity changed the Brownian diffusivity, D, of the particles. Correlations are shown between D and log R, where R = 1/(1 - E). The results indicate the importance of specifying these variables in any referenced filtration test.
Granule Embedment on Shingles and Roofing Membranes
Authors: Dutt O
Published: February 2009

Samples of shingles and modified bituminous membranes covered with stone, slag or slate granules were tested for the amount of granules applied and the coverage provided to the bitumen. The granule embedment in the as-received condition and after wetting was measured by scrubbing the samples with 50 strokes of a steel wire brush. Five representative samples out of the thirteen were also subjected to an extended scrub test, where the number of scrub strokes was increased to 150 (in intervals) to evaluate the retention. The results showed significant variations between samples.

The requirement of a fixed amount of granule loss exists in most standards. Although this is adequate for quality control, the loss should be proportional to the quantity of granules applied, rather than a fixed amount. Proper assessment of granule adhesion requires testing for wet granule loss, for the initial granule coverage and for the tendency for granules to detach under extended scrubbing.
Metal Surface Preparation by Plasma-Polymerized Films
Authors: van Ooij WJ , Sabata A , Zeik DB , Taylor CE , Boerio FJ , Clarson SJ
Published: February 2009

Thin films (<1000 Å thickness) were deposited by polymerization in an RF plasma of hexamethyldisiloxane (HMDS) and ethylene on cold-rolled steel (CRS), electrogalvanized steel (EGS) and on polished pure zinc substrates. Prior to deposition the metals were cleaned in a reactive or nonreactive plasma in the same reactor. The films were characterized by various analytical techniques (FTIR, TOF-SIMS, XPS, and AES) for structure, composition, and metal-polymer interfacial composition. All plasma films appeared to be highly polymerized, crosslinked, and virtually insoluble in organic solvents. The ethylene films also showed a high degree of aromaticity and unsaturation. Both types of films afforded excellent resistance of the metal substrate to corrosion in humidity tests at elevated temperatures. The films were stable in air at temperatures up to at least 175°C. Some films provided corrosion resistance even after severe deformation by deep drawing a 5 cm diameter dome in the panel. The corrosion resistance of the film deposited on zinc substrates was usually better than that of the same films on CRS. Analysis by AES indicated that the film-metal interface compositions for these two metals were different. These differences will be related to the surfaces of the substrates.
Assessment of the Corrosion Behavior of SS 304L in Nitric Acid Environments—An Alternative Approach
Authors: Kain V , Prasad RC , De PK , Gadiyar HS
Published: February 2009

Stainless steel (SS) 304L is widely used as a construction material in industries requiring corrosion resistance in nitric acid environments. Representative samples from 20 heats of SS 304L products were subjected to a testing procedure consisting of testing as per the rapid screening test (Practice A) and the Huey test (Practice C) of ASTM A 262, Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels. The presensitization heat treatment of 677°C for 1 h and the modified heat treatment of 677°C for 20 min were used for characterizing the microstructures in Practice A, whereas only the former presensitization heat treatment was used for Practice C. The percent duality after the two heat treatments has been correlated with the corrosion rate obtained in Practice C. A chemical composition based parameter, Cr effective = [% Cr − 0.18 (%Ni) − 100 (%C)], was calculated for all the heats and correlated with the percent duality after the two heat treatments as well as the corrosion rate in Practice C. It is observed that the SS 304L heats with Cr effective >14.0 and <50% grain boundary coverage after the modified heat treatment (Practice A) show low corrosion rates in Practice C. This eliminates the need for carrying out the lengthy Practice C of ASTM. Examples of heats of SS 304L are given to show that the modified presensitization heat treatment has better efficiency in screening materials and also exhibited better correlation with the results obtained in the Practice C. Guide rules for selection of SS 304L heats for nitric acid service are also suggested. Erratum to this paper appears in 23(2).
Effects of Finishing Treatments on Fabric Friction
Authors: Ajayi JO , Elder HM
Published: February 2009

Simulation of finishing treatments to knitted and woven cotton fabric substrates causes significant changes in their frictional properties. It is found that the smaller the difference between static and kinetic frictional forces, the smoother the fabric surface. The changes in the amplitude of the stick-slip frictional traces appears to be the best indicator for assessing the effectiveness of finishing treatments on the tactile sensation of smoothness.
Two Parameters Characterizing Superficial Mechanical Features
Authors: Li J , Gai X , Kang Z , Wang Z
Published: February 2009

Two parameters, surface yield strength and surface work hardening exponent, have been newly suggested in this paper to characterize the superficial mechanical features in engineering metallic materials. Emphasis was placed on the method by which the two parameters are determined. X-ray stress determination and strain gage techniques were employed to measure stress and strain. The Mises effective stresses at a sample surface under different loading conditions were then calculated with the measured data; hence, the relationship between stress and strain was available. Consequently, with the data processing procedure for general yield point and work hardening exponent of uniaxially loaded materials, the yield point and work hardening exponent at the sample surface can thereby be obtained. Experimental studies on a shot-peened surface showed satisfactory results when the described method was used.
An Evaluation of Three Methods to Measure the Dynamic Elastic Modulus of Steel
Authors: Wolfenden A , Schwanz WR
Published: February 2009

The dynamic elastic modulus of 1018 steel was measured with three different instruments: the Grindo-Sonic, the Modul-R, and the piezoelectric ultrasonic composite oscillator technique (PUCOT). In total, 276 tests were made. The overall mean elastic modulus for all the specimens and all three methods was 207.1 GPa with a standard deviation of 2.75 GPa (1.33%). The mean values of elastic modulus and standard deviation measured by the Grindo-Sonic, the Modul-R, and the PUCOT were 208.1 and 0.86 GPa (0.41%), 205.8 and 3.40 GPa (1.65%), and 207.9 and 2.80 GPa (1.35%), respectively. The means of the elastic modulus for the PUCOT, Grindo-Sonic, and Modul-R methods fell within 0.39%, 0.48%, and 0.63%, respectively, of the overall mean elastic modulus of 207.1 GPa. All three instruments yielded comparable values of elastic modulus and comparable standard deviations. However, the Grindo-Sonic and Modul-R instruments were quicker for use than the PUCOT, but the PUCOT was more forgiving on the specimen geometry than the other two instruments.
Influence of Embedded Markers on the Response of the Host Material
Authors: Ochi SCU , Accorsi ML , Jordan EH
Published: February 2009

The effect of embedded marker particles on global stiffness and strains determined when using these markers as fiducial marks is studied analytically. These effects are important to a recently developed strain measurement method that uses before and after X-ray pictures of the embedded marker particles. Global effect of the markers on the stiffness is studied using micromechanical models available from the literature. The error in the measured strain due to the influence of the markers is assessed by both the finite element method and elasticity theory. It is shown that the global influence is small for marker-volume fractions less than 3%. The induced strain measurement error is small for particles that are five or more marker-diameters apart. A simple formula for the strain measurement error in the case of particles that are five or more marker-diameters apart is derived from elasticity theory.
Relationships between Tensile Stress Relaxation Behavior and Short-Term Elastic Recovery for Linear Low-Density Polyethylenes
Authors: Porzucek K , Lefebvre JM
Published: February 2009

Tensile stress relaxation is shown to be an experimental way to quantify the short-term elastic recovery of linear low-density polyethylenes (LLDPEs). The evolution of the force decrement ΔF with the logarithm of time is described by two linear equations on both sides of a critical time value tc = 100 s.

The slope p1 of the ΔF − ln(t) plot below tc increases linearly with the percentage of elongation ε up to the critical εc value associated with the onset of the yielding plateau; beyond εc, p1 remains almost constant with ε. This constant plp value is a linear function of the Tensile Residual Deformation (TRD) measured at the end of the relaxation: the lower the plp value, the lower the TRD. The determination of ptp thus appears as a predictive tool of the short-term elastic recovery of a material. Results show that the plp slope is slightly more sensitive to density evolutions than the TRD value. Assessing the elastic recovery capability through a stress relaxation analysis offers the following advantages: operator-independence, time-saving, and possibility of information storage for further data treatment.
Torsional Fatigue Test for Adhesive Bonded Butt Joints
Authors: Prakash V , Chen CM , Engelhard A , Powell G
Published: February 2009

A torsional fatigue test for adhesive bonded butt joints is presented. The apparatus for the test is a modification of the standard fixture outlined in the ASTM E 229 test for determining the shear strength of adhesive bonds subject to torsion. This apparatus is designed to be used on a universal testing machine and can be used to determine the fatigue life of adhesive butt joints under torsion. The fixture can be further modified to make it suitable for testing adhesive bonded shaft joints under torsion. Sample results from fatigue tests performed on a joint between steel and phenolic resin-cotton fiber laminate adherends are presented to show the viability of the fatigue test apparatus.
Effect of Cold-Bending and Strain-Age-Embrittlement on the Fracture Behavior of CSA G40.21 M 350 WT Steel
Authors: Bhuyan GS
Published: February 2009

The galvanizing process shifted the scatter band for impact energy values of the CSA 350 WT, category 4, plate material by approximately 10°C. The cold-straining alone produced the most significant shift (30°C) in the ductile-to-brittle transition temperature. This particular steel was found to be less susceptible to strain-age-embrittlement.
Strength Testing of Brittle Materials in Tubular Form Using Elastomeric Inserts
Authors: Vandeput FR
Published: February 2009

The tensile strength of a brittle material can be determined by bursting of tubular test specimens. A bursting test in which a tube is partially pressurized by an elastomeric insert is described. The results of the bursting test can be correlated with the transverse rupture strength of the material by using statistical fracture theories that take into account the size, stress distribution, and stress state in the test specimens. Bursting and three-point bending tests were conducted on cemented tungsten carbide specimens. The transverse rupture strength obtained from the three-point bending tests was correlated with the hoop strength of the tubes using the Barnett-Freudenthal and Weibull theory of fracture.