bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue Performance of Open Drilled Holes with Burrs
Authors: Nishimura T
Published: February 2009

Center hole tension specimens with similar shapes but different sizes were tested under constant and variable amplitude loads. Fatigue degradation due to burrs was found to be small and/or negligible for relatively large holes with diameters such as 10 and 5 mm, but was marked for smaller holes with diameters of 2 and 1 mm. Finite-element analysis shows that peak stress at a semicircular arc-shaped burr increases as the hole becomes smaller, if the same thickness and the same heights of the burrs are assumed. It is indicated that careful deburring is particularly necessary for small holes to prevent fatigue degradation.
On the Experimental Calibration of a Potential Drop System for Crack Length Measurements in a Compact Tension Specimen
Authors: Belloni G , Gariboldi E , Lo Conte A , Tono M , Speranzoso P
Published: February 2009

The present study was focused on the setup of a system for monitoring deep cracks in notched specimens in creep and fatigue laboratory tests. The test configuration features, the instrumentation requirements, and the important problems of the calibration for potential drop application to both fatigue and creep crack growth tests on compact tension specimens are discussed in detail. Experimental tests on the compact tension specimen geometry were carried out at ambient and high temperatures in order to define and validate an experimental calibration for this specimen geometry, to check the effect of temperature, and to compare the crack growth calibration curves under creep or fatigue conditions.
Economical Creep Testing of Ultrahigh-temperature Alloys
Authors: Völkl R , Freund D , Fischer B
Published: February 2009

Specially designed facilities for creep testing of ultrahigh-temperature alloys are presented. Ohmic heating is chosen for easy access to the sample, quickly attainable heating and cooling rates, and simplicity in design and operation. Strain is measured with a video extensometer by means of the software SuperCreep. SuperCreep allows fast and automated analysis of creep curves. For short but precise representations of creep curves, Bézier splines are used. Creep tests on pure Pt, Pt-10 wt% Rh, and the oxide dispersion strengthened Pt-base alloys Pt DPH and Pt-10 wt% Rh DPH between 1200 and 1600°C have proven the reliability of the equipment. Stationary creep rates follow the Norton power law. Stress exponents, activation energies, and pre-exponential factors are given for the four alloys investigated.
Fabrication of Thermal Probes for Estimation of Soil Thermal Resistivity
Authors: Narain Singh D , Devid K , Dali Naidu A
Published: February 2009

Thermal properties of soils are of great importance in view of the subsurface transmission of heated fluids or high electric currents. For these situations, it is essential to estimate the resistance offered by the soil mass in dissipating the heat generated through it. It has been demonstrated by researchers that soil thermal resistivity is a complex phenomenon that depends on various parameters such as type of soil, particle size distribution, and compaction characteristics. This poses a problem in estimating soil thermal resistivity using existing empirical and mathematical models. This calls for fabrication of a laboratory thermal probe that can be used to measure soil thermal resistivity of a soil sample either remolded to the in situ state of the soil or brought to the laboratory in an undisturbed form. However, as the laboratory sample would not represent the actual in situ state of the soil mass, efforts must be made to measure the soil thermal resistivity with the help of a field thermal probe. These probes, which work on the principle of the transient method, are found to be quite effective in measuring soil thermal resistivity.
Finite-Element Analysis of Stress Concentration in ASTM D 638 Tension Specimens
Authors: Garrell MG , Shih AJ , Lara-Curzio E , Scattergood RO
Published: February 2009

Experimental results showed that ASTM D 638 Type IV flat tension specimens, made of a Nylon-11 matrix containing a large volume concentration of Nd-Fe-B particulates, failed at a location where the straight gage section of the specimen ends and the curved transition region begins. The stress distribution in this specimen was analyzed using the finite-element method, and it was found that there is a stress concentration at this location. The stress distributions in tension specimens with both single- and double-arc transition regions were analyzed and stress concentration factors were calculated. A linear relationship between the magnitude of the stress concentration factor and the ratio of the width in the gage section and the arc radius of the transition region is identified. This study shows that it is possible to reduce the magnitude of the stress concentration factor for the ASTM D 638 Type IV flat tension specimen by redesigning the specimen geometry without changing its overall size.
In Situ Fracture Toughness Measurement Using Scanning Electron Microscopy
Authors: Yawny AA , Perez Ipiña JE
Published: February 2009

In situ tests were developed to measure fracture toughness (KIc, JIc, CTOD, R-curves) in small samples, simultaneously observing details of the crack blunting, initiation, and propagation by using scanning electron microscopy (SEM). A small load frame was employed for this purpose and in situ tests were performed in a Philips 515 SEM with a small chamber. A load-load line displacement record could be obtained from the different types of tests in order to calculate any fracture mechanics parameter, determine the initiation and amount of stable crack growth, measure directly the CTOD or Schwalbe's δ5 and correlate any of these parameters with the observed micromechanisms. The applicability of the proposed in situ fracture toughness measurement technique has been exemplified making use of a wide set of materials, and its limitations were also evaluated.
Thermal Conductivity of Alumina Measured with Three Techniques
Authors: Hemrick JG , Kistler CW , Wereszczak AA , Ferber MK
Published: February 2009

Three common ASTM methods (calorimetry, hot-wire, and laser-flash) for determining the thermal conductivity of refractory ceramics were compared using a commonly available bulk material having a microstructure sufficient for all three methods of analysis. Experimental measurements were made between 20–1200°C on a fine-grained, 94 % pure aluminum oxide using each technique. Results from the hot-wire and laser-flash methods were found to be similar and in line with theoretical and literature values. Values obtained by the calorimetry method were found to be lower than those of the other two methods, with a greater deviation at lower temperatures than at higher temperatures.
Development of a Procedure to Determine the Effectiveness of Asphalt-Removing Solvents
Authors: Kulkarni M , Xu Q , Tayebali A
Published: February 2009

Due to environmental protection requirements, most state and federal agencies are now required to use biodegradable solvents instead of diesel fuel or other hydrocarbon solvents. A variety of environmentally friendly and safe asphalt-removing solvents are available in the market. However, there is no quantitative standardized procedure to compare the efficacy of these solvents. This paper outlines the development of a procedure used to evaluate the cleaning efficacy of various solvents. The goal was to develop a standardized procedure that would yield quantitative and repeatable results. After evaluating various alternatives like metal and glass plates, ceramic tiles, and aluminum foils, the aluminum dish was found most suitable for the study. Test results obtained for solvent comparison were found to be consistent and repeatable, with the coefficient of variation for asphalt removed less than 10% for most solvents. Further, this study provides an outline for cost-effective analysis of solvents used in relation to diesel fuel and the procedure is able to rank solvents quantitatively.
A Method for Assessing the Durability of Medical Examination Gloves
Authors: Chaput MP , Teixeira JC , Boivin WS , Kerr LN , Mailhot SA , O'Malley LG
Published: February 2009

A method was developed to test the durability of medical examination gloves. Target failure rate ranges were established for the method by analysis of published failure rates for gloves tested after clinical use. The method consists of two parts: a Simulated Donning Test Procedure and a Shaker Table Abrasion Procedure. FDA water leak testing was performed to detect defects after stressing the gloves. In the donning procedure, a donning apparatus is used to simulate the stresses of donning medical gloves. In the abrasion procedure, a hand phantom is placed inside the glove; the glove is placed into a Fleaker™ beaker containing an abrasive material; and a shaker table agitates the setup and stresses the glove. Failure rates were 4 % for vinyl gloves and 0 % for latex gloves after simulated donning alone and 41 % for vinyl and 11 % for latex after combined donning and abrasion testing. The measured failure rates were within the established target rate ranges.
Experimental Study of the Strain Rate and Temperature Effects on the Mechanical Behavior of a Magnesium-Silicon Carbide Composite
Authors: El-Saied Essa Y , Fernández-Sáez J , Pérez-Castellanos JL
Published: February 2009

The effects of strain rate and temperature on the mechanical behavior of a magnesium alloy (ZC71) and its corresponding composite reinforced with SiC particles are investigated. The experimental procedures of testing at high strain rate and different temperatures are described. The tensile stress-strain responses of both the base and the reinforced materials were found to depend on the applied strain rate (0.003 ≤ έ ≤ 700 s−1), the test temperature (−150 ≤ T ≤ 200°C) and the presence of reinforcement. Comparative results are presented in terms of the main mechanical parameters, and quantitative conclusions are obtained of the influence of temperature and strain rate, using quasistatic and dynamic tests, on the mechanical behavior of these materials.
Evaluation of the Ignition Susceptibility of Plastics in Nitrogen Trifluoride (NF3) by Autogenous Ignition Testing
Authors: Newton B , Jacksier T , Beeson H , Stradling J , Odom G
Published: February 2009

This paper presents the development of a test system to evaluate the ignition susceptibility of several common plastics in nitrogen trifluoride (NF3) as compared to gaseous oxygen. A test system was developed to allow for measurement of the autogenous ignition temperature (AIT) in both gaseous oxygen and NF3. The autogenous ignition temperatures of Kel-F® 81 PCTFE, Neoflon® PCTFE5, Teflon® PTFE, Nylon 101, PVDF, and PVC were determined in gaseous NF3 and in gaseous oxygen.
Measurement of Lateral Deformation in Natural and High Damping Rubbers in Large Deformation Uniaxial Tests
Authors: Amin AFMS , Alam MS , Okui Y
Published: February 2009

In testing the mechanical behavior of rubbers, the incompressibility assumption is used to predict the deformed cross section under loading and thereby to calculate the true stress. There are, however, cases where rubbers can undergo considerable volumetric deformation in large strain experiments. Microstructural investigation through a scanning electron microscope was carried out on a void-filled natural rubber specimen to clarify the effect of voids on the compressibility feature. The microstructure of the natural rubber was observed qualitatively and quantitatively in uniaxial tension and compared to the microstructure in the underformed condition. The existence of the compressibility feature in the void-filled rubber was confirmed from a microstructural viewpoint. The findings indicate the necessity of accurate measurement of the deformed cross section in mechanical tests to obtain the true stress. To this end, an experimental setup capable of measuring the deformed cross section of the rubber specimens subjected to large uniaxial compression is proposed. To do this, the accuracy of laser beams is used for measurement of distance and a mechanical jig is developed to synchronize the movement of the laser transducer with the vertical crosshead of the load cell of a computer-controlled servohydraulic testing machine. Thus the constraints associated with conventional strain gages in measuring large strains are overcome. Finally, two natural rubber specimens and one high damping rubber specimen were tested in the proposed setup to display the adequacy of the developed device in measuring lateral deformation of rubber-like highly deformable solids in large strain uniaxial testing.
Measurement and Analysis of the United Parcel Service Ground Shipping Environment for Large and Heavy Packages
Authors: Singh SP , Burgess GJ , Hays ZG
Published: February 2009

This study investigated the United Parcel Shipping environment for shipping large and heavy packages weighing up to 150 lb. The data were collected using instrumented packages that contained triaxial recorders to measure acceleration levels produced by drops and impacts during shipping and handling. The study showed that the existing test methods used to design and evaluate such packages for this type of shipping environment in accordance with ASTM (American Society for Testing and Materials) and ISTA (International Safe Transit Association) test methods do not replicate the levels of damage found in real shipments. The study recommends tests that would produce more realistic damage levels for this environment.
On the Sensitivity of J Estimation to Materials' Stress-Strain Curves in Fracture Toughness Testing Using the Finite Element Method
Authors: Kim Y-J , Schwalbe K-H
Published: February 2009

The present paper reports the accuracy of the J estimation equations for three typical homogeneous fracture toughness testing specimens: M(T), C(T), and SE(B) specimens, based on systematic 2D FE analyses. A wide range of crack lengths is considered, except for C(T) specimens where only deep cracks are considered, a/W = 0.45 to 0.7. By carefully selecting the properties of the materials in the analysis, particular emphasis is placed on the sensitivity of such equations to the strain hardening as well as the type of stress strain curve, such as continuously hardening materials or materials with Lüders strain. Two different J estimation schemes are considered, one based on load-load line displacement records and the other on load-crack mouth opening displacement (CMOD) records.

For all cases considered, the J estimation based on load-CMOD records gives more accurate results, compared to those based on load-load line displacement records. Moreover, the J estimation is not sensitive to the material's strain hardening and to the type of the stress strain curve, except for shallow-cracked M(T) specimens with a/W < 0.2. For shallow-cracked M(T) specimens with a/W < 0.2, the J estimation equation is not sensitive to the material, for materials with Lüders strain, but is sensitive for continuously hardening materials. The error increases with the hardening, i.e., a higher hardening material gives a larger error in J.
Evaluation and Adjustments for ASTM D 5656 Standard Test Method for Thick-Adherend Metal Lap-Shear Joints for Determination of the Stress-Strain Behavior of Adhesives in Shear by Tension Loading
Authors: Yang C , Huang H , Tomblin JS , Oplinger DW
Published: February 2009

Adhesive-bonded joints have been used widely for composite materials as a necessary alternative to conventional mechanical joint designs. In a bonded joint, the load is transferred from one substrate to the other mainly through adhesive shear stress. One of the greatest drawbacks to predicting the mechanical behavior of bonded joints has been the lack of reliable data on the mechanical properties of adhesives. Among many test methods that have been developed to test structural adhesives in thin film geometries, the ASTM D 5656 “thick-adherend lap shear test” is used frequently to determine the shear properties of adhesives while the samples are loaded in tension. Due to the nonuniformity of adhesive shear stress distribution within the joint, through both the bondedline thickness and overlap length, and the measurement method described in the test method, some errors will be introduced if corrections are not made. A finite element analysis was conducted in order to provide a clear picture of the mechanical behavior of the ASTM D 5656 specimen under loading. Based on the results from finite element analysis, the sources of error were analyzed and three correction factors were introduced to recover the adhesive shear modulus of the specimen. Suggestions of mounting the KGR-1 measurement device are also given in order to avoid some of the errors. Because results from linear finite element analysis were used, only adhesive shear modulus within the linear range is discussed in this article.
Weathering Effects on the Fracture Properties of Polyvinyl Chloride Pipes
Authors: Ragab AR , Alawi H
Published: February 2009

Polyvinyl chloride (PVC) pipes were weathered naturally for periods of up to two years. The effect of weathering on the mechanical properties was investigated by compressing unnotched and radially notched ring specimens in a parallel-plate test. Disregarding the scatter existing among the test results, the general trend indicates deteriorating fracture properties due to exposure. The application of fracture mechanics concepts, explicitly the J-integral value, to the test results helps to reveal the susceptibility of weathered PVC pipe material to brittle fracture compared to its as-received condition.
An Instrumented Microindentation Testing Device
Authors: Öberg H , Larsson P-L , Magnius O
Published: February 2009

An experimental device for microindentation testing has been designed and constructed. The device can be used together with standard testing machines and allows for continuous recording of indentation loads up to approximately 500 N and indentation depths in the range 1 to 100 µm. Special care has been taken in order to minimize the effects of elastic deformations in the experimental setup as well as deformation of the foundation. To check the reliability as well as the accuracy of the experimental device, microindentation tests, using a standard Vickers indenter, were performed on three well-characterized materials and the experimental results compared with earlier experimental and theoretical findings as well as with presently performed three-dimensional finite element calculations.
Method-Specific Precision and Bias Relationships Developed from Data Submitted During USEPA Drinking Water Laboratory Performance Evaluation Studies
Authors: Britton PW
Published: February 2009

This paper documents the process used by the United States Environmental Protection Agency (USEPA) to estimate the mean and standard deviation of data reported by in-control drinking water laboratories during Water Supply (WS) studies. This process is then applied to the data reported for each specific sample, analyte, and method in ten WS studies, and linear relationships between the mean response and true analyte concentration and between the interlaboratory standard deviation of responses and true analyte concentration are presented. Such relationships can be invaluable as background information for anyone who must conduct an interlaboratory study using the same methods to analyze similar interference-free samples or who must evaluate the analytical quality of such data.
Quantification of Coarse Aggregate Shape and Its Effect on Engineering Properties of Hot-Mix Asphalt Mixtures
Authors: Chen J-S , Shiah M-S , Chen H-J
Published: February 2009

This paper is aimed at quantifying coarse aggregate shape in an efficient manner and relating aggregate characteristics to mix properties. Digital image analysis was used to evaluate aggregate characteristics such as elongation, flatness, and other shape indices. The following particle shapes were selected for this study: cubical, rod, disk, and blade. Data showed that the morphological characteristics of coarse aggregate correlated well with the results of other indirect tests such as the particle index. Cubical particles possessed the best rutting resistance over the other shapes. Flaky and/or elongated aggregate in a mixture resulted in a lower resistance to shear deformation. The morphological characteristics of coarse aggregates found from image analysis were in good agreement with the engineering properties of hot-mix asphalt (HMA) mixtures. This paper presents a precise method to evaluate the aggregate characteristics in an HMA mix and demonstrates their effects on pavement performance.
Yield Strength in Relation to Cyclic Loading
Authors: Ichinose K , Fukuda K , Gomi K , Taniuchi K , Sano M
Published: February 2009

The yielding phenomenon under cyclic loading has been investigated for low-carbon steel. Under various loading ratios, the surface state of the specimen was observed with the naked eye, using the Lüders band as an indicator for the yield point elongation. The stress-strain curve was measured simultaneously. The results show that both the surface states and the cyclic stress-strain characteristics vary depending on the load ratio. This makes it questionable to use the yield strength evaluated under monotonic loading to describe the mechanical properties of the specimen material for fatigue tests, though it is a prevailing practice recommended by ASTM. The result of this study also indicates that the Lüders band can be used as a smart sensor to investigate the yield phenomenon.
Nondestructive Evaluation of Fatigue and Creep-Fatigue Damage in 12%Cr Stainless Steel by the Induced Current Focusing Potential Drop Technique
Authors: Yamashita M , Tada S , Sato Y , Shoji T
Published: February 2009

Steam turbine rotor material is subjected to damage by creep, fatigue, and creep-fatigue. It is important to develop nondestructive methods to measure the progress of crack initiation stage damage in materials. In this paper, for 12%Cr stainless steel, detection and evaluation of earlier stages of creep-fatigue damage by the potential drop method are described. Failure tests by fatigue, creep-fatigue, and creep at 600°C were carried out, and specimens intermittently damaged by fatigue, creep-fatigue, and creep at the same temperature were prepared. Morphologies of damage on the surface of damaged specimens were investigated, and quantitative measurements of damage were conducted using the induced current focusing potential drop (ICFPD) method. In creep-fatigue damaged specimens, slip traces were observed at an early damage stage, producing a large number of cracks. Fatigue generated little slip and the number of cracks was smaller. The potential drop data obtained by ICFPD indicate that creep-fatigue damage in 12%Cr stainless steel can be evaluated based on potential drop data obtained by using the ICFPD method.
Evaluation of Powdered Latex Medical Gloves Using ASTM D 6124-00
Authors: Chaput MP , Margolin AB
Published: February 2009

Natural rubber latex proteins are recognized as a cause of Type I (Immediate Type Hypersensitivity) reaction in some individuals who have been exposed to latex devices. Residual former-release, stripping, and/or donning powders have been found to carry these allergenic proteins into the air during handling and use. Exposure to airborne glove powder contaminated with latex allergens is known to provoke respiratory allergic symptoms in latex-sensitized individuals and may make it difficult for these individuals to continue working in jobs involving such exposure. The Food and Drug Administration has proposed a maximum level of 120 mg of donning powder/particulates per glove on powdered gloves. A survey was conducted to determine current powder levels on commercially available powdered latex patient examination gloves and surgeons' gloves. Ninety-seven samples of powdered latex medical gloves representing 32 different brands produced by foreign and domestic manufacturers for the U.S. market were evaluated for residual powders per glove by ASTM D 6124-00, Standard Test Method for Residual Powder on Medical Gloves. Powder levels ranged from 37 to 260 mg per glove for patient examination gloves and 30 to 513 mg per glove for surgeons' gloves. Of the gloves tested, 55.7% met the new maximum powder guidelines.
Review of Design Experiments Using the Taguchi Approach: 16 Steps to Product and Process Improvement
Authors: Rushforth RJ
Published: February 2009

The purpose of the book is to help practicing engineers learn to y Taguchi experimental design techniques through the use of ry, step-by-step applications of concepts, and an introduction he Qualitek-4. software. Common manufacturing floor language sed to make the book understandable by technicians, engineers, managers. Equations are reduced in the text to further litate understanding. The book accomplishes this task and is a readable book. The reader, however, should be alert for occasional graphical errors in the text and calculations, which are always obvious.
Fracture Toughness Testing of Polymers Using Small Compact Specimens and Normalization
Authors: Landes JD , Bhambri SK , Lee K
Published: February 2009

Fracture toughness tests were conducted on a polymeric material used in medical implants. The fracture behavior was ductile so that the toughness was measured using a J-R curve and JIc. The object of the test program was to compare the fracture toughness properties for different material treatments. The focus of this paper is to describe the procedure used to test the materials. Small specimens of the compact geometry are tested. Many parts of the procedure were similar to the standard test method used for metallic materials, but three issues that required a different approach were the focus of this work: the introduction of an initial defect, the testing rate, and the measurement of crack extension. The crack was introduced with a pressed razor blade cut, the loading rate was maintained constant at a rate of 0.06 in./s (0.15 mm/s) and the method of normalization was used to measure crack extension.

The results showed that the razor cut procedure for introducing the initial defect gave comparable toughness results to a specimen that was precracked in fatigue. The loading rate must be maintained over a closer range than the one used for metal testing. Metal testing allows a loading rate range of two orders of magnitude, whereas rate-influenced differences in toughness were observed for these polymer materials over this range. The methods of crack extension measurement used in the standard for metallic materials do not work for polymers. The method of normalization can give comparable results to that of the multiple specimen method used as the basic method for measuring JIc. The procedures studied in this work could form the basis for developing a standard fracture toughness test for polymeric materials.
Fatigue Crack Detection with Estimation of Stress Fields Near a Notch Root of Thin Plate Structures in In-Plane Loading
Authors: Harada T , Noguchi H
Published: February 2009

A practical method is proposed for in situ fatigue crack detection in actual notched structures. This method is available for the cases where the initiation position and propagation direction of a crack are uncertain and the load direction or the load mode changes. In the present method, the stress fields near a notch root are estimated using the general stress function in a polar coordinate system and the stress values obtained from strain gages around the notch root. The stress fields are characterized by the residual stress due to plastic deformation around a fatigue crack. Not only a propagating crack but also a nonpropagating crack can be detected from the characteristic stress field. Moreover, the detection limitation is subject to the strength of the residual stress field relative to an elastic stress field due to external loads. The fatigue experiment of a notched specimen of steel was carried out. In the present experiment, a 0.33-mm-long crack could be detected in the notch whose root radius was 12.5 mm.
Dynamic Characterization of Instrumented Handle and Palm-Adapter Used for Assessment of Vibration Transmissibility of Gloves
Authors: Dong RG , Rakheja S , Smutz WP , Schopper AW , Caporali SA
Published: February 2009

A mechanical testing method to assess the vibration isolation effectiveness of gloves has been standardized (ISO 10819). The instrumented handle and a palm-held adapter recommended in the standard are evaluated systematically in order to identify their potential contributions to the overall measurement errors. The results revealed a nonuniform distribution of vibration along the handle surface. The results also revealed the presence of considerable magnitudes of nonaxial source vibration caused by the nonaxial nature of the feed force imparted by the human hand. An alternate design of the handle is realized to achieve a more uniform distribution of vibration. Three alternative methods are proposed to minimize the contributions due to adapter misalignment and the nonaxial source vibration. An error contour method is proposed to predict the influence of the dynamic features of a handle on the measurement of effective vibration. The characterization methods developed in this study may also be applicable to other types of instrumented handles for the study of hand-arm vibration.
Application of the Master Curve Method and the Engineering Lower Bound Toughness Method to Laser Welded Steel
Authors: Heerens J , Hellmann D
Published: February 2009

The fracture toughness of laser beam welded ferritic steel has been measured in the ductile-to-brittle transition regime using precracked bend specimens. The precracked welded specimens showed a complex fracture behavior, which involves crack path deviation. It was found that the large scatter of the cleavage fracture toughness and its temperature dependence can be characterized by the Master Curve Method (MCM). The results promote the validity of Engineering Lower Bound Method (ELBM) to derive lower bound toughness of laser beam welded steel. To enable a successful application of the Methods, it was necessary to add fracture toughness data censoring to the method, which takes into account the phenomenon of crack path deviation. The application of the censoring criterion requires additional fracture surface investigations, which can be performed easily using a conventional low magnification light microscope.
Application of Acoustic Emission for Measuring Crack Initiation Toughness in Instrumented Charpy Impact Testing
Authors: Tronskar JP , Mannan MA , Lai MO
Published: February 2009

Acoustic Emission (AE) has been used to detect onset of ductile tearing in instrumented Charpy impact tests to enable determination of dynamic ductile tearing initiation toughness using a single specimen method. An AE based method was developed whereby a conventional instrumented impact tester is instrumented with a commercial broadband acoustic emission sensor mounted on the anvil. The results obtained using the new AE based method were compared to the results obtained by other researchers using specially developed AE sensors located inside the tup. Tests using both AE and direct measurement of the load-line displacement during the instrumented Charpy testing were conducted simultaneously on a conventional ship grade steel. V-notched and fatigue precracked test pieces were tested in the temperature range +23°C to −80°C.

The results obtained with AE monitoring were compared to those obtained using the optical Direct Displacement Interferometric Strip (DDIS) method developed by the authors. Good correlation was found between the initiation fracture toughness determined at 0.2 mm blunting and crack extension, J0.2, by the multispecimen Ductile-Brittle Transition (DBT) method and those derived from single specimens applying AE and the new interferometric method to detect ductile fracture initiation. Fast Fourier Transformation (FFT) was applied to analyze the AE signals. The results showed that the different phases of AE and fracture modes could be distinguished based on characteristic frequency and time variance.
Mechanical Testing of Baseball Bats
Authors: Smith LV , Axtell JT
Published: February 2009

Advances in the materials and structure of modern baseball bats have spurred interest in measuring their hitting performance. Many test standards and performance measures have been developed to quantify bat performance. The ability of these tests to simulate a player-swung bat has been largely ignored, however. This study describes the operation of a machine that has been used to measure bat performance and durability. The strain responses of player- and machine-swung bats were compared to determine the ability of laboratory experiments to simulate play conditions. Over much of the range of a full swing, the machine-swung bats experienced considerably higher strain than player-swung bats. During the instant of impact with the ball, however, the response of the player- and machine-swung bats was nearly indistinguishable. The similarity between laboratory tests and a player's swing supports the use of controlled experiments to measure bat performance. The relative response of a bat was shown to depend on the measure used to quantify performance, however. Three measures of bat performance were compared for a series of solid and hollow bats. It was observed that bat-ball efficiency measures may be an unreliable indicator of bat performance in play. Studies have shown that the swing speed depends on the mass properties of the bat and has a large effect on the batted ball speed. Consideration of bat efficiency alone does not fully account for the contribution of a bat-dependent swing speed. It is suggested that bat performance be measured from the batted ball speed in tests using a bat-dependent swing speed.
Erosive Boundary Layers of Ni 200 in Vibratory Cavitation Erosion Tests
Authors: Meged Y
Published: February 2009

The test surface of a specimen for cavitation erosion testing is prepared by several machining operations. These operations induce alterations on the surface and in the material beneath it, thereby forming an affected material zone. The properties of this zone affect the mechanical and metallurgical properties of the material. As a consequence the erosive properties are affected too, but are not easily detected on the cumulative erosion-time curves.

The cumulative erosion-time curves of Ni 200 erosion tests were modeled by the Weibull cumulative distribution function. The equivalent Weibull plot consists of two intersecting straight lines, thereby providing a bimodal plot with a decreasing slope. Each line describes a different erosion mode. The first mode, from test onset to the intersection point, describes the erosion process of the specimen's boundary layer. Since this layer is removed by means of the erosion process, it is designated as the erosive boundary layer.

The second mode, from the intersection point onwards, describes the erosion process of the homogeneous material. Analysis of the Weibull plots of Ni 200 erosion tests enables determination of the erosive boundary layer thickness and erosion time; it further facilitates the evaluation of the erosive boundary layer effect on the entire erosion process. The Weibull method enables construction of plots describing the erosion process of an ideal specimen, with an erosive boundary layer of 1 μm thickness. Plots of this kind may be used to characterize Ni 200 and to compare erosion properties of various materials.
Analysis of Stresses in Spur Gears by the Photoelastic Coating Method
Authors: Çelik M , Bilir ÖG
Published: February 2009

This study uses a photoelastic coating method in spur gear stress analysis, and verifications of the results are made with two-dimensional boundary element analysis. The principal advantage of the photoelastic coating method comes from the fact that it is a full-field technique capable of showing the entire stress distribution over the surface of a part and thus highlighting the regions where the stresses are the largest. The general results of experimental work in which spur gears are analyzed, both in test fixtures and in loading conditions at the critical points, are presented in order to measure actual tooth root, tooth fillet, and blank stresses.
Applicability of ModifiedJas a Fracture Parameter for Polycarbonate
Authors: Wert MJ , Saxena A , Ernst HA
Published: February 2009

The applicability of modified J-integral, JM, as a fracture parameter for plain and impact-modified polycarbonate was examined. Specific issues were:

1. Influence of the non-unique tensile stress-strain behavior, which is characteristic of these materials, on the applicability of JM.

2. Methods of estimating JM in fracture specimens given the load—load-point deflection diagram.

3. Fracture mechanisms that cause ductile and brittle crack growth in this class of materials.

Crack growth resistance (JM-R) curves were obtained from compact-type (CT) specimens of multiple sizes and specimens of another geometry (single edge notch [SEN]). The JM-R curves were consistent for crack extensions up to 2.5 mm for CT specimens of various sizes and were independent of geometry for crack initiation and a limited amount of crack growth (1.5 mm). The JM-R curve for toughened polycarbonate showed a considerably higher resistance to ductile tearing than that of the plain polycarbonate. The fracture mechanisms in both types of materials were characterized using a scanning electron microscope.
The Linearity of Clip Gages Used in Fracture Mechanics Tests
Authors: Smith DJ , Gordon JR
Published: February 2009

The measurement of displacement in fracture toughness tests is generally accomplished using clip gages. This paper describes an experimental study to examine the performance of a number of clip gages. It is shown that double cantilever clip gages exhibit a non-linear response. The degree of non-linearity is shown to vary with temperature. In relation to fracture mechanics test methods it is demonstrated that in some instances relaxation of the test standards is required to-encompass the gage performance. Where data can be stored digitally, the non-linear response can be accounted for using a third-order polynomial calibration. An analytical study shows that the non-linearity is inherent for the large displacements often incurred in fracture mechanics tests.
DynamicKMeasurements in Three-Point-Bend Specimens
Authors: Sharpe WN , Shapiro JM
Published: February 2009

The displacement across the tip of a crack in a three-point-bend specimen loaded in a drop tower was measured with inplane laser interferometry. The equivalent displacement was measured in a statically loaded specimen; the two measurements were combined to produce a dynamic load-time plot. This result is used to compute the stress intensiy factor, K, under dynamic loading. It is compared with an equivalent plot obtained from foil gages at the quarter-points of the specimen. The K based on near-tip measurements is initially higher than the one based on the far-field loads, but the two records agree after approximately 0.5 ms. This transition time, before which inertial and wave propagation effects are important, is in close agreement with recent predictions by others.
Weathering Effects on Some Mechanical Properties of Polyvinyl Chloride Pipes
Authors: Ragab AR , Alawi H , Addassi E
Published: February 2009

Polyvinyl chloride (PVC) pipes have been naturally weathered for periods up to two years. Tests on unnotched and notched tensile specimens and full pipe lengths of these weathered pipes reveal effects of outdoor exposure on their strength and fracture behavior.

Large scatter exists among test results. However, some general experimental trends are observed. Both tensile and burst pressure tests of unnotched specimens demonstrate increasing strength with exposure. Testing of sharply notched specimens reflects higher susceptibility to brittle fracture due to weathering. Such experimental evidence may be important when carefully considering brittle fracture modes in designing PVC pipe systems.
The Use of Miniaturized Tests to Predict Flow Properties and Estimate Fracture Toughness in Deformed Steel Plates
Authors: Haggag FM , Server WL , Lucas GE , Odette GR , Sheckherd JW
Published: February 2009

Prediction of failure in a structure requires knowledge of the mechanical properties of the materials involved. In the case of serious accidents, such as derailments of railroad tank cars carrying hazardous materials, prediction of failure in damaged components is impeded by difficulties in determining the deformed material fracture toughness, the cracks induced by the accident, and the stress state in the damaged region. This paper addresses the problem of determining fracture toughness. Miniaturized shear punch tests on virgin, strained, and deformed steel plates (typical of railroad tank car construction) were conducted over a wide range of test temperatures. These data were compared with tensile properties measurements on identical materials. The use of these data coupled with micromechanical models of fracture allows estimation of the deformed material fracture toughness. Comparisons of the predicted fracture toughness with actual measurements are made.
An Appraisal of Hydration Characteristics of Dead Burnt Dolomite Grains
Authors: Das SK , Ghosh A , Das PK , Banerjee G
Published: February 2009

Five different Indian dolomites are densified by the process of two-stage sintering at 1923 K (1650°C). Hydration of the dead burnt dolomite by all three test methods is found to be strongly influenced by the bulk density and grain size of the dolomite. In spite of wide variations in test conditions, equivalent disintegrating actions have been identified by varying test duration. In all three test methods the distintegration of doloma grain during hydration has been found to be related to the generation of Ca(OH)2. Selective hydration of CaO has been confirmed by SEM study. Results on the disintegration characteristics, bulk density, and rehydration behavior of the hydrated doloma grain are also presented.
A Suggested Procedure for Combined Mode I — Mode III Fracture Toughness Testing
Authors: Manoharan M , Hirth JP , Rosenfield AR
Published: February 2009

Mode I fracture toughness testing is well developed and standards exist for determining both Mode I critical stress intensity factors and J integrals. However, combined Mode I — Mode III testing is not so well developed and no standards exist. The aim of this paper is to suggest a testing procedure for studying mixed-mode crack initiation and growth under linear-elastic and elastic-plastic conditions. Suitably defined formulations of the stress intensity factor denoted Kic and Jiiic were used to characterize linear elastic fracture. Under elastic-plastic conditions, suitable versions of the J integral denoted Jic and Jiiic were used to characterize crack initiation and the slopes of the resolved J resistance curves to characterize crack growth. Effects caused by surface rubbing which operate at high values of the Mode III/Mode I ratio are recognized as a complication in interpreting the data.
Optimal Stress Amplitude Selection in Estimating Median Fatigue Limits Using Small Samples
Authors: Little RE
Published: February 2009

The minimum variance strategy for specimen allocation in estimating median fatigue limits using small sample sizes is explained. Its implementation using microcomputer programs to select automatically the most effective stress amplitude for testing the next specimen is discussed. Applications involving modified up-and-down tests and estimation of strength percentiles are presented. An appendix illustrates strategies effective in preliminary tests.
Hardness Gradients within Roll-Threaded Steel Nails
Authors: White MS , McLain TE , Padla D , Kasal B
Published: February 2009

Standard methods of testing nails include measures of Rockwell hardness, using the C scale. Because of the relatively small cross-sectional area of nail shanks, Rockwell measurements are normally limited to one per nail cross section. Therefore Rockwell hardness tests cannot detect the presence of any hardness gradients within the nail cross section. Since hardness is a direct indicator of certain strength characteristics, such gradients could influence nail quality and hence the performance of nailed joints.

Vickers micro-hardness tests of regions within the shanks of threaded non-hardened and hardened nails of several wire diameters and SAE classes were conducted to assess any hardness gradients within the nail-shank cross section. Mean hardness of both non-hardened and hardened nails increased with increased carbon content over the range of 0.10 to 0.40 wt% (1010, 1022, and 1040 SAE class steel wire).

However, the Vickers hardness number was relatively uniform across the nail shank diameter, indicating a lack of significant hardness gradient. This uniformity was found in all nail-shank diameters within the range of 2.7 to 3.4 mm (0.105 to 0.135 in.) or SAE number classes. Consequently, a single Rockwell macro-hardness measure of several properly prepared nail surfaces should give a reliable indication of nail-shank hardness.
A Computer-Aided Image System for Analyzing Cracks Created by Nailing in Wood
Authors: Lau PWC , Tardif Y
Published: February 2009

Initial crack length is an important parameter in fracture mechanic studies. Driving a nail into wood causes cracks to form which are the bases for subsequent crack development as a result of loading or drying. This report describes a computer-aided image system with which the induced crack size and shape were characterized. Typical examples of measurements of cracks as affected by species, nail type, and initial wood moisture content are also presented. Comparisons between computer-generated images and a reference test pattern indicate that the method is accurate. Crack sizes and shapes were seen to be affected by all the parameters investigated. Crack propagation tends to be at its maximum near or at the nail-exit face but can occur anywhere within the crack profile.