bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory and Application of a Micro-Scale Abrasive Wear Test
Authors: Rutherford KL , Hutchings IM
Published: February 2009

A micro-scale abrasion test has recently been developed that allows measurement of the wear resistance of the surface regions of a material. The typical penetration depth is less than 30 μm. The test uses a simple mechanical and optical system and involves rotating a hard steel sphere against a specimen in the presence of small abrasive particles. The method has been used to investigate the wear resistance of thin PVD coatings (1 to 5 µm), metallic glass ribbons, and paint films in addition to bulk samples of metals, ceramics, and glasses. The associated theory has been extended so that results may be obtained from any curved surface. This furthers its applicability to practical surface-engineered components such as twist drills, bearings, turbine blades, and biomedical prostheses. A detailed characterization of the experimental procedure has been undertaken to provide an understanding of the repeatability and sensitivity of the test. In a study of cutting-tool coatings, the wear resistance measured by this method has been shown to correlate with scratch test response and with the performance of coated end-mills in cutting tests.
First Continuous Remote Bridge Monitoring System Ensures Safe Operation of 65-Year-Old Rolling Bascule Bridge
Authors: Prine D
Published: February 2009

The Infrastructure Technology Institute (ITI) at Northwestern University has installed what is believed to be the first continuous remote monitoring system on a highway bridge in the world. The system was installed on a rolling bascule bridge over Sturgeon Bay in Door County, Wisconsin. It allows engineers located at ITI to closely monitor crack propagation and other conditions on the bridge which is near the end of its design life. The system is intended to serve as the prototype for a new method to monitor the condition of aging bridges in order to ensure public safety and allocate scarce rehabilitation and replacement funds in an optimal manner.
A PC-Based Near Real-Time Ultrasonic Imaging System for Flaw Characterization
Authors: Anand RS , Kumar V
Published: February 2009

This paper presents the description of a PC-based ultrasonic imaging system which generates three types of pulse-echo ultrasound images, namely, A-scan, B-scan, and C-scan, almost in real time. The system has pulser-receiver circuitry employing a single ultrasonic probe working as both the transmitter and the receiver. The generated ultrasound signal is transferred to a PC-AT using the A/D conversion facility of a digital storage oscilloscope where it is processed for target echoes with their amplitude and location. Thereafter, this information is correlated to provide a particular type of image. The probe positioning for the images is accomplished by a motorized mechanical system made up of two stepping motors. This developed ultrasonic imaging system is fully automatic, user-friendly, and operator independent.
Determination of ηpl Factor: Influence of Side Grooving
Authors: Cassanelli AN , de Vedia LA , Herrera R
Published: February 2009

The objective of this paper is to analyze the influence of side grooving on the ηpl factor in the ASTM Standard Test Method for JIc, a Measure of Fracture Toughness (ASTM E 813-89), for C(T) and SE(B) specimens. The method proposed by Sharobean and Landes to calculate the ηpl factor from blunt-notched specimens was utilized. Standard C(T) and SE(B) specimens were prepared out of a 30-mm-thick, 2.25 Cr-1 Mo. ASTM A-387-Gr22 type steel plate. The crack lengths considered ranged from 55% to 75% of the specimen width W, and three sets of specimens were prepared with 0% B, 25% B and 50% B double side grooving, respectively.
Comparison of Chevron-Notched Specimen Types for Fracture Toughness Testing of Aluminum
Authors: Morrison J , Gough JP , KarisAllen KJ
Published: February 2009

There is increasing interest in the use of chevron-notched specimens for the measurement of plane-strain fracture toughness. Attention has been focussed on the short rod/bar specimens, for which several different geometries have been proposed. This paper describes a series of tests on 6061-T651 aluminum alloy aimed at providing a comparison of five short rod/bar specimen types with three different thicknesses. Also included are data from standard compact-tension specimens.
Effects of Small Surface Cracks on Ductility Loss in Low Cycle Fatigue of 70/30 Brass
Authors: Murakami Y , Makabe C , Nisitani H
Published: February 2009

The loss of fracture ductility after strain cycling in low cycle fatigue tests is not due to so-called weakening or losing of the strength quality caused by irreversible slips in crystals but rather is attributable to the existence of small surface cracks. The degree of loss of fracture ductility depends on the crack length ℓ. If ℓ is larger than the critical length ℓc, the fatigue crack causes macroscopic shear fracture in the tensile test after strain cycling. On the other hand, if ℓ < ℓc the fracture surface becomes the so-called cup-and-cone type. For 70/30 brass, ℓc ≅ 400 µm.
Fatigue Crack Propagation Threshold
Authors: Marci G , Castro DE , Bachmann V
Published: February 2009

Service-type fatigue loading conditions are critically analyzed with respect to their relevance for a fatigue crack growth threshold. It was found that a threshold should be experimentally determined as a function of the monotonic-plastic zone size (i.e., as a function of Kmax). For each Kmax the cyclic-plastic zone size depends on the applied ΔK and threshold testing should cover the range ΔK ≈ ΔKth and ΔK (R = 0) for tension fatigue. For a given plastic zone, Kmax and ΔK fixed, the threshold ΔKth could occur anywhere between Kmax and Kmin. This study presents experimental procedures and furnishes results for Inconel 617 and a Ti-6A1-4V alloy which allow one to analyze the influence of the three parameters cited above. It demonstrates the following:

• The threshold decreases “linearly” with increasing monotonic-plastic zone size; this confirms existing data.

• The cyclic-plastic zone has minimal influence on the fatigue threshold with Ti-6A1-4V, while this influence is substantial in the case of Inconel 617.

• A shift of threshold between Kmax and Kmin does not alter the magnitude of the threshold.
A Model to Predict the Sources and Magnitude of Scatter in Toughness Data in the Transition Region
Authors: Anderson TL , Stienstra D
Published: February 2009

Scatter in cleavage fracture toughness data is analyzed with a statistical model. This model indicates that when a material fails by weakest-link cleavage under J-controlled conditions, the corresponding fracture toughness data will follow a two-parameter Weibull distribution with a characteristic slope. This slope is 2.0 for critical J-integral and crack tip opening displacement (CTOD) data, and 4.0 for critical stress intensity values. Published experimental data for a wide range of materials verify these slopes.

The discovery of an invariant Weibull slope that is the same for all materials has important practical implications. For example, it is now possible to predict the relative magnitude of toughness scatter prior to testing. It is also possible to extract useful information from small data sets. The authors demonstrate these applications with sample calculations. A number of additional analyses are presented, including evaluations of the effects of thickness and local brittle zones on toughness. Also, a methodology is presented which allows one to predict fracture toughness distributions when specimens belonging to multiple populations are tested. This latter analysis can be used to assess the effect of experimental error.

The analyses in this article are not valid when cleavage fracture is preceded by large-scale plasticity or stable crack growth. In such cases, the crack tip stresses are lower than predicted by J-integral theory. This causes the Weibull slope to decrease from its theoretical value. Current research is aimed at predicting fracture toughness distributions for large-scale yielding conditions.
Linear-Elastic Fracture of High-Nitrogen Austenitic Stainless Steels at Liquid Helium Temperature
Authors: Tobler RL , Reed RP , Purtscher PT
Published: February 2009

Four commercial Fe-Cr-Ni-Mn austenitic stainless steels containing 0.14, 0.26, 0.28, and 0.37 wt% N were fractured in liquid helium at 4 K, and measurements of the linear-elastic plane-strain stress-intensity factor, KIc, were made. Interstitial nitrogen significantly strengthens these steels at low temperatures so that brittle fractures occur under plane strain conditions at 4 K despite moderate ductility in uniaxial tension. The brittle fracture mechanism at 4 K involves a form of cleavage or slip-band cracking as evidenced by the formation of transgranular facets on {111} planes.
Creep Rupture Behavior of Precorroded Carbon Steel
Authors: Ragab AR , Alawi H , Sorein K
Published: February 2009

Creep rupture tests have been conducted on specimens of AISI 1018 low carbon steel pre-exposed to various environments: polluted seawater, natural seawater, industrial seashore tide, drinking tap water, and industrial air. Exposure to increasingly corrosive environments before creep testing results in decreasing creep strength by appreciable amounts. With suitable extrapolation procedures, creep rupture test data may be cautiously used to generate design creep curves involving service temperature, stress, and life for precorroded steel. Further experiments are needed to investigate the combined effect of corrosion and creep on rupture life over a wider range of environmental test parameters.
Specimen Geometry Effects on the Strength of Unidirectional Resin-Matrix Composites
Authors: Loveless HS
Published: February 2009

This paper describes some of the problems encountered in determining the tensile and flexural strengths of uniaxially aligned glass fiber-resin composites by conventional methods, and suggests alternative procedures for overcoming them. Special emphasis is placed on the effects of test specimen geometry with respect to these properties and equations are developed for the stress-strain properties of half-round, pultruded rods subjected to ordinary bending, assuming elastic behavior.

In addition, measurements carried out on flat, unidirectional moldings are described, which show a linear relationship between the tensile and flexural strengths of these composite materials.
Interlaboratory Evaluation of KIscc and da/dt Determination Procedures for High-Strength Steels
Authors: Wei RP , Novak SR
Published: February 2009

This report is prepared on behalf of ASTM Joint Task Group E24.04.02/G01.06.04 on Test Methods for Measurement of KIscc and SCC Growth Rate. It summarizes and provides an assessment of the results from an interlaboratory program to evaluate the procedures, based on linear fracture mechanics, for determining the threshold stress intensity factor for stress corrosion cracking (KIscc) of high-strength steels and the crack growth rates (da/dt). Problem areas and additional work are identified.
Effects of Temperature on the Fracture Toughness of Carburizing Steels for High-Temperature Applications
Authors: Cutler RA , Leslie WC
Published: February 2009

The fracture toughness of steels with good retention of hardness at elevated temperatures (CarTech EX00053, Timken CBS 600 and 1000M, and Vasco X-2M) was compared with that of conventional carburizing steels (EX55, AISI 4820, 8620, and 9315). The short-rod method was used to determine short rod/short bar fracture toughness KIcSR between 22 and 400°C. Wide variations in fracture toughness were observed over this temperature range. The toughness of EX00053 and CBS 1000M increased sharply between 22 and 100°C with the former having the highest toughness of any of the steels studied.
Review of the Effects of Fatigue Cracking Loads on Plane Strain Fracture Toughness
Authors: Towers OL
Published: February 2009

Plane strain fracture toughness for Mode I loading KIc testing standards impose restrictions on the loads used to prepare the fatigue cracks because experiments have shown that if the loads are too high the resulting toughness measurement might be unconservative. Data displaying the effects of fatigue cracking load level on KQ measurements (“candidate” KIc values) have been reviewed and compared to restrictions imposed by two relevant standards on fatigue cracking load level and on the R ratio (KFmin/KFmax). For the majority of the materials studied these restrictions are sufficiently stringent, but for some materials that display a particular tendency to cyclically soften it may be necessary to increase their severity to the maximum value of stress intensity factor in fatigue KFmax ≯ 0.5 KQ. The basis of the restrictions on R ratio of the two standards is unknown, but relaxation of the limit (≯ 0.1) is difficult to recommend because of lack of relevant data.
Cyclic Stress-Strain and Fatigue Properties of Sheet Steel as Affected by Load Spectra
Authors: Martin JF
Published: February 2009

Axial strain controlled fatigue tests were performed without buckling on thin 1.78-mm (0.070-in.) thick hourglass profile sheet steel specimens. Cyclic strain amplitudes up to ±0.015 were obtained. Material properties for cyclic 1stress-strain behavior varied considerably when obtained by using three different procedures. For fatigue resistance, an initial cyclic overstrain did not appreciably affect fatigue life; however, periodic cyclic overstraining did have a noticeable effect.
Fracture Mechanics Analysis of the Effects of Residual Stress on Fatigue Life
Authors: Throop JF
Published: February 2009

In this paper it is reemphasized that the effect of residual stress in fatigue is analogous to but not the same as the mean stress effect from applied loads. By including a residual stress term in the stress intensity factor range of the fatigue crack propagation rate equation, one is permitted to include the residual stress in calculations of fatigue life estimates. Using crack shape factors calculated for given aspect ratios of surface flaws and integrating the fatigue crack growth rate da/dN, one obtains an equation for the applied stress-cycles to failure S-N curve that includes the residual stress effect on fatigue performance. In this process of calculation that fact that compressive residual stress has a much stronger influence on fatigue life than tensile residual stress is revealed, mainly because the former decreases the stress intensity factor range and increases the critical crack size while the latter only decreases the critical crack size. A numerical solution of an example illustrates an application of these concepts.
Precision of Early Shrinkage Measurements
Authors: Kass JL , Campbell-Allen D
Published: February 2009

A method has been developed for the determination of early shrinkage measurements of higher accuracy than previously attained. Its basis has been a consideration of thermal effects previously disregarded. Experiments have been devised in which movements due to thermal effects and drying shrinkage can be analyzed separately. Thus early drying shrinkage values can be determined without thermal shrinkage interference.
Fatigue-Crack Growth in Type 304 Stainless Steel Weldments at Elevated Temperatures
Authors: James LA
Published: February 2009

The propagation of fatigue cracks in gas-tungsten-arc weldments of Type 304 stainless steel was studied at 75 (24) and 1000 F (538 C). It was found that the crack growth rate for cracks propagating normal to the direction of welding decreased as the crack approached the weld, and then increased as the crack grew through the weld and out the other side. It is postulated that this is due to the residual stresses produced during the welding process, and that metallurgical variations in the weldment play a minor role.
Cyclic Stress, Strain, and Energy Variations under Cumulative Damage Tests in Low-Cycle Fatigue
Authors: Bui-Quoc T
Published: February 2009

Cumulative fatigue damage tests have been carried out on two pressure vessel steels at room temperature with five increasing or decreasing levels of stresses or strains. Variations of stress, strain, and energy are discussed. In the low-cycle region, the behavior of the materials is relatively more stable under strain-controlled than under stress-controlled tests. The total plastic energy at failure is dependent upon the strain range and not upon the strain ratio. A relation is suggested for estimating the plastic energy required for fatigue failure under cumulative damage tests. On a basis of absorbed plastic energy, both materials investigated have the same fatigue resistance at about 10,000 cycles at failure.
Evaluation of Creep Rupture Behavior of 1Cr-1Mo-0.25V Steel with 0.04 wt% Sn
Authors: Bashu SA , Singh K , Chowdary KM
Published: February 2009

Results of creep rupture testing of a commercial quality 1Cr-1Mo-0.25V steel forging with 0.04 wt% Sn at 500, 550, and 600°C over a range of stresses for periods varying from about 4600 to 27 000 h have been reported. Rupture lives were found to be higher and rupture ductilities to be lower than data available in the literature for a similar steel. Auger electron spectroscopic analysis of specimens creep tested at 500 and 550°C for 25 692 h and 27 203 h, respectively, revealed no perceptible segregation of Sn to grain boundaries. Thus Sn (0.04 wt%) does not appear to be responsible for the lower rupture ductilities observed in this investigation. Selected area electron diffraction of carbides extracted by carbon extraction replicas from interrupted creep specimens, currently in progress, may possibly explain the observed anomalies in the creep behavior.
X-Ray Residual Stress Measurements in Notched Test Specimens
Authors: Dowling NE , Hendricks RW , Ranganathan K
Published: February 2009

X-ray residual stress measurements were made in notched test specimens of 7475-T651 aluminum and annealed Ti-6Al-4V in a configuration designed to simulate fatigue testing in a tensile testing machine. An automated and portable X-ray stress analysis system with a position-sensitive proportional counter was used for making the measurements. Sources of error in the measurements resulted from counting statistics, grain size, and preferred orientation in the specimen, and the radius of curvature of the notch. The feasibility of in situ residual stress measurements during brief pauses in fatigue testing is demonstrated.
Strain-Hardening Characteristics of Aluminum-1050A, α-(70/30) Brass, and Austenitic Stainless Steel under Biaxial Loading
Authors: Makinde A , Ferron G
Published: February 2009

The biaxial strain-hardening behaviors of aluminum, α-brass, and austenitic stainless steel are characterized in plane and equibiaxial deformation paths using a novel low-cost biaxial device. These tests are complemented by conventional uniaxial tensile tests and by complex strain path studies consisting of uniaxial tension after biaxial pre-strain. The experimental results are analyzed and compared using two criteria of plasticity: von Mises and Hill. It is shown that different stress-strain curves obtained under different strain paths could not be correlated with the phenomenological yield criteria.
Evaluation Procedure for Low Cycle Fatigue Data
Authors: Foss SK
Published: February 2009

An evaluation procedure for low cycle fatigue data is described that uses engineering judgement as a primary evaluation tool, coupled with a computer and statistics. The procedure is suitable for micro or main-frame computers and can be used by technical personnel. Advantages of this procedure are speed, ease of use, and the ability to maintain automatically the integrity of all necessary equations and yield fatigue properties that can be employed in actual life predictions. The mathematical model used within the procedure is an extension of the S-log N curve and accounts for plastic strain which causes fatigue damage. This model, however, applies only to wrought metals, where internal defects do not govern fatigue life.
Effects of Testing Variables on Damping and Stiffness of Nailed Wood-to-Sheathing Joints
Authors: Polensek A
Published: February 2009

Specifications for experimental evaluation of nail-joint properties under dynamic and pseudodynamic loading are lacking. Because testing conditions affect joint properties, nailed joints between wood and plywood and between wood and gypsum wallboard were tested to determine the effect of the following factors on experimental damping and stiffness: specimen assembly technique, magnitude and rate of loading, and assumption of linear behavior in evaluating slip work. Nailing techniques controlled friction between contact surfaces, which in turn controlled damping and stiffness. Increasing loading rate increased damping and stiffness, but increasing load magnitude diminished both properties. Damping ratios were significantly lower when evaluation of equivalent viscous damping was based on linear, rather than nonlinear, behavior. Standard testing techniques are needed to achieve uniformity in dynamic testing of mechanically connected joints between structural wood materials.
Additives for Bitumen in Road Construction
Authors: Jain JP , Gupta AK , Khanna SK , Jain SS
Published: February 2009

In India most all-weather roads have bituminous surfaces. Properties of bitumen depend upon its source and manufacturing process. Bituminous surfaces sometimes fail prematurely, however, the most common causes are the effect of water and variation in temperature.

In this paper an attempt has been made to document the effects of some additives on conventional properties of bitumen. These properties are penetration value, softening point, ductility, and stripping value. The additives are derived from plants. Various tests have been conducted on a mixture of 80/100 grade bitumen and different types and percentages of additives.

A detailed investigation has been carried out on five additives which have been code-named A, G, S, T, and W. The test results indicate a definite trend in the variation of the conventional physical properties of bitumen for Additives A, G, and W and a spectrum of values with finite variation in the conventional properties for Additives S and T.
Comparison of Compliance Results for the Wedge-Loaded Compact Specimen
Authors: Underwood JH , Newman JC
Published: February 2009

Results of the ratio of stress intensity factor to crack-mouth displacement as a function of crack length are presented for the wedge-loaded compact specimen. Comparisons are made between experimental compliance results, numerical results from collocation methods, and deep-crack limit-solution results. Applications are for crack-arrest and stress-corrosion-cracking tests for metals and other materials under predominantly linear elastic conditions.
Fatigue Threshold Regime of a Low Alloy Ferritic Steel under Closure-Free Testing Conditions: Part II—Hysteresis in Near-Threshold Fatigue Crack Propagation: An Experimental Assessment
Authors: Vaidya WV
Published: February 2009

Near-threshold fatigue crack propagation behavior of a high strength steel was investigated in laboratory air under closurefrec testing conditions at R = 0.7 (= Rcff) and at two different K-gradients. Depending on the criterion assumed, the threshold value differed; the criterion of non-propagation gave a lower threshold value than that assumed by the propagation criterion. Nevertheless. the subsequent propagation following a load increase was discontinuous in both cases, and da/dN versus ΔK curves obtained on the some specimen during the K-decreasing and the K-increasing test were not necessarily identical in the threshold regime. This behavior, hysteresis, is analyzed mainly from the experimental viewpoint, and it is shown that hysteresis is not an artifact.
Fatigue Behavior of (BS 1470 N8-0) Aluminum Alloy and (BS 1501–510) Nickel Steel Double-Fillet and Tee-Butt Welds (Subject to Bending)
Authors: White GC
Published: February 2009

The shell to base welds of liquefied natural gas (LNG) tanks are normally double fillet welds, although in some tanks teebutt welds are used. The fatigue behavior of these welds has been examined by testing 134 full-size specimens. The testing examined the low cycle, high strain performance of the welds in air at +20°C and in liquid nitrogen at −196°C. The results from this work have shown that double fillet weld and tee-butt weld fatigue performance are comparable. The low temperature fatigue performance matched or exceeded that under equivalent ambient conditions. The shell to bottom welds used in British Gas LNG tanks have fatigue lives well in excess of that required for operational duty.
An Experimental Research Program on the Behavior of Stone Masonry Structures
Authors: Chiostrini S , Vignoli A
Published: February 2009

A program of experimental research on the seismic behavior of full-scale masonry specimens is discussed. The main part of this program was developed at the Department of Civil Engineering as part of the C.N.R.-G.N.D.T. (National Council of Researches, National Group for Earthquake Defense)-Subproject 2: Preveation of Building Damages-Working Group 2.2: Experimental Evaluation of the Seismic Behaviour of Structures coordinated research program.

The main objective of this project is to investigate the seismic behavior of commonly used stone masonry constructions in the Florence area. Laboratory and in situ tests were performed in order to assess the mechanical characteristics of stone masonry and its strength under shear forces. This paper presents the setup and results of laboratory diagonal tests of full-scale stone masonry specimens, in situ destructive shear tests, and in situ testing of masonry walls using the flat-jack technique.
Laboratory Study of Microtexture-Related Skid Resistance Characteristics of Concrete Pavement Materials
Authors: Fwa TF , Tan CC
Published: February 2009

This paper reports the results of a laboratory test program conducted to study the variations of microtexture-related skid resistance of concrete materials with moisture condition, measurement temperature, and surface polishing. The materials used for concrete pavement construction in Singapore were studied. Surface wetting was found to produce a surface-wet frictional resistance considerably lower than the initial surface-dry value. However, neither the surface-wet nor surface-dry measurement was affected by the degree of moisture saturation of the materials tested. Surface temperature had a strong influence on the results of surface-wet tests, but not the surface-dry tests. The temperature-dependent variations was highly correlated to either measurement temperature or viscosity of water, always showing a coefficient of correlation exceeding 0.94 in absolute value. Polishing had the effect of reducing both surface-wet and surface-dry resistance. However, cement mortar specimens were found to respond differently from granite and steel slag aggregates due to differences of their surface wear behaviors in the process of polishing.
Use of Pneumatically Driven Staples in the Practice of Orthopaedic Surgery
Authors: Shapiro JS , Walt MJ
Published: February 2009

In 1981, the concept was delineated of driving staples “in a guided fashion with a rapid and reproducible power source” for fixation in orthopaedic surgery. This transformed an inefficient fixator into an efficient one and secondarily allowed its use in many unique applications for fixation of bone to bone, ligament to bone, and cartilage to bone. From first clinical usage in 1983, it has been used in an estimated 40 000 cases worldwide. Fixation has been for solitary, supplemental, and/or temperary applications in metaphyseal bone for such diverse applications as fusions, osteotomies, fractures, and ligament attachment. The system has been tested and improvements in fixation were demonstrated in laboratory and in vitro studies. The rectangular, rough surfaced, titanium staples were designed for pneumatic insertion to bone and have found use in specific applications as well as a ubiquitous backtable instrument. A learning curve exists for proper usage.
Fracture Testing Wood Adhesives with Composite Cantilever Beams
Authors: Scott CT , River BH , Koutsky JA
Published: February 2009

A new approach to evaluating wood-adhesive joints is being used by the Wood Adhesives Science and Technology Research Work Unit at the Forest Products Laboratory. This test involves the measurement of adhesive fracture toughness in Mode I cleavage. It is an extension of the contoured double cantilever beam (CDCB) test developed by Mostovoy and others [1] and generally follows the procedures outlined in ASTM D 3433 [2]. Samples are prepared by bonding thin wood laminates to contoured aluminum beams. The addition of a laminate to the aluminum adherends significantly reduces the change in linear compliance with crack surface area (dC/da) of the composite, thereby influencing the calculation of fracture toughness. This effect is established both experimentally and theoretically.
High Temperature Tube Burst Test Apparatus
Authors: Shelleman DL , Jadaan OM , Butt DP , Tressler RE , Hellmann JR , Mecholsky JJ
Published: February 2009

The design and construction of a high temperature tube burst test apparatus is described. The apparatus consists of an internally heated ceramic tube specimen, internal O-ring pressure seals, water-cooled end caps, steel end plates, and an explosion-resistant steel test chamber. The ceramic tube specimen floats freely on the internal O-ring seal, thus avoiding axial stresses due to end constraints and/or axial thermal expansion. The apparatus is capable of obtaining test temperatures up to 1400°C, pressures to 68.9 MPa (10 000 psi), and capturing tube fragments in a “witness shield” for fractographic analysis. The use of the apparatus is demonstrated by relating strengths measured for 660 mm (26 in.) long by 44 mm (1.75 in.) diameter SiC tubes to the strength distribution of O-ring and C-ring specimens tested at 1200°C using Weibull statistics to scale the specimen sizes. Advantages and disadvantages of the tube burst test apparatus are discussed.
An Evaluation of Strain Measuring Devices for Ceramic Composites
Authors: Gyekenyesi JZ , Bartolotta PA
Published: February 2009

A series of tensile tests were conducted on SiC RBSN composites using different methods of strain measurement. The tests were used to find the optimum strain sensing device for use with continuous fiber reinforced ceramic matrix composites in ambient and high temperature environments. Bonded resistance strain gages were found to offer excellent performance for room temperature tests. The clip-on gage offers the same performance but significantly less time is required for mounting it to the specimen. Low contact force extensometers track the strain with acceptable results at high specimen temperatures. Silicon carbide rods with knife edges are preferred. The edges must be kept sharp. The strain measuring devices should be mounted on the flat side of the specimen. This is in contrast to mounting on the rough thickness side.
Compression of Single-Wall Corrugated Shipping Containers Using Fixed and Floating Test Platens
Authors: Singh SP , Burgess G , Langlois M
Published: February 2009

The compression strengths of five different RSC style corrugated fiberboard containers were obtained using both fised and floating compression test platens in order to determine the effect of the platen on the results. The difference between the compression strength using fixed and floating platen methods was found to be small compared to the normal variation in compression strength between identical boxes. It is concluded that either test method is suitable.
Young's Modulus of a Dispersion Strengthened Al-Fe-V-Si Alloy
Authors: Srinivasan MN , Wolfenden A , Little S , Sridhara S
Published: February 2009

Young's modulus for a dispersion strengthened Al-Fe-V-Si (FVS 1212) alloy has been measured using PUCOT (Piezoelectric Ultrasonic Composite Oscillator Technique), after melt spinning the alloy under different combinations of nozzle size, wheel speed and power input. It is found that the interactions among the three variables exert a strong influence of the Young's modulus. Young's modulus measurements using PUCOT were also made on melt spun ribbons of three other aluminum alloys. Electron diffraction patterns of the ribbon specimens suggest that crystalline structures lead to promote higher modulus in all the aluminum alloys examined.
Monitoring Fatigue Crack Propagation in Compact Tension Specimens via Remote Sensing of Back Face Strain
Authors: Simha KRY , Hande HSS , Arora PR
Published: February 2009

Back face strain (BFS) measurement is now well-established as an indirect technique to monitor crack length in compact tension (CT) fracture specimens [1,2]. Previous work [2] developed empirical relations between fatigue crack propagation (FCP) parameters. BFS, and number of cycles for CT specimens subjected to constant amplitude fatigue loading. These predictions are experimentally validated in terms of the variations of mean values of BFS and load as a function of crack length. Another issue raised by this study concerns the validity of assigning fixed values for the Paris parameters C and n to describe FCP in realistic materials.
Calculation for Rolling Contact Fatigue Life and Strength of Case-Hardened Gear Materials by Computer
Authors: Jiang B , Zheng X , Wang M
Published: February 2009

An analysis of the rolling contact tatigue process of case-hardened gear material by means of clasticity and fracture mechanics theory has been made: the stress intensity range Δk and equation for crack growth da/dN = c(Δk)″ was put forward to calculate their fatigue life and strength in this work. The results show that the calculated data are in good agreement with the experimental ones for compound-treated, sprayed, and carbonitrided specimens. The relative errors of logarithm of cycle number are all less than 5′
Up-and-Down Methodology Applied to Statistically Planned Experiments
Authors: Little RE , Thomas JJ
Published: February 2009

Twenty-four modified small sample up-and-down tests were conducted to estimate the median endurance limits of unplated and cadmium-plated ½-13NC 2A machine screws of SAE Grades 2, 5, and 8, each fastened using standard geometry SAE Grade 2 zincplated nuts or Ranged SAE Grade 8 nuts (termed toolmarker's nuts). The test program was a split-plot experimental design with six mainplots (three grades of machine screws, each unplated or cadmium-plated) and two split-plots (nut-type) within each main-plot. This test program was repeated to form two time-blocks, each time-block involving twelve modified small sample up-and-down fatigue test sequences conducted under test conditions that were as uniform as practical. Based on prior test data, the effect of the split-plot factor, nut-type, was of primary interest in this study. Two statistical analyses are discussed herein: the standard (parametrie), analysis of variance and an alternative nonparametric analysis. Recommendations are made on how to conduct similar multifactor test programs involving up-and-down test sequences to estimate the median endurance limits of interest.
More Rapid Edgewise Crush Test Methods
Authors: Urbanik TJ , Catlin AH , Friedman DR , Lund RC
Published: February 2009

The use of paraffin wax to reinforce the loading edges of corrugated fiberboard edge-crush specimens requires that the specimens be reconditioned after waxing. The traditional practice employing a 24-h reconditioning period is a conservative approach based on the moisture response rate of corrugated containers. An interlaboratory study was conducted to determine the effect of reconditioning time on edgewise compressive strength of waxed specimen prepared by standard test methods. Results showed that reconditioning time can be reduced from 24 h to 2 h wish no significant change in test values. The results apply to flexible-beam and rigidplaten loading machines, but at conventional loading speeds, the flexible-beam machine yielded higher overall streagth values. Other tests were conducted to evaluate the performance of an edge-clamping fixture for use with unwaxed specimens. When tested with heavy basis weight materials, the fixture did not yield equivalent results compared to those obtained with lighter grade waxed apecimens.
Asbestos-Free Gasket Materials for Turbines
Authors: Jones WF , Seth BB
Published: February 2009

The results of a systematic program undertaken to evaluate potential substitute materials for asbestoe-free gaskets used in power plant turbines are reviewed. Thirty-three commercially available materials were subjected to a series of tests reflecting the requirements of a good gasket material for turbine applications. The results identified flexible graphite as the only material to meet or exceed the properties of asbestos gaskets. One limitation of flexible graphite uncovered in the program, however, is its relatively high stress relaxation behavior especially at temperatures above 650°F (343°C). Ten-thousand-hour stress relaxation tests were conducted in the temperature range of 500 to 850°F (260 to 454°C) to determine the usable temperature limit of flexible graphite. The effects of joint flexibility and reloading were also evaluated at high temperatures.
Fatigue and Corrosion Fatigue of Beryllium-Copper Spring Materials
Authors: Bagheri R , Miller GA
Published: February 2009

Fine gage, 0.006-in. (0.15-mm) thick, beryllium-copper (Be-Cu) spring materials with tensile strength in the range of 70 to 145 ksi (482 to 999 MPa) were subjected to cyclic loading in air and salt water environments. Plain and notched (center hole) “hour glass” specimens were subjected to sinusoidal loading with R = (minimum maximum) stress = 0.1 at cyclic frequencies of 50 Hz in air and 1 Hz in salt water. Fatigue life was typically from 104 to 106 cycles with crack initiation as the dominant fatigue process.

The excellence fatigue performance of Be-Cu alloys in salt water is well-known, however, current findings demonstrate 10 to 37% reduction in fatigue strength of unnotched specimens in this environment for a life of 3 × 105 cycles. This strength degradation is attributed to the use of a lower cyclic frequency for present than for previous tests, i.e., 1 versus about 20 Hz. There was no effect of salt water on crack initiation in notched specimens.

The ratios of the fatigue strengths, namely (cold-rolled annealed) and (aged/annealed), for plain and notched specimens tested in air, decreased from 2 to about 1.4 as fatigue life increased from 104 to 106 cycles. This effect is attributed to cyclic hardening of the annealed material. The fatigue stress concentration factor, Kt = (plain notched) fatigue strength, increased by about 30% as fatigue cycles increased from 104 to 106. The ranking of Kf values of the various material conditions from highest to lowest was: cold-rolled, aged, and annealed.
Minimization and Quantification of Error Associated with theKGradient and the Interval of Crack Length Measurement in Fatigue Crack Growth Testing
Authors: Oore M
Published: February 2009

Analytical method has been developed to minimize and quantify the effect of crack length measurement interval Δa on the error due to the K gradient in the interpretation of da dN derived from crack growth test data using the secant method. The associated error has been quantified in a general form and used to demonstrate the specific errors due to the selection of average crack length a per ASTM E 647-91. Test Method for Measurements of Fatigue Crack Growth Rates. It is shown that the selection of the geometric mean (a¯=a1a2) in the data analysis will reduce the associated error in the crack growth rate interpretation. It is recommended that ASTM E 647-91 be revised accordingly.
Effect of Internal Gas Pressure on the Compression Strength of Beverage Cans and Plastic Bottles
Authors: Singh SP , Burgess G
Published: February 2009

This study investigated the compression strength of various sized polyethylene terephthalate (PET) bottles and steel and aluminum two-piece cans. Compression tests were performed on both empty and filled containers under pressure. A stress analysis is developed to provide a simple prediction formula. The predictions are shown to be in fair agreement with actual values obtained from the compression tests. The results show that internal pressure can increase the compression strength of a beverage package by as much as three times. Erratum to this paper appears in 21(4).
The Gel Electrode Revisited: Fatigue Crack Detection with a Polymer Film
Authors: Baxter WJ
Published: February 2009

The gel electrode provides a very seasitive technique for detecting and imaging fatigue cracks in metals. In the past, its utility has been restricted by the requirement that, prior to the formation of a crack, the metal surface must be associated to form a thin insulating film. This film is ruptured as a crack forms, so that an impressed current from a gel electrode flows preferentially to the crack and forms an image. In this study, the anodic film has been replaced by a cathodically deposited polymer film. This film is much easier to apply, is applicable to any metal, and can be applied either before or after crack formation. If applied prior to fatigue loading. it is ruptured in the same manner as an anodic film, but it provides much better insulation, so that freshly formed cracks can now be detected in materials such as cast irons. If applied after fatigue loading, the film does not cover up the previously formed cracks so that the gel electrode current still flows preferentially to the crack. Both sequences of application are illustrated by images of fatigue cracks in low-carbon steel, nodular iron, and austempered ductile iron. The only difficulty experienced has been with previously formed cracks held tightly closed by retained compressive stresses. Otherwise, this combination of a polymer film and the gel electrode will detect cracks as small as 0.3 mm in length.
Infrared Technique as a Research Tool for Measuring Water Vapor Transmission of Roofing Membranes
Authors: Dutt O , Lavallée C , Ashton HE
Published: February 2009

Measurements of the permeability to water vapor of materials intended to prevent its transmission are time-consuming with the usual cup method [1]. Several instruments have been promoted as being capable of providing results rapidly, but doubts about their agreement with cup measurements have delaved their use for more than quality control.

One instrument with an infrared sensor was studied to investigate its accuracy and to correlate results obtained with the standard cup methods. Factors studied include those that contribute to the inconsistent performance of the instrument, especially for research work Techniques for improving the precision and the accuracy of the instrument are discussed. The permeances of roofing papers and telts and of plastic films by both the modified IR instrument and the cup methods are reported and compared to values given in the literature.
A Detection Method of Fatigue Crack Initiation by Analyzing Strain Waveform
Authors: Makabe C , Nishida S , Kaneshiro H
Published: February 2009

A detection method of fatigue crack initiation at some weak section of machine equipment during operation is examined using a partial-notched specimen. The waveform of the strain function composed of strains in the vicinity of the partial notch was observed successionally. It is found that such strain waveform changes its figure at the time when the crack length is 1 mm, due to the crack closure behavior. Therefore, in this experiment, the crack initiation could be detected when the crack length is about 1 mm. Since the engineering crack initiation size is frequently taken to be 1 mm, the present method of detecting crack initiation can be applied to real machine equipment. Also, this waveform was analyzed with FFT (Fast Fourier Transformation). Power spectrum density of the waveform varies immediately after the crack length reaches 1 mm. Furthermore, the figure of the coherence of two waveforms composed of the same strains clearly varies at the same crack length of 1 mm. Thus, it is thought that the engineering size crack initiation can be detected by the analysis of the strain waveform.
Some Microstructural Conditions for Evaluating Fracture Toughness and R-Curve Behavior in Platelet-Reinforced Composites
Authors: Pezzotti G , Niihara K , Nishida T
Published: February 2009

The validity of Kk determinations by various techniques usually employed and compared with each other is discussed in detail for two ceramic materials. They are a simple Si9N4 material fracturing with transgranular crack propagation and a Si9N4-25vol% SiC-platelet measured by four different methods: single-edge V-notched beam (SEVNB), single-edge precracked beam (SEPS), indentation fracture (IF), and chevron-notched beam (CNB). It is generally recognized that, in platelet composites, Kk values can be reliability obtained only by procedures adopting notched specimens in which the wake-zone of precracking is mechanically removed (SEVNB or renotched SEPB). In the present investigation the CNB method, in which the wake contribution to fracture resistance is generally small but not negligible, was also found to give stress-intensity factors at maximum load whose value was almost coincident with the KIc determined by SEVNB method. Using stereological concepts, fractographic observations, and acoustic emission (AE) experiments, the microstructural conditions for negligible wake-contribution during the subcritical stable crack extension in the CNB experiment were worked out and applied to rationalize the behavior of the present composite. Apparent toughness values markedly higher than the “true” Kk of the composite were measured both by the standard SEPB and IF method. Such a discrepancy is considered due, in the former case, mainly to traction forces between the precracked surfaces while, in the latter, to an insufficient account of the residual stress field associated with the indentation.
Metallized Microballoon Filled Composite EMI Shielding Materials
Authors: Radford DW , Cheng BC
Published: February 2009

The need for lightweight, formable materials that can conduct elasticity and shield against electromagnetic interference (EMI) is widespread. Applications ranging from modeled cases for terrestrial electronics to shielding systems for metallize can benefit from such tailorable, lightweight conductive materials. This paper explores the possibility of creating a new family of ultra-lightweight conductive shield materials using metallized microballoons as a conductive filler material. The conductive costings investigated include gold, silver, and aluminum on ceramic microballoons in an epoxy matrix. Factors influencing the electrical conductivity are discussed, and the shielding performance is tested using X-band microwave transmission measurements and anechoic shielding effectiveness testing. Variables available that have the potential to allow application specific tailoring of the shielding material are described. Initial findings are discussed and performance is related to the microballoon volume fraction and costing materials. Results indicate that shield densities significantly below 1.0 g/cm2 are possible, with electrical surface resistivities approaching these of common metals.
Lifetime Predictions of uPVC Pipes from Short Time Tests
Authors: Seldén R , Gradin PA
Published: February 2009

Fracture mechanics tests according to British Standard 3505 have been made on two unplasticized polyvinyl chloride (uPVC) pressure pipes. The applied load was varied and time to failure was measured as a function of load. The results were fitted to an empirical power law, using the concepts of linear elastic fracture mechanics, relating crack growth rate, v, to the stress intensity factor, K1, according to v = A K∞1, where , where A and α are α constants. The parameters A and α were then applied to uPVC pipes provided with assumed Flaws of different sizes and shapes, and lifetime was calculated as a function of internal pressure.

Close agreement with published ductile failure data of uPVC pipes were obtained for elongated, axial flaws on the inside wall, between 0.8 and 1.0 mm in size.