bluuebunny/crossref_metadata_2025 huggingface dataset:
J-Integral Estimates for Strain Hardening Materials in Antiplane Shear Using Fully Plastic Solution
Authors: Shih CF
Published: March 2009

General procedures are proposed which utilize the elastic and the fully plastic solutions to interpolate behavior from the small-scale yielding range to the fully plastic range. The relations between the J-integral, load point displacement, crack opening displacement, and the applied load thus developed, are applicable to test configurations and cracked bodies in general. To assess the accuracy of the estimated relationships, a detailed numerical investigation, which employs an accurate finite element approach, is carried out for a particular configuration under antiplane shear. The results obtained from the full numerical calculations, for values of the applied load well into the fully plastic range, are in excellent agreement with the estimated results.
Fatigue Crack Growth During Gross Plasticity and the J-Integral
Authors: Dowling NE , Begley JA
Published: March 2009

An attempt is made to apply the J-integral concept as an elastic-plastic criterion for fatigue crack growth. Compact tension fracture specimens of A533B steel are subjected to gross cyclic plastic deformations, and fatigue crack growth rates up to 0.01 in./cycle are obtained. The results show correlation with J-integral values estimated from load versus deflection hysteresis loops. Also, agreement is obtained with the extrapolation of linear elastic fatigue crack growth rate data.
Investigation of R-Curve Using Comparative Tests with Center-Cracked-Tension and Crack-Line-Wedge-Loaded Specimens
Authors: Wang DY , McCabe DE
Published: March 2009

This paper provides a comparison of the crack-line-wedge-loaded (CLWL) and center-cracked-tension (CCT) test methods for determining R-curves on a number of high-strength aluminum sheet alloys. In general, R-curves were reasonably close, differing only by amounts which could be explained by differences in testing procedure and in crack driving force curve. Gross stress, Kc, and crack length at instability were predicted satisfactorily for CCT panels from CLWL R-curves. The test results for CCT specimens show that consistent Kc values are obtainable from specimens of various widths provided that the net-section stress at failure is below general yielding.
Ductility, Fracture Resistance, and R-Curves
Authors: Weiss V , Sengupta M
Published: March 2009

A method for analytical predictions of the thickness effect on fracture toughness, and of R-curves is presented. It is based on the recent observation that the fracture resistance KR is proportional to the local fracture strain εF,αβ, where α = σ2/σ1, and β = σ3/σ1 characterize the local stress state. As this stress state varies from the surface, where it is plane stress (α = 0, β = 0.61), to the center, where it approaches plane strain (α = 0.81, β = 0.61) for sufficiently thick specimens, the local fracture resistance varies correspondingly. The model proposed here assumes that the measured fracture resistance represents the average of the local GR values along the crack front. The calculated thickness effect is in excellent agreement with experimental results. From the same model an analytical expression for R-curves is suggested with the additional consideration of the relation between the plastic zone size as a function of crack growth. The preliminary results of the predicted R-curves are in reasonable agreement with the experimental curves.
Resistance to Plane-Stress Fracture (R-Curve Behavior) of A572 Structural Steel
Authors: Novak SR
Published: March 2009

The R-curve behavior of A572 Grade 50 steel was established over the temperature range-40 to +72°F by using state-of-the-art procedures. Both linear-elastic-fracture-mechanics (LEFM) and crack-opening-stretch (COS) analytical techniques were used in assessing experimental results obtained under load-control and displacement-control testing conditions. This study represents a pioneer effort in that it is the first known attempt to evaluate the R-curve behavior of a low-strength structural steel in some depth.

Results showed a steep Kc transition behavior for 1.5-in.-thick (38 mm) plate, with minimum Kc values of 57, 155, and 318 ksi √in (63,171, and 350 MNm-3/2) obtained at-40, +40, and +72°F (-40, +4.5, and + 22°C), respectively. A similar behavior was observed for 0.5-in.-thick (12.7 mm) plate, with minimum Kc values of 150, 273, and >380 ksi √in. (165, 300, and >418 MNm-3/2) obtained at the corresponding test temperatures. The results are discussed in relation to the influence of material and testing method, as well as in relation to earlier KIc results obtained at cryogenic temperatures.

The minimum Kc values measured demonstrate extensive crack tolerance for A572 Grade 50 steel under all combinations of the test conditions studied. With one exception, these minimum behaviors can be translated into total critical flaw lengths that are at least seven times the plate thickness (2acr ≧ 7B) for cracks embedded in large planar structures and subjected to tensile-stress levels equal to three fourths the yield strength. The applicability of acr calculations obtained from R-curve measurements generally, and on the A572 Grade 50 steel specifically, is discussed in relation to typical structural members such as H-beams.
Mixed-Mode Fracture of Shear Panels—A Finite Element Analysis
Authors: Chiu ST , Liu AF
Published: March 2009

The mixed-mode fracture behavior of shear panels is analyzed in this study to provide suitable fracture criteria for the prediction of the residual strength of crack panels under a combined tension and shear loading condition. Finite element models which incorporate a special crack tip element are utilized in the analysis to compute the values of KI and KII and the detailed stress distribution in the crack tip regions. For comparison purposes, analyses are made using the initial crack configurations of the shear panels and a number of selected configurations after a small increment of slow stable crack growth. Failure analysis is made using these results together with test results obtained in a previous experimental study by Liu. It is found that a simple failure criterion of KI/(KI)cr+KII/(KII)cr = 1 is applicable to materials that are not extremely ductile. However, the maximum tensile stress theory should be used to complement this criterion for the purpose of predicting the crack growth direction. The mixed-mode criteria of the strain energy density function and the “angular” stress intensity factor are also examined. In addition, it is shown that a predominantly Mode I condition is produced by oblique crack growth even after a relatively small crack growth increment. Hence, a pure Mode I fracture criterion can be used to predict the slow stable crack growth and subsequent failure of damage structures subjected to combined loads if a practical method can be found to estimate KI during the crack growth period. It should be noted that the present study is restricted to a monotonically increasing loading condition.
A Finite-Element Analysis of Fatigue Crack Closure
Authors: Newman JC
Published: March 2009

Experiments have shown that fatigue cracks close at positive loads during constant-amplitude load cycling. The crack-closure phenomenon is caused by residual plastic deformations remaining in the wake of an advancing crack tip. The present paper is concerned with the application of a two-dimensional, nonlinear, finite-element analysis using an incremental theory of plasticity to predict crack-closure and crack-opening stresses during the crack-growth process under cyclic loading.

A two-dimensional finite-element computer program, which accounts for both elastic-plastic material behavior and changing boundary conditions associated with crack extension and intermittent contact of the crack surfaces under cyclic loading, has been developed. An efficient technique to account for changing boundary conditions under cyclic loading was also incorporated into the nonlinear analysis program. This program was used subsequently to study crack extension and crack closure behavior in a center-cracked panel under constant-amplitude and two-level block loading. The calculated crack-opening stresses were found to be quantitatively consistent with experimental measurements.
Practical Method for Calculating Stress-Intensity Factors Through Weight Functions
Authors: Labbens R , Pellissier-Tanon A , Heliot J
Published: March 2009

The existence for a plane or axisymmetric cracked body of an influence or Green's function, depending on the geometry of the body, allows calculation by means of a simple integral of the stress intensity factor. In this way the respective influence of geometry and load in K calculation are separated. The relationship between this function and the compliance for a concentrated force applied on the crack is shown.

Starting from complex mathematical considerations, Bueckner defined weight functions equivalent to the influence functions and of particular advantage for analytic as well as numerical purposes. Moreover he showed that weight functions behave like d-½ at the distance d from the crack tip. In the sequel we shall refer to weight functions, since they are studied more deeply from a mathematical point of view and are known more widely than influence functions.

A practical calculation method of weight functions by finite elements is shown. This method can be used for any bidimensional cracked body, plane or axisymmetric. Curves of nondimensional weight functions are given for cylindrical geometries currently used in engineering.

It is pointed up that this method is more flexible than the use of handbooks which, in spite of their great interest, cannot foresee all the geometries and loads which are met in engineering problems.
Stress Intensity Factor Solutions for Continuous Surface Flaws in Reactor Pressure Vessels
Authors: Buchalet CB , Bamford WH
Published: March 2009

A two-dimensional finite element method is used to develop stress intensity factor solutions for continuous surface flaws in structures subjected to an arbitrary loading. The arbitrary loading produces a stress profile σ acting perpendicularly to a given section S of the structure. The stress profile is represented by a third degree polynomial σ=A0+A1x+A2x2+A3x3

Stress intensity factor solutions are developed for continuous surface flaws introduced in particular sections S in the structure considered. Solutions are developed for a surface flaw in a flat plate, for both circumferential and longitudinal flaws inside a cylindrical vessel, and for circumferential flaws at several locations inside a reactor vessel nozzle.

The superposition principle is used, and the crack surface is subjected successively to uniform (σ = A0), linear (σ = A1x), quadratic (σ = A2x2), and cubic (σ = A3x3) stress profiles. The corresponding stress intensity factors (KI(0), KI(1), KI(2), KI(3)) are then derived for various crack depths using the calculated stress profile in the region of the crack tip. The total stress intensity factor corresponding to the cracked structure subjected to the arbitrary stress profile is expressed as the sum of the partial stress intensity factors for each type of loading. KI=KI(0)+KI(1)+KI(2)+KI(3)=πa[K0F1+2aπA1F2+a22A2F3+4a23πA3F4] where, a is the crack depth and F1, F2, F3, and F4 are the magnification factors relative to the geometry considered. The results are presented in terms of magnification factors versus fractional distance through the wall (a/t) and reveal the strong influence of the geometry of the structure and of the crack orientation.

The stress intensity factor solutions obtained using this method are compared to solutions obtained using other methods, when available. In the case of the plate geometry, the solution obtained for the linear loading (σ = A0 + A1x) is shown to agree well with the boundary collocation solution reported by Brown and Srawley. The stress intensity factor solutions for the circumferential and longitudinal cracks in the cylindrical vessel compare well with solutions obtained by Labbeins et al using the weight functions method proposed by Bueckner, and are also in good agreement with the solution for uniform loading (σ = A0) obtained using the line spring method proposed by Rice.
Stress Intensity Factors for Through and Part-Through Cracks Originating at Fastener Holes
Authors: Shah RC
Published: March 2009

A procedure is formulated to derive approximate stress intensity factors for both part-through and through-the-thickness cracks originating at open holes and holes containing either loaded or unloaded close tolerance fasteners. The procedure is checked with known solutions for stress intensity factors of one or two through-the-thickness cracks emanating from an open hole in a plate subjected to uniaxial or biaxial loading. Stress intensity factors computed from this procedure for the above mentioned cases agree within seven percent of known results for the crack length to hole radius ratios, L/r, of 0.05 ≤ L/r < ∞. The procedure is then used to derive stress intensity factors for through cracks at loaded close tolerance fasteners in a plate, and for semi-elliptical cracks at open holes and at loaded and unloaded close tolerance fastener filled holes in a thick plate. Stress intensity factors for these part-through cracks are presented in graphical forms as a function of position around the crack periphery, for various crack aspect ratios and crack length to hole radius ratios. Finally, these stress intensity solutions for semi-elliptical cracks at a fastener hole in a thick plate are used to estimate stress intensity factors for quarter-elliptical cracks originating at a fastener hole in a finite thickness plate.
Stress Intensity Factors for Deep Cracks Emanating from the Corner Formed by a Hole Intersecting a Plate Surface
Authors: McGowan JJ , Smith CW
Published: March 2009

A technique consisting of a marriage between stress freezing photo-elasticity and a numerical method was used to obtain stress intensity factors for natural cracks emanating from the corner at which a hole intersects a plate surface. Geometries studied were: crack depth to thickness ratios of approximately 0.2, 0.5, and 0.75; crack depth to crack length ratios of approximately 1.0 to 2.0; and crack length to hole radius ratios of about 0.5 to 2.0. All final crack geometries were grown under monotonic loading, and growth was not self similar, with most of the growth occurring through the thickness under remote extension. Stress intensity factors were determined at the intersection of the flaw border (1) with the plate surface (Ks) and (2) with the edge of the hole (KH). Results showed that for the relatively shallow flaws KH ≃ 1.5 Ks, for the moderately deep flaws KH ≃ Ks and for the deep flaws KH ≃ 0.5 Ks, revealing a severe sensitivity of K to flaw geometry. Results were compared with the Bowie theory, and approximate criteria developed by Hall and Finger, and Hsu and Liu. These comparisons showed that these theories significantly overestimated the SIF for moderately deep flaws a/t ≃ 0.5 at both the plate surface and the hole, but, for shallow flaws, the Hall-Finger theory underestimated the SIF at the hole, and the Bowie theory underestimated the SIF at the surface for deep flaws.
Stress Intensity Factor of a Corner Crack
Authors: Kobayashi AS , Enetanya AN
Published: March 2009

The alternating method for elliptical crack analysis, which is based on the combined use of a pressurized crack solution and a free surface solution, has been limited in its application due to convergence difficulties in the iteration process. By prescribing appropriate fictitious pressure on the elliptical crack surface, which protrudes into the free space, numerical convergence of the iteration was improved. As a result, the pressurized crack solution involving a third-order polynomial pressure distribution with limited use was extended to part-elliptical problems. The improved alternating procedure is then used to determine stress intensity factors in corner flaws with aspect ratios of a/b = 0.98, 0.4, and 0.2 and subjected to uniform or linearly varying pressure distributions.
Predicting Spacecraft Multilayer Insulation Performance from Heat Transfer Measurements
Authors: Stimpson LD , Hagemeyer WA
Published: March 2009

One of the most commonly utilized insulation systems for National Aeronautics and Space Administration spacecraft is multilayer insulation (MLI). The problem of predicting performance of MLI blankets containing discontinuities is described. Design data and test techniques are required which allow correlation of heat leaks through discontinuities with measurable parameters. Some of these design data are obtained using the Jet Propulsion Laboratory's calorimetric testing program.

New materials and testing approaches will be required for more extreme environments of future spacecraft. Both higher and lower environmental temperatures are anticipated. Insulation performance must meet these demands, at the same time avoiding excessive weight.
Design Criteria for Guarded Hot Plate Apparatus
Authors: De Ponte F , Di Filippo P
Published: March 2009

A procedure is suggested, in this paper, for a rational design of guarded hot plate apparatus of assigned performances.

The dimensions of the hot plate, of the guard ring, and of the maximum specimen thickness are derived from the computation of edge heat losses and unbalance errors.

The problem of the best location of the unbalance detectors along the gap is discussed, and some solutions are proposed.

The elements for the design of the cold plates are given for both liquid cooled and gas cooled plates.
Thermal Conductance of Pipe Insulation—A Large-Scale Test Apparatus
Authors: Kimball LR
Published: March 2009

Thermal conductance measurements were carried out for pipe insulation on a large-scale test apparatus. A pipe 18 in. (0.457 m) in diameter and 20 ft (6.08 m) long was used. A chamber cooled to −70°F (−56.7°C) by expansion of liquid nitrogen surrounded the pipe. Water inside the pipe was heated to 160°F (71.1°C) by electrical resistance heaters. Several steady-state tests were made using air and water inside the pipe. A transient heat loss test was also made using water inside the pipe.

Close agreement was found between the theoretical steady-state thermal conductance factor and that experimentally measured. The numerical difference can be explained by center joint heat losses. Close agreement was also found in the transient response of the system to a loss of heat inside the pipe as experimentally recorded and compared to a theoretical approach.
Robinson Line-Heat-Source Guarded Hot Plate Apparatus
Authors: Hahn MH , Robinson HE , Flynn DR
Published: March 2009

This paper presents a description of the line-heat-source guarded hot plate apparatus conceived by the late H. E. Robinson, the results of mathematical analyses of potential sources of uncertainty, and the design of an apparatus of this type being constructed at the National Bureau of Standards. This design utilizes a line source heater, from which heat diffuses laterally in the plate. Such a design does not produce a wholly uniform plate temperature, but does enable calculation of average plate surface, and edge, temperatures utilizing only a few temperature sensors.
Calibrated Hot Box: An Effective Means for Measuring Thermal Conductance in Large Wall Sections
Authors: Mumaw JR
Published: March 2009

A large calibrated hot box apparatus, utilizing highly thermal resistant walls, has been constructed to permit fast and accurate thermal conductance measurements for large vertical sections. The test wall section, nominally 9 by 14 ft (2.7 by 4.2 m), is placed between two chambers maintained at different temperatures. The net heat flow through the test wall is the algebraic sum of the measured input electrical energy and the chamber wall heat transfer which is measured using a heat meter technique. With the use of high thermal resistance walls, the correction for chamber heat flow is generally less than 1 percent. Other data required for the final calculations are obtained using an automatic data monitoring and recording system. Data analysis and report preparation are performed using a computerized program written especially for the equipment.

These, and additional design features, permit a wide variation in mean temperature capability (0 to 100° F), air infiltration measurement capability (0 to 54 standard cubic feet per minute (scfm) at up to 10 in. H2° ΔP), and efficient usage of manpower by automating control, data taking, and analysis (test frequency of three per week for a manpower requirement of 1 to 2 h per day, excluding specimen construction).

Close agreement was found between the expected and measured thermal results, using calibration specimens measured in the ASTM Test for Thermal Conductivity of Materials by Means of the Guarded Hot Plate (C 177-63). Data in support of the basic conclusions of the paper are presented with the addition of suggestions for including the calibrated hot box as a useful ASTM test standard.
Improving the Thermal Performance of the Ordinary Concrete Block
Authors: Knickle HN , Ducharme E
Published: March 2009

Thermal performance tests have been performed on ordinary concrete block walls which have been constructed of sand and gravel concrete blocks and expanded shale concrete blocks. The thermal conductance of these walls were measured according to ASTM Test for Thermal Conductance of Built-Up Sections by Means of the Guarded Hot Box (C 236-66). The sand and gravel block wall conductance was measured, then polystyrene inserts were inserted in these two-core masonry units, and the thermal conductance was remeasured. There was a significant improvement in the thermal conductance. The same procedure was applied to the expanded shale block wall, again resulting in a significant improvement of thermal conductance. Thermal transmittance has been calculated using the measured thermal conductance and film coefficients representing a 15-mph wind and a 0-mph wind. Calculations to show the comparative costs of building walls with and without the polystyrene inserts have been made.
Evacuated Load Bearing Thermal Insulation up to 800°C
Authors: Dickson DJ
Published: March 2009

Evacuation as a means of reducing the gas-conducted heat through a thermal insulation has been considered in the past mainly for low temperature and aerospace applications. The extension of this work to higher temperatures has shown that it is possible to use evacuated load-bearing fibrous insulation up to at least 750°C hot face. Load-bearing tests on thermal insulations showed that microporous silica insulation has very high compressive strength whereas rockwool and aluminosilicate fiber insulations compress by up to 50 percent under atmospheric pressure compressive load. A plane guarded hot plate apparatus to measure thermal conductivity of a load-bearing specimen has been used to obtain data for a range of typical fibrous and block thermal insulations. Of the materials tested, fibrous materials give the largest change in thermal conductance on evacuation, but evacuated opacified microporous silica has the lowest thermal conductivity. A practical device utilizing these data has been built and tested.
Three-Dimensional Analysis of Laminar Composites with Through Cracks
Authors: Hilton PD , Sin GC
Published: March 2009

The variational principle of minimum complementary potential energy is employed to develop an approximate three-dimensional model for the stress distribution in laminar composites. This approximate theory is applied to the problem of a symmetric composite plate containing a through crack subjected to in-plane loading. Asymptotic solutions are obtained for the stress components in the vicinity of the leading crack edge. These solutions are in complete agreement with information obtained from an exact three-dimensional asymptotic analysis; that is, the in-plane variation of the stress components within each layer is described by the singular portion of the elastic, plane-strain crack solution. However, because of the three-dimensional character of the problem, the amplitude of the singular solution for the stress components varies along the leading crack edge. A two-parameter model incorporating the concept of surface and interfacial boundary layers is used to describe this transverse variation.

Results from the modeling and analysis performed here include a description of the through-the-thickness variation of the near-tip stress field, which has already proven to be of use in conjunction with photoelastic measurements, and an average or effective stress intensity factor for finite thickness homogeneous plates and laminates.
Mode I Stress Intensity Factors for Symmetrically-Cracked Orthotropic Strips
Authors: Konish HJ
Published: March 2009

The effects of material anisotropy on the stress intensity factor are investigated numerically for both double-edge-cracked and center-cracked orthotropic tensile strips. The material properties employed correspond to homogeneous material models of mid-plane symmetric fiber composite laminates of varying ply orientation and ply properties.

The effects of anisotropy are found to be dependent on both specimen geometry and material properties. Complete decoupling of these geometric and material influences does not appear possible. However, the principal geometric parameter seems to be the distance from the crack tip to the free edge of the specimen; the effects of material properties appear to correlate with the in-plane elastic shear modulus. It is suggested that anisotropic effects can be sufficiently controlled, by means of specimen geometry, to justify the use of the known isotropic stress intensity factor as a reasonable (and usually conservative) estimate of the anisotropic value in most materials.
Crack Arrestment of Laminated Composites
Authors: Bhatia NM , Verette RM
Published: March 2009

In this paper the potential of the buffer strip concept for providing fracture control in graphite/epoxy laminated composite panels subjected to uniaxial tension static and fatigue loads is evaluated. The specific buffer strip design consists of replacing the 0-deg and 90-deg plies in a π/4 laminate with ±45-deg plies along strips parallel to the uniaxial load direction. A number of specimens were fabricated and tested. The specimens were 8 by 20-in. panels of 8-ply (0, ±45, 90)s Thornel 300/SP286 graphite/epoxy laminates. Two 1-in. wide buffer strips were symmetrically placed 2 in. apart (3 in. center-to-center) and parallel to the longer sides of the panels. Initial flaws consisting of slits and circular holes of various sizes and orientations were machined at the midsection between the two buffer strips. Initial fracture and ultimate failure strengths of the panels were determined. In addition, several panels were fatigue cycled prior to static failure to assess the influence of fatigue loads on post-fatigue performance.

The static tests of the panels not previously fatigue tested showed that crack arrestment occurred when the initial flaw size exceeded 0.50 in. That is, the crack arrest capability was found to depend on the initial flaw size. For panels with 0.75 and 1.00-in. flaws, an initial fast crack was arrested in the buffer strips and the panels subsequently withstood approximately 20 percent more load. The crack initiation load for the panels which were previously fatigue cycled increased by approximately 10 percent as compared to the crack initiation load for an identical panel not previously fatigued. The improvement is attributed to development of zones of crazing and delamination in the crack tip region during fatigue cycling which reduce the local stiffness and the stress concentration. Fractographic examination of the failure surfaces confirmed the existence of this zone.
The Relationship Between Oil Viscosity and Engine Performance-A Literature Search
Authors: Stewart RM , Selby TW
Published: March 2009

This paper summarizes the published information on the relationship between oil viscosity and engine performance that may be of use in developing a new engine oil viscosity classification system. The specific engine performance factors and associated variables considered are wear, oil consumption, fuel economy, hot starting, cold starting, low temperature pumpability, noise, and shear stability.
Engine Oil Viscosity Classifications-Past, Present, and Future
Authors: McMillan ML
Published: March 2009

An extensive effort is under way to revise the SAE Engine Oil Viscosity Classification System to reflect user needs more realistically. To understand how the present system evolved, the history of the classification is traced, from the original version first published in 1911 to the present 1976 version. Reasons for both high- and low-temperature viscosity grades, multigrading, and footnotes to the viscosity table are discussed, as well as other classification systems which have been discarded over the years.

A critical assessment of the present classification is made from opinions offered at an SAE Open Forum last year. It is pointed out that the system has become quite complicated with four low-temperature and four high-temperature grades, five footnotes, and an appendix. Moreover, the high-temperature viscosity grades are based on an unrealistically low temperature of 98.9°C (210°F) and an unrealistically low-shear (kinematic) viscosity compared with engine operating conditions.

Several suggestions for improving the system are offered, although no one particular approach is advocated. It is concluded that to adequately reflect the effects of oil viscosity on engine performance in the field, the classification system must be revised to include a measure of low-temperature oil fluidity and a high-temperature, high-shear measure of viscosity which correlates with engine performance — a measure which has not yet been developed.
European Activity Concerning Engine Oil Viscosity Classification
Authors: Cassiani Ingoni AA , DiLelio GF , Eberan Eberhorst CGA
Published: March 2009

The growing interest and concern over the problem of the high temperature viscosity of engine oils and its effect on the engine performance, following the proposal for revision of the SAE J 300, pushed the CEC Engine Lubricant Technical Committee to establish an Investigation Group (IGL 9) to investigate the subject of Viscosity Measurements at High Temperature.

The Low Temperature aspects are mainly covered by the CEC Investigation Group IGL 8 and the German National Organization DKA Study Group.

The IGL 9 Group agreed to circulate a questionnaire which was gratified with high degree of attention; 31 companies answered confirming the importance of the investigation and the requirement of viscosity measurements more realistic and in line with to day's engine operating conditions.

A first screening work carried out on some reference oils has demonstrated the possibility of correlation among different bench measuring techniques and an engine. The second stage now underway sees a new set of 9 test oils formulated using different polymer species commercially available, to be submitted to 22 “engine viscosity” and “viscosity rig” tests to define correlations where possible.
Measurement of Temporary and Permanent Shear with the Instron Capillary Rheometer
Authors: Johnson TW , O'Shaughnessy MT
Published: March 2009

The Instron Capillary Rheometer, with special extremely fine capillaries, has been used to measure the apparent viscosities of non-Newtonian polymer-thickened multigrade oils at temperatures from 100°F to 320°F and shear rates to 106 sec−1. The same apparatus can produce permanent shear under extreme conditions. Temporary shear data at 100°, 150°, 210°, 280° and 320°F are reported for eight commercial oils and five experimental oils formulated with different VI improvers in the same base oil. Permanent shear data are given for a larger set of oils.
Escherichia coli: The Fecal Coliform
Authors: Dufour AP
Published: March 2009

The use of Escherichia coli as an indicator of fecal pollution and the significance of its presence in surface waters was reviewed. A minidefinition which identifies this organism at least 95 percent of the time was proposed. Membrane filtration and most probable number methods for the enumeration of E. coli were discussed.
Bacterial Indicators and Standards for Water Quality in the Federal Republic of Germany
Authors: Müller G
Published: March 2009

In the Federal Republic of Germany, the choice of the indicator differs with the water that has to be examined. For drinking water, the classical parameters are the total colony count and the Escherichia coli test.

While the colony count seems to be considered of less importance in other European countries, the German legislation contains mandatory limits. Furthermore, E. coli must not be present in 100 ml of drinking water. Fecal streptococci and Pseudomonas aeruginosa are good indicators for the examination of swimming water in pools which have been treated by flocculation, filtration, and chlorination.
Bacterial Indicators of Drinking Water Quality
Authors: Ptak DJ , Ginsburg W
Published: March 2009

The papers presented at the ASTM International Symposium on Bacterial Indicators of Potential Health Hazards Associated with Water in June of 1976 were reviewed and are summarized in this paper as they pertain to bacterial indicators of drinking water quality.
Theory and Application of Evaluation Tests for Detecting Susceptibility to Intergranular Attack in Stainless Steels and Related Alloys— Problems and Opportunities
Authors: Streicher MA
Published: March 2009

The first evaluation methods for stainless steels, the 65 percent nitric acid and the copper sulfate-sulfuric acid tests, were originally simulated service tests. Later, when the results obtained with these tests were used to prevent failures by intergranular attack in other media, they were transformed into methods of general applicability for detecting susceptibility to intergranular attack. Since the 1949 ASTM symposium on this subject, several new methods have been introduced to accomplish this goal more rapidly and effectively. This has led to a large variety of ASTM test methods which also include the nickel-rich, chromium-bearing alloys.

In an overview of all current ASTM test practices for detecting susceptibility to intergranular attack, opportunities for improvements and simplifications are discussed. New data are presented on the properties of the various copper sulfate-sulfuric acid tests and on the performance of the new iron-chromium-molybdenum ferritic stainless steels in evaluation test solutions. The need for assessment criteria for determining the occurrence of intergranular attack in all test practices is emphasized with proposals for such criteria. A plan for a greatly reduced number of improved tests is proposed. The introduction of new melting, refining, and casting methods and of new iron-chromium-molybdenum stainless steels has increased the importance of evaluation test methods and the need for improvements in ASTM test practices.
Comparative Methods for Measuring Degree of Sensitization in Stainless Steel
Authors: Clarke WL , Cowan RL , Walker WL
Published: March 2009

Three test methods for determining degree of sensitization in austenitic stainless steels have been investigated. The results clearly show that all three test methods are capable of detecting moderate-to-severe degrees of sensitization, but the electrochemical potentiokinetic reactivation technique is the most sensitive for quantitatively determining the levels of sensitization which are of primary concern for industrial use. Both the ASTM Recommended Practices for Detecting Susceptibility to Intergranular Attack in Stainless Steels (A 262-75, Practice A) and the electrochemical potentiokinetic reactivation methods appear to saturate at high degrees of sensitization, which results in a loss of discriminating power between different heats of material. While the A 262, Practice E, method does not appear to saturate and retains its discriminating power at high degrees of sensitization, it is not a suitable method for detection at the lower degrees. Of the three test methods, it appears that the electrochemical potentiokinetic reactivation test is the most suitable for determining the quantitative degree of sensitization over the levels of industrial concern.
Niobium and Titanium Requirements for Stabilization of Ferritic Stainless Steels
Authors: Dundas HJ , Bond AP
Published: March 2009

The amount of niobium or titanium necessary to prevent intergranular attack of the weld zone of autogenously welded 18Cr-2Mo and 26Cr-1Mo alloys containing 0.02 to 0.05 percent (C + N) was determined using the copper-copper sulfate (Cu-CuS04)-16 percent sulfuric acid (H2SO4) test. The study demonstrated that a niobium or titanium level equal to or greater than 0.20 percent 4 (C + N) would produce immunity of 18Cr-2Mo alloys to intergranular attack. The use of the 10 percent oxalic acid etch test and exposure in the 10 percent nitric acid (HN03)-3 percent hydrofluoric acid (HF) test, and in a Cu-CuSO4-50 percent H2SO4 solution, or an acidified 10 percent ferric chloride (FeCl3) solution confirmed both the effectiveness of the Cu-CuS04-16 percent H2SO4 test and the recommended stabilization formula for alloys containing C + N levels of 0.03 percent. In contrast, the ferric sulfate (Fe2(SO4)3)-50 percent H2SO4 test produced grain dropping of the weld zone on alloys that were stabilized according to the other tests. Exposure of selected alloys demonstrated that intergranular attack of unstabilized ferritic alloys can also occur in boiling seawater and boiling formic acid.
Intergranular Corrosion Testing and Sensitization of Two High-Chromium Ferritic Stainless Steels
Authors: Nichol TJ , Davis JA
Published: March 2009

The effect of several parameters (alloy chemistry, thermal history, and solution chemistry) on the resistance of two new ferritic stainless steels to intergranular corrosion was investigated. The susceptibility of Types 26-1S and 29-4 to intergranular corrosion depended on the alloy chemistry and the particular test used to evaluate susceptibility. For both alloys, the severity of the standard tests increased in the following order: copper sulfate (CuSO4)-16 percent sulfuric acid (H2SO4), nitric acid (HNO3)-hydrogen fluoride (HF), CuSO4-50 percent H2SO4 and ferric sulfate (Fe2(SO4)3)-50 percent H2SO4. Sensitization was produced in these alloys by either welding or high-temperature annealing followed by air cooling. The most reliable evaluation method was bending of the material combined with optical examination.
Intergranular Corrosion in 12 Percent Chromium Ferritic Stainless Steels
Authors: Lula RA , Davis JA
Published: March 2009

Intergranular corrosion of Types 409, 405, and 410 stainless steels was evaluated in the heat treated and welded condition. Standard ASTM Method A 262 corrosion tests are too severe for 11 to 13 percent chromium steels, and two modified tests were developed: 65 percent nitric acid at 49°C (140°F) and 50 percent sulfuric acid-cupric sulfate at 49°C (140°F). Type 409, a titanium stabilized ferritic steel, shows intergranular corrosion in nitric acid but is immune in the cupric sulfate test. Type 405 with a duplex structure shows intergranular corrosion in both tests. Type 410 with a martensitic structure does not exhibit intergranular corrosion. The behavior of these steels is explained based on their microstructure.
Moisture-Altered Viscoelastic Response of Graphite/Epoxy Composites
Authors: Crossman FW , Mauri RE , Warren WJ
Published: March 2009

Results of experiments to evaluate the degree of moisture-induced swelling and plasticization in T300/934, T300/5209, GY70/339 composites are described. Swelling was found to be a nonlinear reversible function of equilibrium moisture content. Out-of-plane swelling was several times larger than in-plane transverse swelling in the unidirectional composites. Equilibrium moisture content was found to vary with exposure temperature as well as humidity in the 339 and 5209 matrix systems. The in-plane shear properties were determined as a function of time, temperature, and equilibrium moisture content, and master curves of temperature and moisture-compensated modulus versus time were constructed for each material. Nonsymmetric (04/904)T cross-plied laminates were employed to study the alteration of residual stresses in T300/5209 and GY70/339 as a function of temperature and moisture content. The level of residual stresses measured for a given equilibrium moisture content was found to be a function of the temperature at which the moisture was absorbed.
Analysis and Test of Graphite/Epoxy Sandwich Panels Subjected to Internal Pressures Resulting from Absorbed Moisture
Authors: Garrett RA , Bohlmann RE , Derby EA
Published: March 2009

A simple analysis procedure is developed to predict graphite/epoxy sandwich panel internal pressures at elevated temperatures, based on moisture characteristics of the panel constituents, prior environmental exposure, and test temperature time histories. Pressures so predicted are shown to correlate well with measured panel pressure test results. It is further shown that, due to environmental absorbed moisture, internal panel pressures of 65 psig (4.5 kg/cm2) or greater can be produced at 350°F (177°C) in graphite/epoxy sandwich panels with Nomex core. Panel internal pressure test failures at 350°F (177°C) for various initial environmental exposures are also shown to be dependent on the moisture level in the METLBOND 329-7 adhesive at time of failure. Panel failure pressures in excess of 150 psig (10.5 kg/cm2) at 350°F (177°C) are reported for low adhesive moisture levels (room temperature equilibrium relative humidity of 20 percent or less), but as low as 60 psig (4.5 kg/cm2) for high adhesive moisture levels (70 percent relative humidity equilibrium at room temperature). Lap shear and flatwise tension test results of the METLBOND 329-7 adhesive at room temperature and 350°F (177°C) with absorbed moisture are also presented; these tests exhibit similar moisture strength degradation and failure modes as that demonstrated by the panel pressure test specimens.
“Instantaneous” Effect of Internal Moisture Conditions on Strength of Glass-Fiber-Reinforced Plastics
Authors: Ishai O , Arnon U
Published: March 2009

Glass-fiber-reinforced laminates composed of two different commercial epoxy resin matrix formulations, a “medium-temperature” system and a “high-temperature” system, were tested in tension after immersion in hot water. Tests were carried out both in the “as-is” wet condition and after drying. The internal moisture condition was found to have a significant effect on the tensile strength. Dried specimens of the medium-temperature resin were stronger than their wet counterparts. The reverse was the case with specimens based on the high-temperature resin.
Periphyton Measurements and Applications
Authors: Weitzel RL
Published: March 2009

Evaluation of attached microcommunities, that is, periphyton or Aufwuchs, provides an accurate, reliable indicator of water quality. These microcommunities have an important role as primary producers in many aquatic systems, particularly in lotic environments. The periphytic algal component has been shown to be a useful indicator of water quality, responding to and reflecting conditions of the immediate past. The reliability and accuracy of periphyton measurements are affected by physical conditions such as substrate type and condition, water type and movement, and solar incidence, direction and shading, as well as by water quality. Those factors that regulate the growth and development of periphyton should be considered when monitoring periphyton communities, especially when artificial substrates are employed. Data generated from measurements of periphyton, which commonly include species dominance and diversity, biovolume, biomass and chlorophyll a, can be misinterpreted when sampling and other limiting conditions are not fully understood. Through a review of the literature, many of these measurements and limiting factors are discussed in an effort to bring awareness of these problems to the reader who may engage in monitoring water quality by periphyton measurement.
Protozoan Colonization of Artificial Substrates
Authors: Cairns J , Kuhn DL , Plafkin JL
Published: March 2009

Several advantages of utilizing microbial communities, particularly protozoan communities forming on artificial substrates, in the assessment of pollutional stress are discussed. The process of community formation on artificial substrates is likened to that of island colonization, and the means of analyzing and interpreting variations in the dynamics of species accrual are presented. Results from a study conducted in Smith Mountain Lake, Virginia, illustrate how the colonization process reflects characteristics of both the composition and the productivity of the source species pool—the natural protozoan community.
Distinguishing Between Live and Dead Diatoms in Periphyton Communities
Authors: Owen BB , Afzal M , Cody WR
Published: March 2009

A staining procedure was developed that allows the distinction between diatom frustules that had cell contents (“live”) and those that were empty (“dead”) at the time of collection. Preserved samples were stained with acid fuchsin, dehydrated, and mounted in Hyrax. The permanent Hyrax mounts allow the investigator to study diatoms as well as other algae with reasonable taxonomic surety, and to distinguish live from dead diatoms. Studies of samples from diverse habitats indicate that percentages of dead diatoms in periphyton communities can range from 1 to 79 percent, and samples usually contained more than 10 percent empty frustules. Sources of dead diatoms are discussed, and the significance of distinguishing dead from live diatoms is considered relative to community analyses.
Sampling and Interpretation of Epilithic Lotic Diatom Communities
Authors: Pryfogle PA , Lowe RL
Published: March 2009

Benthic diatom communities were quantitatively sampled on epilithic substrates during four different seasons in 1974 and 1975 in Tymochtee Creek, Ohio. Samples were stained to distinguish living from dead diatoms. Each sample was analyzed for density and species diversity of diatoms, and the effect of including dead cells in these analyses was measured. The inclusion of dead cells increased the standing-crop estimates in every instance. In all but three instances the inclusion of dead cells increased community diversity. Summer samples had a relatively greater proportion of dead cells than winter samples. Centric diatoms were relatively more important in periphytic communities near the stream mouth, and raphe-bearing pennate diatoms were relatively more important in upstream samples.
Sample Replication of Periphyton Collected from Artificial Substrates
Authors: Weitzel RL , Sanocki SL , Holecek H
Published: March 2009

Extensive use of and field experiments with a commercially available artificial substrate sampling device suggest limited reproducibility of data, which may or may not be peculiar to this specific device under certain conditions. Use of a coefficient of similarity to compare diatomaceous species associations between replicate samples on glass slides indicated that similarity of at least 70 percent between replicates was common. Replicated side-by-side experiments under natural conditions indicated statistically significant between-sampler differences of biomasses and chlorophyll yields. Within-sampler variation among replicate slides was inconsistent, but usually in the range of 20 to 30 percent; however, these differences were not consistent with slide positions. A direct relationship of surface velocity to biomass and chlorophyll yield was revealed, although this was probably also related to solar incidence. The data indicate the necessity to understand the limits and effective variables regulating periphyton growth on artificial substrates. Significant differences in periphyton yields may reflect inappropriate sampler placement or sampler effects rather than effects of water quality.