bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of Acoustic Emission Techniques to Rock and Rock Structures: A State-of-the-Art Review
Authors: Hardy HR 
Published: March 2009

This paper presents a state-of-the-art review of the subject of acoustic emission as it pertains to the area of rock mechanics, and includes references to some 150 recent papers. Although a limited discussion of laboratory oriented studies are included, the major thrust of the paper is to field applications in geotechnical engineering.
The paper first discusses the general concepts involved in the acoustic emission technique and briefly reviews the early history of the subject. This is followed by a general discussion of techniques currently in use for monitoring and analysis of acoustic emission data, and a description of a number of recent and on-going field studies where acoustic emission techniques are being employed in the general area of geotechnical engineering. Finally, the paper considers the various limitations of the technique as well as areas where further research and development are considered necessary.
Acoustic Emission Behavior and Monitoring of Soils
Authors: Koerner RM , McCabe WM , Lord AE 
Published: March 2009

As far as nondestructive testing methods are concerned, acoustic emission techniques are relatively recent additions to the rock monitoring area (dating from the late 1930's) and to the metal testing area (dating from the 1950's). Its application to soils is an even more recent event with little activity prior to the 1970's. However, over the past five to ten years, interest has been generated in the soils area to the point where at least five equipment manufacturers are currently marketing acoustic emission systems specifically for geotechnical engineering applications. This activity is seemingly well founded, for acoustic emissions are indeed generated by deforming soil masses and technical feasibility is now firmly established.
This state-of-the-art paper on acoustic emission activity in soils presents these findings on the basis of fundamentals, small-scale laboratory tests, and large-scale laboratory tests. Furthermore, the technique has been applied to field situations in a number of cases. These include slope stability monitoring of dams and embankments, soil movements arising from horizontal and vertical deformations, seepage monitoring, and grout/hydrofracture monitoring. Specific case histories in each group are presented.
Collectively taken, the information available seems encouraging enough for many investigators to use the technique for a wide variety of applications. With a multi-faceted attack, the current qualitative status of the technique (that is, no acoustic emission indicates stability; low acoustic emission indicates small movement; moderate acoustic emission indicates larger movement; high acoustic emission indicates instability) should move into a better defined quantitative status. In this latter case, acoustic emission signatures of different soils could lead to instant assessment of actual stress levels in any given situation.
Acoustic Emissions Generated During the Quasi-Static Cone Penetration of Soils
Authors: Villet WCB , Mitchell JK , Tringale PT 
Published: March 2009

As a rigid object is pushed into a soil, acoustic emissions are generated by soil grains sliding over one another, sliding over the penetrating object, and being crushed.
In 1977, a research project was initiated to develop a system for recording such emissions generated during the quasi-static cone penetration of soils, and to evaluate their potential usefulness as a means for the in situ characterization of soils and soil deposits.
In order to ensure knowledge of and control over all factors governing the engineering behavior of tested soils, all initial tests were performed in the laboratory. A field testing program has recently been initiated.
Laboratory tests to date have been performed on a single graded sand. Variables included relative density, confining stress, and state of saturation. Analyses of the obtained acoustic records include the determination of peak-to-peak voltage, root-mean-square voltage, and frequency distribution analysis.
Initial results indicate that:
1. The resultant frequency distribution curves can be divided into two categories, one associated with lower confining stresses and penetration rates, the other with higher confining stresses and penetration rates, the other with higher confining stresses and penetration rates. These categories may well be signatures uniquely associated with the specific soil.
2. The amplitude of the signal increases with penetration rate.
3. The amplitude of the generated signal is larger in a dry, than in a saturated sample.
The limited field tests performed to data indicate that amplitude of the generated signal may be used as an indicator of layering.
The goal of the ongoing project is the development of a new method for the in situ identification and characterization of soils and soil deposits.
Accelerated Stability Test Techniques for Middle Distillate Fuels
Authors: Stavinoha LL , Westbrook SR 
Published: March 2009

Improved test techniques are needed for evaluating the inherent stability of middle distillate fuels both in surveillance and in procurement activities. A project was initiated to define and evaluate the contributing conditions leading to the formation of deleterious products in accelerated aging tests of middle distillate fuels and to relate these results to an experimental definition of more repeatable/reliable middle distillate fuel stability test technique(s).
A literature search was conducted to provide a list of stability test techniques and their interpretations which could be used in a correlative middle distillate fuel stability test program. For this program, seven accelerated stability tests were chosen and evaluated using a set of six test fuels. The test techniques were selected to represent a wide variety of test conditions, including temperature, aging time, and oxygen availability. These six test fuels were purposely chosen to represent a wider range of stabilities than would necessarily be commonly available for procurement. The fuel properties generally measured included both adherent and suspended particulates, steam jet gum, color, and light absorbance at 540 nm. Accelerated stability test results were then related to test results obtained at a storage temperature of 43.3°C, which has generally been regarded as showing good correlation with long-term ambient storage.
The Laughing Gull (Larus atricilla) as a Model for Assessment of Secondary Poisoning
Authors: Fink RJ , Jaber MJ 
Published: March 2009

The assessment of secondary poisoning is an important consideration in the hazard evaluation of predator control agents and rodenticide baits. The selection of an appropriate test animal model is difficult because classic laboratory species are frequently inappropriate, and the availability and reliability of wild species for testing is limited. The laughing gull (Larus atricilla) has demonstrated its usefulness as a secondary poisoning model in the laboratory and shown species sensitivity through case history documentation of secondary poisoning mortality in the field.
A number of new candidate rodenticides are being developed throughout the world for control of rodent pests in domestic, industrial, and agricultural marketplaces. Because one or more of these rodenticides could have a wide variety of outdoor uses, the effects of these substances on the environment must be evaluated in terms of both their toxicity and their exposure. The portion of that evaluation which is to be considered in this paper concerns the assessment of secondary poisoning of birds, utilizing the laughing gull as a model for an avian predator.
Hydroplaning, Hydrodynamic Drag, and Vehicle Stability
Authors: Hayes GG , Ivey DL , Gallaway BM 
Published: March 2009

A comprehensive series of experiments is reported involving a variety of full-scale highway pavements and various automobile tires. Test condition variables include vehicle speed, tread depth, water depth, and pavement inundated length.
Extensive test data are shown which define the tire forces encountered during partial and full dynamic hydroplaning as a function of the ASTM E 274 skid number. This enables an engineer to better interpret the actual friction available under specified conditions and shows vividly one reason it is so difficult to relate wet weather accident frequency to ASTM skid numbers.
In the final section of this paper 27 tests in selected water “puddles” are reported. These tests show that loss of tire/pavement contact can occur during puddle traversal and asymmetrical drag forces can develop which have the potential for precipitating a vehicle loss of control. These puddle depths range from zero on the outer edges to 28.5 mm (1 ⅛in.) in the deepest part. Drag forces up to 135 kg (300 lb) were measured.
It is illustrated that hydroplaning drag forces, in some cases coupled with loss of pavement contact due to hydroplaning, may pose a hazard to drivers who exceed a reasonable speed during wet weather.
Quality Assurance of Graphite/Epoxy by High-Performance Liquid Chromatography
Authors: Sewell TA 
Published: March 2009

Factors contributing to the reliability and reproducibility of high-performance composites include advanced resin matrixes with consistent purity and concentration of chemical constituents, as well as mix homogeneity and processing uniformity. Variation of these matrix parameters can affect manufacturing processibility and finished laminate quality. For these reasons, a wide variety of analytical tools have been evaluated for their capability of ensuring matrix reproducibility. In most cases, test development has been required to optimize and tailor the methodology for each new matrix system. In this way analytical information more precisely characterizes the matrix and monitors batch-to-batch consistency.
This paper covers work under U.S. Air Force Contract F33615-78-C-5177, “Chemical Composition and Processing Specifications for Air Force/Navy Advanced Composite Matrix Material.” It discusses the development of high-performance liquid chromatography (HPLC) as a quality-assurance method of certifying resin matrix composition of Air Force/Navy graphite/epoxy AS/3501-6 advanced composite matrix material. A gradient-elution/binary-solvent separation technique was developed by using a Spectra Physics 8000 liquid chromatograph in reverse-phase mode.
Resin and derived prepreg from full-scale production lots having predefined concentration variations were investigated. Lot variations were verified quantitatively by using a standard production batch for baseline comparisons. Resin matrix ingredients were used as concentration standards for test calibrations. Test data are reported in weight percent for two types of epoxies and one curing agent (diaminodiphenyl sulfone).
Details concerning the evolution of method development are discussed. Data are included to demonstrate test capabilities for quantitative measurements of unreacted epoxies and diaminodiphenyl sulfone. Data are presented for test verification of intentional ingredient alterations and tracking capability for compositional changes due to ambient aging and short thermal advancements due to hot-melt fiber impregnation.
Nondestructive Evaluation of Composite Materials: A Philosophy, An Approach, and An Example
Authors: Duke JC 
Published: March 2009

Composite materials are being used more and more in critical structural members. It is extremely important to be able to nondestructively evaluate their quality. This paper discusses a philosophy regarding nondestructive evaluation (NDE) which suggests that such an evaluation must include inspection and an assessment, in light of specifications, of existing imperfections in the materials. Advancement in the general area of nondestructive evaluation of composite materials requires an approach that seeks to improve both the inspection and assessment aspects in an integrated fashion. An approach of this type is described.
An example of the approach applied to the characterization of the materials response of boron carbide-coated, boron fiber-reinforced titanium is presented.
Laboratory Accreditation: More Than Rules
Authors: Harris R , Castino TG 
Published: March 2009

Effective accreditation of third-party laboratories offering product evaluation and follow-up inspection services requires a prescription of laboratory performance and measures to assure compliance with the prescription. While documenting the established criteria can be considered the major hurdle for effective laboratory accreditation, the most difficult step may well be assuring that the accredited laboratories meet and maintain desired levels of performance. An effective accreditation program is more than rules: it is evaluation, audit, and follow-up.
This paper reviews key elements of laboratory accreditation programs that must be considered to achieve the targets that the rules have established. Consideration is also given to the critical elements required by agencies implementing laboratory accreditation programs.
An analysis of hypothetical programs that lack these critical elements is presented with the purpose of demonstrating that accreditation programs lacking one or more of the critical elements are ineffective and allow laboratory performance to be lowered to a marginally acceptable level.
The Laboratory Evaluation Process of the National Voluntary Laboratory Accreditation Program
Authors: Federline MV 
Published: March 2009

At least 70 laboratory accreditation systems exist in the United States today, and many of them are directed at a single discipline or narrow spectrum of products. The increase in the number of these systems in response to a growing need for laboratory testing services indicates the viability of the laboratory accreditation concept. The National Voluntary Laboratory Acceditation Program (NVLAP) was established by the Department of Commerce to provide a national, multidisciplinary laboratory evaluation scheme.
NVLAP evaluation is based upon compliance with criteria that reflect the latest technology in laboratory operation and management. These criteria are sufficiently flexible to accommodate such diverse testing areas as thermal insulation, carpet, and concrete. The evaluation of laboratories, conducted by the National Bureau of Standards, utilizes a peer review. It combines elements of questionnaire, laboratory on-site survey, and testing of proficiency samples in a comprehensive examination to determine a laboratory’s capability to perform specific tests. NVLAP, an interactive system between laboratory and accreditor, provides a mechanism for overall laboratory improvement.
Proficiency Testing: An Essential Element of Laboratory Performance Evaluation and Accreditation
Authors: Kirkpatrick D , Horlick J 
Published: March 2009

The National Voluntary Laboratory Accreditation Program (NVLAP) is administered by the Department of Commerce to accredit testing laboratories upon request. Accreditation is currently available for laboratories that test carpet, thermal insulation materials, and freshly mixed field concrete. Decisions to accredit laboratories are based on evaluations conducted by the National Bureau of Standards which include questionnaires, on-site examination, and proficiency testing.
It was recognized early that while questionnaires and site visits could provide valuable insight into a laboratory’s ability, a true measure of its capability could only be determined through proficiency testing.
This paper discusses the design and operation of the proficiency testing portion of the evaluation of laboratories that test thermal insulation materials and carpets.
State of the Art: Laboratory Strength Testing of Soils
Authors: Saada AS , Townsend FC 
Published: March 2009

A review and evaluation of the advantages and limitations of laboratory equipment for measuring the shear strength of soils are presented. Equipment evaluated include direct shear, torsional shear, simple shear, triaxial, multiaxial (true triaxial), plane strain, hollow cylinder triaxial, and directional shear devices. The evaluation indicates that the impetus to obtain parameters for constitutive equations and modeling has resulted in the development of improved equipment and testing techniques; specifically, the development of multiaxial (true triaxial) and hollow cylinder triaxial test equipment. Although these devices are more versatile, the conventional solid cylinder triaxial test is still the most popular. The evaluation suggests that direct shear and simple shear devices are best utilized by designers who have gained experience applying the results from such tests to structures that have behaved satisfactorily.
Proper consideration must be given to the effects of membrane penetration, end restrain saturation and consolidation procedures, and rates of loading in any testing program.
A Servo System for Controlled Stress Path Tests
Authors: Law KT 
Published: March 2009

This paper describes a servo system capable of imposing a prescribed stress path for the study of soil behavior in the laboratory. Various conditions were examined: (1) stress paths resembling those in the field, (2) both axisymmetric and plane strain shearing, and (3) large strain or post failure (or yield) state.
The servo system is composed of two main parts: A minicomputer and an electric-pneumatic (E/P) transducer. The minicomputer collects and processes data while the experiment is in progress. The appropriate electrical signals are transmitted to the E/P transducer, which regulates the pressure connected to the back-pressure line of the triaxial or plane strain apparatus. With the axial load applied at a constant strain rate, it is possible to measure the complete stress-strain behavior, including that at large strains, along a prescribed stress path.
A series of tests was carried out to illustrate the capability of the servo system. For the particular case of slope stability analysis, another series of tests was conducted from which peak and post-peak strength envelopes were obtained.
State of the Art: Data Reduction and Application for Analytical Modeling
Authors: Ko H-Y , Sture S 
Published: March 2009

Due to the availability of large digital computers and advances in computational analysis techniques, it has become feasible to perform stress analyses of geotechnical structures involving complex geometries and material behavior. A key element in such analyses is the proper modeling of the constitutive behavior of soils.
Intensive research in recent years has led to a proliferation of constitutive models which have been postulated to represent soil behavior under general loading conditions. In this paper some of these models are reviewed regarding their basic assumptions and the requirement of input data for their characterization. A classification of constitutive models is given on the basis of basic approaches to relating stress and strain. Representative models from each class are selected for detailed examination, with the hyperbolic model, the elastic—perfectly plastic model, the Cam-Clay model, the cap model, Lade's model, Prevost's model, and the endochronic model being selected. Finally, a comparison is made of these models regarding their range of applicability.
Behavior of an Overconsolidated Sensitive Clay in Drained K0-Triaxial Tests
Authors: Silvestri V 
Published: March 2009

In order to understand the mechanisms that govern the development of lateral stresses in overconsolidated clay deposits, specimens of an undisturbed sensitive clay from Lachute (P.Q.) were tested in a triaxial chamber under K0-conditions. The results of these tests show that the response of the clay can be divided into three distinct phases of deformation. At low stress levels, the clay behaves as an elastic material. At intermediate stress levels, the clay behaves as a plastic material. At high stress levels, the clay becomes normally consolidated.
The experimental data are used to establish a model describing the mobilization of lateral stresses, and it is shown that the in situ coefficient of earth pressure at rest cannot be determined by laboratory testing. The theory of anisotropic elasticity is used to predict the development of lateral stresses and pore water pressures at low stress levels. Predicted values are compared with those measured underneath the St. Alban (P.Q.) test fills.
Development, Testing Requirements, and Fitting Procedure of Elastic-Plastic Models
Authors: Baladi GY 
Published: March 2009

During the past few decades the dramatic growth of computer technology has been paralleled by an increasing degree of complexity in material constitutive modeling. This paper discusses the development, testing requirements, and fitting procedure of elastic-plastic models.
A brief overview of the general characteristics of soil behavior which should be displayed by an elastic-plastic model is presented. The basic requirements and conditions of constitutive models are stated.
To construct an elastic-plastic type model the following (minimum) tests are required: (1) loading and unloading in isotropic consolidation and (2) loading and unloading in triaxial shear. Additional tests, such as uniaxial strain tests, proportional loading tests, direct shear tests, etc., are useful for verification of the model fits.
Fatigue Growth of Initially Physically Short Cracks in Notched Aluminum and Steel Plates
Authors: Leis BN , Forte TP 
Published: March 2009

Much of the fatigue life of engineering structures is spent initiating cracks at a notch and propagating one (or more) of these cracks into and through the notch stress field. Experimental results and empirical analysis suggest that early in this process the physically small crack sometimes propagates in a manner inconsistent with analysis based on linear elastic fracture mechanics (LEFM). Available empirical adjustments for this apparent aberration postulate that the data can be made consistent with LEFM by the addition of a constant, with length dimensions, to the current crack length, resulting in a pseudo-crack.
The present paper introduces and analyzes an extensive data set pertinent to this so-called short-crack problem. Included are results for notched plates made from two aluminum alloys and a steel. These plates, which contain either circular or one of two different elliptical notches, have been tested under load or displacement control and encompass both confined flow and gross-section yield. Results for crack lengths as small as 20 μm (0.0008 in.) are reported.
Data presented and analyzed do indeed show trends which differ from those of LEFM analysis of so-called long cracks. More significantly, they show that the so-called short-crack behavior does not occur only for physically short cracks. Results presented indicate that cracks as large as 2.5 mm (0.1 in.) in the aluminum alloys and 1.25 cm (0.5 in.) in the steel also exhibit aberrations in their behavior as compared with longer-crack trends. Also, the results presented suggest that the data cannot be made consistent with the LEFM trend through the addition of a constant pseudo-crack length to the current crack size as has been suggested in one of the currently popular empirical models. It is postulated that the aberrations observed are a consequence of the failure of the LEFM-based analyses to recognize that crack growth in the plastic field of the notch is dominantly displacement-controlled local to the crack tip. Other relevant aspects of the problem are also discussed.