bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Mode I and Mode II Delamination Growth and Thresholds in AS4/PEEK Composites
Authors: Martin RH , Murri GB
Published: March 2009

Composite materials often fail by delamination. As composite materials with tougher matrices are developed to give better delamination resistance, their delamination behavior needs to be fully characterized. In this paper the onset and growth of delamination in AS4/PEEK, a tough thermoplastic matrix composite, was characterized for Mode I and Mode II loadings, using the double-cantilever beam (DCB) and the end-notched flexure (ENF) test specimens, respectively. Delamination growth per fatigue cycle, da/dN, was related to strain energy release rate, G, by means of a power law. However, the exponents of these power laws were too large for them to be adequately used as a life prediction tool. A small error in the estimated applied loads could lead to large errors, at least one order of magnitude, in the delamination growth rates. Hence, strain energy release rate thresholds, Gth, below which no delamination would occur were also measured. Mode I and II threshold G values for no delamination growth were found by monitoring the number of cycles to delamination onset in the DCB and ENF specimens. The maximum applied G for which no delamination growth had occurred until at least 106 cycles was considered the threshold strain energy release rate. The Gth values for both Mode I and Mode II were much less than their corresponding fracture toughnesses. Results show that specimens that had been statically precracked in shear have similar Gth values for Mode I and Mode II for R-ratios of 0.1 and 0.5. An expression was developed which relates Gth and Gc to cyclic delamination growth rate. Comments are given on how testing effects (e.g., facial interference and damage ahead of the delamination front) may invalidate the experimental determination of the constants in the expression.
Three-Dimensional Analysis of Combined Free-Edge and Transverse-Crack-Tip Delamination
Authors: Fish JC , Lee SW
Published: March 2009

The effects of combining a localized free-edge delamination with a transverse crack in [0/90n]s (n = 1, 2, 3, and 4) glass/epoxy laminates are investigated. A three-dimensional finite-element model is used to calculate strain energy release rates associated with delamination growth. The effects of the assumed delamination size, transverse crack length, and thickness of the 90° sublaminate on the strain energy release rate are determined. Transverse cracking significantly increases the potential for delamination growth, raising the strain energy release rate by as much as two orders of magnitude. Furthermore, the introduction of a transverse crack changes the involvement of the different strain energy modes, so that the total strain energy release rate is dominated by the shearing modes with little opening mode involvement. The total strain energy release rate increases for laminates with thicker 90° laminates, but it is relatively insensitive to the size of the delamination.
A Criterion for Mixed-Mode Matrix Cracking in Graphite-Epoxy Composites
Authors: Binienda W , Wang ASD , Zhong Y , Reddy ES
Published: March 2009

In this paper, mixed-mode matrix fracture in graphite-epoxy composites was studied. Experimental investigation was conducted on a family of doubly side-notched unidirectional off-axis specimens. By varying the notch depth and the off-axis angle, a total of 28 fracture conditions of differing mixed-mode ratios were produced. Fracture analysis of the test data suggested that the total strain energy release rate is a suitable material condition for mixed-mode matrix cracking in graphite-epoxy composites.
Delamination Fracture Between Adhesive and Adherends in Bonded Joints
Authors: Chatterjee SN , Ramnath V , Dick WA , Chen YZ
Published: March 2009

The usefulness of a fracture mechanics approach for predicting failure in single lap joints with composite adherends is examined. A finite-element analysis is employed for stress analysis and calculation of strain energy release rates for small disbonds between the adhesive and the adherends. Tests conducted show that delamination growth takes place in the resin-rich areas of the adherends close to the adhesive layer. For this reason, the critical strain energy release rate determined from Mode II tests on composite adherends is used as the fracture parameter and is equated to the total energy release rate for failure prediction. Effects of large out-of-plane deformation in the adherends and nonlinear shear response of the adhesive are also studied. Data from tests with and without major bondline flaws are correlated with the analytical results. The correlations show that with proper material characterization studies and realistic stress analyses, fracture mechanics can be a useful tool for predicting the load-carrying capacity of adhesively bonded joints.
Influence of Load Levels on Damage Growth Mechanisms of Notched Composite Materials
Authors: Razvan A , Bakis CE , Reifsnider KL
Published: March 2009

The effect of cyclic load amplitudes is studied using X-ray radiography and ply level electron microscopic analysis. The influence of fatigue-induced damage on the final fracture of the laminate is presented. From the findings, it is clear that delamination and fiber fracture have well-defined roles in the final fracture of both center-notched quasi-isotropic [0/45/90/-45]s4 and orthotropic [0/45/0/-45]s4 laminates under high- and low-amplitude fully reversed cyclic loading (R = -1). Depending on the material system (eight-harness satin weave Celion 3000/PMR-15, quasi-isotropic T300/5208, and quasi-isotropic and orthotropic AS4/1808), and the load level used, interaction modes between delamination, fiber fracture, localization, and the extent of fiber fracture distribution throughout the damaged zone were found to vary. The load level was also found to influence the interaction between the adjacent fibers in the satin weave Celion 3000/PMR-15 unidirectional system.
Evaluation of the Damage Development in Carbon Fiber Reinforced Plastics by Monitoring Load-Induced Temperature Changes
Authors: Neubert H , Schulte K , Harig H
Published: March 2009

Temperature measurements are used to determine the behavior of materials under monotonic and cyclic loading. In tension tests, linear temperature stress relations result from only elastic deformations of the laminate, while deviations from linearity are indications for dissipative processes such as viscoelastic or plastic matrix deformations or crack formations. Under cyclic loading, the temperature change due to the dissipated work or due to the thermoelastic effect gives direct information about the damage state and damage development. In tests with a stepwise load increase and in constant amplitude loading tests, relations between the temperature changes and the damage state of the material can be found. Damage development is also investigated by strain measurements and radiography.
A Failure Criterion Evaluation for Composite Materials
Authors: Cron SM , Palazotto AN , Sandhu RS
Published: March 2009

Recently research has been presented on the use of off-axis tensile tests which have nearly uniform stress states along the specimen gage lengths. The uniformity of the stress state is achieved by optimizing the amount of tab clamping and selectively locating the point about which the clamps rotate. The procedure uses the linear finite-element method. However, the off-axis specimens generally exhibit nonlinear response under axial loading. This nonlinear behavior herein is analytically approximated by applying the load incrementally. Predicted and experimentally determined responses of off-axis specimens are compared. To determine the load-carrying capacity of the specimens, a criterion which is a function of both stresses and strains is used.
Composite Shear Moduli and Strengths from Torsion of Thick Laminates
Authors: Kurtz RD , Sun CT
Published: March 2009

Composite bars of rectangular cross sections are loaded in torsion to determine the principal shear moduli and interlaminar strengths. The use of rectangular cross sections greatly simplifies the fabrication of specimens. In [0], [90], and cross-plied laminates, torsional rigidity depends only on the principal shear moduli and the dimensions of the cross section. Thus, the shear moduli can be determined from the measured torsional rigidity. This procedure proves very accurate and convenient in determining the transverse shear modulus G23. The use of this technique to measure in-plane shear and interlaminar strengths is also discussed in this paper.
A Deformation-Formulated Micromechanics Model of the Effective Young's Modulus and Strength of Laminated Composites Containing Local Ply Curvature
Authors: Lee J-W , Harris CE
Published: March 2009

A mathematical model based on the Euler-Bernoulli beam theory is proposed for predicting the effective Young's moduli of piecewise isotropic composite laminates with local ply curvatures in the main load-carrying layers. Strains in corrugated layers, in-phase layers, and out-of-phase layers are predicted for various geometries and material configurations by assuming matrix layers as elastic foundations of different spring constants.

The effective Young's moduli measured from corrugated aluminum specimens and aluminum/epoxy specimens with in-phase and out-of-phase wavy patterns coincide very well with the model predictions. Moire fringe analysis of an in-phase specimen and an out-of-phase specimen are also presented, confirming the main assumption of the model related to the elastic constraint due to the matrix layers. The present model is also compared with the experimental results and other models, including the microbuckling models, published in the literature.

The results of the present study show that even a very small-scale local ply curvature produces a noticeable effect on the mechanical constitutive behavior of a laminated composite.
Experimental Investigations and a Model Proposal on Damage Mechanisms in a Reinforced Carbon-Carbon Composite
Authors: Rief C , Lindner M , Kromp K
Published: March 2009

A reinforced carbon-carbon (RCC) composite in a bidirectional lay-up was loaded in three-point bending experiments at room temperature and 1100°C. Failure by delamination was observed up to high span-to-height ratios. Under strict assumptions applicable only to that material, a model is proposed (“stack model”). The failure mode under the present loading conditions is explained well by the model. To test the validity of the model, additional experiments with a different specimen geometry must be performed.
Impact Tester Compliance: Significance, Sensitivity and Evaluation
Authors: Porro F , Trippodo R , Bertozzi R , Garagnani G
Published: March 2009

The compliance is very sensitive to internal mechanical factors concerning the load system, as the hammer, the tup, the anvils and the base to foundation attachement. In order to verify the sensitivity of compliance measurements, a series of experimental tests has been performed, with artificial and real defect located at the most critical parts. In order to overcame the need of an instrumented impact tester an instrumented specimen has been prepared, together with its electronic system for impact tester compliance measurement. The compliance measurement, after verification of the impact tester with direct and indirect methods, as per ASTM E 23 or ISO R 442, can be helpful for verification of the good working condition of the pendulum and for the detection of onset of anomalies.
Evaluation of Fabrication Method for Making Notches for Charpy V-Notch Impact Specimens
Authors: Koester RD , Barcus SE
Published: March 2009

The effect of preparing the notches for Charpy V-Notch impact specimens is evaluated. Two methods of preparation are used for this evaluation. They are grinding and broaching. Impact specimens with two energy levels were used: low energy, 15 J (11 ft∙lbf) and high energy, 94 J (69 ft∙lbf). Twenty-four specimens of each level were made with ground notches and with broached notches. Each was tested with a calibrated impact tester. The material used for the specimens was AISI-4340 alloy steel. The notch characteristics were documented by the following methods: notch angles, notch radii, surface conditions, and near-surface microstructure. Other parameters documented for this study were the ligament thickness, specimen width, and specimen length. In addition, test conditions and results are provided as follows: test temperature, absorbed energy, and lateral expansion. Besides tabular data, photographs give views of the notch surface. Evaluation of the results indicated both types of notches gave equally consistent values, but the ground and broached values differed in their averages. Possible causes for this variation were differences in ligament sizes and bottom of notch radii, surface tears and shallow microstructural deformation in the case of the broached notches.
Significance of Precracking Variables for Slow-Bend Charpy Tests
Authors: Interrante CG , Filliben JJ
Published: March 2009

The significance of four variables in the technique used to precrack Charpy specimens of metallic materials is determined by analyses of seven responses computed from results of slow-bend tests. The variables include crack size, stress-intensity factor at the start of precracking, notch preparation prior to precracking, and material. All four variables are shown here to be significant for more than one of the computed responses. Seven response parameters, each representing alternative methods for evaluations of fracture toughness, were evaluated for each test. Responses are based either on a single value of load or energy absorbed in the test. The results indicate that (1) all seven computed responses are linearly related to crack length and the sensitivity to crack length is a function of both response parameter and material, and (2) precracking at either very high or very low levels of stress-intensity factor, Kf, are to be avoided. This work is the result of a study conducted by ASTM Task Group E-24.03.03 and members of eight participating laboratories.
Influence of Thermal Conditioning Media on Charpy Specimen Test Temperature
Authors: Nanstad RK , Swain RL , Berggren RG
Published: March 2009

The Charpy V-notch (CVN) impact test is used extensively for determining the toughness of structural materials. Research programs in many technologies concerned with structural integrity perform such testing to obtain Charpy energy vs temperature curves. American Society for Testing and Materials Method E 23 includes rather strict requirements regarding determination and control of specimen test temperature. It specifies minimum soaking times dependent on the use of liquids or gases as the medium for thermally conditioning the specimen. The method also requires that impact of the specimen occur within 5 s of removal from the conditioning medium. It does not, however, provide guidance regarding choice of conditioning media. This investigation was primarily conducted to investigate the changes in specimen temperature which occur when water is used for thermal conditioning. A standard CVN impact specimen of low-alloy steel was instrumented with surface-mounted and embedded thermocouples. Dependent on the media used, the specimen was heated or cooled to selected temperatures in the range-100 to 100°C using cold nitrogen gas, heated air, acetone and dry ice, methanol and dry ice, heated oil, or heated water. After temperature stabilization, the specimen was removed from the conditioning medium while the temperatures were recorded four times per second from all thermocouples using a data acquisition system and a computer. The results show that evaporative cooling causes significant changes in the specimen temperatures when water is used for conditioning. Conditioning in the other media did not result in such significant changes. The results demonstrate that, even within the guidelines of E 23, significant test temperature changes can occur which may substantially affect the Charpy impact test results if water is used for temperature conditioning.
A Fracture Mechanics Based Model for Cumulative Damage Assessment as Part of Fatigue Life Prediction
Authors: Vormwald M , Heuler P , Seeger T
Published: March 2009

Most fatigue life prediction concepts are based on the transfer of some characteristic material data to the component under consideration. The implicitly assumed equivalence can be limited by various factors including different surface conditions, sizes, residual stress fields, and cumulative damage-related items such as transient endurance limit and load-dependent failure mechanisms. This paper concentrates on aspects related to cumulative damage and presents a model for cumulative damage assessment. It allows prediction of crack initiation life where crack initiation means the occurrence of cracks of an engineering size (≃ 1 mm). Though formulated in terms of a cumulative damage calculation, it is based on the consideration of short crack growth behavior. The main features are: • Consideration of load sequence dependent crack opening and closing levels controlled by the elasto-plastic strain history. • Damage sum (i.e., crack length) dependent decrease of the fatigue limit. • Derivation of a crack-driving parameter based on elasto-plastic fracture mechanics.

An experimental test program including two steels and an aluminum alloy and several types of loading spectra revealed the improved accuracy of the model in comparison with previous approaches. The improvement can be attributed to the consideration of the most important aspects determining the physical process of the formation and growth of short cracks under variable amplitude loading.
Thermo-Mechanical Fatigue Life Prediction Methods
Authors: Sehitoglu H
Published: March 2009

Synergistic effects of oxidation on high temperature isothermal and thermo-mechanical fatigue behavior are studied. Experiments were conducted under different strain-temperature variations and atmospheres to reveal the varying severities of oxide induced failure. Conditions conducive to intergranular creep damage under thermo-mechanical fatigue are identified, and the competing damage mechanisms are classified for steels, Ni-based superalloys, and Al alloys. Requirements and a solution procedure are outlined for a thermo-mechanical fatigue life prediction model which is then applied to 1070 steel, MarM-247 nickel-based superalloy, and A12xxx-T4 aluminum alloy.
Evaluation of the Effect of Creep and Mean Stress on Fatigue Life Using a Damage Mechanics Approach
Authors: Abuelfoutouh NM
Published: March 2009

A method for fatigue life prediction of high temperature polycrystalline materials under high rate fully reversed strain cycles (HRSC) was previously derived using a continuum damage mechanics approach. The method is generalized in this paper to predict the fatigue life of balanced cyclic creep rupture (BCCR), tensile cyclic creep rupture (TCCR), and compressive cyclic creep rupture (CCCR). It is assumed that creep deformation mechanisms dominate during the creep portion of the fatigue cycle and that plasticity mechanisms dominate during the plastic portion of the cycle. The interaction of plasticity and creep with the mean applied stress and the effect of this interaction on the fatigue life are investigated. A sample calculation is applied to René 80 at 1255 K (1800°F).
Modeling High Crack Growth Rates under Variable Amplitude Loading
Authors: Dougherty DJ , de Koning AU , Hillberry BM
Published: March 2009

A two-component crack growth model has been developed to treat fatigue crack growth under constant and variable amplitude loading. The model is based on a concept introduced by Paris which relates the crack growth to the instantaneous plastic zone size ahead of the crack-tip. This concept was applied to describe crack growth in the presence of cyclic and primary plastic flow. The model was formulated on an incremental basis in which a particular component of the model is integrated about a discrete portion of the load excursion. The model includes the effects of cyclic and monotonic crack growths and crack closure. The results for fatigue crack growth data reported in the literature for multiple overload and severe flight sequences are compared with the model predictions. The model was shown to describe accelerated crack growth behavior typically observed during these sequences. Acceleration effects occur in the presence of primary plastic flow which is related to the ductile tearing mechanism and is not dependent upon crack closure or other load-history effects. Moreover, the model describes the phenomenological variation of the acceleration effects over such sequences. The predicted crack growth agrees well with the experimental data.
Small Crack Growth in Multiaxial Fatigue
Authors: Reddy SC , Fatemi A
Published: March 2009

The small crack problem in multiaxial fatigue is studied using available crack growth data from thin-walled tubular specimens made of Inconel 718 and 1045 HR steels. The loadings consist of axial, torsional, proportional and nonproportional axial-torsional with or without mean stress, and biaxial tension tests. An equivalent strain based intensity factor range based on Irwin's energy release rate, as well as a proposed strain based intensity factor range formulation based on the critical plane approach, are used to correlate the crack growth data obtained from different loading conditions. The proposed formulation is an attempt to present a unified approach to crack initiation as well as crack propagation, based on the physical mechanisms of the multiaxial fatigue damage process. Crack growth rate correlations and small crack effects with respect to the microstructure and different loading paths are discussed.
Failure Modes in a Type 316 Stainless Steel under Biaxial Strain Cycling
Authors: Zamrik SY , Davis DC , Kulowitch PJ
Published: March 2009

Discussed are the failure modes observed in a Type 316 stainless steel under biaxial high temperature low cycle fatigue (HTLCF) and creep-fatigue strain cycling. All tests were carried out in air at 621°C (1150°F) using thin-walled tubular type specimens specially designed for axial, torsional, and combined axial-torsional (biaxial) cyclic loadings. Results from HTLCF and creep-fatigue tests at six different biaxiality ratios (λ = Δγxy/Δεxx): 0.0, 1.0, 2.0, 2.5, 3.6, and ∞, are given. At these biaxiality ratios, crack initiation in HTLCF is a shear process and crack propagation occurs mainly in a normal mode. With the introduction of creep through a combined in-phase tensile-torsional hold-time imposed on the biaxial HTLCF cycle, the direction of the crack propagation was found to be dominated by the axial creep-fatigue component. These results are compared with some multiaxial fatigue strain-based failure criteria.
Damage Evaluation in Composite Materials Using Thermographic Stress Analysis
Authors: Zhang D , Sandor BI
Published: March 2009

Damage in composite materials initiates and propagates randomly at many sites, which makes both the monitoring and evaluation of its local and global effects difficult. The recently developed thermographic stress analysis method (TSA) provides unique opportunities for full-field damage investigation. To make quantitative analysis possible, a thermoelasticity theory for damage in anisotropic materials was developed. The TSA method associated with this theory opens new doors in investigating the microstructure-mechanics connection of multiphase materials, and in establishing quantitative prediction capabilities of microscopic behaviors and service lives.

Experiments have been performed to measure the damage parameter D, the normalized effective mass density ρc/ρ, and the effective modulus Ec in glass/epoxy [0/90/0/90/0]sand [0/90]5 laminates by the TSA method. Good correlations between the effective moduli of the laminates measured by the TSA method and by an extensometer are found. A relationship between the effective modulus Ec, the undamaged material's modulus E, the number of damaging cyclic loads N, and the peak nominal stress σmax is used to describe the progressive reduction of the modulus. In light of the new thermoelasticity theory for damage, the normalized effective mass density is determined quite easily by the TSA method in comparison with conventional experimental techniques.
Fatigue Life Prediction and Experimental Verification for an Automotive Suspension Component Using Dynamic Simulation and Finite Element Analysis
Authors: Baek WK , Stephens RI
Published: March 2009

An integrated fatigue life prediction methodology is presented using multi-body dynamic simulation, finite element analysis, and fatigue life prediction methods. This methodology was applied for predicting the finite life of an automotive suspension component. Experimental verification of the predicted life is described. The results indicate this integrated fatigue life prediction methodology can be used as a reliable tool to reduce expense and time of design iteration.
Plasticity and Fatigue Damage Modeling of Severely Loaded Tubing
Authors: Tipton SM , Newburn DA
Published: March 2009

The deformation and fatigue behavior of a tubular component under repeated flexural bending and static internal pressure are investigated. The bending strains induced in the component result in gross cyclic plasticity and fatigue lives on the order of a few hundred cycles. Results from a case study are presented that describe considerations in measuring dynamic, high elongation strains using a variety of experimental techniques during full-scale component testing. Measured strains are used with an incremental plasticity model to compute corresponding tube stresses and utilized in an algorithm to predict tube fatigue behavior. A number of local strain-based multiaxial fatigue theories are investigated, including several critical plane approaches, an extension of Sines methodology, an approach which considers hydrostatic stress effect and plastic work. Several of the theories make reasonable life estimates for tests involving negligible internal pressure but do not reflect the damage imposed by higher values of internal pressure. Nonlinear damage summation may be required to correlate fatigue lives.
Toward Digital Geologic Map Standards: A Progress Report
Authors: Ulrich GE , Reynolds MW , Taylor RB
Published: March 2009

Establishing modern scientific and technical standards for geologic maps and their derivative map products is vital to both producers and users of such maps as we move into an age of digital cartography. Application of earth-science data in complex geographic information systems, acceleration of geologic map production, and reduction of publication costs require that national standards be developed for digital geologic cartography and computer analysis.

Since December 1988, under commission of the Chief Geologist of the U.S. Geological Survey and the mandate of the National Geologic Mapping Program (with added representation from the Association of American State Geologists), a committee has been designing a comprehensive set of scientific map standards. Three primary issues were: (1) selecting scientific symbology and its digital representation; (2) creating an appropriate digital coding system that characterizes geologic features with respect to their physical properties, stratigraphic and structural relations, spatial orientation, and interpreted mode of origin; and (3) developing mechanisms for reporting levels of certainty for descriptive as well as measured properties.

Approximately 650 symbols for geoscience maps, including present usage of the U.S. Geological Survey, state geological surveys, industry, and academia, have been identified and tentatively adopted. A proposed coding system comprises four-character groupings of major and minor codes that can identify all attributes of a geologic feature. Such a coding system allows unique identification of as many as 105 geologic names and values on a given map.

The new standard will track closely the latest developments of the Proposed Standard for Digital Cartographic Data soon to be submitted to the National Institute of Standards and Technology by the Federal Interagency Coordinating Committee on Digital Cartography. This standard will adhere generally to the accepted definitions and specifications for spatial data transfer. It will require separate specifications of digital cartographic quality relating to positional accuracy and ranges of measured and interpreted values such as geologic age and rock composition.

Provisional digital geologic map standards will be published for trial implementation. After approximately two years, when comments on the proposed standards have been solicited and modifications made, formal adoption of the standards will be recommended. Widespread acceptance of the new standards will depend on their applicability to the broadest range of earth-science map products and their adaptability to changing cartographic technology.
Remote Sensing and Geographic Information Systems: Image-Integrated Geographic Information Systems
Authors: Ehlers M
Published: March 2009

Remote sensing image analysis systems and geographic information systems (GIS) show great promise for the integration of a wide variety of spatial information as a support to tasks such as urban and regional planning, natural resources management, agricultural studies, topographic and thematic mapping, civil engineering, hydrology studies, and geological exploration. Current and future remote sensing satellite programs are based on a variety of imaging sensors that will provide timely and repetitive multisensor earth observation data on a global scale. Visible, infrared, and microwave images of high spatial and spectral resolution will be available eventually for all parts of the earth. However, it is essential that efficient synergistic processing techniques be developed to cope with the large multisensor data volumes and to allow efficient GIS integration.

Many preliminary efforts to unite remote sensing and GIS into one technology for information management have been made over the past few years, both in the commercial and the academic world. In the first part of this paper, some of the achievements so far in the areas of topographic mapping, cartographic feature extraction, and urban and regional planning are discussed. A characteristic of most successful integrated systems is that they are confined to very specific problems. In the second part of the paper, these successes are placed in the context of a vision of longterm integration. Obstacles and concerns related to such integration are discussed.
Application of Remotely Sensed Data to Geologic Exploration Using Image Analysis and Geographic Information Systems
Authors: Hornsby JK , Harris JR
Published: March 2009

Remotely sensed data are becoming widely applied to geologic exploration activities throughout the world. With the proliferation of geographic information systems (GIS) the potential contribution of remote sensing to geologic mapping has increased. This paper addresses some current, largely experimental, as well as operational methods for using remotely sensed data for geologic mapping using examples from Nova Scotia and Newfoundland, Canada.

Investigations were conducted into integrating and modelling geologic data sets including remote sensing derived geological information, geochemical, and geophysical data sets within a geographic information system. Techniques for incorporating remotely sensed data into the modelling of different geologic data sets were addressed.

Results have indicated useful remotely sensed data products for incorporation into a GIS. Two approaches to modelling of the geologic data sets for mineral exploration were demonstrated. The first approach uses a priori geologic knowledge (mineral deposit model) to drive the modelling procedures whereas the second does not rely on a priori knowledge and focuses on the definition of anomalies in each data set.

A comparison was made between state-of-the-art methods of data integration for mineral exploration within a GIS and current operational methodologies.
Using AutoCAD as a Desktop Geographic Information System for Hydrogeological Investigations
Authors: Varljen MD , Wehrmann HA
Published: March 2009

The popular personal computer-based computer aided drafting program AutoCAD has been utilized for the purpose of assembling and mapping information for ground-water quality studies. The power of this methodology for information management is its capacity to coalesce information from many different sources and formats, and present it in a common graphical format. The basis of this system consists of commercially available AutoCAD drawing files created from U.S. Geological Survey digital databases which contain information on terrain elevations, the location of transportation and water features, and the names of cities, towns, and major landmarks. Using these drawing files as base maps, a graphical hydrogeological database for a particular area can be assembled by importing different types of information such as bedrock topography, hydraulic conductivity distributions, or potential contaminant source locations into different data planes, or layers. Any desired combination of layers can be displayed concurrently at the same scale. Furthermore, output from ground-water flow or contaminant transport models as well as statistical estimation routines can be imported and displayed simultaneously in correct geographic orientation in relation to previously mapped features. This capability of overlaying mapped information allows for the recognition of data relationships that might not have been apparent otherwise. Examples are provided which illustrate all of these operations and indicate how appropriate mapping of available information can provide valuable insight for hydrogeological investigations.
Development of Ground-Water Vulnerability Database for the U.S. Environmental Protection Agency's Hazard Ranking System Using a Geographic Information System
Authors: Clarke JS , Sorensen JW , Strickland HG , Collins G
Published: March 2009

Geographic information system (GIS) methods were applied to the U.S. Environmental Protection Agency's (EPA) hazard ranking system (HRS) to evaluate the vulnerability of ground water to contamination from actual or potential releases of hazardous materials from waste-disposal sites. Computerized maps of four factors influencing ground-water vulnerability—hydraulic conductivity, sorptive capacity, depth to water, and net precipitation—were derived for the Southeastern United States from digitized copies of published maps and from computerized databases, including the U.S. Geological Survey's (USGS) national water information system.

To test the accuracy of the derived data coverages used to assess ground-water vulnerability, GIS-derived values for hydraulic conductivity, depth to water, and net precipitation were compared to corresponding values assigned by EPA's field investigation teams (FIT) at 28 hazardous waste sites. For each factor, site data were divided into three physiographic groupings:(1) Coastal Plain, (2) Valley and Ridge-Interior Low Plateaus, and (3) Piedmont-Blue Ridge. The best correlation between the paired data sets was for the net precipitation factor, where most GIS-derived values were within 0 to 40% of the FIT data, and 79% were within the same HRS scoring range. for the hydraulic conductivity factor, the best correlation between GIS and FIT data was for values derived from a published surficial deposits map, where most of the values were within one order of magnitude of the FIT data, and on the average were within 1.24 orders of magnitude of the FIT data. For this map, the best match between data sets was in the Coastal Plain province, where the difference in order of magnitude averaged 0.92. For the depth-to-water factor, most of the GIS derived values were within 51 to 100% of the FIT data, and only 44 to 50% of the sites were within a common scoring range. The best correlation for depth to water was in the Coastal Plain where GIS derived values were within 8 to 10% of the FIT data.
Use of Geographic Information System Technology for Siting a Low-Level Radioactive Waste Disposal Facility
Authors: Connolly KJ , Dressen AL
Published: March 2009

A geographic information system (GIS) was used for siting a low-level radioactive waste disposal facility for the state of New York. The New York State Low-Level Radioactive Waste Management Act, passed in 1986, established a framework for developing a low-level radioactive waste disposal facility that will accept only New York's waste. Under the terms of the law, the Low-Level Radioactive Waste Siting Commission bears the responsibility for selecting an appropriate site and disposal method for the facility

A stepwise screening process that effectively applies a systematic GIS methodology to assist in the selection of one or more suitable sites was used. Such a process allows clear documentation and traceability for the siting methodology. The process is designed to balance geologic, hydrologic, and environmental considerations with social, economic, and political needs, while incorporating ideas and recommendations identified through a public involvement program. The process provides a number of key decision-making points where public involvement can be solicited and also allows for public education efforts to gradually build as the focus of the screening process narrows down to the more local level, where the degree of public interest and concern is expected to be the greatest. The Commission and its consultant team have completed the following three steps in the screening process: Step 1—Statewide exclusionary screening to eliminate areas where regulatory or legal constraints prohibit the development of a low-level waste disposal facility. Step 2—Screening of the remaining areas using additional criteria to identify ten candidate areas with the greatest potential for suitable sites. Step 3—Detailed screening of the candidate areas, limited on-site observations, and comparative evaluations to identify five potential sites that may be suitable for waste disposal.

Spatial information used in site screening is being carried forward and will be supplemented with the site-specific data from detailed on-site characterization studies. The GIS and database management technologies will be used to manage the voluminous data that will result from characterizing five sites and will support decision-making on the selection of a preferred site for licensing.
ITEMS: A Workbench for Environmental Data Processing and Display
Authors: Duplancic N , Buckle G , Montojo L
Published: March 2009

A database management system has been developed for recording, processing, and displaying analytical and environmental data. The system is being used to support monitoring studies, investigations, and remedial actions at hazardous waste sites. The various modules of the system allow the user to enter field data; receive analytical results in electronic format; prepare standard and ad hoc reports; produce graphs; construct two- and three-dimensional plots of ground water elevations and contaminant concentrations; and automatically generate boring logs. Easy-to-use interfaces are provided to standard off-the-shelf software packages. A unique feature of the system is a reference chemical database consisting of over 2500 of the most commonly tested chemical substances. The system, which is entirely menu-driven, runs on MS-DOS microcomputers.
Waste Site Characterization and Prioritization Using a Geographic Information System
Authors: Soby MT , Connolly KJ , Folsom R
Published: March 2009

The Department of Defense (DOD), is faced with the monumental task of assessing the extent to which its past activities have effected the environmental quality of the properties it owns. Also, because of limited budgets, DOD needs to establish the capability to prioritize the waste sites based on various criteria including, but not limited to, the types, levels, and location of contaminants and site scoring generated through the use of a variant of EPA's hazard ranking system (HRS) model. In support of these efforts a geographic information system (GIS), is being used to store, analyze, summarize, and report on the prodigious amounts of data collected by field crews. Particular areas to be discussed include the design of the system (that is, the user interfaces, the database schemas, and the software), types of data accepted by the system, the analyses performed, the standard information (that is, reports) provided, ad hoc reporting capabilities, and the use of the GIS to produce highly complementary, single or multithematic base maps. The overall project (which these tools/systems are supporting), currently in the site precharacterization phase, is being undertaken by both DOD and several WESTON technical groups.
The Use of Steel Slag in Asphaltic Concrete
Authors: Ali NA , Chan JSS , Papagiannakis T , Theriault EG , Bergan AT
Published: March 2009

Advanced testing and evaluation were performed on laboratory prepared Marshall specimens from eight asphalt concrete mixes. Five of these mixes contain steel slag aggregates. These were characterized and results were compared to the remaining three conventional asphalt concrete mixes commonly used in the province of Nova Scotia, Canada. Advanced testing included indirect tensile strength, resilient modulus, creep and permanent deformation, moisture damage, and fatigue. Laboratory results showed that asphalt mixtures containing steel slag aggregates exhibited more superior characteristics than those of conventional mixes. Pavement performance of three idealized pavement cross-sections were modelled using VESYS and with material properties measured. Mixes which contained 100% steel slag aggregate had shown better resistance to rutting and to cold temperature cracking.
Effects of Aggregate Absorption and Crush Percentage on Bituminous Concrete
Authors: Bouchard GP
Published: March 2009

Recently, the push to improve bituminous concrete mixtures has resulted in higher fractions of crushed aggregate. Since coarse aggregate is becoming more difficult to extract as gravel sources are depleted, the cost of supplying crushed aggregate is increasing. Adding too much crushed aggregate can produce two mechanisms for problem mixes. The first arises from the crushing and washing of the manufactured fines portion of the aggregate. Hammermill, impact or cone crushers have a tendency to produce gradations for fine aggregates below the maximum density line when washed. This can lower the voids in mineral aggregate which is important to resist rutting.

A theory is advanced that aggregate water absorption can be used to predict the bonding surface volume available to improve results of heavy traffic mixes. Let the bonding surface volume be defined as the volume around each particle opened by pores. The second mechanism can be described as the propensity for shearing of mastic to aggregate bonds over time when aggregates with low water absorption values are used. Marshall stability tests for a mix using aggregates with generally high values of water absorption are compared to tests for a mix using aggregates with low values of water absorption. The conclusion supports the premise that shearing under load increases as average water absorption values decrease.
Effect of Filler Type and Content on Properties of Asphalt Concrete Mixes
Authors: Al-Suhaibani A , Al-Mudaiheem J , Al-Fozan F
Published: March 2009

Some of the newly constructed highway pavements in the Kingdom of Saudi Arabia have shown premature failures with consequential negative impacts on both roadway safety and economy. A major type of these failures is permanent deformation (rutting). Fillers were suspected to be major contributors to rutting susceptibility. The effect of filler type and content on the rutting potential of asphalt concrete as well as other mixes properties was investigated. The wheel tracking test (LCPC) was employed to investigate susceptibility of these mixes to rutting. The mechanical properties of mixes were studied using tests such as resilient modulus, indirect tensile strength, Hveem stability and Marshall criteria. Results of this study indicate that partial replacement of limestone dust by hydrated lime or portland cement aggravates resistance of the mixes to rutting. Furthermore, an analytical model was developed for predicting rutting potential based on various mixes properties.
A Simple Method for Determining the Surface Area of Fine Aggregates and Fillers in Bituminous Mixtures
Authors: Chapuis RP , Légaré P-P
Published: March 2009

In bituminous mixtures the finer fraction of the sand and the filler have the highest surface area or specific surface. Surface related physico-chemical properties are known to largely influence the performance of asphalt mixtures. Usual methods to determine the surface area are approximate, often based on local experience with specific crushed rock materials. They may yield poor estimates of the true surface area. This paper proposes a simple method which does not involve an interpretation of the operator to visually determine some shape factor. Only the gradation curves of the fine aggregate and the filler, and their apparent specific gravity are considered in the proposed method, which does not use a shape factor or “fudge” factor. This method is demonstrated with five fillers for which the surface area was measured independently according to ASTM C 204.
Laboratory Evaluation of Rutting Potential of Asphalt Mixtures
Authors: Fwa TF , Tan SA
Published: March 2009

This paper describes a laboratory procedure to evaluate the rutting potential of asphalt mixtures using a wheel tracking machine. Moving loads were applied through solid rubber tired wheels that travel with a reciprocating motion on slab specimens of asphalt mixtures. The specimens were prepared in parallepipedal steel molds by means of static compression to achieve fairly uniform density distribution within individual specimens. The machine allows rut tests to be conducted at different temperatures, magnitudes of applied loads, and speeds of loading. Results of a test program are reported to illustrate the application of the procedure to study the effects of temperature and loading speed on rut development in an asphalt mixture.
Effects of Aggregate Type and Gradation on Fatigue and Permanent Deformation of Asphalt Concrete
Authors: Kim YR , Kim N , Khosla NP
Published: March 2009

This paper presents laboratory test results demonstrating the effects of aggregate type and gradation on fatigue and permanent deformation of asphalt concrete. Diametral fatigue tests and uniaxial incremental static creep tests were performed under varying temperatures and mixture variables, including aggregate type and gradation.

The effects of aggregate type and gradation on permanent deformation were evaluated under test combinations with changing asphalt type, asphalt content, air voids content, temperature, and applied stress level. For the fatigue study, the effect of aggregate type was evaluated by changing asphalt content, air voids content, and temperature. The test results were analyzed using statistical analysis and graphical comparison of data. The analysis of variance (ANOVA) tests were performed to investigate the main effects and interactions of the test variables with the aggregate type or gradation.

The analysis revealed that, with the size of experimentation used in this study, aggregate type has significant effects on fatigue resistance and permanent deformation of asphalt concrete, indicating better performance from the mixtures comprised of aggregates with a rough surface texture and an angular shape. Coarse gradation, meaning a larger proportion of coarse aggregates with the same nominal maximum aggregate size compared to medium gradation, did not show significant effects on permanent deformation. Interactions of aggregate type with gradation, asphalt type, air voids, and temperature were found to be significant for the permanent deformation of asphalt concrete, whereas no interaction appeared to be significant for fatigue with the given size of experimentation.