bluuebunny/crossref_metadata_2025 huggingface dataset:
Realism in Cyclic Cabinet Corrosion Testing of Coil-Coated Steel for Building Applications
Authors: Lyon SB , Scantlebury JD , Johnson JB
Published: March 2009

ASTM B-117, Method of Salt Spray (Fog) Testing, is one of the most widely used methods for accelerated materials testing. The test is often used both for quantitative and for relative (i.e. ranking) performance testing of uncoated and particularly coated materials. Although the test is well accepted, the use of a continuous spray of 5% NaCl solution does not reproduce natural weathering conditions. In addition, assessment criteria are generally based on subjective methods such as visual standards. For these reasons the use of the unmodified test has recently become subject to extensive criticisms. Specific data from a controlled test programme on pre-coated steel panels are reported here and provide a direct comparison between B-117 and a cyclic wet/dry spray test using artificial acid rain solution. Results show that the angle to the vertical at which the samples are set (the pitch) is a major factor in achieving realistic data. This has relevance in the testing of coil coated products for use in the roofing and siding of buildings. Also the wet/dry test de-emphasises less important factors (such as blistering) while retaining significant discrimination to edge and scratch disbondment (at shallow pitch). Additionally, the use of objectivity in assessment of coating performance, for example by accurate measurement of degree of disbondment, is demonstrated in this work. The use of image analysis and digital imaging of current photographic standards as a properly objective tool is suggested.
Update on the Development of an Improved Cosmetic Corrosion Test by the Automotive and Steel Industries
Authors: Roudabush LA , McCune DC , Townsend HE
Published: March 2009

The American Iron and Steel Institute's (AISI) Task Force on Automotive Corrosion is making significant progress in its continuing efforts towards development of an accelerated laboratory test for ranking the cosmetic corrosion resistance of automotive steel sheet products. This paper provides an overview of this work and reviews major accomplishments to date. Accelerated tests conducted by the AISI and by the SAE's Automotive Corrosion and Prevention Committee (ACAP) Division 3 are compared to long-term on vehicle exposure tests now in progress for four years in Montreal, Quebec and St. John's, Newfoundland. A license-plate exposure test has also been initiated to broaden the basis for real-world performance. Statistical methods for comparing the results of the various tests are described. A designed experiment (Plackett-Burman L8) is under way to evaluate the effects of seven key cycle test parameters on the rankings of the test materials in a laboratory cyclic corrosion test.
Aspects of Contact Dynamics Relevant to Wear
Authors: Soom A
Published: March 2009

An overview is provided of the generation and modeling of dynamic loads and motions that can occur at sliding contacts. Dynamic loads can be generated by disturbances within the contact or can be transmitted from remote locations within a system. The presence of contact vibrations can add fluctuating loads to the average loads that must be supported, potentially increasing wear. Due to the nonlinear character of most contacts, dynamic loads can affect both the instantaneous motions and the average configuration of a sliding system. These motions can increase or decrease wear rates, depending on the circumstances. Sliding contacts exhibit mechanical stiffness and damping behavior, often ignored, which, in conjunction with the loading and overall system characteristics, determine contact loads and motions. Furthermore, the running in and wear of surfaces can alter the dynamic characteristics of both the contact and the sliding system.
Bearing Forces as a Function of Mechanical Stiffness and Vibration Isolation in a Fourbar Linkage
Authors: Norton RL , Ault HK , Wiley J , Parks T , Calawa R , Wickstrand M
Published: March 2009

A fourbar linkage test-bed has been designed, built, and instrumented to measure the effects of dynamic balancing, vibration isolation and system stiffness on the dynamic forces and torques generated at the pivot bearings and on the ground plane. The system was initially designed and modelled using the Aries solids modelling package, the ADAMS dynamic simulation package, program Dynafour, and ANSYS finite element analysis software. The theoretical dynamic forces and accelerations at particular points on the links were calculated in advance, based on the system kinematics and the mass properties of all moving members as defined by the Aries solids modeller. The device was built using accurate NC machining equipment. The finished assembly is instrumented with piezoelectric accelerometers and force transducers. The design allows three bivalent modalities of operation, unbalanced/dynamically balanced, stiff/compliant torque coupling, stiff/compliant motor mounts, all of which may be intermixed in various combinations. The assembly was run under all combinations of modalities and the dynamic forces and accelerations measured and transformed to the frequency domain. The results were subjected to an analysis of variance and compared to those of the theoretical model. The differences were statistically significant in all but a few cases. As expected, the compliances and clearances in the physical model created significantly larger dynamic accelerations, torques and forces on the bearings than was predicted theoretically by a rigid dynamic model. These increased forces will affect bearing and journal wear. This paper reports on the details of this experimental/theoretical study and draws some conclusions relevant to making design decisions applicable to similar mechanical devices. Work is continuing on the theoretical modelling of the system's nonlinearities as well as on measurement of the effects of bearing clearances on the vibration and modal behavior of the physical system.
Limits of J-T Characterization of Elastic—Plastic Crack—Tip Fields
Authors: Wang Y-Y , Parks DM
Published: March 2009

Plane strain elastic-plastic analyses were performed on a variety of 2-D planar cracked geometries and loading conditions, based on a small strain formulation and de-formation theory plasticity (termed finite boundary (FB) analysis hereafter). For the majority of the cases analyzed, the crack-tip fields in the mechanistically significant region around the crack tip agreed well with those of the corresponding modified boundary layer (MBL) solutions for load levels up to large scale yielding. The crack-tip fields in the MBL solutions were normalized using the elastic-plastic J values and the elastically-scaled T-stress values of the corresponding FB specimens. However, good agreement could be obtained with (J, T) only up to moderate scale yielding for a center-cracked tension (CCT) geometry. At large scale yielding, the MBL solution based on the elastically-scaled T-stress could not capture the effects of crack tip stress and strain redistribution in the CCT. An alternative method was proposed to calculate the T-stress using weight functions and the elastic-plastic remote stress field of the CCT (termed effective T-stress). Incorporating the effective T-stress into the MBL solutions, good agreement in both stress and strain fields was obtained between the MBL solution and the FB CCT solution at load levels up to general yielding. To demonstrate the limits of two-parameter characterizations in accurately describing elastic-plastic cracktip fields, a three-point-bend specimen was analyzed for load levels up to large plasticity. It is shown that although Q-values could be operationally defined at large plasticity, in general, no complete, consistent, two-parameter description was forthcoming to accurately describe the crack-tip stress and strain fields beyond certain limits. The inherent limits of two-parameter characterization of elastic-plastic crack tip fields should be recognized, analogous to those of one-parameter (J) characterization. A locus of two-parameter (J, T) characterization limits is proposed based on the crack-tip stress fields of the geometry and loading configurations analyzed. The J-T based two-parameter approach is shown to greatly extend the validity domain of fracture mechanics analysis for specimens with negative T-stress.
Modeling Crack Growth Resistance Using Computational Cells with Microstructurally—Based Length Scales
Authors: Shih CF , Xia L
Published: March 2009

Many metals which fail by void growth mechanism display a macroscopically planar fracture process zone of one or two void spacing in thickness characterized by intense plastic flow in the ligaments between the voids. To model this process cell elements, each of which contains a void, are employed on the plane ahead of the initial crack. The linear dimension of these elements is D. We use Gurson model to describe the hole growth in a cell resulting in material softening and, ultimately, loss of stress carrying capacity leading to void coalescence and formation of new crack surface thereby advancing the crack. The void-free material surrounding the cells is described by the J2 flow theory of plasticity. The two cell parameters, D and f0, characterize the mean spacing and volume fraction of voids in the material lying in the plane of fracture.

Finite element calculations have been carried out for plane strain, mode I crack growth under small scale yielding. A wide range of fracture behavior is captured by proper combinations of D and f0 Resistance curves are calculated for crack extensions two orders of magnitude larger than D. The parameters affecting fracture resistance are discussed emphasizing the roles of microstructural parameters and continuum properties of the material. Geometry effects on fracture resistance are investigated by way of the T-stress. As a final application, resistance curves for a deep and a shallow crack bend bar are computed. These are compared with experimental data.
The Second Parameter in J-R Curves: Constraint or Triaxiality ?
Authors: Brocks W , Schmitt W
Published: March 2009

J-R curves are used to assess the stability of growing cracks in ductile materials. Since initiation and crack-extension resistance are geometry dependent any transfer of the measured data to a structural component is subject to the individual responsibility of the engineer. The introduction of a second parameter for failure assessments beyond J-control has, therefore, been widely discussed, recently, and different approaches have been used to quantify the local stress triaxiality and crack tip constraint. Three basic ideas underlie these various approaches, — including higher order terms in the analysis of asymptotic fields at the crack tip, — utilizing the J-CTOD relationship as a measure of crack tip constraint,-considering micro-mechanisms of ductile failure.

Before adding new results of tests or calculations to the existing ones it seems worthwhile to discuss the different concepts with respect to their advantages and drawbacks, limitations and generality of application, physical evidence, etc. It seems that constitutive models of damage have the highest degree of physical evidence and generality of applications. “Constraint effects” do not even arise as separate problems since triaxiality of stresses enters the model directly. The investigation of micro-mechanical mechanisms helps to identify significant parameters.
Interpretation of Constraint Effects Under PTS Conditions Based on J-Q Fracture Methodology
Authors: Shum DKM
Published: March 2009

This study explores the possibility of using J-Q-related constraint concepts to describe the nature of the crack-tip loading in a reactor pressure vessel (RPV) under pressurized thermal shock (PTS) conditions. The fracture response of an RPV subjected to three postulated PTS transients that incorporate effects of loading, unloading and reloading (via repressurization) of the crack tip has been examined. Analysis results indicate that minimal loss of constraint relative to conditions of K-dominant small-scale yielding (SSY) is observed during the monotonic-loading phase of the transients. The extent of constraint loss upon reloading is sensitive to the time of repressurization, with minimal (significant) loss of constraint observed for the transient with “early” (“late”) repressurization. The nature of the constraint loss, when it occurs, corresponds to a spatially varying hydrostatic field relative to K-dominant SSY conditions. Based on an assumed correlation between loss of crack-tip constraint and fracture toughness, preliminary analysis results indicate that inclusion of constraint effects could provide significant reduction in the value of the calculated conditional probability of vessel failure relative to their exclusion.
Charpy Impact Test Results on Five Materials and NIST Verification Specimens Using Instrumented 2-mm and 8-mm Strikers
Authors: Nanstad RK , Sokolov MA
Published: March 2009

The Heavy-Section Steel Irradiation Program at Oak Ridge National Laboratory is involved in two cooperative projects, with international participants, both of which involve Charpy V-notch impact tests with instrumented strikers of 2-mm and 8-mm radii. Two heats of A 533 grade B class 1 pressure vessel steel and a low upper-shelf (LUS) submerged-arc (SA) weld were tested on the same Charpy machine, while one heat of a Russian Cr-Mo-V forging steel and a high upper-shelf (HUS) SA weld were tested on two different machines. The number of replicate tests at any one temperature ranged from 2 to 46 specimens. Prior to testing with each striker, verification specimens at the low, high, and super high energy levels from the National Institute of Standards and Technology (NIST) were tested. In the two series of verification tests, the tests with the 2-mm striker met the requirements at the low and high energy levels but not at the super high energy. For one plate, the 2-mm striker showed somewhat higher average absorbed energies than those for the 8-mm striker at all three test temperatures. For the second plate and the LUS weld, however, the 2-mm striker showed somewhat lower energies at both test temperatures. For the Russian forging steel and the HUS weld, tests were conducted over a range of temperatures with tests at one laboratory using the 8-mm striker and tests at a second laboratory using the 2-mm striker. Lateral expansion was also measured for all specimens and the results are compared with the absorbed energy results. The overall results showed generally good agreement (within one standard deviation) in energy measurements by the two strikers. Load-time traces from the instrumented strikers were also compared and used to estimate shear fracture percentage. Four different formulas from the European Structural Integrity Society draft standard for instrumented Charpy test are compared and a new formula is proposed for estimation of percent shear from the force-time trace.
Design and Evaluation of a Verification System for Force Measurement Using Instrumented Impact Testing Machines
Authors: Mackin TJ , Tognarelli DF
Published: March 2009

A series of controlled impact experiments using a charpy pendulum were conducted to address the possibility of dynamic verification and calibration of instrumented tups. The methodology involved striking an instrumented pendulum tup against a rigidly fixtured transducer. The guiding principal is as follows: If a NIST traceable dynamic load cell is impacted by a service load cell, a comparison of the signals can be used to verify the performance of the service load cell. In this fashion, tups can be verified and calibrated electronically, without resorting to the use of standard test specimens. A relatively compliant Nylon bumper was placed between the pendulum tup and the fixed load cells to dampen the excitation of high frequencies during the impact event. During each impact, load-time signals measured by both the pendulum and fixtured tups were recorded, compared and Fourier analyzed. Results of the Fourier analysis justified a simple two-mass-two-spring model of the impact behavior. Results of the experiments are rationalized using the mass-spring model, and present guidelines for designing a verification system for both pendulum and drop-weight testing machines.
Fatigue Crack Growth Measurements in TMF Testing of Titanium Alloys Using an ACPD Technique
Authors: Dai Y , Marchand NJ , Hongoh M
Published: March 2009

A thermal-mechanical fatigue (TMF) testing system has been developed which is capable of studying the fatigue behaviors of gas turbine materials under simultaneous changes of temperatures and strains (or stresses). Furthermore, an advanced alternating current potential difference (ACPD) measurement technique has been developed successfully to perform on-line monitoring of fatigue crack initiation and growth in specimens tested under isothermal and TMF conditions. In this paper, the basic principles of the ACPD technique as well as all the relevant experimental procedures for performing ACPD measurements, including probe setup, choice of alternating currents (AC) and frequencies, noise rejection, data acquisition, and signal processing, are described. The linear relationship between ACPD signals and crack lengths, as well as the effects of thermal cycling on the ACPD signal, are presented and discussed. The capabilities of the TMF and ACPD systems are well illustrated by fatigue crack initiation and growth test results under isothermal and TMF conditions. These tests were performed on two titanium forgings, Ti-6Al-4V (Ti64) and Ti-6Al-2Sn-6Mo (Ti6246), respectively. Alloy Ti64 was TMF cycled between 150 and 400°C, while Ti6246 was cycled between 200 and 482°C. The resolution for detecting crack initiation at the root of notches was found to be 50 μm with 95% confidence while the resolution for crack growth was 2 μm per mV change of ACPD. An environmental assisted cracking model applied to TMF crack growth is proposed for rationalizing the data.
Nondestructive Crack Size and Interfacial Degradation Evaluation in Metal Matrix Composites Using Ultrasonic Microscopy
Authors: Karpur P , Matikas TE , Blodgett MP , Jira JR , Blatt D
Published: March 2009

Ultrasonic scanning acoustic microscopy is a nondestructive method useful for material elastic property quantification as well as crack size determination for surface and subsurface cracks. The advantage of the method over destructive methods for crack size determination is that the imaging technique can provide the crack sizing information while helping in the detection of interface degradation and early crack initiation so that their growth can be monitored during interrupted fatigue tests. Various metal matrix composite systems with titanium based matrix and SCS-6 fibers have been evaluated for this study [Ti-24Al-11Nb (atomic percent), Ti-6Al-2Sn-4Zr-2Mo (weight percent), and Ti-15Mo-3Nb-3Al-0.2Si (weight percent)]. The scanning acoustic microscope technique has been applied to materials subjected to both room temperature and elevated temperature fatigue cycling in addition to thermomechanical fatigue (in-phase and out-of-phase) conditions. A 50 MHz scanning acoustic microscope has been used for the imaging and evaluation of the damage initiation and growth of surface/subsurface cracks and interfacial degradation. All the images have been produced by exploiting the surface wave component of the ultrasonic signals from the scanning acoustic microscope because of the higher sensitivity of surface waves to both surface/subsurface cracks and perhaps also due to the changes in interfacial elastic properties. The results shown in this paper provide a very good understanding of the crack initiation and growth as well as interfacial degradation process of titanium based metal matrix composites when subjected to cyclical stresses at elevated temperatures and room temperature. The results indicate that the combination of high temperature and stress is very severe to the interface between the matrix and the fiber.
Impact of Air Infiltration in Frame Walls on Energy Loads: Taking Advantage of the Interaction between Infiltration, Solar Radiation, and Conduction
Authors: Claridge DE , Liu M , Bhattacharyya S
Published: March 2009

The energy impact of air leakage has classically been treated independently of conduction gains and losses through building envelopes. However, an increasing body of evidence shows that heat exchange in envelope components resulting from interactions between air leakage and conduction and solar radiation systematically changes (generally reducing) the energy load of air infiltration. A systematic study performed by the authors shows that this heat exchange can substantially reduce the air infiltration energy requirements in frame structures or walls under laboratory conditions depending on airflow rate and leakage configurations. The interaction of airflow with solar radiation is an important consideration—perhaps as important as the interaction of airflow with conduction under outdoor conditions, and depressurizing a house during winter and pressurizing during summer using a fan may reduce energy consumption significantly. This paper reviews earlier theoretical and experimental work in this area and summarizes results of a series of experiments and theoretical work conducted by the authors.
Air Leakage in the Perspective of International Standards
Authors: Levin PA , Wilson DJ , Ackerman MY
Published: March 2009

There exist a number of national standards and a draft international standard for the fan pressurization method for measuring air leakage. Although the standardized methods in principle are the same, the way of interpreting and presenting the results is different.

In previous studies, houses that have a relatively large leakage area at a low pressure difference (4 to 10 Pa) still can seem comparatively airtight at a high pressure difference (50 Pa). This fact is a consequence of differences in the flow exponent in the power-law equation, which is the normal equation used to fit to the data points, and can be a source of error when trying to compare the relative airtightness of houses. Extrapolating results from high pressure differences to low pressures, which are out of the measured range, can thus result in substantial errors. Air leakage testing of windows normally starts at 50 Pa, which should be accounted for when trying to use these results as inputs in network air infiltration models. Measurement results on low pressure air leakage are discussed in the paper and compared with high pressure air leakage.

Pressurization test data from 105 tests in one house at the Alberta Home Heating Research Facility are used for the study. The tests were made automatically over a seven-month period in low wind conditions. A wide range of pressure differences were tested and the results cover the test specifications for most standards. In addition to comparing standards, these tests were used to measure seasonal effects on air leakage in a wood-frame house with a plastic film air/vapor barrier.

The results show some significant differences between the standards, and also a variation with month of test, indicating a seasonal variation in air leakage.
Measured Airtightness of 24 Detached Houses over Periods of up to Three Years
Authors: Proskiw G
Published: March 2009

Regular airtightness tests were performed on 24 new houses, over periods of up to three years, to evaluate their air barrier systems and to search for evidence, air barrier degradation. Ten of the houses were constructed with polyethylene air barriers while the remaining 14 used an early version of the Airtight Drywall Approach (ADA). The 24 project houses were architecturally similar and of approximately equal size and general layout; stucco was the predominate exterior wall finish. All were exposed to similar terrain shielding.

The study found that the airtightness of the polyethylene air barrier houses remained stable over their respective monitoring periods. Although two of the ten houses demonstrated possible, albeit slight, evidence of airtightness degradation, the magnitude of these changes was small and judged not to be of practical significance. With respect to the critical issue of air barrier degradation, no evidence could be found to indicate polyethylene is unsuited for use as an air barrier material in residential construction. For example, all but one of the polyethylene houses met the airtightness requirements of the Canadian R-2000 Standard for energy efficient housing at the end of their monitoring periods.

The study found that the airtightness of the 14 ADA houses also remained stable over their monitoring periods. Although six of the 14 houses displayed possible, but slight, evidence of airtightness degradation, the magnitude of the changes was small and not of practical significance. It was concluded that no evidence could be found to indicate that the ADA system is unsuited for use in residential construction. All 14 ADA houses met the airtightness requirements of the R-2000 Program at the end of their respective monitoring periods.
Rigid Pavement Joint Sealant Effectiveness in Reducing Chloride Intrusion
Authors: Abo-Qaidis SA , Al-Qadi IL
Published: March 2009

To study the effectiveness of sealants in reducing chlorides and water intrusion into pavement joint openings, nine 122 x 91.5 x 20.3 cm concrete slabs were fabricated. One slab was cast without a joint and was used as a control; two were cast with non-sealed joints, and the other six were cast with joints which were sealed, after slabs were cured, with either type “A” or type “B” sealant, which are one-component rigid pavement joint sealants. Three dowel bars were installed below the joint at the mid-thickness of each slab, used for load transfer. Two types of dowels were used: epoxy-coated and uncoated. The joints were formed by installing removable styrofoam prior to concrete casting. A crack was formed from the bottom of the joint to the slabs's bottom, through the cross section of the slab to simulate field conditions; construction paper was used for this purpose. To accelerate the possibility of dowel bar corrosion and to examine pavement joint sealant effectiveness in abating chloride intrusion, the slabs were exposed to alternate ponding cycles of 6% (by weight) sodium chloride solution (3-days ponding and 4-days dry). The corrosion progress was monitored by measuring corrosion current density (icorr) using a Three-Electrode Linear Polarization (3LP) device. Also, chloride contamination was measured by collecting powdered concrete samples from each slab at four different depths to allow for chloride penetration profile assessment. The collected samples were analyzed to measure the percent of chloride diffused into the concrete and compared to background chloride percent in concrete. An analysis of results provided for the evaluation of icorr and chloride contents over a period of 18 months. The results show that the unjointed slab has higher resistance to chloride penetration, followed by jointed slabs sealed with type “A” sealant, then jointed slabs sealed with type “B” sealant. In addition, the performance of epoxy-coated dowel bars in abating corrosion was better than that of uncoated dowels.
Polysulfide Systems for Environmental Protection
Authors: Lee TCP
Published: March 2009

Legislation in most advanced industrial countries is demanding more stringent protection of the water table. Chemical spillage and the diffusion of chemicals into the ground, leading to contamination of water, is being strictly controlled. A good example of these regulations is the containment of spillages of gasoline and diesel on gas station forecourts. Previous systems relied on the use of membranes (for example, heavy duty polyethylene sheeting). These are no longer thought to be reliable in the long term and more durable systems have been developed. These consist of fuel impervious concrete, sometimes in the form of hexagonal blocks, with joints sealed with fuel resistant sealants. The long term adhesion of the sealant/primer system to concrete immersed in fuels is one of the more difficult requirements of the specification. Other applications of polysulfide systems in pollution control are described.
European Insulated Glass Unit Testing
Authors: Lowe GB
Published: March 2009

The European Community is pledged to reach a situation where there is no technical barrier to trading between the community partners. To this end the Commité European de Normalisation (CEN) committee TC129 — Glass in Buildings was set up. The Working Group WG4 has the specific task of writing a specification for Insulating Glass Units.

The instructions to the committee were that any insulating glass units currently meeting there own national standard should not be disadvantaged, at least in the first instance, by not being able to meet the new specification.

Naturally National views were put forward in the early stages, and there has been a period of intense negotiation, and compromise, before the specification started to take shape.

The current situation is that although not complete, the specification is now taking shape and a series of Round Robin comparisons have been carried out to verify the tests included.
Laboratory Effectiveness Testing of Water-in-Oil Emulsion Breakers
Authors: Fingas MF , Fieldhouse B , Bier I , Conrod D , Tennyson E
Published: March 2009

The physics and chemistry of water-in-oil emulsions dominate the development of effectiveness tests. Emulsions are variable in stability ‐ this variability is largely dependent on oil type and degree of weathering. These factors complicate the development of a test. Emulsions which have low stability will apparently break easily with chemical emulsion breakers. Broken emulsions will form a foam-like material, called “rag”, which retains water which is not part of the stable emulsions.

Analytical methods used to determine the final stability of the broken or unbroken emulsion were evaluated. Measurements of water content and viscosity measurements show correlation to emulsion stability. Viscosity provides a more reliable measure of emulsion stability but water content measurements are more convenient and are largely used in this study.

Twelve tests were developed in the past. Two testing methods have been developed to a usable stage. These tests are described and data using them provided. The effects of mixing time, agent amount, settling time and mixing energy on effectiveness results are presented.
Toxicity of Oil and Dispersed Oil to the Eggs and Larvae of Seven Marine Fish and Invertebrates from the Gulf of Mexico
Authors: Fucik KW , Carr KA , Balcom BJ
Published: March 2009

The early life stages of seven invertebrate and vertebrate species from the Gulf of Mexico were exposed to two oils, Corexit 9527, and dispersed oil mixtures. Chemical analyses found that hydrocarbon concentrations between exposures were relatively consistent. The hydrocarbon concentrations were initially highest in the dispersed oil mixtures compared to the water accommodated fractions (WAF) of the oils. However, hydrocarbon concentrations in both dispersed oil and WAF exposures were generally similar after 24 hours. The levels of toxicity in the dispersed oil mixtures were not proportionately greater than that in the WAF.
A Research Program to Facilitate Resolution of Ecological Issues Affecting the Use of Dispersants in Marine Oil Spill Response
Authors: Aurand D
Published: March 2009

The use of dispersants in oil spill response in the United States remains a controversial environmental topic. At the center of this controversy is a lack of confidence in the available data to evaluate the effects of dispersants on “local” biota. The main reasons that many of the attempts around the country to resolve concerns over dispersant use have been unsuccessful are that they have either 1.) failed to focus on the true issues of concern, 2.) collected laboratory (and sometimes field) data which cannot be effectively applied in decision-making, or 3.) failed to effectively communicate information to the participants in the decision process. These issues can be addressed by a research program intentionally designed to examine issues in an ecosystem context and which focuses on information dissemination and communication, which are the central themes of the Marine Spill Response Corporation (MSRC) initiative. The MSRC environmental program contains four elements: improved use and synthesis of existing information, improved methods for laboratory toxicity evaluations and interpretation, development of a realistic mesocosm testing program, and field experiments to correlate laboratory and mesocosm data to real world situations. This paper describes the rationale for the program and the progress made over the first two and one-half years.
Computerized Materials Data Integration in an Air Force Analytical Design Package
Authors: Mack TE , Whitney TJ , Kipp TE , Gran MG
Published: March 2009

To exploit the benefits of concurrent engineering and avoid the usual problems associated with nonconforming materials, an Air Force program for creating an aircraft transparency design engineering workstation, ADP2 (Analytical Design Package), was structured around a materials data server (M/VISION coupled with PATRAN). The data server at the core of the system is used to integrate a variety of applications and databanks, both commercial off-the-shelf (COTS) and special purpose items developed by the Air Force and the University of Dayton Research Institute (UDRI). It provides the focal point for loading, processing, cataloging and transferring of data between the various applications.

As a part of the frameless transparency program (FTP), ADP2 is a design tool consisting of existing analysis codes and computer aided engineering (CAE) software. The objective of ADP2 is to develop an integrated design methodology for frameless transparencies, aircraft interfaces, and their corresponding tooling. The scope goes all the way from materials testing through design and analysis to manufacturing and full life cycle maintenance. Several categories of materials data are handled, including raw test data, manufacturer's product data, evaluated property and specification data (such as from Military Handbooks), synthesized or simulated properties data, as well as data on service history. The functional environment requires multiple iterations through the design process with evolving materials properties and processing parameters for various testing, manufacturing, and analysis environments.

The basic features of the ADP2 system and the development process are described. Insight into how the system is used is given by virtue of an example involving the materials data integration module. The incorporation of technology and concepts from evolving standards like ISO/STEP and ASTM Committee E49 on Computerization of Material and Chemical Property Data proved very beneficial.
The Development and Evolution of the Cone Calorimeter: A Review of 12 Years of Research and Standardization
Authors: Babrauskas V
Published: March 2009

The preliminary work describing the Cone Calorimeter dates to 1982 when NIST (then NBS) presented the results of their research to ASTM Committee E5. In the next few years, the hardware was improved and finalized. ASTM first adopted a draft standard (P 190) in 1985, followed by full adoption as ASTM E 1354 in 1990. By now, more than 100 laboratories have adopted Cone Calorimeters, and several hundred papers have been written by researchers. The present paper reviews some of the highlights of the Cone Calorimeter development and its R&D utilization. It then discusses regulatory and specification usage of the apparatus and finally describes some potential applications yet to be realized.
International Developments in Fire Safety Engineering
Authors: Cooke GME
Published: March 2009

The paper describes international progress in preparing standards and codes dealing with fire safety engineering. It identifies the challenge, defines fire safety engineering, lists its benefits and gives an account of work within a number of organisations and countries. In particular it describes the work within ISO TC92/SC4 which uses a sub-systems approach and permits a deterministic or probabilistic approach to design for fire safety in buildings. The paper concludes that a framework code is the cornerstone in gaining further acceptance of engineering approaches to Eire safety in buildings, and identifying topics and priorities for research needed to fill the gaps in current knowledge.
The Use of Time-Temperature Superposition to Fundamentally Characterize Asphaltic Concrete Mixtures at Low Temperatures
Authors: Hiltunen DR , Roque R
Published: March 2009

An analytical approach for the determination of the viscoelastic properties of asphaltic concrete mixtures at low temperatures is described. The properties are derived from laboratory test data obtained from the mixture test selected by the Strategic Highway Research Program (SHRP) to support the new mixture specification for thermal cracking. It is shown that the principle of time-temperature superposition can adequately represent the time- and temperature-dependent stiffness properties of asphaltic concrete mixtures at low temperatures. In addition, it is shown that a generalized Maxwell model (Prony series) can accurately represent the master creep compliance curve of asphaltic concrete mixtures at low temperatures.
Evaluation of Aging of Hot-Mix Asphalt Using Wave Propagation Techniques
Authors: Li Y , Nazarian S
Published: March 2009

A methodology for determining the degree of aging of hot-mix asphalt (HMA) is presented. The evaluation of aging involves relating the wave propagation velocities to the elastic modulus of the mixture, before and after aging. The nondestructive nature of the methodology and its high degree of repeatability make it attractive to monitor the variation in modulus of an HMA specimen through the entire aging process. In addition, field tests very similar to the laboratory tests can be easily implemented.
Removal of Contaminated Sediments: Equipment and Recent Field Studies
Authors: Herbich JB
Published: March 2009

The problem of contaminated marine sediments has emerged as an environmental issue of national importance. Harbor areas in particular have been found to contain high levels of contaminants in bottom sediments due to wastes from municipal, industrial, and riverine sources. This paper briefly examines the extent and significance of marine sediment contamination in the United States, and reviews the state of the art of contaminated sediment cleanup and recent field studies or demonstrations.
Strategies for Management of Contaminated Sediments
Authors: Palermo MR , Miller J
Published: March 2009

In 1985, the U.S. Army Corps of Engineers (USACE) developed a Management Strategy for evaluation of dredged material alternatives which focused on contaminant testing and controls. The Environmental Protection Agency (EPA) later initiated development of a similar management strategy focusing on environmental considerations of disposal alternatives. A USACE/EPA work group was subsequently formed for the purpose of developing a joint Technical Framework endorsed by both agencies. In 1992, the USACE and EPA published the Technical Framework as a guidance document for their agencies' personnel to follow in identifying environmentally acceptable alternatives for the management of dredged material. The USACE and EPA are also cooperating in developing strategies for managing sediment remediation projects. This paper provides a summary of the strategies that can be used in management of contaminated sediments, a description of the more detailed guidance documents available, and plans for future developments.
Experimental Application of Methodologies to Quantify the Effect of Constraint on Jc for a 3-D Flaw Geometry
Authors: Porr WC , Link RE , Waskey JP , Dodds RH
Published: March 2009

In an effort to validate methodologies to quantify the effect of crack tip constraint on cleavage fracture toughness, a series of experiments were conducted to measure the cleavage fracture toughness, Jc, of an ASTM A515 Grade 70 steel utilizing large plate bend specimens containing semi-elliptical surface cracks, SC(B), (3-D flaw geometry). Jc was estimated with modified EPRI and Turner design curve schemes from load and remote strains measured at initiation. The cleavage toughness of the A515 steel used for this testing was previously characterized using a series of through-cracked single edge notch bend specimens, SE(B), (2-D flaw geometry) with various initial crack-depth to specimen-width ratios, a/W. The toughness values estimated for the surface cracked plate specimens were consistent with the toughness ranges predicted from the SE(B) results using the two parameter fracture mechanics (J-Q) methodology to account for differences in crack tip constraint. This result indicates the applicability of small specimen, constraint adjusted, results to engineering structural integrity predictions for the case of cleavage fracture.
An Experimental Study of CTOD for Mode I/Mode II Stable Crack Growth in Thin 2024-T3 Aluminum Specimens
Authors: Amstutz BE , Sutton MA , Dawicke DS , Newman JC
Published: March 2009

An experimental study of crack tip opening displacement (CTOD) for Mode I/Mode II stable crack growth in thin sheet 2024-T3 aluminum has been conducted. To perform the experiments, an Arcan specimen and fixture was modified so that (1) slippage in the grips was eliminated, (2) large rotations of the fixture components were achievable and (3) bending stresses were minimized. Defining Θ to be the angle between the Mode I loading direction (perpendicular to the crack line) and the direction of applied loading, experimental results indicate that (a) for large amounts of crack extension, a ≥ 10 mm, the value of CTOD at 1 mm behind the crack tip appears to approach a constant value of 0.1 mm for all modes of loading, (b) the direction of crack extension varied with applied mixed mode loading, (c) Mode I crack extension is predominant for 0° ≤ Θ ≤ 60°, (d) Mode II crack extension is predominant for 75° ≤ θ ≤ 90° and (e) a transition zone exists for angles θ near 75°.
Constraint Effects Observed in Crack Initiation Stretch
Authors: Lambert DM , Ernst HA
Published: March 2009

The current paper characterizes constraint in fracture: J-modified resistance (JMR) curves were developed for two tough structural materials, 6061-T651 (aluminum) and IN718-STA1 (nickel-base superalloy). A wide variety of configurations was tested to consider load configurations from bending to tension including three specimen types (compact tension, center-crack tension, and single-edge notched tension), and a range of ligament lengths and thicknesses, as well as side-grooved and smooth-sided ligaments.

The JMR curves exhibited an inflection point after some crack extension, and the data were excluded beyond the inflection. Qualified JMR curves for the two materials showed similar behavior, but R-curves were identical for equal ligament length-to-thickness ratio, RL, for the aluminum alloy, with increasing slope for increasing RL, while for the nickel, the resistance curves aligned for equal ligament thickness, B, and the slope increased for decreasing B.

Displacements at the original crack tip (δ5) were recorded throughout the test for several specimens. δ5-versus-crack extension curves were developed, and data were excluded beyond the inflection point (as with the JMR curves). The data collapsed into two distinct curves, thought to represent the surface, plane stress effect and the central, plane strain effect. This was observed for both materials.

A technique called profiling is presented for the aluminum alloy only, where the crack face displacements are recorded at the final point of the test as a function of the position throughout the crack cavity, along with an effort to extract the observations in a usable form. Displacements were consistent throughout the cross-section at and behind the original crack tip. In the region where the crack grew, this displacement was developed by a combination of stretch and crack growth. The stretch required to initiate crack extension was a function of the depth beneath the surface into the cross-section.
Investigation of Fracture Mechanical Behaviour of Nodular Cast Iron and Welded Joints with Parent-Material-Like Weld Metal
Authors: Baer W , Pusch G
Published: March 2009

The focus of the investigations was the determination of fracture mechanical characteristics and crack resistance curves of the J-Integral and CTOD concept by application of the partial unloading compliance technique and D.C. potential drop technique (four point bend) under static load.

The results show a close correlation between crack initiation values as well as crack resistance curves and graphite morphology parameters determined by means of quantitative microstructural analysis where the influence of the matrix (distance of graphite particles) dominates the crack resistance and fracture performance of ferritic nodular cast iron under consideration of the notch effect of graphite particles.

SEM in-situ tensile tests showed that due to a beneficial shielding effect of the strength overmatching parent-material-like weld metal (mis-match ratio M=1.21), cracks positioned directly in the plane of the fusion line did not deviate into the weld metal in spite of its lower toughness compared to that of the parent material. They also showed an unsymetrical formation of damage in front of the crack tip.
Fracture Toughness Testing of Bi-Material Joints with High Strength Mis-Match
Authors: Koçak M , Hornet P , Cornec A , Schwalbe K-H
Published: March 2009

This paper deals with the influence of strength mis-match on CTOD (δ5) R-curves obtained from homogeneous and electron beam (EB) welded bimaterial CT and SENB specimens of two aluminium alloys. The R-curves of metal-metal bimaterial specimens are compared with the R-curves of each alloy to determine the effect of strength mismatch on the locally measured CTOD (δ5) fracture toughness properties. The homogeneous specimens of two different aluminium alloys, namely 2024-FC and 2024-T351 with yield strengths of 80 and 360 MPa respectively, as well as EB welded bi-material 5 mm thick CT and SENB specimens (a/W=0.15 and 0.5) have been tested at room temperature. The local CTOD (δ5) fracture toughness measurements on such composite specimen configurations produced generally strength mis-match and geometry independent R-curves.
Predicting Crack Growth in Continuous-Fiber Composite Materials
Authors: Cordes JA , Yazici R
Published: March 2009

Pre-notched composite lamina with unidirectional fibers were studied experimentally and using finite element analysis. Experiments were conducted on notched graphite/aluminum and glass/epoxy panels and the results were compared to a finite element method. Under remote tensile loading, cracks in the graphite/aluminum panels propagated perpendicular to the applied load without stable crack growth. In the glass/epoxy panels, crack propagation was initially stable and parallel to the fibers. A nonlinear damage zone method (DZM) was used to predict the crack growth directions, estimate damages, model stable and unstable crack growths, and predict the loads at failure. For both materials, the predicted loads at failure were within 20% of experimental loads.
Fatigue Fracture of Thin Plates Under Tensile and Transverse Shear Stresses
Authors: Viz MJ , Zehnder AT , Bamford J-D
Published: March 2009

Crack growth in thin sheets loaded under tension and transverse shear is studied experimentally and the mechanics of such problems are reviewed. A small scale yielding approach is adopted that describes the crack tip fields using a combination of Kirchhoff plate theory and plane stress elasticity. Techniques for calculating the relevant stress intensity factors are presented and validated with results from six test cases. Fatigue crack growth rates are measured using a double-edge notch test specimen configuration loaded in tension and torsion. A geometrically nonlinear finite element computation is used to determine the stress intensity factors as functions of axial load, torque, and crack length.