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Molecular mechanism of crystallization impacting calcium phosphate cements (open access)

Molecular mechanism of crystallization impacting calcium phosphate cements

In summary, SPM data has shown that (1) Mg inhibits growth on all steps but relatively high Mg/Ca ratios are needed. Extracting the mechanism of interaction requires more modeling of the kinetic data, but step morphology is consistent with incorporation. (2) Citrate has several effects depending on the citrate/Ca ratio. At the lowest concentrations, citrate increases the step free energy without altering the step kinetics; at higher concentrations, the polar step is slowed. (3) Oxalate also slows the polar step but additionally stabilizes a new facet, with a [100]{sub Cc} step. (4) Etidronate has the greatest kinetic impact of the molecules studied. At 7{micro}M concentrations, the polar step slows by 60% and a new polar step appears. However, at the same time the [10-1]{sub Cc} increases by 67%. It should be noted that all of these molecules complex calcium and can effect kinetics by altering the solution supersaturation or the Ca to HPO{sub 4}{sup 2-} ratio. For the SPM data shown, this effect was corrected for to distinguish the effect of the molecule at the crystal surface from the effect of the molecule on the solution speciation. The goal of this paper is to draw connections between fundamental studies of …
Date: May 31, 2009
Creator: Giocondi, J L; El-Dasher, B S; Nancollas, G H & Orme, C A
System: The UNT Digital Library
Progress towards Managing Residential Electricity Demand: Impacts of Standards and Labeling for Refrigerators and Air Conditioners in India (open access)

Progress towards Managing Residential Electricity Demand: Impacts of Standards and Labeling for Refrigerators and Air Conditioners in India

The development of Energy Efficiency Standards and Labeling (EES&L) began in earnest in India in 2001 with the Energy Conservation Act and the establishment of the Indian Bureau of Energy Efficiency (BEE). The first main residential appliance to be targeted was refrigerators, soon to be followed by room air conditioners. Both of these appliances are of critical importance to India's residential electricity demand. About 15percent of Indian households own a refrigerator, and sales total about 4 million per year, but are growing. At the same time, the Indian refrigerator market has seen a strong trend towards larger and more consumptive frost-free units. Room air conditioners in India have traditionally been sold to commercial sector customers, but an increasing number are going to the residential sector. Room air conditioner sales growth in India peaked in the last few years at 20percent per year. In this paper, we perform an engineering-based analysis using data specific to Indian appliances. We evaluate costs and benefits to residential and commercial sector consumers from increased equipment costs and utility bill savings. The analysis finds that, while the BEE scheme presents net benefits to consumers, there remain opportunities for efficiency improvement that would optimize consumer benefits, according …
Date: May 30, 2009
Creator: McNeil, Michael A. & Iyer, Maithili
System: The UNT Digital Library
Acting Globally: Potential Carbon Emissions Mitigation Impacts from an International Standards and Labelling Program (open access)

Acting Globally: Potential Carbon Emissions Mitigation Impacts from an International Standards and Labelling Program

This paper presents an analysis of the potential impacts of an international initiative designed to support and promote the development and implementation of appliances standards and labelling programs throughout the world. As part of previous research efforts, LBNL developed the Bottom Up Energy Analysis System (BUENAS), an analysis framework that estimates impact potentials of energy efficiency policies on a global scale. In this paper, we apply this framework to an initiative that would result in the successful implementation of programs focused on high priority regions and product types, thus evaluating the potential impacts of such an initiative in terms of electricity savings and carbon mitigation in 2030. In order to model the likely parameters of such a program, we limit impacts to a five year period starting in 2009, but assume that the first 5 years of a program will result in implementation of 'best practice' minimum efficiency performance standards by 2014. The 'high priority' regions considered are: Brazil, China, the European Union,India, Mexico and the United States. The products considered are: refrigerators, air conditioners, lighting (both fluorescent and incandescent), standby power (for consumer electronics) and televisions in the residential sector, and air conditioning and lighting in commercial buildings. In …
Date: May 29, 2009
Creator: McNeil, Michael A; Letschert, Virginie E.; de la Rue du Can, Stephane & Egan, Christine
System: The UNT Digital Library
Enduse Global Emissions Mitigation Scenarios (EGEMS): A New Generation of Energy Efficiency Policy Planning Models (open access)

Enduse Global Emissions Mitigation Scenarios (EGEMS): A New Generation of Energy Efficiency Policy Planning Models

This paper presents efforts to date and prospective goals towards development of a modelling and analysis framework which is comprehensive enough to address the global climate crisis, and detailed enough to provide policymakers with concrete targets and achievable outcomes. In terms of energy efficiency policy, this requires coverage of the entire world, with emphasis on countries and regions with large and/or rapidly growing energy-related emissions, and analysis at the 'technology' level-building end use, transport mode or industrial process. These elements have not been fully addressed by existing modelling efforts, which usually take either a top-down approach, or concentrate on a few fully industrialized countries where energy demand is well-understood. Inclusion of details such as appliance ownership rates, use patterns and efficiency levels throughout the world allows for a deeper understanding of the demand for energy today and, more importantly, over the coming decades. This is a necessary next step for energy analysts and policy makers in assessment of mitigation potentials. The modelling system developed at LBNL over the past 3 years takes advantage of experience in end use demand and in forecasting markets for energy-consuming equipment, in combination with known technology-based efficiency opportunities and policy types. A particular emphasis has …
Date: May 29, 2009
Creator: McNeil, Michael A.; de la Rue du Can, Stephane & McMahon, James E.
System: The UNT Digital Library
Evaluation of Life-Cycle Assessment Studies of Chinese Cement Production: Challenges and Opportunities (open access)

Evaluation of Life-Cycle Assessment Studies of Chinese Cement Production: Challenges and Opportunities

The use of life-cycle assessment (LCA) to understand the embodied energy, environmental impacts, and potential energy-savings of manufactured products has become more widespread among researchers in recent years. This paper reviews recent LCA studies in the cement industry in China and in other countries and provides an assessment of the methodology used by the researchers compared to ISO LCA standards (ISO 14040:2006, ISO 14044:2006, and ISO/TR 14048:2002). We evaluate whether the authors provide information on the intended application, targeted audience, functional unit, system boundary, data sources, data quality assessment, data disaggregation and other elements, and draw conclusions regarding the level of adherence to ISO standards for the papers reviewed. We found that China researchers have gained much experience during last decade, but still have room for improvement in establishing boundaries, assessing data quality, identifying data sources, and explaining limitations. The paper concludes with a discussion of directions for future LCA research in China.
Date: May 29, 2009
Creator: Lu, Hongyou; Masanet, Eric & Price, Lynn
System: The UNT Digital Library
Misleading Performance Claims in Parallel Computations (open access)

Misleading Performance Claims in Parallel Computations

In a previous humorous note entitled 'Twelve Ways to Fool the Masses,' I outlined twelve common ways in which performance figures for technical computer systems can be distorted. In this paper and accompanying conference talk, I give a reprise of these twelve 'methods' and give some actual examples that have appeared in peer-reviewed literature in years past. I then propose guidelines for reporting performance, the adoption of which would raise the level of professionalism and reduce the level of confusion, not only in the world of device simulation but also in the larger arena of technical computing.
Date: May 29, 2009
Creator: Bailey, David H.
System: The UNT Digital Library
NCSX Trim Coil Design (open access)

NCSX Trim Coil Design

The National Compact Stellarator Experiment (NCSX) was being constructed at the Princeton Plasma Physics Laboratory in partnership with Oak Ridge National Laboratory before work was stopped in 2008. The objective of this experiment was to develop the stellarator concept and evaluate it's potential as a model for future fusion power plants. Stellarator design requires very precisely positioned Modular Coils of complex shape to form 3D plasmas. In the design of NCSX, Trim Coils were required to compensate for both the positioning of the coils during assembly and the fabrication tolerances of the Modular Coils. Use of the Trim Coils allowed for larger tolerances increasing ease of assembly and decreasing overall cost. A set of Trim coils was developed to suppress the toroidal flux in island regions due to misalignment, magnetic materials, and eddy currents. The requirement imposed upon the design forced the toroidal flux in island regions below 10% of the total toroidal flux in the plasma. An analysis was first performed to evaluate candidate Trim Coil configurations iterating both the size, number, and position of the coils. The design was optimized considering both performance and cost while staying within the tight restraints presented by the space limited geometry. The …
Date: May 29, 2009
Creator: M. Kalish, A. Brooks, J. Rushinski, R. Upcavage
System: The UNT Digital Library
A Novel Demountable TF Joint Design for Low Aspect Ratio Spherical Torus Tokamaks (open access)

A Novel Demountable TF Joint Design for Low Aspect Ratio Spherical Torus Tokamaks

A novel shaped design for the radial conductors and demountable electrical joints connecting inner and outer legs of copper TF system conductors in low aspect ratio tokamaks is described and analysis results are presented. Specially shaped designs can optimize profiles of electrical current density, magnetic force, heating, and mechanical stress.
Date: May 29, 2009
Creator: Woolley, R.D.
System: The UNT Digital Library
Semi-inclusive Deep Inelastic Scattering at Small-x (open access)

Semi-inclusive Deep Inelastic Scattering at Small-x

We study the semi-inclusive hadron production in deep inelastic scattering at small-x.A transverse momentum dependent factorization is found consistent with the resultscalculated in the color-dipole framework in the appropriate kinematic region. The transverse momentum dependent quark distribution can be studied in this processas a probe for the small-x saturation physics. Especially, the ratio of the quark distributions as functions of transverse momentum at different x demonstrates strong dependence on the saturation scale. The Q2 dependence of the same ratio is also studied by applying the Collins-Soper-Sterman resummation method.
Date: May 29, 2009
Creator: Marquet, C.; Xiao, B.-W. & Yuan, Feng
System: The UNT Digital Library
Upgrading the TFTR Transrex Power Supplies (open access)

Upgrading the TFTR Transrex Power Supplies

In order to provide improved and expanded experimental capabilities, the existing Transrex power supplies at PPPL are to be upgraded and modernized. Each of the 39 power supplies consists of two six pulse silicon controlled rectifier sections forming a twelve pulse power supply. The first modification is to split each supply into two independent six pulse supplies by replacing the existing obsolete twelve pulse firing generator with two commercially available six pulse firing generators. The second change replaces the existing control link with a faster system, with greater capacity, which will allow for independent control of all 78 power supply sections. The third change replaces the existing Computer Automated Measurement and Control (CAMAC) based fault detector with an Experimental Physics and Industrial Control System (EPICS) compatible unit, eliminating the obsolete CAMAC modules. Finally the remaining relay logic and interfaces to the "Hardwired Control System" will be replaces with a Programmable Logic Controller (PLC).
Date: May 29, 2009
Creator: Lawson, J. E.; Marsala, R.; Ramakrishnan, S.; Zhao, X. & Sichta, P.
System: The UNT Digital Library
PILOT-SCALE HYDRAULIC TESTING OF RESORCINOL FORMALDEHYDE ION EXCHANGE RESIN (open access)

PILOT-SCALE HYDRAULIC TESTING OF RESORCINOL FORMALDEHYDE ION EXCHANGE RESIN

Savannah River National Laboratory (SRNL) performed pilot-scale hydraulic/chemical testing of spherical resorcinol formaldehyde (RF) ion exchange (IX) resin for the River Protection Project-Hanford Tank Waste Treatment & Immobilization Plant (WTP) Project. The RF resin hydraulic cycle testing was conducted in two pilot-scale IX columns, 1/4 and 1/2 scale. A total of twenty-three hydraulic/chemical cycles were successfully completed on the spherical RF resin. Sixteen of these cycles were completed in the 24-inch IX Column (1/2 scale column). Hydraulic testing showed that the permeability of the RF resin remained essentially constant, with no observed trend in the reduction of the permeability as the number of cycles increased. The permeability during the pilot-scale testing was 3 times better than the design requirements of the WTP full-scale IX system. The RF resin bed showed no tendency to form fissures or pack more densely as the number of cycles increased. Particle size measurements of the RF resin showed no indication of particle size change (for a given chemical) with cycles and essentially no fines formation. The permeability of the resin bed was uniform with respect to changes in bed depth. Upflow Regeneration and Simulant Introduction in the IX columns revealed another RF resin benefit; negligible …
Date: May 28, 2009
Creator: Adamson, D.
System: The UNT Digital Library
"DIANA" - A New, Deep-Underground Accelerator Facility for Astrophysics Experiments (open access)

"DIANA" - A New, Deep-Underground Accelerator Facility for Astrophysics Experiments

The DIANA project (Dakota Ion Accelerators for Nuclear Astrophysics) is a collaboration between the University of Notre Dame, University of North Carolina, Western Michigan University, and Lawrence Berkeley National Laboratory to build a nuclear astrophysics accelerator facility 1.4 km below ground. DIANA is part of the US proposal DUSEL (Deep Underground Science and Engineering Laboratory) to establish a cross-disciplinary underground laboratory in the former gold mine of Homestake in South Dakota, USA. DIANA would consist of two high-current accelerators, a 30 to 400 kV variable, high-voltage platform, and a second, dynamitron accelerator with a voltage range of 350 kV to 3 MV. As a unique feature, both accelerators are planned to be equipped with either high-current microwave ion sources or multi-charged ECR ion sources producing ions from protons to oxygen. Electrostatic quadrupole transport elements will be incorporated in the dynamitron high voltage column. Compared to current astrophysics facilities, DIANA could increase the available beam densities on target by magnitudes: up to 100 mA on the low energy accelerator and several mA on the high energy accelerator. An integral part of the DIANA project is the development of a high-density super-sonic gas-jet target which can handle these anticipated beam powers. The …
Date: May 28, 2009
Creator: Leitner, M.; Leitner, D.; Lemut, A.; Vetter, P. & Wiescher, M.
System: The UNT Digital Library
Glass Formulation for the Hanford Tank Waste Treatment and Immobilization Plant (Wtp) (open access)

Glass Formulation for the Hanford Tank Waste Treatment and Immobilization Plant (Wtp)

A computational method for formulating Hanford HLW glasses was developed that is based on empirical glass composition-property models, accounts for all associated uncertainties, and can be solved in Excel{sup R} in minutes. Calculations for all waste form processing and compliance requirements included. Limited experimental validation performed.
Date: May 27, 2009
Creator: Kruger, A. A.; Vienna, J. D.; Kim, D. S. & Jain, V.
System: The UNT Digital Library
NEPTUNIUM OXIDE PROCESSING (open access)

NEPTUNIUM OXIDE PROCESSING

The Savannah River Site's HB-Line Facility completed a campaign in which fifty nine cans of neptunium oxide were produced and shipped to the Idaho National Laboratory in the 9975 shipping container. The neptunium campaign was divided into two parts: Part 1 which consisted of oxide made from H-Canyon neptunium solution which did not require any processing prior to conversion into an oxide, and Part 2 which consisted of oxide made from additional H-Canyon neptunium solutions which required processing to purify the solution prior to conversion into an oxide. The neptunium was received as a nitrate solution and converted to oxide through ion-exchange column extraction, precipitation, and calcination. Numerous processing challenges were encountered in order make a final neptunium oxide product that could be shipped in a 9975 shipping container. Among the challenges overcome was the issue of scale: translating lab scale production into full facility production. The balance between processing efficiency and product quality assurance was addressed during this campaign. Lessons learned from these challenges are applicable to other processing projects.
Date: May 27, 2009
Creator: Jordan, J; Watkins, R & Hensel, S
System: The UNT Digital Library
Polarized gun and ERL R and D for eRHIC (open access)

Polarized gun and ERL R and D for eRHIC

At Jefferson Laboratory charge density and charge lifetime during electron beam delivery are over 2 x 10{sup 5} C/cm{sup 2} and 200 C, respectively. A 200 C charge lifetime at 2 mA corresponds to 10{sup 5} seconds. In a more recent result, charge lifetimes of about an order of magnitude larger were achieved by a load-lock gun with a larger cathode area.
Date: May 27, 2009
Creator: Ben-Zvi, Ilan
System: The UNT Digital Library
RAPID DETERMINATION OF ACTINIDES IN URINE BY INDUCTIVELY-COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY: A HYBRID APPROACH (open access)

RAPID DETERMINATION OF ACTINIDES IN URINE BY INDUCTIVELY-COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY: A HYBRID APPROACH

A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed using a streamlined calcium phosphate precipitation. Similar technology has been applied to separate actinides prior to measurement by alpha spectrometry, but this new method has been developed with elution reagents now compatible with ICP-MS as well. Purified solutions are split between ICP-MS and alpha spectrometry so that long- and short-lived actinide isotopes can be measured successfully. The method allows for simultaneous extraction of 24 samples (including QC samples) in less than 3 h. Simultaneous sample preparation can offer significant time savings over sequential sample preparation. For example, sequential sample preparation of 24 samples taking just 15 min each requires 6 h to complete. The simplicity and speed of this new method makes it attractive for radiological emergency response. If preconcentration is applied, the method is applicable to larger sample aliquots for occupational exposures as well. The chemical recoveries are typically …
Date: May 27, 2009
Creator: Maxwell, S. & Jones, V.
System: The UNT Digital Library
Results of Compact Stellarator Engineering Trade Studies (open access)

Results of Compact Stellarator Engineering Trade Studies

number of technical requirements and performance criteria can drive stellarator costs, e.g., tight tolerances, accurate coil positioning, low aspect ratio (compactness), choice of assembly strategy, metrology, and complexity of the stellarator coil geometry. With the completion of a seven-year design and construction effort of the National Compact Stellarator Experiment (NCSX) it is useful to interject the NCSX experience along with the collective experiences of the NCSX stellarator community to improving the stellarator configuration. Can improvements in maintenance be achieved by altering the stellarator magnet configuration with changes in the coil shape or with the combination of trim coils? Can a mechanical configuration be identified that incorporates a partial set of shaped fixed stellarator coils along with some removable coil set to enhance the overall machine maintenance? Are there other approaches that will simplify the concepts, improve access for maintenance, reduce overall cost and improve the reliability of a stellarator based power plant? Using ARIES-CS and NCSX as reference cases, alternative approaches have been studied and developed to show how these modifications would favorably impact the stellarator power plant and experimental projects. The current status of the alternate stellarator configurations being developed will be described and a comparison made to the …
Date: May 27, 2009
Creator: Brown, Tom; Bromberg, L. & Cole, M.
System: The UNT Digital Library
VALIDATION OF ANALYTICAL METHODS AND INSTRUMENTATION FOR BERYLLIUM MEASUREMENT: REVIEW AND SUMMARY OF AVAILABLE GUIDES, PROCEDURES, AND PROTOCOLS (open access)

VALIDATION OF ANALYTICAL METHODS AND INSTRUMENTATION FOR BERYLLIUM MEASUREMENT: REVIEW AND SUMMARY OF AVAILABLE GUIDES, PROCEDURES, AND PROTOCOLS

Method validation is the process of evaluating whether an analytical method is acceptable for its intended purpose. For pharmaceutical methods, guidelines from the United States Pharmacopeia (USP), International Conference on Harmonisation (ICH), and the United States Food and Drug Administration (USFDA) provide a framework for performing such valications. In general, methods for regulatory compliance must include studies on specificity, linearity, accuracy, precision, range, detection limit, quantitation limit, and robustness. Elements of these guidelines are readily adapted to the issue of validation for beryllium sampling and analysis. This document provides a listing of available sources which can be used to validate analytical methods and/or instrumentation for beryllium determination. A literature review was conducted of available standard methods and publications used for method validation and/or quality control. A comprehensive listing of the articles, papers and books reviewed is given in the Appendix. Available validation documents and guides are listed therein; each has a brief description of application and use. In the referenced sources, there are varying approches to validation and varying descriptions of the valication process at different stages in method development. This discussion focuses on valication and verification of fully developed methods and instrumentation that have been offered up for use …
Date: May 27, 2009
Creator: Ekechukwu, A
System: The UNT Digital Library
WASTE DISPOSITION ON THE HANFORD PLATEAU REMEDIATION CONTRACT (open access)

WASTE DISPOSITION ON THE HANFORD PLATEAU REMEDIATION CONTRACT

None
Date: May 27, 2009
Creator: Moak, Don J.; Triner, Glen C. & Waters, Mike S.
System: The UNT Digital Library
800MHz Crab Cavity Conceptual Design For the LHC Upgrade (open access)

800MHz Crab Cavity Conceptual Design For the LHC Upgrade

In this paper, we present an 800 MHz crab cavity conceptual design for the LHC upgrade. The cell shape is optimized for lower maximum peak surface fields as well as higher transverse R/Q. A compact coax-to-coax coupler scheme is proposed to damp the LOM/SOM modes. A two-stub antenna with a notch filter is used as the HOM coupler to damp the HOM modes in the horizontal plane and rejects the operating mode at 800MHz. Multipacting (MP) simulations show that there are strong MP particles at the disks. Adding grooves along the short axis without changing the operating mode's RF characteristics can suppress the MP activities. Possible input coupler configurations are discussed.
Date: May 26, 2009
Creator: Xiao, Liling; Li, Zenghai; Ng, Cho-Kuen; Seryi, Andrei & /SLAC
System: The UNT Digital Library
Coherent Soft X-Ray Generation in the Water Window with the EEHG Scheme (open access)

Coherent Soft X-Ray Generation in the Water Window with the EEHG Scheme

Recently a scheme entitled echo-enabled harmonic generation (EEHG) was proposed for producing short wavelength FEL radiation that allows far higher harmonic numbers to be accessed as compared with the normal limit arising from incoherent energy spread. In this paper we study the feasibility of a single EEHG stage to generate coherent radiation in the 'water window' (2--4 nm wavelength) directly from a UV seed laser at 190-nm wavelength. We present time-dependent simulation results which demonstrate that the single-stage EEHG FEL can generate high power soft x-ray radiation in the water window with narrow bandwidth close to Fourier transform limit directly from a UV seed laser. The schemes to generate short x-ray pulse from femtosecond to attosecond using EEHG FEL are also discussed.
Date: May 26, 2009
Creator: Xiang, D. & Stupakov, G.
System: The UNT Digital Library
Collins Mechanism Contributions to Single Spin Asymmetry (open access)

Collins Mechanism Contributions to Single Spin Asymmetry

We present recent developments on the single transverse spin physics, in particular, the Collins mechanism contributions in various hadronic reactions, such as semi-inclusive hadron production in DIS process, azimuthal distribution of hadron in high energy jet in pp collisions. We will demonstrate that the transverse momentum dependent and collinear factorization approaches are consistent with each other in the description of the Collins effects in the semi-inclusive hadron production in DIS process.
Date: May 26, 2009
Creator: Yuan,F.
System: The UNT Digital Library
Endothelial Cell Migration and Vascular Endothelial Growth Factor Expression Are the Result of Loss of Breast Tissue Polarity (open access)

Endothelial Cell Migration and Vascular Endothelial Growth Factor Expression Are the Result of Loss of Breast Tissue Polarity

Recruiting a new blood supply is a rate-limiting step in tumor progression. In a three-dimensional model of breast carcinogenesis, disorganized, proliferative transformed breast epithelial cells express significantly higher expression of angiogenic genes compared with their polarized, growth-arrested nonmalignant counterparts. Elevated vascular endothelial growth factor (VEGF) secretion by malignant cells enhanced recruitment of endothelial cells (EC) in heterotypic cocultures. Significantly, phenotypic reversion of malignant cells via reexpression of HoxD10, which is lost in malignant progression, significantly attenuated VEGF expression in a hypoxia-inducible factor 1{alpha}-independent fashion and reduced EC migration. This was due primarily to restoring polarity: forced proliferation of polarized, nonmalignant cells did not induce VEGF expression and EC recruitment, whereas disrupting the architecture of growth-arrested, reverted cells did. These data show that disrupting cytostructure activates the angiogenic switch even in the absence of proliferation and/or hypoxia and restoring organization of malignant clusters reduces VEGF expression and EC activation to levels found in quiescent nonmalignant epithelium. These data confirm the importance of tissue architecture and polarity in malignant progression.
Date: May 26, 2009
Creator: Chen, Amy; Cuevas, Ileana; Kenny, Paraic A; Miyake, Hiroshi; Mace, Kimberley; Ghajar, Cyrus et al.
System: The UNT Digital Library
Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites (open access)

Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites

Nonlinear-elastic fracture mechanics methods are used to assess the fracture toughness of bulk metallic glass (BMG) composites; results are compared with similar measurements for other monolithic and composite BMG alloys. Mechanistically, plastic shielding gives rise to characteristic resistance?curve behavior where the fracture resistance increases with crack extension. Specifically, confinement of damage by second?phase dendrites is shown to result in enhancement of the toughness by nearly an order of magnitude relative to unreinforced glass.
Date: May 26, 2009
Creator: Launey, Maximilien E.; Hofmann, Douglas C.; Suh, Jin-Yo; Kozachkov, Henry; Johnson, William L. & Ritchie, Robert O.
System: The UNT Digital Library