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2014

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Articles 1171 - 1200 of 1522

Full-Text Articles in Civil and Environmental Engineering

Compressibility Characteristics Of Low-Plasticity Silt Before And After Liquefaction, Shuying Wang, Ronaldo Luna Jan 2014

Compressibility Characteristics Of Low-Plasticity Silt Before And After Liquefaction, Shuying Wang, Ronaldo Luna

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Low-plasticity silt is known to have a potential to liquefy during earthquakes. The compressibility characteristics could change before and after a dynamic event that produces liquefaction. This research investigates the liquefaction resistance and post liquefaction reconsolidation characteristics of Mississippi River Valley (MRV) silt using laboratory cyclic triaxial compression testing. The MRV silt experienced initial liquefaction under cyclic loading, and the results are presented as cyclic stress ratio versus loading cycle curve. After cyclic loading, the liquefied specimens were reconsolidated. Permeability did not change significantly as a result of liquefaction. The reconsolidation curves are more parallel to the compression line than …


Characterization Of Shear Wave Velocity And Its Anisotropy In Uniform Granular Materials, Xin Kang, Bate Bate, Louis Ge Jan 2014

Characterization Of Shear Wave Velocity And Its Anisotropy In Uniform Granular Materials, Xin Kang, Bate Bate, Louis Ge

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Small strain stiffness of granular materials is important to many engineering applications, such as earthquake engineering, pavement, machine foundation, embankment subjected to tidal impacts, and foundations for structures under wind loads. Shear wave velocity, which is an indicator of stiffness, was measured with a newly developed bender element testing system. Test data supported that this testing system is effective in evaluating the shear wave velocity and its anisotropy of uniform spherical granular materials, including glass beads, uniform medium, and fine sands. Influencing factors on the Vs such as grain size and applied stress were studied. Two components of the soil …


Effects Of Mix Design Parameters And Rheological Properties On Dynamic Stability Of Self-Consolidating Concrete, B. Esmaeilkhanian, Kamal Khayat, A. Yahia, D. Feys Jan 2014

Effects Of Mix Design Parameters And Rheological Properties On Dynamic Stability Of Self-Consolidating Concrete, B. Esmaeilkhanian, Kamal Khayat, A. Yahia, D. Feys

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Stability is a crucial property for successful placement and performance of self-consolidating concrete (SCC). Dynamic stability refers to the segregation resistance of concrete during flow and is not thoroughly described in literature to date. In this research, a newly developed dynamic stability test, the Tilting-box test, was employed to evaluate the effect of different mix design parameters on the dynamic segregation of SCC. Paste volume, water-to-binder ratio (w/b), maximum size of aggregate (MSA), aggregate density, and aggregate grain-size distribution were shown to affect the dynamic stability of SCC, while the coarse aggregate shape did not have a significant influence. The …


Effects Of Interaction Conditions On Internal Network Structure Of Crumb Rubber-Modified Asphalts, Mohyeldin Ragab, Magdy Abdelrahman Jan 2014

Effects Of Interaction Conditions On Internal Network Structure Of Crumb Rubber-Modified Asphalts, Mohyeldin Ragab, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Investigation of the effect of interaction conditions on the development of the internal network structure of crumb rubber-modified asphalt (CRMA) was carried out. Enhancements in the CRMA physical properties, such as stiffness, expressed in the complex modulus (G*), and elasticity, expressed in the phase angle (δ), as a result of the development of three-dimensional (3-D) entangled network structure were achieved. These results came from controlling the interaction conditions of CRMA synthesis to regulate the crumb rubber-modified (CRM) components that were responsible for the formation of the 3-1) entangled network structure. Dissolution tests and thermogravimetric analysis (TGA) were performed on the …


Reflections On Energy, Greenhouse Gases, And Carbonaceous Fules, Eugene Coyle, William Grimson, Biswajit Basu, Mike Murphy Jan 2014

Reflections On Energy, Greenhouse Gases, And Carbonaceous Fules, Eugene Coyle, William Grimson, Biswajit Basu, Mike Murphy

Books/Book chapters

In this chapter, we review the history of man’s dependence on carbonaceous fuels for survival, beginning with pre-industrial civilizations, during which charcoal was pro- cessed for thousands of years to smelt iron and copper. In the eighteenth and nineteenth centuries, however, coke and coal became prime energy resources which powered the engine rooms of the industrial revolution. Accompanying the economic and societal benefits of this period was the recognition of the damage resulting from smog owing to excessive burning of coal, which affected both human health and the natural envi- ronment. These pivotal centuries laid the foundation for the advancement …


Tank Sizing And Optimizing Loop Placement In A Branched Water Distribution System, Colin G. Mccorkle Jan 2014

Tank Sizing And Optimizing Loop Placement In A Branched Water Distribution System, Colin G. Mccorkle

Dissertations, Master's Theses and Master's Reports - Open

More than eighteen percent of the world’s population lives without reliable access to clean water, forced to walk long distances to get small amounts of contaminated surface water. Carrying heavy loads of water long distances and ingesting contaminated water can lead to long-term health problems and even death. These problems affect the most vulnerable populations, women, children, and the elderly, more than anyone else. Water access is one of the most pressing issues in development today.

Boajibu, a small village in Sierra Leone, where the author served in Peace Corps for two years, lacks access to clean water. Construction of …


Assessment Of Flood Risk Under Future Climate Conditions, Kaye M. Lafond Jan 2014

Assessment Of Flood Risk Under Future Climate Conditions, Kaye M. Lafond

Dissertations, Master's Theses and Master's Reports - Open

Global climate change is predicted to have impacts on the frequency and severity of flood events. In this study, output from Global Circulation Models (GCMs) for a range of possible future climate scenarios was used to force hydrologic models for four case study watersheds built using the Soil and Water Assessment Tool (SWAT). GCM output was applied with either the "delta change" method or a bias correction. Potential changes in flood risk are assessed based on modeling results and possible relationships to watershed characteristics. Differences in model outputs when using the two different methods of adjusting GCM output are also …


Improvements In Sustainability Of Gravity-Fed Water Systems In The Comarca Ngäbe-Buglé, Panama: Spring Captures And Circuit Rider Model, Erica Kathryn Jones Jan 2014

Improvements In Sustainability Of Gravity-Fed Water Systems In The Comarca Ngäbe-Buglé, Panama: Spring Captures And Circuit Rider Model, Erica Kathryn Jones

Dissertations, Master's Theses and Master's Reports - Open

Gravity-flow aqueducts are used to bring clean water from mountain springs in the Comarca Ngäbe-Buglé, Panama, to the homes of the indigenous people who reside there. Spring captures enclose a spring to direct the flow of water into the transmission line. Seepage contact springs are most common, with water appearing above either hard basalt bedrock or a dense clay layer. Spring flows vary dramatically during wet and dry seasons, and discharge points of springs can shift, sometimes enough to impact the capture structure and its ability to properly collect all of the available water.

Traditionally, spring captures are concrete boxes. …


Occurrence Of Synthetic Amino-Polycarboxylate Chelating Compounds In Oregon Surface Waters, Nathan A. Hersey Jan 2014

Occurrence Of Synthetic Amino-Polycarboxylate Chelating Compounds In Oregon Surface Waters, Nathan A. Hersey

Civil and Environmental Engineering Master's Project Reports

Cation sequestering compounds are contained in many industrial, commercial and personal care products. The most widely used chelating agents, EDTA and DTPA, are commonly found in natural and industrial settings. When chelating compounds are present, the activity and transport of metal cations in the environment and the uptake of metals in natural systems can be affected. Surface water samples from across the United States were analyzed, as well as local collection and analysis of surface waters and wastewater treatment plant effluent from around Northwest Oregon. Results indicate presence of synthetic chelating compounds in areas with human activity, and absence in …


Seismic Retrofitting Of Existing Structures, Cetin Sahin Jan 2014

Seismic Retrofitting Of Existing Structures, Cetin Sahin

Civil and Environmental Engineering Master's Project Reports

This research project will give a brief presentation about earthquake resistant design and the methodology about seismic evaluation and rehabilitation of existing structures. It also provides certain aspects of computer software modeling against seismic loads and shows the necessity of seismic upgrading in a steel moment-frame building.

The seismic evaluation process consists of investigating if the structure meets the defined target structural performance levels. The main goal during earthquakes is to assure that building collapse doesn’t occur and the risk of death or injury to people is minimized and beyond that to satisfy post-earthquake performance level for defined range of …


Degradable Plastics And Their Potential To Affect Solid Waste Systems, Krista L. Thyberg, David J. Tonjes Jan 2014

Degradable Plastics And Their Potential To Affect Solid Waste Systems, Krista L. Thyberg, David J. Tonjes

Technology & Society Faculty Publications

Plastic waste forms a substantial part of municipal solid waste and has caused environmental concerns, particularly due to chemical contamination of the environment and effects from persistent litter. Plastics also complicate waste management processes, such as by having poor recovery rates through recycling, and causing contamination in composting operations. One potential means to address some of these challenges is through degradable plastics which, unlike conventional plastics, are designed to decompose at an accelerated rate in specific environments. Degradable plastics aim to address the end-of-life of plastic products and are intended to reduce the environmental impacts associated with their use and …


Employment Opportunities And Skills Requirements For Construction And Property Surveying 2014 - 2018, Roisin Murphy, Stephen Walsh Jan 2014

Employment Opportunities And Skills Requirements For Construction And Property Surveying 2014 - 2018, Roisin Murphy, Stephen Walsh

Reports

In Autumn 2012, a number of Society members expressed their increasing struggle to find qualified graduate surveyors to fill vacancies in their practices. At the same time, members working in academic institutions reported a severe reduction in the number of students enrolling on surveying courses at third level.


Enhancing Building Performance And Environmental Learning: A Case Study Of Virginia Beach City Public Schools, Shannon Chance, John Timothy Cole Jan 2014

Enhancing Building Performance And Environmental Learning: A Case Study Of Virginia Beach City Public Schools, Shannon Chance, John Timothy Cole

Books/Book Chapters

School buildings directly affect their natural and socio-cultural environments. They do this through their construction, maintenance, operation, and demolition. Most of the school buildings we have in stock today drain natural resources and inadvertently perpetuate a culture of environmental, social, and long-term economic ignorance and misuse. When approached thoughtfully, however, the design of school buildings can help inform and enrich society. Well-designed buildings can impart environmental knowledge and values. They can foster more effective behaviors among the people who learn in and from them. Effectively designed buildings can also conserve natural resources and—at their best—even help replenish the natural environment. …


Active Confinement Of Weakened Concrete Columns, Niall Holmes, Dervilla Niall, C. O’Shea Jan 2014

Active Confinement Of Weakened Concrete Columns, Niall Holmes, Dervilla Niall, C. O’Shea

Articles

This paper investigates the advantages of using of external active confinement to improve the compression load capacity of concrete cylinders using mild steel band clamps. For this, passive and actively pre-stressed steel bands have been attached to concrete cylinders to mimic real structural columns which may otherwise have to be removed and replaced due to poor strength performance. The experimental programme included compression load testing a number of unreinforced concrete cylindrical specimens to establish the effect the confinement had on the compressive load-carrying capacity and the stress-strain behaviour. A number of parameters were investigated in the study including the effect …


Longitudinal Shear Resistance Of Composite Slabs Containing Crumb Rubber In Concrete Toppings, Niall Holmes, Kevin Dunne, John O'Donnell Jan 2014

Longitudinal Shear Resistance Of Composite Slabs Containing Crumb Rubber In Concrete Toppings, Niall Holmes, Kevin Dunne, John O'Donnell

Articles

This paper investigates the behaviour and longitudinal shear capacity of metal deck composite slabs with the inclusion of crumb rubber in the concrete toppings. The ability of the slabs to act compositely is governed by the shear interaction between the concrete topping and the profiled steel deck. Results here show that crumb rubber concrete (CRC) improve the overall shear bond capacity between the steel deck and topping following an experimental study on full scale loading tests in accordance with Eurocode 4. The results confirm that composite slabs incorporating crumb rubber had no effect on the longitudinal shear resistance with similar …


A Review Of The Hl-93 Bridge Traffic Load Model Using An Extensive Wim Database, Cathal Leahy, Eugene J. Obrien, Bernard Enright, Donya Hajializadeh Jan 2014

A Review Of The Hl-93 Bridge Traffic Load Model Using An Extensive Wim Database, Cathal Leahy, Eugene J. Obrien, Bernard Enright, Donya Hajializadeh

Articles

HL-93, the current bridge traffic load model used in the United States, is examined here. Weigh-in-motion from 17 sites in 16 states, and containing 74 million truck records, is used to assess the level of consistency in the characteristic load effects implied by the HL-93 model. The load effects of bending moment and shear force are considered on single-lane and two-lane same-direction slab and girder bridges with a range of spans. It is found that the ratio of WIM-implied to HL-93 load effect varies considerably from one load effect to another. An alternative model is proposed which achieves improvements in …


Experimental Design Of Photo-Fenton Reactions For The Treatment Of Car Wash Wastewater Effluents By Response Surface Methodological Analysis, Maha Tony, Zeinab Bedri Jan 2014

Experimental Design Of Photo-Fenton Reactions For The Treatment Of Car Wash Wastewater Effluents By Response Surface Methodological Analysis, Maha Tony, Zeinab Bedri

Articles

Establishing a treatment process for practical and economic disposal of car wash wastewater has become an urgent environmental concern. Photo-Fenton’s process as one of the advanced oxidation processes is a potentially useful oxidation process in treating such wastewater. Lab-scale experiments with UV source, coupled with Fenton’s reagent, showed that hydrocarbon oil is degradable through such a process. The feasibility of photo-Fenton’s process to treat wastewater from a car wash is investigated in the present study. A factorial design based on the response surface methodology was applied to optimize the photo-Fenton oxidation process conditions using chemical oxygen demand (COD) reduction as …


Adaptive Traffic Speed Estimation, Brian Portugais, Mandar Khanal Jan 2014

Adaptive Traffic Speed Estimation, Brian Portugais, Mandar Khanal

Civil Engineering Faculty Publications and Presentations

Active traffic management aims to dynamically manage congestion based on existing and predicted traffic conditions. A challenge in this is that it is not usually possible to process data in real-time and use the output in control algorithms or in traveler information systems. A solution to this is to predict the traffic state based on assessments of current and past measurements. The work described in this paper develops an adaptive forecasting method to predict traffic speeds using dynamic linear models with Bayesian inference from a priori distributions. This study incorporates speeds collected from radar based sensors and validates the results …


Cyber-Physical Codesign Of Distributed Structural Health Monitoring With Wireless Sensor Networks, Gregory Hackmann, Weijun Guo, Guirong Yan, Zhuoxiong Sun, Chenyang Lu, Shirley Dyke Jan 2014

Cyber-Physical Codesign Of Distributed Structural Health Monitoring With Wireless Sensor Networks, Gregory Hackmann, Weijun Guo, Guirong Yan, Zhuoxiong Sun, Chenyang Lu, Shirley Dyke

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Our Deteriorating Civil Infrastructure Faces the Critical Challenge of Long-Term Structural Health Monitoring for Damage Detection and Localization. in Contrast to Existing Research that Often Separates the Designs of Wireless Sensor Networks and Structural Engineering Algorithms, This Paper Proposes a Cyber-Physical Codesign Approach to Structural Health Monitoring based on Wireless Sensor Networks. Our Approach Closely Integrates 1) Flexibility-Based Damage Localization Methods that Allow a Tradeoff between the Number of Sensors and the Resolution of Damage Localization, and 2) an Energy-Efficient, Multilevel Computing Architecture Specifically Designed to Leverage the Multiresolution Feature of the Flexibility-Based Approach. the Proposed Approach Has Been Implemented …


Experimental Tools To Study Molecular Recognition Within The Nanoparticle Corona, Markita P. Landry, Sebastian Kruss, Justin T. Nelson, Gili Bisker, Nicole M. Iverson, Nigel F. Reuel, Michael S. Strano Jan 2014

Experimental Tools To Study Molecular Recognition Within The Nanoparticle Corona, Markita P. Landry, Sebastian Kruss, Justin T. Nelson, Gili Bisker, Nicole M. Iverson, Nigel F. Reuel, Michael S. Strano

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Advancements in optical nanosensor development have enabled the design of sensors using synthetic molecular recognition elements through a recently developed method called Corona Phase Molecular Recognition (CoPhMoRe). The synthetic sensors resulting from these design principles are highly selective for specific analytes, and demonstrate remarkable stability for use under a variety of conditions. An essential element of nanosensor development hinges on the ability to understand the interface between nanoparticles and the associated corona phase surrounding the nanosensor, an environment outside of the range of traditional characterization tools, such as NMR. This review discusses the need for new strategies and instrumentation to …


Linking Solid Particle Packing Of Eco-Scc To Material Performance, Florian V. Mueller, Olafur H. Wallevik, Kamal Khayat Jan 2014

Linking Solid Particle Packing Of Eco-Scc To Material Performance, Florian V. Mueller, Olafur H. Wallevik, Kamal Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The concept of Eco-SCC aims to achieve self-compacting concrete (SCC) design for intermediate compressive strength mixtures that are commonly used in the ready-mix concrete industry. Contrary to many other approaches, in which the reactive cement clinker is replaced by a less reactive component, Eco-SCC involves the reduction of the total powder content. In the approach presented in this paper, the lubricant volume is increased by using a non-reactive filler. An improved particle packing with an enhanced lattice effect can minimize the lubricant demand and enhance the stability of the concrete. The effect of particle-size distribution on stability and performance of …


Making Bridges Outlast Rising Waters, Daniel Cox Jan 2014

Making Bridges Outlast Rising Waters, Daniel Cox

TREC Project Briefs

During Hurricanes Ivan in 2004 and Katrina in 2005, at least 11 highway and railroad bridges along the U.S. Gulf Coast were damaged by wave forces. The spans of these bridges typically rested on bent column supports, and were attached to the supports by a variety of connection methods. Failure of these connections caused bridge spans to be washed away when the water rose high enough to lift them off. To build bridges that can withstand such forces, engineers must be able to estimate the effects the forces will have.

Investigator Daniel Cox of Oregon State University has conducted wave …


A Comparative Assessment Of Crowded Source Travel Time Estimates: A Case Study Of Bluetooth Vs Inrix On A Suburban Arterial, Fahad Fasha Alhajri Jan 2014

A Comparative Assessment Of Crowded Source Travel Time Estimates: A Case Study Of Bluetooth Vs Inrix On A Suburban Arterial, Fahad Fasha Alhajri

Civil and Environmental Engineering Master's Project Reports

Travel time is one of the most widely used measures of traffic performance monitoring for the transportation systems. It is a simple concept that refers to the time required to traverse between two points of interest. Travel time is communicated and used by a wide variety of audience such as commuters, media reporters, and transportation engineers and planners. Recent developments within the wireless communication area made it possible to collect travel time data at a relatively low cost. These emerging technologies include mobile phone based technologies, in-vehicle navigation technologies and automatic vehicle identification technologies. Although these technologies offer a great …


Parametric Analysis Of Resilient Modulus Modeling For Recycled Asphalt Pavement In Base Layer, Ehab Noureldin, Magdy Abdelrahman Jan 2014

Parametric Analysis Of Resilient Modulus Modeling For Recycled Asphalt Pavement In Base Layer, Ehab Noureldin, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The resilient modulus (MR) has been found to be the most important parameter in the Mechanistic-Empirical Pavement Design Guide (MEPDG) for the base layer. A literature review showed that the use of recycled asphalt pavement (RAP) in the base layer had many economic and structural benefits. The prediction of MR with the specific MEPDG model for the base layer mixed with RAP was found to be reliable for several field conditions. However, further studies of the MEPDG model are needed for an understanding of the physical meaning of each parameter in the model. The most important factor …


Low Cost Adsorbents For Sustainable Dye Containing-Wastewater Treatment, Siew Teng Ong, Pei Sin Keng, Siew Ling Lee, Yung Tse Hung Jan 2014

Low Cost Adsorbents For Sustainable Dye Containing-Wastewater Treatment, Siew Teng Ong, Pei Sin Keng, Siew Ling Lee, Yung Tse Hung

Civil and Environmental Engineering Faculty Publications

Dyes are coloured substances that can be applied to various substrates such as textile materials, leather, paper and hair. The usage of dyes has continuously increased in many industries but the removal of this pollutant remains as a problematic issue as they are generally stable to light and oxidizing agents and are resistant to aerobic digestion. This literature review paper provides and lists several low cost adsorbents to serve as an alternative method for dye removal. Adsorption using low cost materials can be viewed as a sustainable treatment process because most of these materials are of naturally occurring, locally available …


Water Resource Systems Analysis And Management - Amirkabir University Of Technology, Jamshid Mousavi Jan 2014

Water Resource Systems Analysis And Management - Amirkabir University Of Technology, Jamshid Mousavi

All ECSTATIC Materials

Course taught at Amirkabir University of Technology.


Effect Of Crumb Rubber Dissolution On Low-Temperature Performance And Aging Of Asphalt-Rubber Binder, Amir Ghavibazoo, Magdy Abdelrahman Jan 2014

Effect Of Crumb Rubber Dissolution On Low-Temperature Performance And Aging Of Asphalt-Rubber Binder, Amir Ghavibazoo, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Asphalt binder plays a critical role in defining the low-temperature performance of asphalt pavement, and, therefore, enhancing its mechanical behavior at low service temperatures through modification always has been of great interest. Crumb rubber modification of asphalt is one of the common practices in the industry. However, the effect of a crumb rubber modifier (CRM) on low-temperature performance of the binder is not well understood. A CRM swells by absorbing the aromat-ics and light molecular components of asphalt at low interaction temperatures (i.e., 160°C) and dissolves at higher interaction temperatures (i.e., 190°C, 220°C). Each of those activities affects the performance …


A Quantitative Analysis Of The Impact Of Wind Energy Penetration On Electricity Prices In Ireland, Micheal O'Flaherty, Niall Riordan, Noel O'Neill, Ciara Ahern Jan 2014

A Quantitative Analysis Of The Impact Of Wind Energy Penetration On Electricity Prices In Ireland, Micheal O'Flaherty, Niall Riordan, Noel O'Neill, Ciara Ahern

Articles

The maturity of wind technology combined with availability of suitable sites means Ireland is on course to generate 40% of its electricity from the wind by 2020.This work sets out to quantify, to what degree, if any, increased wind penetration translates into reduced wholesale and retail prices for electricity. The consensus from the literature is that increasing wind penetration reduces wholesale electricity prices, but views vary as to what degree this translates into reduced retail prices for the consumer.

This work demonstrates the effect of wind energy penetration on the price of electricity in Ireland using quantitative data from the …


Impact Of Organic Coatings On Frictional Strength Of Organically Modified Clay, B. Bate, Q. Zhao, S. E. Burns Jan 2014

Impact Of Organic Coatings On Frictional Strength Of Organically Modified Clay, B. Bate, Q. Zhao, S. E. Burns

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Organic matter is frequently encountered in both naturally occurring and engineered particulate media. Charged functional groups in the organic matter can lead to cation exchange within the clay interlayer, which results in the formation of an organic coating on the clay surfaces and alters the interfacial frictional regime in the soil mass. This study investigated the triaxial shear frictional behavior of montmorillonite particles coated with a controlled organic phase composed of quaternary ammonium cations. Through cation exchange, organic cations were loaded onto the clay's interlayer exchange sites, with control on the density of organic coverage and structure of the organic …


A Probabilistic Based Failure Model For Components Fabricated From Anisotropic Graphite, Chengfeng Xiao Jan 2014

A Probabilistic Based Failure Model For Components Fabricated From Anisotropic Graphite, Chengfeng Xiao

ETD Archive

The nuclear moderator for high temperature nuclear reactors are fabricated from graphite. During reactor operations graphite components are subjected to complex stress states arising from structural loads, thermal gradients, neutron irradiation damage, and seismic events. Graphite is a quasi-brittle material. Two aspects of nuclear gradegraphite, i.e., material anisotropy and different behavior in tension and compression, are explicitly accounted for in this effort. Fracture mechanic methods are useful for metal alloys, but they are problematic for anisotropic materials with a microstructure that makes it difficult to identify a "critical" flaw. In fact cracking in a graphite core component does not necessarily …