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Development Of Lightweight Frp Bridge Deck Designs And Evaluations, Isaac Lem Howard
Development Of Lightweight Frp Bridge Deck Designs And Evaluations, Isaac Lem Howard
Graduate Theses, Dissertations, and Problem Reports
The focus of this study was to develop and analyze lightweight FRP bridge decks and determine their adequacy under AASHTO's HS25 loading case with minimum stringer spacings of five feet. Two different multicellular decks were designed and tested during this study. Both decks had fiber volume fractions of approximately 54% and weighed 14--15 lb/ft2 of deck area. Testing was performed to determine both the elastic and failure response at the component level and the elastic response at the system level. Theoretical correlation of stiffness was made via approximate classical lamination theory, and maximum transverse load distribution factors were predicted. In …
Calculation Of Thermal Expansion Of Iron -Aluminides With Transition Metal Additives, Tatiana Seletskaia
Calculation Of Thermal Expansion Of Iron -Aluminides With Transition Metal Additives, Tatiana Seletskaia
Graduate Theses, Dissertations, and Problem Reports
The addition of transition metal elements can significantly modify physical properties of intermetalic compounds. We studied the influence of Mo and V additives on thermal expansion coefficient (CTE) of Fe3Al and FeAl over the wide range of temperatures. The site preference of both transition metals was determined by FP-LMTO method. Fe3Al in DO3 structure has three non-equivalent lattice sites: FeI site surrounded by eight iron atoms, FeII site with four iron and four aluminum nearest neighbors and Al site. Our calculations show that Fe, site is energetically more favorable for both Mo and V. The obtained site-selection energies of Mo …
Aging Model For Commercial Polymers, Kevin J. Ford
Aging Model For Commercial Polymers, Kevin J. Ford
Graduate Theses, Dissertations, and Problem Reports
Physical aging of polyvinyl chloride, high-density polyethylene, and polyester reinforced with polyester fibers specimens have been investigated. These materials are commercially available and are currently used in trenchless relining of sewer pipes. The analysis uses the effective-time theory and time-temperature superposition (TTSP) methods proposed by Struik, as well as variations of these methods, as proposed by Chai and McCrum, Guerdoux et al. and others. The creep data generated by this study show that the time-dependent creep properties of these materials can be modeled within experimental error with slight changes to the above methods. To predict the creep behavior of full-scale …
Long-Term Creep Of Encased Polymer Liners, Shalini Rangarajan
Long-Term Creep Of Encased Polymer Liners, Shalini Rangarajan
Graduate Theses, Dissertations, and Problem Reports
Due to increasing costs and inconveniences in replacing deteriorated sewer pipelines by conventional excavation methods, the trenchless or 'no-dig' technology is being extensively used. In trenchless technology, a polymer or reinforced polymer is applied to the inside of the deteriorated host pipe to prevent ground water from seeping into the sewer pipelines. In this work, a testing method was developed to determine the long-term creep behavior of encased polymer liners.;Short-term tests, following the ASTM D790 procedure, were conducted on pipe liner samples to determine the initial elastic modulus and compare it to the elastic modulus obtained from long-term testing of …
Gamma Prime Precipitation Modeling And Strength Responses In Powder Metallurgy Superalloys, Jian Mao
Gamma Prime Precipitation Modeling And Strength Responses In Powder Metallurgy Superalloys, Jian Mao
Graduate Theses, Dissertations, and Problem Reports
Precipitation-hardened nickel-based superalloys have been widely used as high temperature structural materials in gas turbine engine applications for more than 50 years. Powder metallurgy (P/M) technology was introduced as an innovative manufacturing process to overcome severe segregation and poor workability of alloys with high alloying contents. The excellent mechanical properties of P/M superalloys also depend upon the characteristic microstructures, including grain size and size distribution of gamma' precipitates. Heat treatment is the most critical processing step that has ultimate influences on the microstructure, and hence, on the mechanical properties of the materials. The main objective of this research was to …