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Browsing by Author "Kyriakides, Steven"

Now showing 1 - 3 of 3
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    Engineering Students Design Composite Bracing System for the Virginia Tech Athletic Department
    Kyriakides, Steven (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    Engineering Students Design Composite Bracing System for the Virginia Tech Athletic Department.
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    Mechanical Behavior of Nafion and BPSH Membranes
    Kyriakides, Steven (Virginia Tech Department of Materials Science and Engineering, 2005-09-22)
    A brief characterization of the mechanical behavior of Nafion® 117 and BPSH-35 membranes took place through uniaxial loading, stress relaxation, and creep compliance tests. Membranes were subjected to uniaxial loading at various strain rates to observe yield and fracture behavior. Stress relaxation tests measured relaxation response to strain rate and relaxation strain. Creep compliance tests led to the formation of a creep master curve for the Nafion® membrane. Tests showed that for Nafion®, higher strain rates produced higher yield stresses and yield strains as well as faster initial relaxation. Strain rate had no effect on strain at fracture. Higher re­ laxation strains also led to faster initial stress relaxation in both Nafion® and BPSH. BPSH results showed no yield trends in uniaxial loading, though they illustrated lower breaking strains with higher strain rates.
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    Particle Spacing Effects on the Strengthening of Discontinuously-Reinforced Polymer Matrix Composites
    Kyriakides, Steven; Persing, Ramsey (Virginia Tech Department of Materials Science and Engineering, 2006-09-22)
    In metal matrix composites, the spacing between discontinuous reinforcements can affect strengthening by interfering with the motion of dislocations through the metal.This project looks for similar phenomena in polymer matrix composites (PMCs), since the molecular activity of the polymer chains should be altered in the vicinity of the reinforcements.Awareness of such a trend can improve the understanding of PMC mechanics, which in turn can improve PMC characterization and selection techniques.This project sought a relationship between particle spacing and overall strengthening in a discontinuously-reinforced PMC test case composed of alumina particles in a polyphenylene sulfide matrix.Tensile tests were run on hot-pressed composite samples with varying reinforcement volume fraction and particle size.Data showed that composite strength increases as particle spacing increases, except at high volume fractions where this trend reverses.These results provide preliminary data but demonstrate a need for more in-depth investigation.