Browsing by Subject "Mechanical properties"

Now showing 1 - 4 of 4
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    Characterizing the Mechanical Properties of Biological Tissues
    (2019-11-12) Wallace, Niko J
    This research provides information indicating individual pixel strains can be calculated via a uniaxial test to map the mechanical properties of tissue including the anisotropic nature of diseased tissue.
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    Exceptionally Elastic Single-Component Pharmaceutical Crystals
    (ACS, 2019) Sun, Changquan C.; Wang, Kunlin; Mishra, Manish
    We report here the first elastically bendable single-component pharmaceutical crystal, celecoxib. Interlocked molecular packing without the slip plane and the presence of an isotropic hydrogen bond network are major structural features responsible for both the exceptional elastic flexibility and high stiffness of the celecoxib crystal as revealed by bending and nanomechanical studies. The molecular model of the exceptional elasticity is rationalized by the inhomogeneous spatial separations of molecules in the bent crystal, which is further confirmed by micro-Raman spectroscopy. The celecoxib crystal, exhibiting both therapeutic effects and elastic mechanical behavior, could be used to manufacture functional microdevices with novel medical applications.
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    Mechanical Properties of High Strength Concrete
    (Minnesota Department of Transportation, 1998-01) Mokhtarzadeh, Alireza; French, Catherine E.
    Researchers conducted an experimental program to investigate production techniques and mechanical properties of high-strength concrete and to provide recommendations for using these concretes in manufacturing precast/prestressed bridge girders. High-strength concretes with 28-day compressive strengths in the range of 8,000 to 18,600 psi (55.2 to 128 MPa) were produced. Test variables included total amount and composition ofcementitious material, portland cement, fly ash, and silica fume; type and brand of cement; type of silica fume, dry densified and slurry; type and brand of high-range water-reducing admixture; type of aggregate; aggregate gradation; maximum aggregate size; and curing. Testing determined the effects of these variables on changes in compressive strength and modulus of elasticity over time, on splitting tensile strength, on modulus of rupture, on creep, on shrinkage, and on adsorption potential as an indirect indicator of permeability. The study also investigated the effects of test parameters such as mold size, mold material, and end condition. More than 6,300 specimens were cast from approximately 140 mixes over a period of three years.
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    The mechanical response of common nanoscale contact geometries
    (2008-03) Mook, William Moyer
    Characterizing the mechanical response of common nanoscale contact geometries is vitally important to fields such as microelectromechanical systems (MEMS) where the behavior of nanoscale contacts can in large part determine system reliability and lifetime. Therefore a research program was undertaken that focused on the development of innovative nanoindentation-based techniques capable of quantifying the mechanical response of freestanding nanostructures. Nanoindentation was used since it is a non-destructive, high resolution technique that has been proven to be very useful in characterizing materials at the nanoscale. Examples of tested structures include single crystalline nanoparticles and polycrystalline nanoposts. From these experiments methods to characterize the structures' effective elastic modulus, flow stress, fracture toughness and activation volume required for plasticity have been developed. It was noted that both modulus and toughness in nanoparticles scale with average contact stress. This result has lead to the development of an experimental analysis technique that accounts for the hydrostatic component of pressure which develops in a material under contact. The effect of hydrostatic pressure on indentation modulus is currently not accounted for in nanoindentation even though it is shown to be important at length scales below 100 nm.