A. James Clark School of Engineering

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

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    Inverse Hybrid Method for Determining Explosive Loading on Plates Due to Buried Mines
    (2007-12-11) Bretall, Damien Carl; Fourney, William; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Due to the changing face of warfare there is an ever growing need to protect the underside of combat vehicles from mine blasts. This research effort presents a new method to better characterize the pressure profiles experienced by a plate as the blast develops. The explosive deformation of a small-scale plate was recorded using synchronized high-speed digital cameras, and then analyzed using 3D Digital Image Correlation software. Time-varying pressure profiles were input into an axisymmetric FEM simulation by fitting curves to data obtained from tests using Kolsky bars to measure pressures. These were then modified to find possible profiles that produce the measured deformations. It was discovered that the final deformation cannot be determined from only total impulse or peak pressures, it is very sensitive to the time and spatial decay of the pressures, and a deforming plate travels with greater initial velocity than a nondeforming plate of equal mass.
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    NANO ELECTRIC DISCHARGE MACHINING OF GOLD THIN FILMS WITH A MODIFIED SCANNING TUNNELING MICROSCOPE
    (2005-05-03) Golub, Marcia A.; Gomez, Romel D; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This Master's thesis presents the development of an instrument and a technique to locally ablate solid surfaces using a scanning tunneling microscope and an electrostatic discharge processes. The design and construction of the scanning tunneling microscope inside the scanning electron microscope along with the designs of the control electronics are reported. Several methods of surface modification are investigated, namely mechanical contact and near-surface discharge in air and vacuum. Images of gold and graphite surfaces in air and vacuum, and feature formation using electrostatic discharge in air and vacuum are discussed. Analysis of the relationship between energy of the discharge and feature's size is presented, along with a discussion of the geometrical characteristics of the features.