Mechanical Engineering

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    Characterization of Exfoliated Graphite and Latex Composite as Temperature Sensors to Produce Thermal Images
    (2014) Sauerbrunn, Elizabeth; Bruck, Hugh A; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Temperature sensing is crucial in spacecraft to ensure all systems remain within operating temperatures. Sensing over an area would allow thermal management systems to effectively see the temperature profile in real time, which is not being done with thermocouple and RTD systems used today. The resistance response as a function of temperature for exfoliated graphite and latex composite sensors was investigated. The effect of the substrate CTE and the EG loading level were observed and 30 wt% EG sensors were calibrated on a carbon fiber substrate. Above room temperature, the percent resistance change and temperature relationship is linear, while below room temperature the relationship is exponential. The resistance response from twelve sensor grids was converted into a temperature field to produce thermal images over a surface. These temperature profiles were compared to thermal simulation data, proving that the sensor grids successfully mapped the proper temperature patterns.
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    Determination of Mixed Mode Energy Release Rates in Laminated Carbon Fiber Composite Structures Using Digital Image Correlation
    (2012) Puishys, Joseph Francis; Bruck, Hugh A; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Carbon fiber composites have recently seen a large scale application in industry due to its high strength and low weight. Despite numerous beneficial attributes of composite materials, they are subject to several unique challenges; the most prevalent and troubling is delamination fracture. This research program is focused on developing an appropriate damage model capable of analyzing microscopic stress strain growth at the crack tip of laminated composites. This thesis focuses on capturing and identifying the varying stress and strain fields, as well as other microstructural details and phenomena unique to crack tip propagation in carbon fiber panels using a novel mechanical characterization technique known as Digital Image Correlation (DIC).