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Epoxy resins and composite materials are well characterized in their mechanical properties. However these properties change as the materials age under different conditions, as their microstructure undergoes changes from the absorption or desorption of water. Many of these microstructural changes occur at the interfacial region between where the matrix of the composite meets the reinforcement fiber, but still result in significant effects in the material properties. These effects have been studied and characterized under a variety of conditions by artificially aging samples. The artificial aging process focuses on exposing samples to environmental conditions such as high temperature, UV light, and humidity. While conditions like this are important to study, in real world applications the materials will not be simply resting in a laboratory created environment. In most circumstances, they are subjected to some kind of stress or impact. This report will focus on designing an experiment to analyze aged samples under tensile loading and creating a fixture that will sustain loading while the samples are aged. . The conditions that will be tested are control conditions at standard temperature and humidity in the laboratory, submerged, thermal heating, submerged and heated, and hygrothermal.
ContributorsNothern, Bradley James (Author) / Yekani Fard, Masoud (Thesis director) / Chattopadhyay, Aditi (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
TiO2 has been studied in the degradation of ethanol for indoor application. A dynamic flowing non-loop system was utilized. The reactor was a quartz tube filled with the TiO2 catalyst with glass wool on the ends. The analytical equipment used were Vernier's ethanol and CO2 sensors with a two-point calibration performed on the ethanol sensor. The purpose of the calibration was to create a known standard to establish accurate readings. The experimental procedure followed the scheme of bypassing the reactor, flowing into the reactor without the UV lights on for a small period, turning the UV lights on for five minutes, and then going back to the bypass. A CFD simulation using ANSYS Fluent was done to determine the optimal inlet and outlet positions of the biochamber that housed the sensors. The objective of the simulation was to determine which inlet and outlet locations provided the best fluid flow for sensor contact and mixing. Sensitivity analysis of varying parameters were tested to determine the optimal settings in producing accurate results to fulfill the simulation goals. It was determined that a vertical position biochamber with an inlet centered on the top face and the outlet on the bottom of a side face was ideal. The main experimental results showed that ethanol of both low and high concentrations were completely or almost fully degraded into carbon-products. The results showed that there was CO2 consumption and it was most likely due to a combination of sensor inaccuracy and accumulation onto the catalyst surface. However, the sensor inaccuracy would not account for the entirely of the CO2 consumption and previous studies have shown that carbon-products do form on the catalyst surface. Therefore, it can be asserted that CO2 has accumulated on the catalyst and the inclusion of water may have caused catalyst deactivation. Having the light on the photoreactor the whole time rather than waiting to turn on the light has shown to decrease the period of degradation but has no effect on the amount of degradation. Research from Nimlos, Muggli, etc., have determined that intermediate products such as acetaldehyde, acetic acid, formaldehyde, and formic acid form during ethanol degradation and this can be assumed to have occurred in this research as well. These intermediate products were not analyzed for this study, but has been included in the go-forward for future works. For indoor applications, TiO2 catalyst have already been implemented into consumer and commercialized air purifiers, but there is tremendous potential for HVAC systems. There are concerns with HVAC application as discussed, but if implemented correctly, it can be a useful tool for indoor air purification.
ContributorsNguyen, Jeremy Franklin (Author) / Andino, Jean (Thesis director) / An, Keju (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Composite insulators on overhead lines are frequently subjected to corona discharges due to increased electric field intensities under various conditions. These discharges can cause localized heating on the surface and affect the hydrophobicity of the insulator. A study has been undertaken to quantify and evaluate the thermal degradation that composite insulation is subjected to from corona discharges. This has been conducted primarily at the power frequency (60 Hz) and at the low frequency range (37 kHz). Point to plane corona discharge experiments have been performed in the laboratory at both the frequencies and varying levels of thermal degradation has been observed. The amplitude and the frequency of current spikes have been recorded at different voltage levels. A temperature model based on the amplitude and the frequency of current data has been formulated to calculate the maximum temperature attained due to these discharges. Visual thermal degradation has been found to set in at a low frequency range while there is no visual degradation observed at power frequency even when exposed to discharges for relatively much longer periods of time. However, microscopic experiments have been conducted which revealed degradation on the surface at 60 Hz. It has also been found that temperatures in excess of 300 Celsius have been obtained at 37 kHz. This corroborates the thermo gravimetric analysis data that proves thermal degradation in silicone rubber samples at temperatures greater than 300 Celsius. Using the above model, the maximum temperature rise can be evaluated due to discharges occurring on high voltage insulation. This model has also been used to calculate the temperature rise on medium voltage distribution equipment such as composite bushings and stand-off plugs. The samples were subjected to standard partial discharge tests and the corresponding discharge magnitudes have been recorded. The samples passed the tests and the corresponding temperatures plotted have been found to be within thermal limits of the respective insulation used on the samples. The experimental results concur with the theoretical model. A knowledge of the maximum temperatures attained due to these discharges can help in design of insulation with better thermal properties.
ContributorsSangaraju Venkateshwara, Pradeep Varma (Author) / Gorur, Ravi S (Thesis advisor) / Farmer, Richard (Committee member) / Vittal, Vijay (Committee member) / Arizona State University (Publisher)
Created2010