Master of Science

thesisPeople with lower limb physical disabilities have been traditionally limited in their options for recreational sports and outdoor activities, including paragliding. The Phoenix paragliding system has been created to help these individuals paraglide safely. In order to address the limitations of this populace, Able Pilot, a local nonprofit organization approached the department of mechanical engineering at the University of Utah to build a mobility device, called Phoenix. The university accepted this partnership due to Able Pilot's established research instructional program. Able Pilot's program is designed to establish and support the development and testing of formal paragliding and their Ultralight instructional protocols and methods for pilots with various disabilities. The purpose of this study is to evaluate a proposed improvement of the existing Phoenix 1.5 paragliding system. The Phoenix 2.0 is similar to previous versions; however, changes in design have been introduced to better meet customer requirements received after test flights with the earlier versions. The new version is proposed to be constructed from lightweight materials without losing strength. The frame is made of aluminum alloy 6061-T6 tubing with an outer diameter of 1 in. and wall thickness of 0.095 in. The Phoenix 2.0 is constructed from an aluminum alloy opposed to the Phoenix 1.5' s Chromalloy steel alloy frame. This results in a lighter device. Substituting an aluminum alloy led designers to request engineering analyses, especially finite element analysis, to verify that this version's structure is strong enough to protect the pilot during various landing scenarios. In order to improve pilot safety, analysis and design changes have been made to the headrest, which also acts as roll protection during adverse landings. Final recommendations include continuing work on the headrest to increase its utility as both a handle and a safety feature, upgrading the wheels to heavy duty mountain bike wheels, and regularly inspecting and replacing these wheels. These recommendations, supported by the work presented in this thesis, will ensure that the Phoenix 2.0 will safely allow people with lower limb disabilities to fly the blue skies

Development of Hot Wire-Laser Beam Displacement Technique for Determining Thermal Conductivity and Thermal Diffusivity of Nanofluids

A nanofluid is a fluid containing suspended nanoparticles, with sizes of the order of nanometer. Heat conductors of nanofluid are better than that of base fluid. Therefore, the most important point to know is its thermal conductivity and thermal diffusivity. The focus of this work is on determining the thermal conductivity and thermal diffusivity of nanofluids containing metallic and non metallic nanoparticles. The specific objectives were the determination of the effects of sonication time, volume fraction concentration, particle size, particles materials, and two materials mixture nanoparticles on the thermal conductivity and thermal diffusivity of nanofluids. Thermal conductivity and thermal diffusivity measurements were performed by hot wire-laser beam displacement technique. The hot wire-laser probe beam displacement setup consists of a CW He-Ne laser beam as the probe beam, a thin circular Ni-Cr alloy resistance wire which serves as a heat source, and a position sensitive detector (PSD). The developed coupled transient heat conduction equations of the heating wire and the nanofluid were solved simultaneously by using the Finite Difference Method. A numerical model, which took the thermal conductivity and thermal diffusivity of the test nanofluids as parameters to calculate the probe beam deflection, was established separately. By comparing the time-varying deflection curve from the numerical model with that recorded in the experiment, the nanofluids thermal conductivity and thermal diffusivity in the model were adjusted to give the best agreement between the model and the experimental results. The nanofluid samples were aluminum (Al) 18 nm, chromium (Cr) 20 nm, and aluminum oxide nanoparticles (Al2O3) 11 nm, 25 nm, 50 nm, and 63 nm dispersed in distilled water, ethylene glycol,and ethanol. These nanofluid samples were prepared using the one-step method. The results of the thermal conductivity and thermal diffusivity measurements showed the best interval time of sonicated was 6 hours. The results showed that the thermal conductivity and thermal diffusivity of all samples of nanofluid increased linearly with increases of volume fraction concentration of nanoparticles in base fluid. Where, the thermal conductivity of Al nanofluid suspension in distilled water at volume fraction concentration between 0.42 % to 0.085 was 0.732 W/m.K to 0.648 W/m.K,respectively. The results of the thermal conductivity and thermal diffusivity measurements of Al2O3 nanofluids containing different sizes of nanoparticles (11 nm to 63 nm) showed that the smaller nanoparticles yielded lower thermal conductivity and thermal diffusivity. Where the thermal conductivity of Al2O3 of particles size 11 nm suspension in distilled water at volume fraction concentration 1.4 % was (0.676 W/m.K) and thermal diffusivity was (1.727x10-7 m2/s), while the thermal conductivity and thermal diffusivity of Al2O3 of particle size 63 nm at the same volume fraction concentration was 0.705 W/m.K and 1.793x10-7 m2/s, respectivilly. This means that the thermal conductivity and thermal diffusivity have increased with increase particle size. The result also showed that the thermal conductivity and thermal diffusivity depended on the material of the nanoparticles, where the thermal conductivity and thermal diffusivity of metallic nanoparticles higher than the nonmetallic nanoparticles. Measurement of thermal conductivity and thermal diffusivity of bimetallic nanofluid was also conducted, and the result showed that the thermophysical properties of two metallic mixture nanofluids improved 15.82 % - 7.94 % for bimetallic in water, 17.44 % - 9.3 % in ethylene glycol, and 19.65 % - 10.4% in ethanol

Mud Weight Prediction for Offshore Drilling

Selecting a proper mud-weight during drilling is important to prevent wellbore breakout. Through development of computer software, the optimum range of mud-weight can be computed by trial-and-error using finite element elasto-plastic model. Even though the results are very accurate and precise, inherited parameter uncertainties associated with the vertical to horizontal earth stress ratios, fracgradients, Coulomb friction angle and cohesion means the precision attained in such software is meaningless and could be misleading to field engineers working on site. An even more pressing problem to the drilling manager is that these software are too specialist oriented and required input parameters that are not available practically in a day-to-day operation to make in-situ decision. The idea behind this project is to propose a new workflow of mud-weight prediction that does not require a precise input of parameters and develop a simple prototype lab-version program that could be used in-house

Carbon black mediated conductive polymer composite

The central goal of this thesis is to produce electrically conductive nanocomposites made out of carbon black obtained from waste tires as filler into a polymeric matrix. Waste tires are discarded in substantial numbers on a daily basis, posing a significant environmental concern. By weight, about 25-35% of a tire is carbon black. Pyrolysis is a convenient and environmentally friendly process to produce carbon black from tires. Due to carbon black’s low density, high electrical conductivity and economical feasibility, this thesis investigates the electrical conductivity of nanocomposites that utilizes carbon black particles as fillers. As a result of its modified and controllable properties, composites with fillers present a radical alternative to conventional polymers and their blends. The small size of the fillers leads to exceptionally large interfacial area in the composites. The interface controls the degree of the interaction between the filler and the polymer thus controlling the properties. The effect of annealing temperature (550°C-1250°C) on the electrical properties of carbon black obtained from tires was investigated. Generally, the DC electrical conductivity improved when the annealing temperature increased. The modulation of the electrical conductivity as a function of annealing temperatures was explored using Raman spectroscopy, Energy dispersive X-ray, Scanning electron microscopy, X-Ray diffraction and thermo-gravimetric analysis. Annealed carbon black was used as filler in a polymeric matrix. The annealed waste carbon black was blended into epoxy at different wt. % to investigate the electrical conductivity. Furthermore, annealed carbon black was used as filler in a Carbon Fiber Reinforced vii Polymer (CFRP) and then the effect of different percentage of waste carbon black was studied. After that, through plane electrical conductivity, surface electrical conductivity, through plane thermal conductivity and flexural strength were examined. The results showed that the electrical conductivity for the annealed carbon black at 1250°C was improved to a value 40 σ/cm. Furthermore, impregnating a high amount of annealed carbon black (40 wt. %) in a polymeric matrix resulted in a low electrical conductivity of 0.0034 σ/cm. Blending annealed carbon black into carbon fiber reinforced polymer (CFRP) resulted in alternating the electrical conductivity of the composite material. The surface conductivity of carbon fiber polymer was 2.5 σ (per square). However, the surface conductivity of impregnating 2 wt. % of annealed waste carbon black into CFRP was 13 σ (per square). The results also showed that addition of 5 wt. % of waste carbon black noticeably decreased the area specific resistance of CFRP from 199 to 98 mΩ.cm2. The through-plane thermal conductivity of CFRP increased as carbon black wt. % increased. The through plane-thermal conductivity increased by 78% when the waste carbon black loading reached 16 wt. %. However, loading the composite with waste carbon black resulted in decreasing the flexural strength. It is recommended to blend 5 wt. % of waste carbon black annealed at 1250°C into CFRP to provide enhancement in both the through-plane and surface electrical conductivity. The surface conductivity was enhanced by 80% when blending 5 wt. % of waste carbon black. The through plane resistivity reduced 51% by adding 5 wt. %of waste carbon black. However, the flexural strength was negatively affected with a reduction of 8% only by blending 5 wt. % of waste carbon black

CARBON BLACK MEDIATED CONDUCTIVE POLYMER COMPOSITE

The central goal of this thesis is to produce electrically conductive nanocomposites made out of carbon black obtained from waste tires as filler into a polymeric matrix. Waste tires are discarded in substantial numbers on a daily basis, posing a significant environmental concern. By weight, about 25-35% of a tire is carbon black. Pyrolysis is a convenient and environmental friendly process to produce carbon black from tires. Due to carbon black’s low density, high electrical conductivity and economic feasibility, this thesis investigates the electrical conductivity of nanocomposites that utilizes carbon black particles as fillers. As a result of its modified and controllable properties, composites with fillers present a radical alternative to conventional polymers and their blends. The small size of the fillers leads to exceptional large interfacial area in the composites. The interface controls the degree of the interaction between the filler and the polymer thus controlling the properties. The effect of annealing temperature (550°C-1250°C) on the electrical properties of carbon black obtained from tires was investigated. Generally, the DC electrical conductivity improved when the annealing temperature increased. The modulation of the electrical conductivity as a function of annealing temperatures was explored using Raman spectroscopy, Energy dispersive X-ray, Scanning electron microscopy, X-Ray diffraction and thermo-gravimetric analysis. Annealed carbon black was used as filler in a polymeric matrix. The annealed waste carbon black was blended into epoxy at different wt. % to investigate the electrical conductivity, Furthermore, annealed carbon black was used as a filler in a Carbon Fiber Reinforced Polymer (CFRP) and then the effect of different percentage of waste carbon black was studied. After that, through plane electrical conductivity, surface electrical conductivity, through plane thermal conductivity and flexural strength were examined. The results showed that the electrical conductivity for the annealed carbon black at 1250°C was improved to a value 40 σ/cm. Furthermore, impregnating a high amount of annealed carbon black (40 wt. %) in a polymeric matrix resulted in a low electrical conductivity of 0.0034 σ/cm. Blending annealed carbon black into carbon fiber reinforced polymer (CFRP) resulted in alternating the electrical conductivity of the composite material. The surface conductivity of carbon fiber polymer was 2.5 σ (per share). However, the surface conductivity of impregnating 2 wt. % annealed waste carbon black into CFRP was 13 σ (per square). The results also showed that addition of 5 wt. % of waste carbon black noticeably decreased the area specific resistance of CFRP from 199 to 98 mΩ.cm2. The through-plane thermal conductivity of CFRP increased as carbon black wt. % increased. The through-plane thermal conductivity increased by 78% when the waste carbon black loading reached 16 wt. %. However, loading the composite with waste carbon black resulted in decreasing the flexural strength. It is recommended to blend 5 wt. % of waste carbon black annealed at 1250°C into CFRP to provide enhancement in both the through-plane and surface electrical conductivity. The surface conductivity was enhanced by 80% when blending 5 wt. % of waste carbon black. The through plane resistivity reduced 51% by adding 5 wt. % of waste carbon black

Pulsed Eddy Current Imaging of Inclined Surface Cracks

Inclined fatigue cracks can potentially cause severe damage to metallic structures as they affect larger region in the tested structure compared to crack perpendicular to the sample surface. The abilitiy to detect and characterize such cracks is paramount in non-destructive testing (NDT). Pulsed eddy current testing (PEC) is known to offer a broadband of excitation frequencies, which in conjuction with C-scan imaging, may offer discrimination of inclination angles of cracks. Finite element modelling (FEM) was carried out to study the effects of different crack inclination angles, while experimental results were used to verify the FEM results. Selection of both time and frequency domain features for C-scan image construction was also presented, where C-scan images of peak value and amplitude at 200 Hz were shown to be potentially capable in determining different inclination angles. Nevertheless, between these two signal teatures, the amplitude at 200 Hz was found to be more effective in the discriminataion of inclined cracks