Matching Items (77)
Filtering by

Clear all filters

132111-Thumbnail Image.png
Description
An understanding of aerodynamics is crucial for automobile performance and efficiency. There are many types of “add-on” aerodynamic devices for cars including wings, splitters, and vortex generators. While these have been studied extensively, rear spoilers have not, and their effects are not as widely known. A Computational Fluid Dynamics (CFD)

An understanding of aerodynamics is crucial for automobile performance and efficiency. There are many types of “add-on” aerodynamic devices for cars including wings, splitters, and vortex generators. While these have been studied extensively, rear spoilers have not, and their effects are not as widely known. A Computational Fluid Dynamics (CFD) and wind tunnel study was performed to study the effects of spoilers on vehicle aerodynamics and performance. Vehicle aerodynamics is geometry dependent, meaning what applies to one car may or may not apply on another. So, the Scion FRS was chosen as the test vehicle because it is has the “classic” sports car configuration with a long hood, short rear, and 2+2 passenger cabin while also being widely sold with a plethora of aftermarket aerodynamic modifications available. Due to computing and licensing restrictions, only a 2D CFD simulation was performed in ANSYS Fluent 19.1. A surface model of the centerline of the car was created in SolidWorks and imported into ANSYS, where the domain was created. A mesh convergence study was run to determine the optimum mesh size, and Realizable k-epsilon was the chosen physics model. The wind tunnel lacked equipment to record quantifiable data, so the wind tunnel was utilized for flow visualization on a 1/24 scale car model to compare with the CFD.

0° spoilers reduced the wake area behind the car, decreasing pressure drag but also decreasing underbody flow, causing a reduction in drag and downforce. Angled spoilers increased the wake area behind the car, increasing pressure drag but also increasing underbody flow, causing an increase in drag and downforce. Longer spoilers increased these effects compared to shorter spoilers, and short spoilers at different angles did not create significantly different effects. 0° spoilers would be best suited for cases that prioritize fuel economy or straight-line acceleration and speed due to the drag reduction, while angled spoilers would be best suited for cars requiring downforce. The angle and length of spoiler would depend on the downforce needed, which is dependent on the track.
ContributorsNie, Alexander (Author) / Wells, Valana (Thesis director) / Huang, Huei-Ping (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-12
131841-Thumbnail Image.png
Description
This paper presents the design of a pneumatic actuator for a soft ankle-foot orthosis, called the Multi-material Actuator for Variable Stiffness (MAVS). This pneumatic actuator consists of an inflatable soft fabric actuator fixed between two layers of rigid retainer pieces. The MAVS is designed to be integrated with a soft

This paper presents the design of a pneumatic actuator for a soft ankle-foot orthosis, called the Multi-material Actuator for Variable Stiffness (MAVS). This pneumatic actuator consists of an inflatable soft fabric actuator fixed between two layers of rigid retainer pieces. The MAVS is designed to be integrated with a soft robotic ankle-foot orthosis (SR-AFO) exosuit to aid in supporting the human ankle in the inversion/eversion directions. This design aims to assist individuals affected with chronic ankle instability (CAI) or other impairments to the ankle joint. The MAVS design is made from compliant fabric materials, layered and constrained by thin rigid retainers to prevent volume increase during actuation. The design was optimized to provide the greatest stiffness and least deflection for a beam positioned as a cantilever with a point load. The design of the MAVS took into account passive stiffness of the actuator when combining rigid and compliant materials so that stiffness is maximized when inflated and minimal when passive. An analytic model of the MAVS was created to evaluate the effects in stiffness observed by varying the ratio in length between the rigid pieces and the soft actuator. The results from the analytic model were compared to experimentally obtained results of the MAVS. The MAVS with the greatest stiffness was observed when the gap between the rigid retainers was smallest and the rigid retainer length was smallest. The MAVS design with the highest stiffness at 100 kPa was determined, which required 26.71 ± 0.06 N to deflect the actuator 20 mm, and a resulting stiffness of 1,335.5 N/m and 9.1% margin of error from the model predictions.
ContributorsHertzell, Tiffany (Author) / Lee, Hyunglae (Thesis director) / Sugar, Thomas (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
131374-Thumbnail Image.png
Description
This paper investigates Surface Mechanical Attrition Treatment (SMAT) and the influence of treatment temperature and initial sample surface finish on the corrosion resistance of 7075-T651 aluminum alloy. Ambient SMAT was performed on AA7075 samples polished to 80-grit initial surface roughness. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used

This paper investigates Surface Mechanical Attrition Treatment (SMAT) and the influence of treatment temperature and initial sample surface finish on the corrosion resistance of 7075-T651 aluminum alloy. Ambient SMAT was performed on AA7075 samples polished to 80-grit initial surface roughness. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used to characterize the corrosion behavior of samples before and after SMAT. Electrochemical tests indicated an improved corrosion resistance after application of SMAT process. The observed improvements in corrosion properties are potentially due to microstructural changes in the material surface induced by SMAT which encouraged the formation of a passive oxide layer. Further testing and research are required to understand the corrosion related effects of cryogenic SMAT and initial-surface finish as the COVID-19 pandemic inhibited experimentation plans.
ContributorsDeorio, Jordan Anthony (Author) / Solanki, Kiran (Thesis director) / Rajagopalan, Jagannathan (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
131428-Thumbnail Image.png
Description
The ASU Compact X-ray Free Electron Laser (CXFEL) is a first of its kind instrument that will illuminate the processes of life and allow scientists to create more effective treatments for disease. The dimensions of the linear accelerator (LINAC) cavities must remain stable during operation, for a change in the

The ASU Compact X-ray Free Electron Laser (CXFEL) is a first of its kind instrument that will illuminate the processes of life and allow scientists to create more effective treatments for disease. The dimensions of the linear accelerator (LINAC) cavities must remain stable during operation, for a change in the geometry alters the standing wave microwave energy resonance within the cavities and leads to reflected rather than coupled and useful microwave energy to electric field coupling. This disturbs the electron bunch acceleration dynamics critical to the ultimate generation of x-ray pulses. Cooling water must be supplied to the electron generating RF-GUN, and linear accelerator (LINAC) structures at unique flowrate and temperature setpoints that are specific to the operating mode of the CXFEL. Design specifications for the water supply to the RF-GUN and three LINACs and were made for the nominal operating mode, which adds a 3 kW heat load to the water. To maintain steady cavity dimensions, water must be supplied to each device under test at 30.0 ºC ± 0.06 ºC. The flowrate of water must be 3.5 GPM to the RF-GUN and 2.5 GPM to each of the three LINACs with ± 0.01 GPM flowrate resolution. The primary function of the Dedicated-Precision Thermal Trim Unit (D-PTTU) is to control the flowrate and temperature of water supply to each device under test. A simplified model of the system was developed to select valves that would meet our design specifications for flowrate and temperature control. After using this model for valve selection, a detailed system model was created to simulate relevant coupled-domain physics of the integrated system. The detailed system model was used to determine the critical sensitivities of the system and will be used to optimize the performance of the system in the future. Before the detailed system model can be verified and tuned with experiments, the sensors were calibrated in an ice-bath to ensure the sensors measure accurate and precise values. During initial testing, the D-PTTU was able to achieve ± 0.02 ºC temperature resolution, which exceeds the design specification by a factor of three.
ContributorsGardeck, Alex John (Author) / Holl, Mark (Thesis director) / Smith, Dean (Committee member) / Department of Physics (Contributor) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
131469-Thumbnail Image.png
Description
This thesis project examines the stability margin for different rotor configurations for a quadcopter and compares them against each other to determine the most stable flight configuration possible. The first configuration develops a “standard” for quadcopters with each motor in a corner of a cube at a 60-degree angle from

This thesis project examines the stability margin for different rotor configurations for a quadcopter and compares them against each other to determine the most stable flight configuration possible. The first configuration develops a “standard” for quadcopters with each motor in a corner of a cube at a 60-degree angle from the Y-Axis. The remaining tests increase the angle five degrees per configuration, allowing the motors to get incrementally closer to each other until no longer viable. Five different tests are outlined below depicting the microscopic changes in the pitch and roll of the device. The on-board controller in the quad-copter tracks both the acceleration and gyroscopic movements of the device to obtain the stability margin of each test. Computational analysis is then used to calculate and compare the values found to determine the most stable configuration.
ContributorsCorino, Tyler Michael (Author) / Kuo, Chen-Yuan (Thesis director) / Lynch, John (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
164645-Thumbnail Image.png
Description
Arizona has been rapidly expanding in both population and construction over the last 20 years, and with the hot summer climate, many homeowners experience a significant increase in their utility bills. The cost to reduce these energy bills with home renovations can become expensive. This has become increasingly apparent over

Arizona has been rapidly expanding in both population and construction over the last 20 years, and with the hot summer climate, many homeowners experience a significant increase in their utility bills. The cost to reduce these energy bills with home renovations can become expensive. This has become increasingly apparent over the last few years with the impact that covid had on the global supply chain. Prices of materials and labor have never been higher, and with this, the price of energy continues to increase. Therefore, it is important to explore methods to make homes more energy-efficient without the price tag. In addition to benefitting the homeowner by decreasing the cost of their monthly utility bills, making homes more energy efficient will aid in the overall goal of reducing carbon emissions.
ContributorsFiller, Peyton (Author) / Phelan, Patrick (Thesis director) / Parrish, Kristen (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2022-05
Description

The concept of entrainment broadly applies the locking of phases between 2 independent systems [17]. This physical phenomenon can be applied to modify neuromuscular movement in humans during bipedal locomotion. Gait entrainment to robotic devices have shown great success as alternatives to labor intensive methods of rehabilitation. By applying additional

The concept of entrainment broadly applies the locking of phases between 2 independent systems [17]. This physical phenomenon can be applied to modify neuromuscular movement in humans during bipedal locomotion. Gait entrainment to robotic devices have shown great success as alternatives to labor intensive methods of rehabilitation. By applying additional torque at the ankle joint, previous studies have exhibited consistent gait entrainment to both rigid and soft robotic devices. This entrainment is characterized by consistent phase locking of plantarflexion perturbations to the ‘push off’ event within the gait cycle. However, it is unclear whether such phase locking can be attributed to the plantarflexion assistance from the device or the sensory stimulus of movement at the ankle. To clarify the mechanism of entrainment, an experiment was designed to expose the user to a multitude of varying torques applied at the ankle to assist with plantar flexion. In this experiment, no significant difference in success of subject entrainment occurred when additional torque applied was greater than a detectable level. Force applied at the ankle varied from ~60N to ~130N. This resulted in successful entrainment ~88\% of the time at 98 N, with little to no increase in success as force increased thereafter. Alternatively, success of trials decreased significantly as force was reduced below this level, causing the perturbations to become undetectable by participants. Ultimately this suggests that higher levels of actuator pressure, and thus greater levels of torque applied to the foot, do not increase the likelihood of entrainment during walking. Rather, the results of this study suggest that proper detectable sensory stimulus is the true mechanism for entrainment.

ContributorsKruse, Anna (Author) / Lee, Hyunglae (Thesis director) / Berman, Spring (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2022-12