Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
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In this study, a scissor jack was structurally analyzed and compared to a FEA model to study the structure of the jack. the system was simplified to a 2D system, and one of the truss members was analyzed for yielding, fatigue, and buckling.
ContributorsLedalla, Aishwarya (Author) / Kosaraju, Srinivas (Thesis director) / Patel, Jay (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
This paper describes the development of a software tool used to automate the preliminary design of aircraft wing structure. By taking wing planform and aircraft weight as inputs, the tool is able to predict loads that will be experienced by the wing. An iterative process is then used to select optimal material thicknesses for each section of the design to minimize total structural weight. The load analysis checks for tensile failure as well as Euler buckling when considering if a given wing structure is valid. After running a variety of test cases with the tool it was found that wing structure of small-scale aircraft is predominantly buckling driven. This is problematic because commonly used weight estimation equations are based on large scale aircraft with strength driven wing designs. Thus, if these equations are applied to smaller aircraft, resulting weight estimates are often much lower than reality. The use of a physics-based approach to preliminary sizing could greatly improve the accuracy of weight predictions and accelerate the design process.
ContributorsKolesov, Nikolay (Author) / Takahashi, Timothy (Thesis director) / Patel, Jay (Committee member) / Kosaraju, Srinivas (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-12
Description
This experiment analyzed the degradation mechanisms in polymer matrix composite (PMC) samples after more than 50 years of simulated exposure to hygrothermal conditioning. This strong, form-adaptive, lightweight material is suitable for use on critical structures including nuclear powerplants and spacecrafts as primary reinforcers to improve fracture toughness. Current literature regarding PMC material has a poor understanding of its delamination trends and varying interphase properties that determine its overall reliability under extreme weather conditions. This paper will evaluate the long-term impact from exposure to heat and humidity regarding the material’s stiffness and degradation to confirm PMC’s reliability for use in structures that undergo these conditions. To study this phenomenon, aged and unaged PMC samples were analyzed on the nanoscale using PeakForce Quantitative Nanomechanical mode (PF-QNM) of Atomic Force Microscopy with an indentation tip no greater than 10nm in radius. This paper compares this testing method to the results from recent research on other microscopy modes to discuss the validity of the PF-QNM model as it is used for this analysis. The data obtained allowed for analysis of crack propagation and quantification of strength in interphase between the composite’s constituents. This research verifies the testing method for which a comprehensive understanding of the environmental influences on PMC mechanical properties could be achieved.
ContributorsTotillo, Anita (Co-author, Co-author) / Yekani Fard, Masoud (Thesis director) / Patel, Jay (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
In this conference paper, nanoscale material property data and ASTM mode I interlaminar fracture results for three-phase buckypaper samples are presented and analyzed. Vacuum filtration and surfactant-free methods were used to manufacture buckypaper membranes. Epoxy infused buckypaper membranes were placed in front of the crack tip in a stitch bonded carbon fiber polymer matrix composite using a hand layup technique. Peak Force Quantitative Nanomechanical Mapping (PFQNM), using probes with nominal tip radius in the range of 5 to 8 nm were used. PFQNM fully characterized the interphase region between a three-phase sample of carbon monofilament, epoxy resin, and multi-walled carbon nanotube (MWCNT) buckypaper. This experiment captured reproducible nanoscale morphological, viscoelastic, elastic and energy properties of porous MWCNT buckypaper samples. An enlarged interphase region surrounding the CNT buckypaper was found. The buckypaper and epoxy interphase thickness was found to be 50nm, higher than the 10-40nm reported for epoxy and carbon monofilaments. The observed MWCNT structure provides explanation of the increased surface roughness compared to the smooth carbon monofilaments. The increased surface roughness likely improves mechanical interlocking with the epoxy of adjacent lamina. The interphase and subsurface characterization data at the nanoscale level provide explanation for a change in crack propagation toughness. Nanoscale analysis of the buckypaper surface proved the inhomogeneous properties even at the scale of a few square micrometer. The improvement in crack initiation and propagation energy is due to mechanical interlocking, crack path diversion, and the large interphase zone surrounding the buckypaper.
ContributorsMester, Jack (Author) / Yekani Fard, Masoud (Thesis director) / Patel, Jay (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Carbon emissions have become a major concern since the turn of the century. This has increased the demand of hybrid vehicles in United States market. Hence, there is a need to make these vehicles more efficient. This thesis focuses on creating a thermal model that could be used for optimization of these vehicles. The project was accomplished in collaboration with EcoCar3, and the temperature data obtained from the model was compared with the experimental temperature data gathered from EcoCar's testing of the vehicle they built. The data obtained through this study demonstrates that the model was accurately able to predict thermal behavior of the electric motor and the high-voltage batteries in the vehicle. Therefore, this model could be used for optimization of the powertrain in a hybrid vehicle.
ContributorsMuthuvenkatesh, Nikhil (Author) / Mayyas, Abdel (Thesis director) / Patel, Jay (Committee member) / W.P. Carey School of Business (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05