Matching Items (4)
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- All Subjects: Aircrafts
- Creators: Takahashi, Timothy
Description
Dimensional Metrology is the branch of science that determines length, angular, and geometric relationships within manufactured parts and compares them with required tolerances. The measurements can be made using either manual methods or sampled coordinate metrology (Coordinate measuring machines). Manual measurement methods have been in practice for a long time and are well accepted in the industry, but are slow for the present day manufacturing. On the other hand CMMs are relatively fast, but these methods are not well established yet. The major problem that needs to be addressed is the type of feature fitting algorithm used for evaluating tolerances. In a CMM the use of different feature fitting algorithms on a feature gives different values, and there is no standard that describes the type of feature fitting algorithm to be used for a specific tolerance. Our research is focused on identifying the feature fitting algorithm that is best used for each type of tolerance. Each algorithm is identified as the one to best represent the interpretation of geometric control as defined by the ASME Y14.5 standard and on the manual methods used for the measurement of a specific tolerance type. Using these algorithms normative procedures for CMMs are proposed for verifying tolerances. The proposed normative procedures are implemented as software. Then the procedures are verified by comparing the results from software with that of manual measurements.
To aid this research a library of feature fitting algorithms is developed in parallel. The library consists of least squares, Chebyshev and one sided fits applied on the features of line, plane, circle and cylinder. The proposed normative procedures are useful for evaluating tolerances in CMMs. The results evaluated will be in accordance to the standard. The ambiguity in choosing the algorithms is prevented. The software developed can be used in quality control for inspection purposes.
To aid this research a library of feature fitting algorithms is developed in parallel. The library consists of least squares, Chebyshev and one sided fits applied on the features of line, plane, circle and cylinder. The proposed normative procedures are useful for evaluating tolerances in CMMs. The results evaluated will be in accordance to the standard. The ambiguity in choosing the algorithms is prevented. The software developed can be used in quality control for inspection purposes.
ContributorsVemulapalli, Prabath (Author) / Shah, Jami J. (Thesis advisor) / Davidson, Joseph K. (Committee member) / Takahashi, Timothy (Committee member) / Arizona State University (Publisher)
Created2014
Description
The thesis is an investigation on current regulations of commercial aircraft landing and take-off procedures and an analysis of potential weaknesses within the regulatory system for commercial aerospace. To determine such flaws, an area of worse-case scenarios with regard to the aforementioned flight operations was researched. The events selected to best-depict these scenarios where incidents of aircraft overrunning the runway, referred to as runway excursions. A case-study conducted of 44 federal investigations of runway excursions produced data indicating four influential factors within these incidents: weather, pilot error, instrument malfunction, and runway condition. Upon examination, all but pilot error appeared to have federal enforcement to diminish the occurrence of future incidents. This is a direct result of the broad possibilities that make up this factor. The study then searched for a consistent fault within the incidents with the results indicating an indirect relationship of thrust reversers, a technique utilized by pilots to provide additional braking, to these excursions. In cases of thrust reverser failure, pilots' over-reliance on the system lead to time being lost from the confusion produced by the malfunction, ultimately resulting in several different runway excursions. The legal implication with the situation is that current regulations are ambiguous on the subject of thrust reversers and thus do not properly model the usage of the technique. Thus, to observe the scope of danger this ambiguity presents to the industry, the relationship of the technique to commercial aerospace needed to be determined. Interviews were set-up with former commercial pilots to gather data related to the flight crew perspective. This data indicated that thrust reversers were actively utilized by pilots within the industry for landing operations. The problem with the current regulations was revealed that the lack of details on thrust reverser reflected a failure of regulations to model current industry flight operations. To improve safety within the industry, new data related to thrust reverser deployment must be developed and enforced to determine appropriate windows to utilize the technique, thus decreasing time lost in confusion that results from thrust reversers malfunction. Future work would be based on producing simulations to determine said data as well as proposing the policy suggestions produced by this thesis.
ContributorsCreighton, Andrew John (Author) / Takahashi, Timothy (Thesis director) / Marchant, Gary (Committee member) / Kimberly, Jimmy (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / School of Politics and Global Studies (Contributor)
Created2014-05
Description
This paper describes an aircraft design optimization tool for wave drag reduction. The tool synthesizes an aircraft wing and fuselage geometry using the Rhinoceros CAD program. It then implements an algorithm to perform area-ruling on the fuselage. The algorithm adjusts the cross-sectional area along the length of the fuselage, with the wing geometry fixed, to match a Sears-Haack distribution. Following the optimization of the area, the tool collects geometric data for analysis using legacy performance tools. This analysis revealed that performing the optimization yielded an average reduction in wave drag of 25% across a variety of Mach numbers on two different starting geometries. The goal of this project is to integrate this optimization tool into a larger trade study tool as it will allow for higher fidelity modeling as well as large improvements in transonic and supersonic drag performance.
ContributorsLeader, Robert William (Author) / Takahashi, Timothy (Thesis director) / Middleton, James (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
This paper outlines the development of a script which utilizes a series of user-defined input parameters to construct base-level CAD models of aircraft landing gear. With an increased focus on computation development of aircraft models to allow for a rapidprototyping design process, this program seeks to allow designers to check for the validity of design integration before moving forward on systems testing. With this script, users are able to visually analyze the landing gear configurations on an aircraft in both the gear up and gear down configuration. The primary purpose this serves is to determine the validity of the gear's potential to fit within the limited real estate on an aircraft body. This, theoretically, can save time by weeding out infeasible designs before moving forward with subsystem performance testing. The script, developed in Python, constructs CAD models of dual and dual-tandem main landing gear configurations in the CAD program Rhino5. With an included design template consisting of 33 parameters, the script allows for a reasonable trade off between conciseness and flexibility of design.
ContributorsPatrick, Noah Edward (Author) / Takahashi, Timothy (Thesis director) / Middleton, James (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05