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Articles 1 - 6 of 6
Full-Text Articles in Engineering
Stability Analysis, Modeling, Simulation And Experimental Testing Of An Ems Maglev System With Structural Flexibility, Aravind M. Hanasoge
Stability Analysis, Modeling, Simulation And Experimental Testing Of An Ems Maglev System With Structural Flexibility, Aravind M. Hanasoge
Mechanical & Aerospace Engineering Theses & Dissertations
Vehicle-guideway interaction studies of Magnetically Levitated (Maglev) vehicles indicate that structural flexibility can adversely affect the overall stability and performance of such systems. This is one of the reasons why guideways are generally made very rigid. This in turn leads to increased cost of the overall system since guideway construction forms a significant portion of the overall cost. In this dissertation, the influence of structural flexibility on the stability of Electromagnetic Suspension (EMS) Maglev systems is studied. It is shown how inherently unstable and flexible structure EMS Maglev systems can achieve guaranteed stability by using collocated actuators and sensors, along …
Numerical/Experimental Investigation Of Plunge Stage And Effect Of Donor Material In Friction Stir Welding, Saptarshi Mandal
Numerical/Experimental Investigation Of Plunge Stage And Effect Of Donor Material In Friction Stir Welding, Saptarshi Mandal
Mechanical & Aerospace Engineering Theses & Dissertations
Friction Stir Welding (FSW) was developed in 1991 as a robust solid-state joining technique that uses a specially shaped rotating tool to generate heat and plasticize material around the tool. The tool then mixes plasticized material along the joint line to produce the weld. Over the last decade, FSW has become increasingly popular for welding aluminum. The combination of attractive properties of the weld and cost-efficiency has led researchers to investigate the feasibility of using FSW for steel. One of the major impediments for using friction stir welding for harder materials such as steel is tool wear. It is well-documented …
Multidisciplinary Design Optimization For Sonic Boom Mitigation, Isik A. Ozcer
Multidisciplinary Design Optimization For Sonic Boom Mitigation, Isik A. Ozcer
Mechanical & Aerospace Engineering Theses & Dissertations
Automated, parallelized, time-efficient surface definition and grid generation and flow simulation methods are developed for sharp and accurate sonic boom signal computation in three dimensions in the near and mid-field of an aircraft using Euler/Full-Potential unstructured/structured computational fluid dynamics. The full-potential mid-field sonic boom prediction code is an accurate and efficient solver featuring automated grid generation, grid adaptation and shock fitting, and parallel processing. This program quickly marches the solution using a single nonlinear equation for large distances that cannot be covered with Euler solvers due to large memory and long computational time requirements. The solver takes into account variations …
Mitigating Crack Propagation In A Highly Maneuverable Flight Vehicle Using Life Extending Control Logic, Mohamed Mostafa Yousef Bassyouny Elshabasy
Mitigating Crack Propagation In A Highly Maneuverable Flight Vehicle Using Life Extending Control Logic, Mohamed Mostafa Yousef Bassyouny Elshabasy
Mechanical & Aerospace Engineering Theses & Dissertations
In this research, life extending control logic is proposed to reduce the cost of treating the aging problem of military aircraft structures and to avoid catastrophic failures and fatal accidents due to undetected cracks in the airframe components. The life extending control logic is based on load tailoring to facilitate a desired stress sequence that prolongs the structural life of the cracked airframe components by exploiting certain nonlinear crack retardation phenomena. The load is tailored to include infrequent injections of a single-cycle overload or a single-cycle overload and underload. These irregular loadings have an anti-intuitive but beneficial effect, which has …
Modeling And Simulation Of Coaxial Helicopter Rotor Aerodynamics, Murat Gecgel
Modeling And Simulation Of Coaxial Helicopter Rotor Aerodynamics, Murat Gecgel
Mechanical & Aerospace Engineering Theses & Dissertations
A framework is developed for the computational fluid dynamics (CFD) analyses of a series of helicopter rotor flowfields in hover and in forward flight. The methodology is based on the unsteady solutions of the three-dimensional, compressible Navier-Stokes equations recast in a rotating frame of reference. The simulations are carried out by solving the developed mathematical model on hybrid meshes that aim to optimally exploit the benefits of both the structured and the unstructured grids around complex configurations. The computer code is prepared for parallel processing with distributed memory utilization in order to significantly reduce the computational time and the memory …
Selection Of Pressure Equation For Preliminary Planing Hull Design Using Modified Analytical Hierarchy Process, Pamela Sue Fergen
Selection Of Pressure Equation For Preliminary Planing Hull Design Using Modified Analytical Hierarchy Process, Pamela Sue Fergen
Mechanical & Aerospace Engineering Theses & Dissertations
In the early stages of design when data availability is limited, engineers often times rely upon experience and regression analysis to select the most suitable design equation among many competitive ones. This study presents an alternative that applies a modified Analytical Hierarchy Process (AHP) to select the most suitable design equation. The Analytical Hierarchy Process, a multi-criteria decision making method, has been utilized in the business and management world to collect and evaluate experts' opinions in order to arrive at a final decision. The Analytical Hierarchy Process employed here will treat each of the design equations as an expert and …