Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Finite element method (3)
- Active magnetic bearing (2)
- Airplanes -- Motors (2)
- Magnetic bearings (2)
- Modeling (2)
-
- Roller bearings (2)
- Rotors -- Dynamics (2)
- Sliding mode control (2)
- Structural analysis (Engineering) (2)
- Vibration (2)
- AMB (1)
- Active magnetic actuator (1)
- Actuators (1)
- Adaptive control (1)
- Adaptive control systems (1)
- Aerofoils (1)
- Aircraft engine (1)
- Aircraft engine control (1)
- Biotechnology (1)
- Boundary layer (1)
- CFD (1)
- Cavity depth (1)
- Commercialization (1)
- Dean flow (1)
- Design (1)
- Dissimilar bearing support (1)
- Double-ended hollow roller (1)
- Electric power systems (1)
- FEA analysis of novel design (1)
- Fea (1)
Articles 1 - 14 of 14
Full-Text Articles in Mechanical Engineering
Model Identification, Updating, And Validation Of An Active Magnetic Bearing High-Speed Machining Spindle For Precision Machining Operation, Adam C. Wroblewski
Model Identification, Updating, And Validation Of An Active Magnetic Bearing High-Speed Machining Spindle For Precision Machining Operation, Adam C. Wroblewski
ETD Archive
High-Speed Machining (HSM) spindles equipped with Active Magnetic Bearings (AMBs) are envisioned to be capable of autonomous self-identification and performance self-optimization for stable high-speed and high quality machining operation. High-speed machining requires carefully selected parameters for reliable and optimal machining performance. For this reason, the accuracy of the spindle model in terms of physical and dynamic properties is essential to substantiate confidence in its predictive aptitude for subsequent analyses.This dissertation addresses system identification, open-loop model development and updating, and closed-loop model validation. System identification was performed in situ utilizing the existing AMB hardware. A simplified, nominal open-loop rotor model was …
Probabilistic Structural And Thermal Analysis Of A Gasketed Flange, Atul G. Tanawade
Probabilistic Structural And Thermal Analysis Of A Gasketed Flange, Atul G. Tanawade
ETD Archive
Performance of a flange joint is characterized mainly by its 'strength' and 'sealing capability'. A number of analytical and experimental studies have been conducted to study these characteristics under internal pressure loading. However, with the advent of new technological trends for high temperature and pressure applications, an increased demand for analysis is recognized. The effect of steady-state thermal loading makes the problem more complex as it leads to combined application of internal pressure and temperature. Structural and thermal analysis of a gasketed flange was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties …
Probabilistic Stress Analysis Of Circular Fins Of Different Profiles, Sridhar Madhira Venkata
Probabilistic Stress Analysis Of Circular Fins Of Different Profiles, Sridhar Madhira Venkata
ETD Archive
The temperature distribution and thermal Stresses induced by a temperature difference for steady state heat transfer in silicon carbide (SiC) ceramic tube heat exchanger with circular fins was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for Hoop and Radial stresses due to the structural and thermodynamic random variables. These results are used to identify the most critical design variables in order to optimize the design and make it cost effective. The probabilistic analysis leads to the selection of the …
Cfd Simulations For The Effect Of Unsteady Wakes On The Boundary Layer Of A Highly Loaded Low Pressure Turbine Airfoil (L1a), Samuel J. Vinci
Cfd Simulations For The Effect Of Unsteady Wakes On The Boundary Layer Of A Highly Loaded Low Pressure Turbine Airfoil (L1a), Samuel J. Vinci
ETD Archive
The study of a very high lift, low-pressure turbine airfoil in the presence of unsteady wakes was performed computationally and compared against experimental results. The experimental data were collected in a low speed wind tunnel under high (4.9 ) and then low (0.6 ) freestream turbulence intensity conditions on a linear cascade with wakes that were produced from moving rods upstream of the cascade. The flow coefficient was kept at 0.7 while the rod to blade spacing was changed from 1 to 1.6 to 2 blade spacings. These cases were conducted for Reynolds number equal to 25,000 and 50,000, based …
A Cfd Model Of Mixing In A Microfludic Device For Space Medicine Technology, Terri Lynn Mckay
A Cfd Model Of Mixing In A Microfludic Device For Space Medicine Technology, Terri Lynn Mckay
ETD Archive
The DNA Medicine Institute (DMI) is currently developing a device to be used for blood analysis to satisfy the unique requirements of space medicine applications. A key component of that device is the micromixer, which will ensure mixing and dilution of reagents utilized for detection assays. As part of the device design process, the micromixer was modeled, and the mixing characteristics were analyzed and compared to experimental data. The experimental data was based on a top-view of the system and, lacking data throughout the fluid domain, could not provide the insight into the mixing process that modeling could readily provide. …
Fabrication And Testing Of A Nonstandard Thin-Film Heat Flux Sensor For Power System Applications, Scott D. Wilson
Fabrication And Testing Of A Nonstandard Thin-Film Heat Flux Sensor For Power System Applications, Scott D. Wilson
ETD Archive
Stirling convertors are being operated by NASA Glenn Research Center for many years to demonstrate a Radioisotope Power System (RPS) capable of providing reliable power for potential multi-year space missions. Techniques used to monitor Stirling convertors for change in performance include measurements of temperature, pressure, energy addition, and power output. It is difficult to measure energy addition to Stirling convertors due to the complex geometries of the hot components, temperature limits of sensor materials, and invasive integration of sensors. A thin-film heat flux sensor was used to directly measure heat energy addition to a Stirling convertor. The one micron thick, …
Evaluation Of Lean Systems In Rail Maintenance Operations, Mert Baykut
Evaluation Of Lean Systems In Rail Maintenance Operations, Mert Baykut
ETD Archive
The recognized strength of lean systems is its broad applicability to every process industry even though they include some complicated and time-intensive processes. However, this conception is based on the tools and philosophy of Lean systems and the nature of the industry. The required craftsmanship and repetitive processes in rail maintenance define the uniqueness of this research The objective of this thesis was to research the opportunities and applicability for lean systems in rail maintenance. During the research a unique system, consisting of Lean systems and systems engineering tools, is realized and tried to integrate instead of a pure Lean …
A Systems Engineering Reference Model For Fuel Cell Power Systems Development, T. L. Blanchard
A Systems Engineering Reference Model For Fuel Cell Power Systems Development, T. L. Blanchard
ETD Archive
This research was done because today the Fuel Cell (FC) Industry is still in its infancy in spite over one-hundred years of development has transpired. Although hundreds of fuel cell developers, globally have been spawned, in the last ten to twenty years, only a very few are left struggling with their New Product Development (NPD). The entrepreneurs of this type of disruptive technology, as a whole, do not have a systems engineering 'roadmap", or template, which could guide FC technology based power system development efforts to address a more environmentally friendly power generation. Hence their probability of achieving successful commercialization …
Fea Analysis Of Novel Design Of Cylindrical Roller Bearing, Prasanna Subbarao Bhamidipati
Fea Analysis Of Novel Design Of Cylindrical Roller Bearing, Prasanna Subbarao Bhamidipati
ETD Archive
This work presents a finite element stress analysis of a novel design of cylindrical roller. The focus of this study is to create a uniform contact-stress distribution along the length of the roller and to recommend a roller bearing design which is easier to fabricate. The new design relies on creating symmetric cylindrical cavities at both ends of a roller. The cavity is concentric with the main body of the roller. The new roller design reduces overall mass of the typical assembly with helps to improve bearing life and its overall performance. The FEA results published herein shows that new …
Vibratory Behavior Of Rolling Element Bearings: A Lagrangian Approach, Phani Krishna Kalapala
Vibratory Behavior Of Rolling Element Bearings: A Lagrangian Approach, Phani Krishna Kalapala
ETD Archive
Vibratory behavior of a rolling element bearing on a horizontal rotor is studied in this work. This Thesis analyzes the dynamics of a typical roller bearing as a result of internal excitations. These internal excitations stem from the geometric deviations of the interacting surfaces from their ideal geometry. Such deviations in turn are the results of either manufacturing limitations or normal wear of the bearing surfaces. Lagrangian approach is implemented to derive the dynamic equations of motion. Matlab is used to solve the equation of motion of governing the vibrations of the system. Parametric studies are conducted to provide results …
Adaptive Sliding Mode Control For Aircraft Engines, Kathryn C. Ebel
Adaptive Sliding Mode Control For Aircraft Engines, Kathryn C. Ebel
ETD Archive
Aircraft engine control has been evolving since its beginning. With advancements in technology more and more control methods are being applied to this area. This thesis presents the design of an adaptive PID sliding mode control (A-SMC) for a turbofan engine. The controller design methodology is presented. Using an aircraft engine simulation environment developed by NASA, called Commercial Modular Aero-Propulsion System Simulation, the developed controller is tested. The results from three simulations are analyzed to investigate the application of this new design scheme. The A-SMC is able to follow the demanded fan speed for short flight simulations. However, some of …
Multivariable Sliding Mode Control Design For Aircraft Engines, Sirirat Sangwian
Multivariable Sliding Mode Control Design For Aircraft Engines, Sirirat Sangwian
ETD Archive
Many control theories are used in controlling aircraft engines. However, the multivariablesliding mode control is not yet established in this application even though ithas a lot of potential in dealing with complex and nonlinear systems such as aircraftengines. Therefore, a guideline in developing multivariable sliding mode control law for an aircraft engine is presented in this thesis. The problem of chattering in thesliding mode control is suppressed by the use of the boundary layer method. The controllogic is tested by implementing NASA's Commercial Modular Aero-PropulsionSystem Simulation 40k (C-MAPSS40k). Simulation results are analyzed and comparedto the results obtained from the baseline …
Modeling And Performance Investigation Of A Rotor With Dissimilar Bearing Support System, Yunlu Li
Modeling And Performance Investigation Of A Rotor With Dissimilar Bearing Support System, Yunlu Li
ETD Archive
Different types of bearings have different dynamic characteristics. By using one type of bearing at one end of a rotor and another type of bearing at the other end of the rotor, it is possible to exploit the advantages of both types in the same system. One example of such combination is a bronze bushing and active magnetic bearing (AMB). In the available literature, there are examples of such systems but are not fully explored with regard to how to model the system to fully utilize both support type properties. This thesis investigates the modeling and performance of such a …
Application Of Active Magnetic Force Actuator For Control Of Flexible Rotor System Vibrations, Volodymyr Mykhaylyshyn
Application Of Active Magnetic Force Actuator For Control Of Flexible Rotor System Vibrations, Volodymyr Mykhaylyshyn
ETD Archive
The purpose of this work was to develop and experimentally demonstrate a novel approach to minimize lateral vibrations of flexible rotor. The applied feed forward control approach employed magnetic force actuator to inject a specially designed force to counteract the rotor unbalance force. By specific selection of frequency and phase as functions of the rotor running speed and rotor natural frequency, the proposed simplified injection waveform has been shown to be effective both in reducing the rotor's vibrations and for hardware implementation. A model of the test rig was constructed using the finite element (FE) method and was validated using …