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Mechanical and Aerospace Engineering Faculty Research & Creative Works
- Keyword
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- Aircraft Landing Gear Applications (1)
- Catastrophic Consequences (1)
- Composition Analysis (1)
- Compressive Strength (1)
- Deposition (1)
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- Direct Diode Laser (1)
- Fatigue Properties (1)
- Flight Control (1)
- Heating and Cooling Rates (1)
- High-Speed Optical Techniques (1)
- Landing Gear (aircraft) (1)
- Laser-Cladding Process (1)
- Metallic Thin Films (1)
- Microcracks (1)
- Molecular Dynamics Method (1)
- Nanoparticles (1)
- Nickel (1)
- Observers for Nonlinear Systems (1)
- Optimal Control (1)
- Phase Change Materials (1)
- Phase Separation (1)
- Scanning Electron Microscopy (1)
- Stainless Steel (1)
- Stainless Steel 316L (1)
- Stress Corrosion Cracking (1)
- Tensile Strength (1)
- Thermal conductivity (1)
Articles 1 - 9 of 9
Full-Text Articles in Engineering
Phase Change Mechanisms During Femtosecond Laser Pulse Train Ablation Of Nickel Thin Films, Xin Li, Lan Jiang, Hai-Lung Tsai
Phase Change Mechanisms During Femtosecond Laser Pulse Train Ablation Of Nickel Thin Films, Xin Li, Lan Jiang, Hai-Lung Tsai
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The mechanisms of nickel thin films irradiated by femtosecond laser pulse trains are studied by a model using molecular dynamics simulations and two-temperature model. It is found that the pulse train technology can change energy transport and corresponding phase change processes. Compared with single pulse ablation at the same total fluence, the pulse trains lead to (1) lower ablation rate with more and smaller uniform nanoparticles, (2) higher film surface temperatures and longer thermalization time, (3) much lower electron thermal conductivity that can further control heat-affected zone, (4) significantly smaller film compressive stresses and tensile stresses which reduce microcracks, and …
Increase Of Heat Transfer To Reduce Build Time In Rapid Freeze Prototyping, Ming-Chuan Leu, Sriram Praneeth Isanaka, Von Richards
Increase Of Heat Transfer To Reduce Build Time In Rapid Freeze Prototyping, Ming-Chuan Leu, Sriram Praneeth Isanaka, Von Richards
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Reduction of part build time in the Rapid Freeze Prototyping (RFP) process, which fabricates a 3D ice part layer-by-layer by depositing and freezing water droplets, has been achieved by increase of heat transfer. Three mechanisms have been experimentally investigated: 1) cooling the substrate, 2) use of forced convection, and 3) use of a chilling plate. Cooling the substrate is effective for parts of small heights but becomes ineffective with increase in part height. Forced convection produced desirable reduction in part build time but with the undesirable formation of frost on the built ice part. The use of chilling plate to …
Development Of Extrusion-On-Demand For Ceramic Freeze-Form Extrusion Fabrication, Thomas Oakes, Parimal Kulkarni, Robert G. Landers, Ming-Chuan Leu
Development Of Extrusion-On-Demand For Ceramic Freeze-Form Extrusion Fabrication, Thomas Oakes, Parimal Kulkarni, Robert G. Landers, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In the Freeze-form Extrusion Fabrication (FEF) process, extrusion-on-demand (EOD) refers to the ability to control the start and stop of paste extrusion on demand and is vital to the fabrication of parts with complex geometries. This paper describes the development of EOD for ceramic FEF through modeling and control of extrusion force, selection of appropriate process parameters, and a dwell technique for start and stop of extrusion. A general tracking controller with integral action is used to allow tracking of a variety of reference forces while accounting for the variability in the paste properties. Experiments are conducted to model the …
Fuel Cell Development Using Additive Manufacturing Technologies -- A Review, Nikhil P. Kulkarni, Gargi Tandra, Frank W. Liou, Todd E. Sparks, Jianzhong Ruan
Fuel Cell Development Using Additive Manufacturing Technologies -- A Review, Nikhil P. Kulkarni, Gargi Tandra, Frank W. Liou, Todd E. Sparks, Jianzhong Ruan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Fuel cells are being perceived as the future clean energy source by many developed countries in the world. The key today for clean power is the reliance of fuel cells not only to power automobiles but also for residential, small commercial, backup power etc. which calls for production on a large scale. Additive manufacturing is perceived as a way to develop cost effective fuel cells. It imparts flexibility to design different kinds of fuel cells along with reduction in material wastage. This paper deals with the review of additive manufacturing processes for research and development of fuel cell components, such …
Evaluation Of Direct Diode Laser Deposited Stainless Steel 316l On 4340 Steel Substrate For Aircraft Landing Gear Application, Tian Fu, Todd E. Sparks, Frank W. Liou, Joseph William Newkirk, Zhiqiang Fan, Syamala Rani Pulugurtha, Jianzhong Ruan, Hsin-Nan Chou
Evaluation Of Direct Diode Laser Deposited Stainless Steel 316l On 4340 Steel Substrate For Aircraft Landing Gear Application, Tian Fu, Todd E. Sparks, Frank W. Liou, Joseph William Newkirk, Zhiqiang Fan, Syamala Rani Pulugurtha, Jianzhong Ruan, Hsin-Nan Chou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
300M steel is used extensively for aircraft landing gears because of its high strength, ductility and toughness. However, like other high-strength steels, 300M steel is vulnerable to corrosion fatigue and stress corrosion cracking, which can lead to catastrophic consequences in the landing gear. Stainless steels offer a combination of corrosion, wear, and fatigue properties. But for an aircraft landing gear application a higher surface hardness is required. A laser cladding process with fast heating and cooling rates can improve the surface hardness. AISI 4340 steel is used as a lower cost alternative to 300M due to its similar composition. In …
Development Of A Melt Pool Tracking Vision System For Laser Deposition, Todd E. Sparks, Lie Tang, Frank W. Liou
Development Of A Melt Pool Tracking Vision System For Laser Deposition, Todd E. Sparks, Lie Tang, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper chronicles the development of a vision system for tracking melt pool morphology in the laser metal deposition process. This development is to augment an existing temperature feedback control system. Monitoring both the temperature and shape of the melt pool is necessary because of the effects of local geometry on the cooling rate at the melt pool. Temperature feedback alone cannot accommodate this effect without complex process planning. The vision system's hardware, software, and integration into the laser deposition system's controller is detailed in this paper. Preliminary testing and the effects on depositionquality is also discussed.
A New State Observer And Flight Control Of Highly Maneuverable Aircraft, S. N. Balakrishnan, Ming Xin
A New State Observer And Flight Control Of Highly Maneuverable Aircraft, S. N. Balakrishnan, Ming Xin
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In this paper, a new nonlinear observer (θ-D observer) is proposed to estimate the feedback states for optimal control of a highly maneuverable aircraft. This observer is derived by constructing the dual of a recently developed nonlinear optimal control technique-known as the θ-D technique. The θ-D optimal control approach provides an approximate closed-form solution to the Hamilton-Jacobi-Bellman (HJB) equation. An optimal flight controller using this technique is designed for a highly maneuverable aircraft operating at high angle of attack where the θ-D observer is employed to estimate the states for feedback. The structure of this observer is similar to the …
Procedure To Validate Direct Numerical Simulations Of Wall-Bounded Turbulence Including Finite-Rate Reactions, Lian Duan, M. Pino Martín
Procedure To Validate Direct Numerical Simulations Of Wall-Bounded Turbulence Including Finite-Rate Reactions, Lian Duan, M. Pino Martín
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper first discusses the constitutive relations and surface catalytic model for direct numerical simulation of wall-bounded turbulence including finite-rate chemistry and gas-surface interaction and then provides a systematic procedure to test the validity of the simulations by dividing the whole problem into different components and testing each component separately. Namely, comparisons against similarity solutions and other established hypersonic boundary-layer solutions are used to test the validity of laminar mean flow with and without gas-phase chemical reactions; comparisons against the analytic solution for the one-dimensional diffusion equation are used to test the validity of the surface catalysis boundary condition; and …
Thermal Converter Devices, Systems And Control Methods, Richard A. Flanagan, Rod E. Hosilyk, Rob Arlt, Kakkattukuzhy M. Isaac, Ronald E. Loving, David Alan Gordon
Thermal Converter Devices, Systems And Control Methods, Richard A. Flanagan, Rod E. Hosilyk, Rob Arlt, Kakkattukuzhy M. Isaac, Ronald E. Loving, David Alan Gordon
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A system is provided for reducing exhaust emissions. The system can comprise a series of chambers, an injector head, and a controller. The controller can maintain desired temperature zones and chemical environments inside the series of chambers, and the chambers and structures inside the system 10 can provide a desired travel path for the air, fuel, and untreated exhaust mixture inside.