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Articles 511 - 540 of 1144
Full-Text Articles in Mechanical Engineering
A Statistical Approach To Broadband Noise Suppression, Walter Eversman
A Statistical Approach To Broadband Noise Suppression, Walter Eversman
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A method for estimating achievable attenuation for broadband noise in an inlet duct, consistent with Dyer's suggestion that an appropriate model includes all propagating acoustic modes at equal power and random phase, is proposed. Broadband noise is represented in a frequency domain analysis by a statistical distribution of propagating duct modes. The required number of modes is estimated by Rice's approximation method and verified in FEM modeling. For each propagating circumferential mode propagating radial modes have equal acoustic power and random phase. Source acoustic power is distributed among circumferential modes according to the number of propagating radial modes in the …
Linear Burn Rates Of Monopropellants For Multi-Mode Micropropulsion, Alex J. Mundahl, Steven P. Berg, Joshua L. Rovey
Linear Burn Rates Of Monopropellants For Multi-Mode Micropropulsion, Alex J. Mundahl, Steven P. Berg, Joshua L. Rovey
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Multi-mode micro propulsion is a potential game-changing technology enabling rapidly composable small satellites with unprecedented mission flexibility. Maximum mission flexibility requires propellant that is shared between the chemical and electric propulsion systems. Previous research has identified a promising monopropellant that is both readily catalytically exothermically decomposed (chemical mode) and electro sprayable (electric mode). In this work the linear burn rate of this monopropellant is determined to aid design of the microtube catalytic chemical thruster. A pressurized fixed volume reactor is used to determine the linear burn rate. Benchmark experiments use a 13-molar mixture of hydroxylammonium nitrate and water and show …
Direct Position Control Of Dielectric Barrier Discharge Filaments, Matthew C. Paliwoda, Joshua L. Rovey, Mitchell Wainwright
Direct Position Control Of Dielectric Barrier Discharge Filaments, Matthew C. Paliwoda, Joshua L. Rovey, Mitchell Wainwright
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Controllable patterns of plasma filaments are being explored for reconfigurable metamaterial applications. When operated in a filamentary mode, volume dielectric barrier discharges are known to produce patterns of self-organizing plasma filaments. In this work the presence and intensity of a single filament at a fixed location is controlled by an isolated and independently electrically adjusted needle electrode. Time-averaged normalized light intensity, current, and voltage are measured while varying the voltage of the needle through a self-biasing resistance. For a 7.5 kV, 3.2 kHz DBD, the needle-controlled filament discharges similar to adjacent filaments at low potentials but stops discharging at a …
Mass Spectrometry Of Selected Ionic Liquids In Capillary Electrospray At Nanoliter Volumetric Flow Rates, Shawn W. Miller, Benjamin D. Prince, Raymond J. Bemish, Joshua L. Rovey
Mass Spectrometry Of Selected Ionic Liquids In Capillary Electrospray At Nanoliter Volumetric Flow Rates, Shawn W. Miller, Benjamin D. Prince, Raymond J. Bemish, Joshua L. Rovey
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Capillary-based electrospray thrusters allow user-enabled control of the volumetric flow rate of the propellant. This control, coupled with mass spectrometry techniques spanning a large mass-to-charge range, enables elucidation of the composition of the electrospray beam and through further analyses, a better understanding of the physics occurring at the liquid/vacuum interface. In this work, mass spectra of selected ionic liquids electro sprayed from a capillary emitter are measured, using time-of-flight mass spectrometry, over a wide range of volumetric flow rates. The time-of-flight mass spectrometer enables simultaneous acquisition over a mass-to-charge range of 20 amu/q to ~500,000 amu/q in a single pulse …
Comparison Of Robust And Probabilistic Lmi-Based Design Of Adaptive Flight Controllers With Uncertain Input Dynamics, Mario Luca Fravolini, Tansel Yucelen, Benjamin Gruenwald, Merve Dogan, Marcello R. Napolitano
Comparison Of Robust And Probabilistic Lmi-Based Design Of Adaptive Flight Controllers With Uncertain Input Dynamics, Mario Luca Fravolini, Tansel Yucelen, Benjamin Gruenwald, Merve Dogan, Marcello R. Napolitano
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Adaptive control-based schemes have been implemented to date in a variety of different ap-plications. However, the ability to obtain a predictable transient closed-loop performance in adaptive systems is still a challenging problem from a verification and validation point of view. To face this problem we have recently introduced an analysis and design framework for adaptive control systems in the presence of bounded uncertainty and bounded adaptive control (the boundedness can be enforced, for instance, by a parameter projection mechanism) showing that the transitory performance of a MRAC system can be expressed, analyzed, and optimized via a convex optimization formulation based …
Geometric Consideration Of Nanostructures For Energy Storage Systems, Jonghyun Park, Jie Li, Wei Lu, Ann Marie Sastry
Geometric Consideration Of Nanostructures For Energy Storage Systems, Jonghyun Park, Jie Li, Wei Lu, Ann Marie Sastry
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Battery performance and its fade are determined by various aspects such as the transport of ions and electrons through heterogeneous internal structures; kinetic reactions at the interfaces; and the corresponding interplay between mechanical, chemical, and thermal responses. The fundamental factor determining this complex multiscale and multiphysical nature of a battery is the geometry of active materials. In this work, we systematically consider the tradeoffs among a selection of limiting geometries of media designed to store ions or other species via a diffusion process. Specifically, we begin the investigation by considering diffusion in spheres, rods, and plates at the particle level, …
Output Feedback Adaptive Control With Low-Frequency Learning And Fast Adaptation, Tanmay Rajpurohit, Wassim M. Haddad, Tansel Yucelen
Output Feedback Adaptive Control With Low-Frequency Learning And Fast Adaptation, Tanmay Rajpurohit, Wassim M. Haddad, Tansel Yucelen
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Although adaptive control has been used in numerous applications to achieve system performance without excessive reliance on system models, the necessity of high-gain learning rates for achieving fast adaptation can be a serious limitation of adaptive controllers. Specifically, in safety-critical systems involving large system uncertainties and abrupt changes in system dynamics, fast adaptation is required to achieve stringent tracking performance specifications. However, fast adaptation using high-gain learning rates can cause high-frequency oscillations in the control response, resulting in system instability. This paper develops an output feedback adaptive control framework for continuous-time minimum-phase multivariable dynamical systems for output stabilization and command …
A Comprehensive Model Of The Transport Phenomena In Gas Metal Arc Welding, Junling Hu, Zhenghua Rao, Hai-Lung Tsai
A Comprehensive Model Of The Transport Phenomena In Gas Metal Arc Welding, Junling Hu, Zhenghua Rao, Hai-Lung Tsai
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A comprehensive two-dimensional gas metal arc welding (GMAW) model was developed to take into account all the interactive events in the gas metal arc welding process, including the arc plasma, melting of the electrode, droplet formation, detachment, transfer, and impingement onto the workpiece, and the weld-pool dynamics and weld formation. The comprehensive GMAW model tracks the free surface using the volume of fluid method and directly modeled the coupling effects between the arc domain and the metal domain, thus eliminating the need to assign boundary conditions at the interface. A thorough investigation of the plasma arc characteristics was conducted to …
Electronic Musical Instrument To Generate Musical Tones To Imitate A Stringed Instrument, Mizuki Nakagawa, Ikuo Tanaka, Shun Takai
Electronic Musical Instrument To Generate Musical Tones To Imitate A Stringed Instrument, Mizuki Nakagawa, Ikuo Tanaka, Shun Takai
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Provided are an electronic musical instrument, computer storage device, and method for generating tone. A sound source in an electronic musical instrument generates a first tone at a first pitch in response to a first tone generation instruction received by an input device of the electronic musical instrument. A second tone generation instruction is received to generate a second tone at a second pitch while generating the first tone at the sound source. A determination is made of a pitch difference of the first and the second pitches. The sound source is controlled to generate the second tone and to …
Evaluation Of Non-Volatile Particulate Matter Emission Characteristics Of An Aircraft Auxiliary Power Unit With Varying Alternative Jet Fuel Blend Ratios, Prem Lobo, Simon Christie, Bhupendra Khandelwal, Simon G. Blakey, David W. Raper
Evaluation Of Non-Volatile Particulate Matter Emission Characteristics Of An Aircraft Auxiliary Power Unit With Varying Alternative Jet Fuel Blend Ratios, Prem Lobo, Simon Christie, Bhupendra Khandelwal, Simon G. Blakey, David W. Raper
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The aviation industry is increasingly focused on the development of sustainable alternative fuels to augment and diversify fuel supplies while simultaneously reducing its environmental impact. The impact of airport operations on local air quality and aviation-related greenhouse gas emissions on a life cycle basis have been shown to be reduced with the use of alternative fuels. However, the evaluation of incremental variations in fuel composition of a single alternative fuel on the production of non-volatile particulate matter (nvPM) emissions has not been explored. This is critical to understanding the emission profile for aircraft engines burning alternative fuels and the impact …
Materials For Programmed, Functional Transformation In Transient Electronic Systems, Suk Won Hwang, Seung Kyun Kang, Xian Huang, Mark A. Brenckle, Fiorenzo G. Omenetto
Materials For Programmed, Functional Transformation In Transient Electronic Systems, Suk Won Hwang, Seung Kyun Kang, Xian Huang, Mark A. Brenckle, Fiorenzo G. Omenetto
Mechanical and Aerospace Engineering Faculty Research & Creative Works
(Graph Presented). Materials and device designs are presented for electronic systems that undergo functional transformation by a controlled time sequence in the dissolution of active materials and/or encapsulation layers. Demonstration examples include various biocompatible, multifunctional systems with autonomous behavior defined by materials selection and layout.
Coalescence-Induced Jumping Of Nanoscale Droplets On Super-Hydrophobic Surfaces, Zhi Liang, Pawel Keblinski
Coalescence-Induced Jumping Of Nanoscale Droplets On Super-Hydrophobic Surfaces, Zhi Liang, Pawel Keblinski
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Coalescence-Induced Jumping of Tens of Microns Size Droplets on Super-Hydrophobic Surfaces Has Been Observed in Both Experiments and Simulations. However, Whether the Coalescence-Induced Jumping Would Occur for Smaller, Particularly Nanoscale Droplets, is an Open Question. using Molecular Dynamics Simulations, We Demonstrate that in Spite of the Large Internal Viscous Dissipation, Coalescence of Two Nanoscale Droplets on a Super-Hydrophobic Surface Can Result in a Jumping of the Coalesced Droplet from the Surface with a Speed of a Few M/s. Similar to the Coalescence-Induced Jumping of Microscale Droplets, We Observe that the Bridge between the Coalescing Nano-Droplets Expands and Impacts the …
Molecular Simulations And Lattice Dynamics Determination Of Stillinger-Weber Gan Thermal Conductivity, Zhi Liang, Ankit Jain, Alan J.H. Mcgaughey, Pawel Keblinski
Molecular Simulations And Lattice Dynamics Determination Of Stillinger-Weber Gan Thermal Conductivity, Zhi Liang, Ankit Jain, Alan J.H. Mcgaughey, Pawel Keblinski
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Bulk Thermal Conductivity of Stillinger-Weber (SW) Wurtzite GaN in the [0001] Direction at a Temperature of 300 K is Calculated using Equilibrium Molecular Dynamics (EMD), Non-Equilibrium MD (NEMD), and Lattice Dynamics (LD) Methods. While the NEMD Method Predicts a Thermal Conductivity of 166 ± 11 W/m·K, Both the EMD and LD Methods Predict Thermal Conductivities that Are an Order of Magnitude Greater. We Attribute the Discrepancy to Significant Contributions to Thermal Conductivity from Long-Mean Free Path Phonons. We Propose that the Grüneisen Parameter for Low-Frequency Phonons is a Good Predictor of the Severity of the Size Effects in NEMD …
Near Field Transducer For Heat Assisted Magnetic Recording, Xianfan Xu, Edward C. Kinzel
Near Field Transducer For Heat Assisted Magnetic Recording, Xianfan Xu, Edward C. Kinzel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
An antenna for heat assisted magnetic recording is disclosed. The antenna includes an optically opaque material and an optically transparent material positioned on the optically opaque material, the optically transparent material includes a half bowtie shape which includes a first half-wing substantially shaped in form of a right angle trapezoid, having a height substantially equal to the overall height of the half bowtie, a second half-wing Substantially shaped in form of a mirror image of the first half-wing and formed proximate and coupled to the first half-wing by a Substantially rectangular aperture having an aperture width and an aperture height. …
Enhanced Structural Color Generation In Aluminum Metamaterials Coated With A Thin Polymer Layer, F. Cheng, Xiaodong Yang, D. Rosenmann, L. Stan, D. Czaplewski, Jie Gao
Enhanced Structural Color Generation In Aluminum Metamaterials Coated With A Thin Polymer Layer, F. Cheng, Xiaodong Yang, D. Rosenmann, L. Stan, D. Czaplewski, Jie Gao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Ultrasensitive Detection And Characterization Of Molecules With Infrared Plasmonic Metamaterials, F. Cheng, Xiaodong Yang, Jie Gao
Ultrasensitive Detection And Characterization Of Molecules With Infrared Plasmonic Metamaterials, F. Cheng, Xiaodong Yang, Jie Gao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Shear Lag Sutures: Improved Suture Repair Through The Use Of Adhesives, S. W. Linderman, I. Kormpakis, R. H. Gelberman, Victor Birman, U. G. K. Wegst, G. M. Genin, S. Thomopoulos
Shear Lag Sutures: Improved Suture Repair Through The Use Of Adhesives, S. W. Linderman, I. Kormpakis, R. H. Gelberman, Victor Birman, U. G. K. Wegst, G. M. Genin, S. Thomopoulos
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Laser Metal Deposition Of Functionally Gradient Materials From Elemental Copper And Nickel Powders, Sreekar Karnati, Todd E. Sparks, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, William J. Seufzer
Laser Metal Deposition Of Functionally Gradient Materials From Elemental Copper And Nickel Powders, Sreekar Karnati, Todd E. Sparks, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, William J. Seufzer
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This work deals with the planning and fabrication of a functionally gradient copper-nickel composition via Laser Metal Deposition (LMD). Various compositions of copper and nickel were made by blending different weight percentages which were then sequentially deposited to fabricate functionally gradient copper-nickel thin-wall structures. Analyses were performed by sectioning the thin-wall samples for metallographic, hardness, X-ray diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS) studies. The fabrication was studied for identifying and corroborating the deposited compositions and their corresponding gradients. XRD analyses were performed to identify the crystal structure of the deposit. EDS analysis was instrumental in identifying the variation …
Microstructure And Property Of Tib-Reinforced Ti Alloy Composites By Laser Metal Deposition, Yunlu Zhang, Jingwei Zhang, Frank W. Liou, Joseph William Newkirk
Microstructure And Property Of Tib-Reinforced Ti Alloy Composites By Laser Metal Deposition, Yunlu Zhang, Jingwei Zhang, Frank W. Liou, Joseph William Newkirk
Mechanical and Aerospace Engineering Faculty Research & Creative Works
TiB-reinforced Ti alloy composites have been laser deposited with pre-alloyed Ti-6Al4V-1B powder. The microstructure of the as-deposited and heat treated composites have been characterized in detail using scanning electron microscope (SEM). A homogeneous dispersion of needle-like TiB precipitates is formed in the Ti-6Al-4V α/β matrix. TiB precipitates promote formation of small near equaxed α/β grain after β annealing process. The micro-hardness of the laser deposited composites increase 20-30% with 5 vol. % TiB precipitates compared to unreinforced Ti-6Al-4V deposits.
Effects Of Temperature On Aqueous Freeform Extrusion Fabrication, Jie Li, Ming-Chuan Leu, Greg Hilmas
Effects Of Temperature On Aqueous Freeform Extrusion Fabrication, Jie Li, Ming-Chuan Leu, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
An experimental study was conducted to investigate the effect of temperature on ceramic parts produced by paste extrusion based additive manufacturing followed by sintering. A computer-controlled gantry system equipped with a piston extruder was used to extrude aqueous alumina paste. The system includes a temperature control subsystem that allows for freeform extrusion fabrication inside a low-temperature (<0°C) chamber. It can also be used for fabricating parts on a hot plate at ambient or higher temperatures (≥20°C). Test specimens were fabricated from aqueous aluminum pastes at -20°C in the low-temperature chamber and also on the hot plate at 40°C. The minimum angles achievable by these two processes for part fabrication, without use of support material, were compared. Also compared were the relative density and mechanical properties of the parts obtained after sintering. Microstructures were examined via scanning electron microscopy in order to obtain a deeper understanding of the effect of fabrication temperature.
Freeform Extrusion Fabrication Of Titanium Fiber Reinforced Bioactive Glass Scaffolds, Albin Thomas, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas
Freeform Extrusion Fabrication Of Titanium Fiber Reinforced Bioactive Glass Scaffolds, Albin Thomas, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Although implants made with bioactive glass have shown promising results for bone repair, their application in repairing load-bearing long bones is limited due to their low fracture toughness and fairly fast degradation response in vivo. In this paper, we describe our investigation of freeform extrusion fabrication of silicate based 13-93 bioactive glass scaffolds reinforced with titanium fibers. A composite paste was prepared with 13-93 bioactive glass filled with titanium fibers (~16 µm in diameter and aspect ratio of ~250) having a volume fraction of 0.4 vol. %. This paste was then extruded to fabricate scaffolds with an extrudate diameter …
Optimal Rastering Orientation In Freeform Extrusion Fabrication Processes, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Robert G. Landers
Optimal Rastering Orientation In Freeform Extrusion Fabrication Processes, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Many researchers have tried to optimize the build direction of additively manufactured parts to minimize the vertical staircase effect. However, the horizontal staircase effect should also be considered when fully dense parts are to be fabricated. In this paper, part inaccuracy due to the horizontal staircase effect is considered in order to determine the optimal rastering orientation in building the part. An algorithm is developed to estimate this inaccuracy and a technique is proposed to minimize it. The effect of rastering orientation on staircase errors is examined, and the particle swarm optimization method is used to determine the optimum rastering …
Direct Laser Deposition Of Ti-6al-4v From Elemental Powder Blends, Lei Yan, Xueyang Chen, Wei Li, Frank W. Liou, Joseph William Newkirk
Direct Laser Deposition Of Ti-6al-4v From Elemental Powder Blends, Lei Yan, Xueyang Chen, Wei Li, Frank W. Liou, Joseph William Newkirk
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A thin-wall structure composed of Ti-6Al-4V has been deposited using direct laser deposition (DLD) from blended Ti, Al, and V elemental powders. The microstructure and composition distribution along the build height direction were intensively investigated using optical microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), and Vickers hardness testing. The microstructures of the as-deposited Ti-xAl-yV were studied using EDS to determine appropriate weight percentage for Al and V in the blended powders before mixing. The effects of laser power and laser transverse speed on the microstructure were investigated and optimized laser processing parameters were concluded.
Modeling Of Powder Bed Processing -- A Review, Aaron Flood, Frank W. Liou
Modeling Of Powder Bed Processing -- A Review, Aaron Flood, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Many models have been developed to model powder beds and these methods can be implemented to model a powder bed for Selective Laser Sintering, Selective Laser Melting and any other technique of additive manufacturing which uses powder beds. Two of the main systems are the Discrete Element Method (DEM) and the Geometric Method. The purpose of this paper is to analyze each of the methods. It will first highlight how each of the models creates the powder bed. The next aspect reviewed is the computational time and its causes. And lastly, each of the methods will be examined for their …
Solid Freeform Fabrication Of Transparent Fused Quartz Using A Filament Fed Process, J. Luo, L. J. Gilbert, C. Qu, B. Morrow, Douglas A. Bristow, Robert G. Landers, J. Goldstein, A. Urbas, Edward C. Kinzel
Solid Freeform Fabrication Of Transparent Fused Quartz Using A Filament Fed Process, J. Luo, L. J. Gilbert, C. Qu, B. Morrow, Douglas A. Bristow, Robert G. Landers, J. Goldstein, A. Urbas, Edward C. Kinzel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Glass is a critical material for many scientific and engineering applications including optics, communications, electronics, and hermetic seals. Despite this technological relevance, there has been minimal research toward Additive Manufacturing (AM) of glass, particularly optically transparent glass. Additive Manufacturing of transparent glass offers potential advantages for lower processing costs for small production volumes, increased design freedom, and the ability to locally vary the optical properties of the part. Compared to common soda lime glass, fused quartz is better for AM since it has lower thermal expansion and higher index homogeneity. This paper presents a study of additive manufacturing of transparent …
Dc-Gain Layer-To-Layer Stability Criterion In Laser Metal Deposition Processes, Patrick M. Sammons, Douglas A. Bristow, Robert G. Landers
Dc-Gain Layer-To-Layer Stability Criterion In Laser Metal Deposition Processes, Patrick M. Sammons, Douglas A. Bristow, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In Laser Metal Deposition (LMD), a blown powder metal additive manufacturing process, functional metal parts are fabricated in a layer-by-layer fashion. In addition to the in-layer dynamics, which describe how the process evolves within a given layer, the additive-fabrication property of LMD creates a second set of dynamics which describe how the process evolves from layer-to-layer. While these dynamics, termed layer-to-layer dynamics, are coupled with both the in-layer dynamics and the process operating conditions, they are not widely considered in the modeling, process planning, or process control of LMD operations. Because of this, seemingly valid choices for process parameters can …
Performance Metric For Powder Feeder Systems In Additive Manufacturing, Venkata Sivaram Bitragunta, Todd E. Sparks, Frank W. Liou
Performance Metric For Powder Feeder Systems In Additive Manufacturing, Venkata Sivaram Bitragunta, Todd E. Sparks, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In blown powder Direct Metal Deposition (DMD) process, parts are built by adding metal powder on the melt pool created by the laser system. At low feed rates powder feeder systems have perturbations. The study focused on relationship between the perturbation frequencies by inherent powder feeder designs and its impact on deposition quality. Performance metric determine the relation between perturbations in the powder flow and quality of the deposit. To determine performance metric, various powder feeder designs were analyzed. Perturbation frequencies were introduced to the disk feeder design. The quality of the deposit was determined by the surface roughness of …
Parameter Determination And Experimental Validation Of A Wire Feed Additive Manufacturing Model, Kannan Suresh Kumar, Todd E. Sparks, Frank W. Liou
Parameter Determination And Experimental Validation Of A Wire Feed Additive Manufacturing Model, Kannan Suresh Kumar, Todd E. Sparks, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser metal deposition with wire feed is one of the additive manufacturing methods with great scope and robustness. Process parameters plays an important role in controlling the process and obtaining an ideal manufactured part. Simulations tools are highly essential in determining the ideal parameters and melt pool conditions. The current work is a transient 3D model of wire feed additive manufacturing which realizes the heat transfer and fluid flow behavior of the process with varying laser power and power density. The model was programmed in Python and a 1 KW Gaussian beam fiber laser was used to conduct experiments. The …
Depth Of Cut Monitoring For Hybrid Manufacturing Using Acoustic Emission Sensor, Haythem Gaja, Frank W. Liou
Depth Of Cut Monitoring For Hybrid Manufacturing Using Acoustic Emission Sensor, Haythem Gaja, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser Metal Deposition LMD is a hybrid manufacturing process consist of a laser deposition system combined with a 5-axis CNC milling system. During laser deposition many parameters and their interaction affect the dimensional accuracy of the part produced, powder flow rate, laser power and travel speed are some of these parameters. Sensing the acoustic emission during milling marching gives feedback information regarding depth of metal being cut subsequent part dimensions, if an error in dimensions is found certain actions, such as remaching, close loop control, or laser remelting can be carried out to correct it. Thus a reliable hybrid manufacturing …
Methods Of Extrusion On Demand For High Solids Loading Ceramic Paste In Freeform Extrusion Fabrication, Wenbin Li, Amir Ghazanfari, Ming-Chuan Leu, Robert G. Landers
Methods Of Extrusion On Demand For High Solids Loading Ceramic Paste In Freeform Extrusion Fabrication, Wenbin Li, Amir Ghazanfari, Ming-Chuan Leu, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Fabrication of highly dense parts with complex geometry by paste-extrusion-based solid freeform fabrication processes requires a precise control of the extrusion flow rate to dispense material on demand, which is often referred as Extrusion-On-Demand (EOD). The extrusion process for aqueous ceramic pastes is complex and difficult to control due to their non-Newtonian behavior, compressibility and inhomogeneity. In this study, three methods of EOD (based on ram extruder, needle valve, and auger valve) are introduced and investigated for the extrusion of high solids loading (i.e., > 50%, volumetric) aqueous alumina paste. Optimal extrusion process parameters for these methods are determined through printing …