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Articles 541 - 570 of 1287
Full-Text Articles in Engineering
Probabilistic Analysis And Verification Framework For Adaptive Flight Control, Mario Luca Fravolini, Tansel Yucelen, Marcello Napolitano
Probabilistic Analysis And Verification Framework For Adaptive Flight Control, Mario Luca Fravolini, Tansel Yucelen, Marcello Napolitano
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A crucial aspect that could facilitate the applications of adaptive control systems in aerospace applications is the development of effective validation and verification procedures. Most of the existing analysis and design frameworks for adaptive controllers are based on the Lyapunov direct method. One well-known drawback of this approach is the conservatism in the estimation of the uniform ultimate boundedness region with little practical utility. To overcome this limitation, a probabilistic framework for the design of uniform ultimate boundedness regions is proposed where uncertain parameters and adaptive controls are considered as random variables. In this framework, the design is translated into …
Plume Characterization Of Electric Solid Propellant Pulsed Microthrusters, Matthew S. Glascock, Joshua L. Rovey, Shae Williams, Jason Thrasher
Plume Characterization Of Electric Solid Propellant Pulsed Microthrusters, Matthew S. Glascock, Joshua L. Rovey, Shae Williams, Jason Thrasher
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Electric solid propellants are an attractive option for propulsion because they are ignited only by an applied electric current. This leads to capabilities such as on-demand throttling and reignition in chemical combustion operation, and it lends itself to application in electric propulsion. In this work, the plasma plume created by electric solid propellant pulsed micro thrusters is investigated using a nude Faraday probe, a triple Langmuir probe, and residual gas analysis. The thrusters are tested at a vacuum level of 2 x 10-5torr. Results indicate an average plume electron temperature of 1.7 eV and a density of 1011 to 1014cm-3. …
Nanoparticle-Induced Unusual Melting And Solidification Behaviours Of Metals, C. Ma, Lianyi Chen, C. Cao, X.C. Li
Nanoparticle-Induced Unusual Melting And Solidification Behaviours Of Metals, C. Ma, Lianyi Chen, C. Cao, X.C. Li
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Aerodynamic Design Of A Rectangular Wing In Subsonic Inviscid Flow By Surrogate-Based Optimization, Xiaosong Du, Anand Amrit, Andrew Thelen, Leifur Leifsson, Yu Zhang, Zhong Hua Han, Slawomir Koziel
Aerodynamic Design Of A Rectangular Wing In Subsonic Inviscid Flow By Surrogate-Based Optimization, Xiaosong Du, Anand Amrit, Andrew Thelen, Leifur Leifsson, Yu Zhang, Zhong Hua Han, Slawomir Koziel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The paper presents results of aerodynamic design of a rectangular wing in subsonic inviscid flow using surrogate-based local and global search algorithms. The aerodynamic design problem is formulated in Benchmark Cases 3 and 6 developed by the AIAA Applied Aerodynamics Discussion Group. Both involve lift-constrained drag minimization at a Mach number of 0.5 with relatively low lift coefficients (0.2625 and 0.375) with several nonlinear constraints and a small number design variables (up to 15). In this work, the local search is performed using variable-fidelity modelling and output space mapping, whereas the global search is performed using approximation-based surrogates. The paper …
Aerodynamic Design Of The Rae 2822 In Transonic Viscous Flow: Single- And Multi-Objective Optimization Studies, Anand Amrit, Xiaosong Du, Andrew Thelen, Leifur Leifsson, Slawomir Koziel
Aerodynamic Design Of The Rae 2822 In Transonic Viscous Flow: Single- And Multi-Objective Optimization Studies, Anand Amrit, Xiaosong Du, Andrew Thelen, Leifur Leifsson, Slawomir Koziel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper addresses a benchmark aerodynamic design problem proposed by the AIAA Aerodynamic Design Optimization Discussion Group: Drag minimization of the RAE 2822 in transonic viscous flow at a fixed lift coefficient with constraints on the pitching moment coefficient and the cross-sectional area. The single-objective optimization (SOO) problem is solved using surrogate-based optimization (SBO) with the surrogates constructed through output space mapping and variable-resolution Reynolds-Averaged Navier-Stokes computational fluid dynamics models. Improving the implementation of our search algorithms enabled us to obtain the SOO optimal design four times faster than in our prior work in terms of CPU time. To explore …
Airfoil Design Under Uncertainty Using Non-Intrusive Polynomial Chaos Theory And Utility Functions, Xiaosong Du, Leifur Leifsson, Slawomir Koziel, Adrian Bekasiewicz
Airfoil Design Under Uncertainty Using Non-Intrusive Polynomial Chaos Theory And Utility Functions, Xiaosong Du, Leifur Leifsson, Slawomir Koziel, Adrian Bekasiewicz
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Fast and accurate airfoil design under uncertainty using non-intrusive polynomial chaos (NIPC) expansions and utility functions is proposed. The NIPC expansions provide a means to efficiently and accurately compute statistical information for a given set of input variables with associated probability distribution. Utility functions provide a way to rigorously formulate the design problem. In this work, these two methods are integrated for the design of airfoil shapes under uncertainty. The proposed approach is illustrated on a numerical example of lift-constrained airfoil drag minimization in transonic viscous flow using the Mach number as an uncertain variable. The results show that compared …
Local Field Effects On Magnetic Suppression Of The Converging Richtmyer-Meshkov Instability, Vincent Wheatley, Wouter Mostert, D. M. Bond, Ravi Samtaney
Local Field Effects On Magnetic Suppression Of The Converging Richtmyer-Meshkov Instability, Vincent Wheatley, Wouter Mostert, D. M. Bond, Ravi Samtaney
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We examine how the suppression of the converging shockdriven Richtmyer-Meshkov instability by an applied magnetic field is dependent on the local magnetic field strength and orientation. In particular, we examine whether the extent of suppression can be reasonably predicted by a linear model for the planar case. This is done for cylindrically converging cases with a high perturbation wavenumber and two different initial magnetic field configurations.
Materials, Mechanics, And Patterning Techniques For Elastomer-Based Stretchable Conductors, X. Yu, B. Mahajan, W. Shou, Heng Pan
Materials, Mechanics, And Patterning Techniques For Elastomer-Based Stretchable Conductors, X. Yu, B. Mahajan, W. Shou, Heng Pan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Effects Of The Cooling Rate On The Shear Behavior Of Continuous Glass Fiber/Impact Polypropylene Composites (Gf-Ipp), H. Wafai, G. Lubineau, A. Yudhanto, M. Mulle, W. Schijve, N. Verghese
Effects Of The Cooling Rate On The Shear Behavior Of Continuous Glass Fiber/Impact Polypropylene Composites (Gf-Ipp), H. Wafai, G. Lubineau, A. Yudhanto, M. Mulle, W. Schijve, N. Verghese
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Fiber-reinforced composites with improved dissipation of energy during impact loading have recently been developed based on a polypropylene copolymer commonly called impact polypropylene (IPP). Composites made of IPP reinforced with glass fibers (GF) are particularly attractive to the automotive industry due to their low cost and good impact resistance. In such composites, the cooling rate varies depending on processing techniques and manufacturing choices. Here, we study the effects of the cooling rate of GF-IPP composites on shear behavior, which is critical in impact applications, using [±45]s monotonic and cyclic (load/unload) tensile specimens. The specimens were manufactured under a wide range …
Effect Of Amino-Functionalization On Insulin Delivery And Cell Viability For Two Types Of Silica Mesoporous Structures, Abdollah Zakeri Siavashani, Masoumeh Haghbin Nazarpak, Fateme Fayyazbakhsh, Tayebeh Toliyat, Steven James Peter Mcinnes, Mehran Solati-Hashjin
Effect Of Amino-Functionalization On Insulin Delivery And Cell Viability For Two Types Of Silica Mesoporous Structures, Abdollah Zakeri Siavashani, Masoumeh Haghbin Nazarpak, Fateme Fayyazbakhsh, Tayebeh Toliyat, Steven James Peter Mcinnes, Mehran Solati-Hashjin
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Inorganic Mesoporous Structures Are a Class of Novel Biomaterials that Have Shown Practical Applications in Delivery of a Variety of Therapeutic Agents. in the Present Study, Two Mesoporous Structures Were Prepared, and the Effect of Surface Modification on their Insulin Delivery and in Vitro Cytotoxicity Was Evaluated. Morphological and Structural Characterizations of Silica Particles Were Accomplished by Different Analytical Techniques, Including Scanning Electron Microscopy, X-Ray Diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) Surface Area Analyses. the Drug Loading Capacity and in Vitro Drug Release Behavior of Silica Structures Were Investigated under Simulated Gastrointestinal Conditions and Phosphate-Buffered Saline Solution …
Characterising The Loading Direction Sensitivity Of 3d Woven Composites: Effect Of Z-Binder Architecture, Mohamed Nasr Saleh, Arief Yudhanto, Prasad Potluri, Gilles Lubineau, Constantinos Soutis
Characterising The Loading Direction Sensitivity Of 3d Woven Composites: Effect Of Z-Binder Architecture, Mohamed Nasr Saleh, Arief Yudhanto, Prasad Potluri, Gilles Lubineau, Constantinos Soutis
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Three different architectures of 3D carbon fiber woven composites (orthogonal, ORT; layer-to-layer, LTL; angle interlock, AI) were tested in quasi-static uniaxial tension. Mechanical tests (tensile in on-axis of warp and weft directions as well as 45° off-axis) were carried out with the aim to study the loading direction sensitivity of these 3D woven composites. The z-binder architecture (the through-thickness reinforcement) has an effect on void content, directional fiber volume fraction, mechanical properties (on-axis and off-axis), failure mechanisms, energy absorption and fiber rotation angle in off-axis tested specimens. Out of all the examined architectures, 3D orthogonal woven composites (ORT) demonstrated a …
High-Frequency Instabilities Of Stationary Crossflow Vortices In A Hypersonic Boundary Layer, Fei Li, Meelan Choudhari, Pedro Paredes-Gonzalez, Lian Duan
High-Frequency Instabilities Of Stationary Crossflow Vortices In A Hypersonic Boundary Layer, Fei Li, Meelan Choudhari, Pedro Paredes-Gonzalez, Lian Duan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Hypersonic boundary layer flows over a circular cone at moderate incidence angle can support strong crossflow instability in between the windward and leeward rays on the plane of symmetry. Due to more efficient excitation of stationary crossflow vortices by surface roughness, such boundary layer flows may transition to turbulence via rapid amplification of the high-frequency secondary instabilities of finite-amplitude stationary crossflow vortices. The amplification characteristics of these secondary instabilities are investigated for crossflow vortices generated by an azimuthally periodic array of roughness elements over a 7° half-angle circular cone in a Mach 6 free stream. The analysis is based on …
Experimental And Numerical Investigations Of Dust Effects On Surface Charging In Plasma, Kevin Chou, Daoru Frank Han, Joseph J. Wang
Experimental And Numerical Investigations Of Dust Effects On Surface Charging In Plasma, Kevin Chou, Daoru Frank Han, Joseph J. Wang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A series of 3-D, fully kinetic particle-in-cell (PIC) simulations were performed to simulate mesothermal plasma flow self-consistently with surface charging. Simulation results of plasma charging of a conducting surface covered by a thin dust layer in a plasma of cold ions and thermal electrons are presented. The surface potentials and potentials inside the dust layer are compared with experimental results. Results show that a layer of dust over a conducting surface creates a capacitance, which drives the surface more negative with respect to the ambient plasma.
The Concentration Of Stress At The Rotator Cuff Tendon-To-Bone Attachment Site Is Conserved Across Species, F. Saadat, A. C. Deymier, Victor Birman, S. Thomopoulos, G. M. Genin
The Concentration Of Stress At The Rotator Cuff Tendon-To-Bone Attachment Site Is Conserved Across Species, F. Saadat, A. C. Deymier, Victor Birman, S. Thomopoulos, G. M. Genin
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
All-Metal Structural Color Printing Based On Aluminum Plasmonic Metasurfaces, Z. Li, W. Wang, D. Rosenmann, D. Czaplewski, Xiaodong Yang, Jie Gao
All-Metal Structural Color Printing Based On Aluminum Plasmonic Metasurfaces, Z. Li, W. Wang, D. Rosenmann, D. Czaplewski, Xiaodong Yang, Jie Gao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Numerical Modeling Of Dust Dynamics Around Small Asteroids, William Yu, Joseph J. Wang, Daoru Frank Han
Numerical Modeling Of Dust Dynamics Around Small Asteroids, William Yu, Joseph J. Wang, Daoru Frank Han
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Dynamics of dust transport around an airless body has been a focused area of research in recent years, however, various challenging aspects still remain to be addressed. This paper presents an investigation of charged dust transport and distribution around small asteroids utilizing a full particle Particle-in-Cell (PIC) model to simulate plasma flow around an asteroid and calculate surface charging self-consistently from charge deposition on asteroid. Material properties of asteroid are also explicitly included in the simulation. PIC simulation results are fed into a 3D dust dynamics model to simulate charged dust levitation, transport and distribution. In addition to electrostatic and …
On Event-Triggered Adaptive Architectures For Decentralized And Distributed Control Of Large-Scale Modular Systems, Ali Albattat, Benjamin C. Gruenwald, Tansel Yucelen
On Event-Triggered Adaptive Architectures For Decentralized And Distributed Control Of Large-Scale Modular Systems, Ali Albattat, Benjamin C. Gruenwald, Tansel Yucelen
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The last decade has witnessed an increased interest in physical systems controlled over wireless networks (networked control systems). These systems allow the computation of control signals via processors that are not attached to the physical systems, and the feedback loops are closed over wireless networks. The contribution of this paper is to design and analyze event-triggered decentralized and distributed adaptive control architectures for uncertain networked large-scale modular systems; that is, systems consist of physically interconnected modules controlled over wireless networks. Specifically, the proposed adaptive architectures guarantee overall system stability while reducing wireless network utilization and achieving a given system performance …
Investigation Of Heat-Affected 304l Ss Powder And Its Effect On Built Parts In Selective Laser Melting, Caitlin S. Kriewall, Austin T. Sutton, Ming-Chuan Leu, Joseph William Newkirk, Ben Brown
Investigation Of Heat-Affected 304l Ss Powder And Its Effect On Built Parts In Selective Laser Melting, Caitlin S. Kriewall, Austin T. Sutton, Ming-Chuan Leu, Joseph William Newkirk, Ben Brown
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Selective laser melting (SLM) is a powder bed based additive manufacturing process in which a layer of powder is laid over the surface of a substrate and a laser with sufficient energy is employed to selectively melt particles to build a part layer by layer. During the SLM process, dark smoke was observed coming off of the powder bed surface where the laser was interacting with powder. This phenomenon resulted from heat-affected powder that was visibly different than the base powder. Since the concentration of the heat-affected powder differs throughout the build chamber as a result of the recirculating argon …
Modeling And Experimental Investigation Of Pre-Mixed Multi-Powder Flow In Fabricating Functional Gradient Material By Laser Metal Deposition Process, Wei Li, Jingwei Zhang, Sreekar Karnati, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, W. L. Seufzer
Modeling And Experimental Investigation Of Pre-Mixed Multi-Powder Flow In Fabricating Functional Gradient Material By Laser Metal Deposition Process, Wei Li, Jingwei Zhang, Sreekar Karnati, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, W. L. Seufzer
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser Metal Deposition (LMD) is an effective process to fabricate Functionally Graded Material (FGM) from pre-mixed powders. Since the supplied multi-powder directly affects the deposited FGM’s composition, investigation on Pre-Mixed Multi-Powder (PMMP) flow during LMD is greatly needed. This paper presents a comprehensive numerical PMMP flow model. By solving discrete particle force balance equations coupled with continuity equations and momentum equations for carrier gas, the dynamic behavior of PMMP flow through powder feeder tube and out of nozzle was calculated. With this model, the particle sizes of multi-powder were optimized to obtain considered FGM composition. To verify the modeling results, …
Investigation Of Tensile Properties Of Bulk And Slm Fabricated 304l Stainless Steel Using Various Gage Length Specimens, Sreekar Karnati, I. Axelsen, Frank W. Liou, Joseph William Newkirk
Investigation Of Tensile Properties Of Bulk And Slm Fabricated 304l Stainless Steel Using Various Gage Length Specimens, Sreekar Karnati, I. Axelsen, Frank W. Liou, Joseph William Newkirk
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The complex solidification dynamics and thermal cycling during Selective Laser Melting process is expected to result in non-equilibrium material characteristics. There is an essential need for characterization techniques which are critical towards the estimation of anisotropies. The current investigation is targeted towards establishing tensile testing methodologies and their relation to differing gage lengths. Dog-bone shaped specimen designs with gage lengths of 1”, 0.3” and 0.12” were employed in this research. The characterization was performed on hot rolled-annealed 304 stainless and SLM fabricated 304L stainless. It was theorized that smaller gage length specimens would be instrumental in mapping material property anisotropy …
A Novel Extrusion-Based Additive Manufacturing Process For Ceramic Parts, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Greg Hilmas
A Novel Extrusion-Based Additive Manufacturing Process For Ceramic Parts, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
An extrusion-based additive manufacturing process, called the Ceramic On-Demand Extrusion (CODE) process, for producing three-dimensional ceramic components with near theoretical density is introduced in this paper. In this process, an aqueous paste of ceramic particles with a very low binder content ( < 1 vol%) is extruded through a moving nozzle at room temperature. After a layer is deposited, it is surrounded by oil (to a level just below the top surface of most recent layer) to preclude non-uniform evaporation from the sides. Infrared radiation is then used to partially, and uniformly, dry the just-deposited layer so that the yield stress of the paste increases and the part maintains its shape. The same procedure is repeated for every layer until part fabrication is completed. Several sample parts for various applications were produced using this process and their properties were obtained. The results indicate that the proposed method enables fabrication of large, dense ceramic parts with complex geometries.
Selective Laser Sintering Of Low Density, Low Coefficient Of Thermal Expansion Silica Parts, John M. Hostetler, Jonathan T. Goldstein, Augustine M. Urbas, Rodrigo E. Gutierrez, Theresa E. Bender, Charles S. Wojnar, Edward C. Kinzel
Selective Laser Sintering Of Low Density, Low Coefficient Of Thermal Expansion Silica Parts, John M. Hostetler, Jonathan T. Goldstein, Augustine M. Urbas, Rodrigo E. Gutierrez, Theresa E. Bender, Charles S. Wojnar, Edward C. Kinzel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper presents a study of selective laser sintering of silica-gel. The objective of this work is to investigate a technique to create free-form, low to zero coefficient of thermal expansion structures. This offers potential cost savings over the conventional casting of large pieces of glass-ceramic followed by machining lightening features. In this paper, A CO2 laser is coupled through a gantry system and focused onto a binder-free silica-gel powder bed (15-40 μm particles). Prior to writing each layer, powder is dispensed by sifting it onto the build platform as opposed to a conventional wiper system. This avoids contacting …
Bubble Formation In Additive Manufacturing Of Borosilicate Glass, Junjie Luo, Theresa Bender, Douglas A. Bristow, Robert G. Landers, Jonathan T. Goldstein, Augustine M. Urbas, Edward C. Kinzel
Bubble Formation In Additive Manufacturing Of Borosilicate Glass, Junjie Luo, Theresa Bender, Douglas A. Bristow, Robert G. Landers, Jonathan T. Goldstein, Augustine M. Urbas, Edward C. Kinzel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Entrapped bubbles are an important problem in conventional glass manufacturing. It is also a significant factor determining the quality of glass products produced using additive manufacturing (AM). This paper reports on the bubble formation and entrapment in filament-fed AM printing of borosilicate glass. This process involves maintaining a local molten region using a CO2 laser. A 2 mm filament is fed continuously into the molten region while CNC stages position the workpiece relative to the laser and filament feed. Two different bubble regimes are identified in experiments with borosilicate glass. These regimes can be related to different physical phenomena, …
3d Printing Of A Polymer Bioactive Glass Composite For Bone Repair, Caroline Murphy, Krishna C. R. Kolan, M. Long, Ming-Chuan Leu, Julie A. Semon, D. E. Day
3d Printing Of A Polymer Bioactive Glass Composite For Bone Repair, Caroline Murphy, Krishna C. R. Kolan, M. Long, Ming-Chuan Leu, Julie A. Semon, D. E. Day
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A major limitation of synthetic bone repair is insufficient vascularization of the interior region of the scaffold. In this study, we investigated the 3D printing of adipose derived mesenchymal stem cells (AD-MSCs) with polycaprolactone (PCL)/bioactive glass composite in a single process. This offered a three-dimensional environment for complex and dynamic interactions that govern the cell’s behavior in vivo. Borate based bioactive (13-93B3) glass of different concentrations (10 to 50 weight %) was added to a mixture of PCL and organic solvent to make an extrudable paste. AD-MSCs suspended in Matrigel was extruded as droplets using a second syringe. Scaffolds measuring …
Designed Extrudate For Additive Manufacturing Of Zirconium Diboride By Ceramic On-Demand Extrusion, Devin Mcmillen, Wenbin Li, Ming-Chuan Leu, Greg Hilmas, Jeremy Lee Watts
Designed Extrudate For Additive Manufacturing Of Zirconium Diboride By Ceramic On-Demand Extrusion, Devin Mcmillen, Wenbin Li, Ming-Chuan Leu, Greg Hilmas, Jeremy Lee Watts
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This work describes a process by which zirconium diboride (ZrB2) parts may be fabricated using the Ceramic On-Demand Extrusion (CODE) process. An oxide-carbide-nitride system consisting of ceramic powders and pre-ceramic organics, designed to yield ZrB2 after reaction sintering, has been developed to produce an aqueous-based extrudate for subsequent processing in the CODE system. Pressurelessly sintered test specimens containing 1 wt% PVA binder achieve high relative density ≥ 99%. The viscoelastic response of the extrudate was characterized via spindle rheometry with a small sample adapter. Batches with 1 wt% PVA and 0.5 wt% Methocel show strong shear thinning characteristic, under …
Effect Of Sparse-Build Internal Structure On Performance Of Fused Deposition Modeling Tools Under Pressure, S. Meng, L. Mason, Gregory Taylor, X. Wang, Ming-Chuan Leu, K. Chandrashekhara, Mike Matlack, James Castle
Effect Of Sparse-Build Internal Structure On Performance Of Fused Deposition Modeling Tools Under Pressure, S. Meng, L. Mason, Gregory Taylor, X. Wang, Ming-Chuan Leu, K. Chandrashekhara, Mike Matlack, James Castle
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Two different approaches to design a sparse-build tool for fabrication by the fused deposition modeling (FDM) process are compared. One approach uses a 2D lattice structure and the other approach is inspired by topology optimization. Ultem 9085 is used as the material, and the amount of material used to build the tool is kept constant to ensure a fair comparison. A solid tool is also included in the comparison. The performance of the tool under uniform pressure is simulated using finite element analysis (FEA) and the accuracy of the FEA results is verified by comparing them with experimentally measured data …
Effects Of Build Parameters On Compression Properties For Ultem 9085 Parts By Fused Deposition Modeling, Krishna P. Motaparti, Gregory Taylor, Ming-Chuan Leu, K. Chandrashekhara, James Castle, Mike Matlack
Effects Of Build Parameters On Compression Properties For Ultem 9085 Parts By Fused Deposition Modeling, Krishna P. Motaparti, Gregory Taylor, Ming-Chuan Leu, K. Chandrashekhara, James Castle, Mike Matlack
Mechanical and Aerospace Engineering Faculty Research & Creative Works
It has been observed by various researchers that parts fabricated by the Fused Deposition Modeling (FDM) process have anisotropic properties. The research presented in the present paper was aimed to study the compression properties of FDM parts and to comprehend their dependence on build parameters. In this study Ultem 9085 was used as the material to fabricate both solid and sparse-build coupons with variations in build direction, raster angle and air gap. A full factorial experimental design was used to study the individual and combined effects of these build parameters on the mechanical properties of the coupons. The mechanical properties …
Novel Extrusion-Based Additive Manufacturing Process For Ceramic Parts, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Greg Hilmas
Novel Extrusion-Based Additive Manufacturing Process For Ceramic Parts, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
An extrusion-based additive manufacturing process, called the Ceramic On-Demand Extrusion (CODE) process, for producing three-dimensional ceramic components with near theoretical density is introduced in this paper. In this process, an aqueous paste of ceramic particles with a very low binder content (< 1 vol%) is extruded through a moving nozzle at room temperature. After a layer is deposited, it is surrounded by oil (to a level just below the top surface of most recent layer) to preclude non-uniform evaporation from the sides. Infrared radiation is then used to partially, and uniformly, dry the just-deposited layer so that the yield stress of the paste increases and the part maintains its shape. The same procedure is repeated for every layer until part fabrication is completed. Several sample parts for various applications were produced using this process and their properties were obtained. The results indicate that the proposed method enables fabrication of large, dense ceramic parts with complex geometries.
Properties Of Partially Stabilized Zirconia Components Fabricated By The Ceramic On-Demand Extrusion Process, Wenbin Li, Amir Ghazanfari, Devin Mcmillen, Ming-Chuan Leu, Greg Hilmas, Jeremy Lee Watts
Properties Of Partially Stabilized Zirconia Components Fabricated By The Ceramic On-Demand Extrusion Process, Wenbin Li, Amir Ghazanfari, Devin Mcmillen, Ming-Chuan Leu, Greg Hilmas, Jeremy Lee Watts
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Ceramic On-Demand Extrusion (CODE) process is a novel additive manufacturing process for fabricating dense ceramic components from aqueous pastes of high solids loading. In this study, 3 mol% Y2O3 stabilized tetragonal zirconia polycrystal (3Y-TZP) parts were fabricated using the CODE process. The parts were then dried in a humidity controlled environmental chamber and sintered under atmospheric pressure. Mechanical properties of the sintered parts were examined using ASTM standard test techniques, including density, Young’s modulus, flexural strength, Weibull modulus, fracture toughness and Vickers hardness. The microstructure was analyzed, and grain size was measured using scanning electron microscopy. …
Laser Line Scan Characterization Of Geometric Profiles In Laser Metal Deposition, Michelle L. Gegel, A. Nisbett, Douglas A. Bristow, Robert G. Landers
Laser Line Scan Characterization Of Geometric Profiles In Laser Metal Deposition, Michelle L. Gegel, A. Nisbett, Douglas A. Bristow, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser Metal Deposition (LMD) is an additive manufacturing process in which material is deposited by blowing powdered metal into a melt pool formed by a laser beam. When fabricating parts, the substrate is subjected to motion control such that the melt pool traces a prescribed path to form each part layer. Advantages of LMD include relatively efficient powder usage, the ability to create functionally-graded parts and the ability to repair high-value parts. The process, however, is sensitive to variations in process parameters and a need for feedback measurements and closed-loop control has been recognized in the literature [1, 2]. To …