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Articles 121 - 150 of 209
Full-Text Articles in Manufacturing
Additive Manufacturing Laser Deposition Of Ti‐6al‐4v For Aerospace Repair Applications, Nanda Kumar Dey, Frank W. Liou, C. Nedic
Additive Manufacturing Laser Deposition Of Ti‐6al‐4v For Aerospace Repair Applications, Nanda Kumar Dey, Frank W. Liou, C. Nedic
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Parts or products from high performance metal are very expensive, partly due to the processing complexities during manufacturing. The purpose of this project is to use additive laser deposition and machining processes to repair titanium parts, thus extending the service life of these parts. The study broadly included preparing the defects, laser deposition, machining, sample preparation and mechanical tests. Comparative study of mechanical properties (UTS, YS, percentage elongation) of the repaired samples to the ideal conditions was undertaken. The research throws up interesting facts where the data from the test sample shows enhancement of properties of the repaired part.
Experimental Investigation Of Different Cellular Lattice Structures Manufactured By Fused Deposition Modeling, Osman Iyibilgin, Cemil Yigit, Ming-Chuan Leu
Experimental Investigation Of Different Cellular Lattice Structures Manufactured By Fused Deposition Modeling, Osman Iyibilgin, Cemil Yigit, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Experimental tests were conducted to evaluate the compressive properties (yield strength and compressive modulus) and build time for five different cellular lattice structures fabricated by the Fused Deposition Modeling (FDM) process. The lattice structures had repeating unit cells, and the shapes of the unit cell under study included honeycomb, square, diamond, triangle, and circle. Test specimens were manufactured by a Stratasys Fortus 400mc machine using ABS (Acrylonitrile Butadiene Styrene) as the part material. The five different lattice structures were compared with each other and also with the sparse and sparse-double dense build styles that are directly available from the Fortus …
Numerical Analysis Of Thermal Stress And Deformation In Multi-Layer Laser Metal Deposition Processes, Heng Liu, Todd E. Sparks, Frank W. Liou, David M. Dietrich
Numerical Analysis Of Thermal Stress And Deformation In Multi-Layer Laser Metal Deposition Processes, Heng Liu, Todd E. Sparks, Frank W. Liou, David M. Dietrich
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Direct metal deposition (DMD) has gained increasing attention in the area of rapid manucooling rate, resulting in residual stresses and distortion. This paper presents a 3D sequentially coupled thermo-mechanical finite element model to predict residual stresses and deformations. The temperature distribution, thermal stress field and geometry deformation across domain are illustrated. The effect of deposition parameters on residual stress and deflections are also explored. A set of validation experiments for mechanical effects were conducted using laser displacement sensor. The comparisons between the simulated and experimental results show good agreement
Vision-Based Process Monitoring For Laser Metal Deposition Processes, Sreekar Karnati, Niroop Matta, Todd E. Sparks, Frank W. Liou
Vision-Based Process Monitoring For Laser Metal Deposition Processes, Sreekar Karnati, Niroop Matta, Todd E. Sparks, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser Metal deposition is a process with immense scope and promise for becoming a robust manufacturing technology in the near future. Monitoring process variables is very instrumental in process planning and output monitoring. The current work deals with realizing the effect of power modulation on size of the high temperature region during deposition with varying powder feed. A thermal camera was used to visualize and analyze the deposition process. The area of the high temperature region through the deposition was identified and compared to realize the effect of each variable parameter during deposition. The power modulation was fruitful in modulating …
The Applications Of Additive Manufacturing Technologies In Cyber-Enabled Manufacturing Systems, Sriram Praneeth Isanaka, Frank W. Liou
The Applications Of Additive Manufacturing Technologies In Cyber-Enabled Manufacturing Systems, Sriram Praneeth Isanaka, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The application of networked sensors and control in various areas, such as smart grids and infrastructures, has become a recent trend, called cyber-physical systems. The Cyber Enabled Manufacturing (CEM) environment is to apply these technologies in manufacturing systems to handle a significantly greater magnitude of manufacturing data. Additive manufacturing techniques print or place material layer by layer to form a part, thus have a great potential to help accelerate CEM process by printing or embedding sensors and actuators in the proper locations. This paper summarizes the roles of additive manufacturing technologies to help establish a CEM environment.
Interactions Of An Additive Manufacturing Program With Society, Frank W. Liou, Ming-Chuan Leu, Robert G. Landers
Interactions Of An Additive Manufacturing Program With Society, Frank W. Liou, Ming-Chuan Leu, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Additive Manufacturing (AM) has shown considerable promise for the future but also proposes some challenges. Many AM barriers tend to be non-technical and instead are human-centric issues such as lack of education of practitioners in AM capabilities, cultural differences, vested interests, and potentially lack of imagination. It is highly desirable for all research and educational institutions to help address these issues. This paper summarizes the additive manufacturing research and education program at the Missouri University of Science and Technology (Missouri S&T) and its interactions with various constituents, including K-12 students, undergraduate and graduate students, distance students, and industry.
Experimental Study Of Polymer Electrolyte Membrane Fuel Cells Using A Graphite Composite Bipolar Plate Fabricated By Selective Laser Sintering, Nannan Guo, Ming-Chuan Leu
Experimental Study Of Polymer Electrolyte Membrane Fuel Cells Using A Graphite Composite Bipolar Plate Fabricated By Selective Laser Sintering, Nannan Guo, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Selective Laser Sintering (SLS) can be used to fabricate graphite composite bipolar plates with complex flow fields for Polymer Electrolyte Membrane (PEM) fuel cells. The additive manufacturing process can significantly reduce the time and cost associated with the research and development of bipolar plates as compared to other fabrication methods such as compression molding. In this study, bipolar plates with three different designs, i.e., parallel in series, interdigitated, and bio-inspired, were fabricated using the SLS process. The performance of these SLS-fabricated bipolar plates was studied experimentally within a fuel cell assembly under various operating conditions. The effect of temperature, relative …
Comparison Of Compression Molding And Selective Laser Sintering Processes In The Development Of Composite Bipolar Plates For Proton Exchange Membrane Fuel Cells, Ehsan Taghipour, Ming-Chuan Leu, Nannan Guo
Comparison Of Compression Molding And Selective Laser Sintering Processes In The Development Of Composite Bipolar Plates For Proton Exchange Membrane Fuel Cells, Ehsan Taghipour, Ming-Chuan Leu, Nannan Guo
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Bipolar plates are key components of Proton Exchange Membrane (PEM) fuel cells. They carry current away from the cell and withstand the clamping force of the stack assembly. Therefore, PEM fuel cell bipolar plates must have high electrical conductivity and adequate mechanical strength, in addition to being light weight and low cost in terms of both applicable materials and production methods. In order to attain these goals, we have manufactured graphite-carbon- polymer composite plates using Compression Molding (CM), which is suitable for mass production, and Selective Laser Sintering (SLS), which is suitable for making prototypes. In this paper, the electrical …
Modeling, Analysis And Simulation Of Paste Freezing In Freeze-Form Extrusion Fabrication, Mingyang Li, Robert G. Landers, Ming-Chuan Leu
Modeling, Analysis And Simulation Of Paste Freezing In Freeze-Form Extrusion Fabrication, Mingyang Li, Robert G. Landers, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
During the freeze-form extrusion fabrication process for aqueous-based pastes, the sub-zero temperature environment aids the part in maintaining its shape by freezing the water present in the paste. The paste freezes very quickly when deposited on a substrate in a freezing environment. However, as the part’s height increases, the freezing time increases as the heat conduction rate to the substrate decreases. The freezing time can exceed the time required to extrude one layer of paste due to water’s high latent heat, thus leaving the extruded paste in its semi-liquid state and causing the part to deform or even collapse. Therefore, …
Effect Of Particle Size, Binder Content And Heat Treatment On Mechanical Properties Of 13-93 Bioactive Glass Scaffolds, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Mariano Garcia Velez
Effect Of Particle Size, Binder Content And Heat Treatment On Mechanical Properties Of 13-93 Bioactive Glass Scaffolds, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Mariano Garcia Velez
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Particle size, binder content and the post-processing schedule are important parameters that affect the microstructure, and, hence, the mechanical properties of parts produced using the indirect selective laser sintering process. 13-93 bioactive glass, with mean particle sizes ranging from 10 μm to 44 μm, is mixed with different amounts of stearic acid binder to fabricate green scaffolds. Through the design of the post-processing schedule, the time required for postprocessing the green scaffolds is reduced from the initial 80 hrs to 12 hrs. The compressive strength varies from 41 MPa for a part with~60% porosity to 157 MPa for a part …
Freeze-Form Extrusion Fabrication Of Composite Structures, Ming-Chuan Leu, Lie Tang, Bradley K. Deuser, Robert G. Landers, Greg Hilmas, Shi C. Zhang, Jeremy Lee Watts
Freeze-Form Extrusion Fabrication Of Composite Structures, Ming-Chuan Leu, Lie Tang, Bradley K. Deuser, Robert G. Landers, Greg Hilmas, Shi C. Zhang, Jeremy Lee Watts
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A Freeze-form Extrusion Fabrication (FEF) process capable of making three-dimensional (3D) parts and structures with graded composite materials is presented in this paper. The process development includes the design and manufacture of a gantry machine with a triple-extruder mechanism and the associated electronics hardware and computer software for fabricating functionally graded parts from multiple aqueous pastes. A rheological behavior study with Al2O3 paste is performed to identify an efficient binder for transforming the paste into a pseudoplastic with a high yield stress. A green part is first fabricated using the triple-extruder FEF machine in a layer-by-layer manner …
Bio-Inspired Design Of Bipolar Plate Flow Fields For Polymer Electrolyte Membrane Fuel Cells, Nannan Guo, Ming-Chuan Leu, Maoliang Wu
Bio-Inspired Design Of Bipolar Plate Flow Fields For Polymer Electrolyte Membrane Fuel Cells, Nannan Guo, Ming-Chuan Leu, Maoliang Wu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The flow field of a bipolar plate distributes hydrogen and oxygen for polymer electrolyte membrane (PEM) fuel cells and removes the produced water from the fuel cells. It greatly influences the performance of fuel cells, especially regarding reduction of mass transport loss. Flow fields with good gas distribution and water removal capabilities reduce the mass transport loss, thus allowing higher power density. Inspired by natural structures such as veins in tree leaves and blood vessels in lungs, which efficiently feed nutrition from one central source to large areas and are capable of removing undesirable by-products, a mathematic model has been …
Numerical Simulation Of Ram Extrusion Process For Ceramic Materials, Mingyang Li, Lie Tang, Fei Xue, Robert G. Landers
Numerical Simulation Of Ram Extrusion Process For Ceramic Materials, Mingyang Li, Lie Tang, Fei Xue, Robert G. Landers
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The freeze–form extrusion process for aqueous-based ceramic paste is complex due to the non-Newtonian behavior of the paste. In this paper the process is studied numerically using a developed mathematical model. The ceramic paste viscosity is characterized by the Herschel-Bulkley model. The relationship between plunger velocity and extrusion force is computed numerically. The influence of air, which is mixed with the paste during the loading process, is also examined. Due to the compressibility introduced by the trapped air, the plunger force dynamic response is typically dominated by a first order response. It is also shown that the extrusion plunger force …
A Strategy For Fabricating Complex Structures Via A Hybrid Manufacturing Process, Tarak A. Amine, Todd E. Sparks, Frank W. Liou
A Strategy For Fabricating Complex Structures Via A Hybrid Manufacturing Process, Tarak A. Amine, Todd E. Sparks, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The purpose of this paper is to introduce a strategy for fabricating complex structures via a hybrid manufacturing process. The Laser Aided Manufacturing Process (LAMP) lab at Missouri S&T has developed a hybrid process combining both a direct metal deposition process and a five-axis CNC milling. Accessibility is a difficulty when finish machining internal features. The concept is to pause the deposition process to finish machine an internal feature while it is still visible is one possible solution to this issue. However, this must be done in a manner that will not be spoiled when the deposition process continues. This …
Octree Approach For Simulation Of Additive Manufacturing Toolpath, Ch. Sweta Dhaveji, Todd E. Sparks, Jianzhong Ruan, Frank W. Liou
Octree Approach For Simulation Of Additive Manufacturing Toolpath, Ch. Sweta Dhaveji, Todd E. Sparks, Jianzhong Ruan, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Machine simulation is an effective way of checking additive manufacturing tool paths for both interferences and errors in part produced. This paper presents an algorithm to visually simulate a multi axis additive manufacturing system as it executes a process plan. Simulation results are intended to be used as a verification step before physically producing the part. Verification is particularly important for large builds of expensive materials. The algorithm uses an octree approach to efficiently model the deposition of part geometry and its changes. This paper discusses development of the simulation algorithm, including both the representation of the additive manufacturing machine …
Process Planning And Control For Functionally Graded Material Fabrication Using Freeze-Form Extrusion Fabrication, Brad Deuser, Lie Tang, Jeff Geldmeier, Robert G. Landers, Ming-Chuan Leu
Process Planning And Control For Functionally Graded Material Fabrication Using Freeze-Form Extrusion Fabrication, Brad Deuser, Lie Tang, Jeff Geldmeier, Robert G. Landers, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using multiple materials in additive manufacturing technologies is critical for building parts with functionally gradient geometries. In order to achieve a desired material gradient, an advanced process planning and control system is required. This paper details the development of a process planning method and control system for functionally graded material fabrication using a triple extruder Freeze-form Extrusion Fabrication (FEF) system including motion code generation, extruder dynamic modeling and control, and composition gradient control. The effect that extruding multiple materials from a single orifice via static mixing has on the time delay of the resulting mixture is taken into account for …
Mea Manufacturing Using An Additive Manufacturing Process To Deposit A Catalyst Pattern In An Mea And Its Impact On Cost Reduction, Nikhil P. Kulkarni, Todd E. Sparks, Gargi Tandra, Frank W. Liou
Mea Manufacturing Using An Additive Manufacturing Process To Deposit A Catalyst Pattern In An Mea And Its Impact On Cost Reduction, Nikhil P. Kulkarni, Todd E. Sparks, Gargi Tandra, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The manufacturing of a fuel cell Membrane Electrode Assembly (MEA) is a significant cost driver in polymer-electrolyte membrane (PEM) fuel cell technologies, primarily due to the inclusion of expensive materials in the catalyst layer. The selective deposition of a catalyst on the MEA of a fuel cell can drastically reduce the costs depending upon the catalyst, method used for deposition, and production volume. In this paper, testing and analysis of a novel catalyst iridium oxide is discussed. The performance of the catalyst will be compared with the conventional catalysts which will give us an estimate of its effectiveness however, in …
Laser Based Rapid Manufacturing Of Metallic Gas Diffusion Layers For Pem Fuel Cells, Gargi Tandra, Todd E. Sparks, Shyam Barua, Nikhil P. Kulkarni, Frank W. Liou
Laser Based Rapid Manufacturing Of Metallic Gas Diffusion Layers For Pem Fuel Cells, Gargi Tandra, Todd E. Sparks, Shyam Barua, Nikhil P. Kulkarni, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Gas Diffusion layers (GDL’s) are an essential component of Polymer Electrolyte Membrane Fuel cells (PEMFC’s) which aid in thermal & electrical conductivities, water management and act as backup layers for the membrane electrode assemblies. This paper summarizes the effort to prototype metallic GDL designs using a miniature laser deposition system developed at Missouri University of Science & Technology. The pore sizes are controlled by masking the diverging laser beam using stainless steel masks of varying sizes and shapes. The through pore feature and further treatment of the GDL’s for hydrophobicity reduces the water management issue and thereby increases the performance …
Multi-Axis Planning System (Maps) For Hybrid Laser Metal Deposition Processes, Frank W. Liou, Jianzhong Ruan, Todd E. Sparks
Multi-Axis Planning System (Maps) For Hybrid Laser Metal Deposition Processes, Frank W. Liou, Jianzhong Ruan, Todd E. Sparks
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper summarizes the research and development of a Multi-Axis Planning System (MAPS) for hybrid laser metal deposition processes. The project goal is to enable the current direct metal deposition systems to fully control and utilize multi-axis capability to make complex parts. MAPS allows fully automated process planning for multi-axis layered manufacturing to control direct metal deposition machines for automated fabrication. Such a capability will lead to dramatic reductions in lead time and manufacturing costs for high-value, low-volume components with high performance material. The overall approach, slicing algorithm, machine simulation for planning validation, and the planning results will be presented.
Optimization Of Selective Laser Sintering Process For Fabrication Of Zirconium Diboride Parts, Ming-Chuan Leu, Shashwatashish Pattnaik, Greg Hilmas
Optimization Of Selective Laser Sintering Process For Fabrication Of Zirconium Diboride Parts, Ming-Chuan Leu, Shashwatashish Pattnaik, Greg Hilmas
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Selective Laser Sintering (SLS) was investigated to fabricate Zirconium Diboride (ZrB2) parts for ultra-high temperature applications. Experiments were conducted to determine values of SLS process parameters (laser power, scan speed, line spacing, and layer thickness) that can be used to build ZrB2 parts with high integrity and sharp geometrical features. A sacrificial plate with a proper number of layers (determined from experimentation) separated from the main part was built in order to reduce thermal gradients when building the main part. The sacrificial plate was found to assist in eliminating cracks in the bottom of the main part. …
Development Of A Low Cost Imaging System For A Laser Metal Deposition Process, Shyam Barua, Todd E. Sparks, Frank W. Liou
Development Of A Low Cost Imaging System For A Laser Metal Deposition Process, Shyam Barua, Todd E. Sparks, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The size of the melt pool created by the laser is one of the most important quality characteristic in a laser metal deposition process. This paper discusses the development of a low-cost vision system to automatically determine the size of the melt pool for in-process control. To cope with the intense infrared signal from the laser and melt pool, external ultraviolet illumination is paired with narrow bandpass filters on a usb microscope to achieve a clear image of the melt pool. The sensitivity of the melt pool to changes in system parameters and various substrate materials are also evaluated.
Uncertainty Analysis In Laser Deposition Finish Machining Operations, Jomy Francis, Todd E. Sparks, Frank W. Liou
Uncertainty Analysis In Laser Deposition Finish Machining Operations, Jomy Francis, Todd E. Sparks, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Laser Aided Manufacturing Process (LAMP) from Missouri S&T is a laser based metals rapid manufacturing process that uses machining to improve the final part's surface finish. When free-form machining, the absence of enough deposited material results in inconsistent scallop heights which result in poor surface finish or incorrect geometry in the final part. This paper investigates a probabilistic approach to various uncertainties involved in the deposition and subsequent machining of an arbitrary part. Furthermore, this paper analyses the machine errors which makes the response of Scallop Height to exceed the predefined maximum scallop height when traveling along the tool …
Selective Laser Sintering Of 13-93 Bioactive Glass, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Mariano Garcia Velez
Selective Laser Sintering Of 13-93 Bioactive Glass, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Mariano Garcia Velez
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Bioactive glasses are more promising than biopolymers in fabricating scaffolds for bone tissue repair because they convert to hydroxyapatite, when implanted in vivo. Both direct and indirect selective laser sintering (SLS) methods of 13-93 bioactive glass were considered in this research to study the feasibility of fabricating scaffolds for bone repair applications. Stearic acid was used as the binder in the indirect method to fabricate the scaffolds. The green scaffolds underwent binder burnout and sintering at various soaking conditions between 675⁰C and 700⁰C, achieving a maximum compressive strength of 23.6 MPa, which is higher than that of the human cancellous …
Selective Laser Sintering And Freeze Extrusion Fabrication Of Scaffolds For Bone Repair Using 13-93 Bioactive Glass: A Comparison, Krishna C. R. Kolan, Nikhil P. Doiphode, Ming-Chuan Leu
Selective Laser Sintering And Freeze Extrusion Fabrication Of Scaffolds For Bone Repair Using 13-93 Bioactive Glass: A Comparison, Krishna C. R. Kolan, Nikhil P. Doiphode, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
13-93 glass is a third-generation bioactive material which accelerates the bone’s natural ability to heal by itself through bonding with surrounding tissues. It is an important requirement for synthetic scaffolds to maintain their bioactivity and mechanical strength with a porous internal architecture comparable to that of a human bone. Additive manufacturing technologies provide a better control over design and fabrication of porous structures than conventional methods. In this paper, we discuss and compare some of the common aspects in the scaffold fabrication using two such processes, viz. selective laser sintering (SLS) and freeze extrusion fabrication (FEF). Scaffolds fabricated using each …
Computer Aided Contour Profiling Of High Strength Deposits, Sriram Praneeth Isanaka, Amar Bala Sridhar, Frank W. Liou, Joseph William Newkirk
Computer Aided Contour Profiling Of High Strength Deposits, Sriram Praneeth Isanaka, Amar Bala Sridhar, Frank W. Liou, Joseph William Newkirk
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Additive manufacturing processes suffer from the effect of ripples, edge rounding and surface variations. To reduce their effect, ideal process parameters for the laser deposition process were investigated. Also, a new method was identified to analyze deposits by accurately plotting their contours. This was achieved through point cloud data of the deposits generated using coordinate measurement and 3D scanning. Curve fitting was performed on the data in Matlab to generate the contours of the deposit. The intercept values, heights, and contact angle of the curves give an indication of the uniformity of deposits and aid in reducing defects.
Effect Of Different Graphite Materials On Electrical Conductivity And Flexural Strength Of Bipolar Plates Fabricated By Selective Laser Sintering, Nannan Guo, Ming-Chuan Leu
Effect Of Different Graphite Materials On Electrical Conductivity And Flexural Strength Of Bipolar Plates Fabricated By Selective Laser Sintering, Nannan Guo, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Graphite is an excellent material for bipolar plates used in Proton Exchange Membrane (PEM) fuel cell due to its great chemical resistance, but the brittle nature makes it difficult to manufacture. Selective Laser Sintering (SLS) based on layer-by-layer manufacturing technology can fabricate graphite bipolar plates with complex gas flow channels. To improve the performance of bipolar plates including electrical conductivity and flexural strength, different graphite materials (natural graphite, synthetic graphite, carbon black, and carbon fiber) were investigated to fabricate test samples. These samples then went through post processing including carbonization and infiltration. The results show that bipolar plates with electrical …
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 …
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 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.