Manufacturing Commons^™

Effects Of Particle Size Distribution With Efficient Packing On Powder Flowability And Selective Laser Melting Process, Zachary Young, Minglei Qu, Meelap Michael Coday, Qilin Guo, Seyed Mohammad H. Hojjatzadeh, Luis I. Escano, Kamel Fezzaa, Lianyi Chen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The powder bed-based additive manufacturing (AM) process contains uncertainties in the powder spreading process and powder bed quality, leading to problems in repeatability and quality of the additively manufactured parts. This work focuses on identifying the uncertainty induced by particle size distribution (PSD) on powder flowability and the laser melting process, using Ti6Al4V as a model material. The flowability test results show that the effect of PSDs on flowability is not linear, rather the PSDs near dense packing ratios cause significant reductions in flowability (indicated by the increase in the avalanche angle and break energy of the powders measured by …

Industry 4.0 Remanufacturing: A Novel Approach Towards Smart Remanufacturing, Prashansa Ragampeta

Masters Theses

“Smart remanufacturing has become more popular in recent years as a result of its multiple benefits and the growing need for society to encourage a circular economy that leads to sustainability. One of the most common end-of-life (EoL) choices that can lead to a circular economy is remanufacturing. As a result, at the end-of-life stage of a product, it is critical to prioritize this choice over other accessible options because it is the only recovery option that retains the same quality as a new product. This work focuses on the numerous technologies that can aid in the improvement of smart …

A Convolutional Neural Network (Cnn) For Defect Detection Of Additively Manufactured Parts, Musarrat Farzana Rahman

Masters Theses

“Additive manufacturing (AM) is a layer-by-layer deposition process to fabricate parts with complex geometries. The formation of defects within AM components is a major concern for critical structural and cyclic loading applications. Understanding the mechanisms of defect formation and identifying the defects play an important role in improving the product lifecycle. The convolutional neural network (CNN) has been demonstrated to be an effective deep learning tool for automated detection of defects for both conventional and AM processes. A network with optimized parameters including proper data processing and sampling can improve the performance of the architecture. In this study, for the …

Characterization Of High Cycle Fatigue And Laser-Aided Machining And Polishing Of Additively Manufactured Materials, Mohammad Masud Parvez

Doctoral Dissertations

“Additive manufacturing (AM) and laser-aided machining and polishing (LAMP) of materials are emerging manufacturing processes both for research and industrial sectors. The AM process can manufacture near-net-shape parts with complex geometries. Meanwhile, the LAMP process integrated with an AM system offers a high processing rate, minimum heat-affected zone, and easily adjustable process parameters during machining and polishing. In mechanical properties characterization of AM metals and alloys, fatigue is a vitally important test method to understand the behavior of materials in cycling loading and unloading circumstances since most mechanical failures of structures are due to fatigue. To characterize AM metal fatigue …

Effect Of The Melt Pool Boundary Network On The Anisotropic Mechanical Properties Of Selective Laser Melted 304l, Myranda Spratt, Joseph William Newkirk, Okanmisope Fashanu, K. Chandrashekhara

Materials Science and Engineering Faculty Research & Creative Works

Anisotropic mechanical properties are a well-known issue in selective laser melted parts. The microstructure produced by selective laser melting (SLM) is directional, including the solidified melt pool structures and grains. This work investigates the melt pool boundary's effects on 304L stainless steel's compressive properties. 304L stainless steel solid cylinders were built using a pulse laser SLM machine in four directions using three hatch angle rotations: 0⁰, 67⁰, and 105⁰ . The twelve samples were compression tested, and the results were analyzed. Numerical models were also created with the different hatch angles and directions. The melt pool boundary network (MPBN) in …

Anisotropy In Impact Toughness Of Powder Bed Fused Aisi 304l Stainless Steel, Sreekar Karnati, Atoosa Khiabhani, Aaron Flood, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The current effort involved investigation into the anisotropy of AISI 304L fabricated through laser powder bed fusion. Charpy V‐notch specimens made from material fabricated at three different build orientations were tested and analyzed. A statistically significant difference among the toughness values indicates the presence of anisotropy within the additively manufactured material. While the lowest toughness was found in vertically built specimens, the horizontal specimens were found to exhibit the highest toughness. From the fracture surfaces, an atypical mode of failure was observed. Exclusive crack propagation along the interlayer track boundaries was observed. The toughness variation correlated with the ease of …

Experimental Investigation Of Additive Manufacturing Of Continuous Carbon Fiber Composites With Multifunctional Electro-Tensile Properties, Ritesh Ghimire, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Manufacturing processes for monofunctional and multifunctional materials vary depending on the design optimization. Multifunctional continuous carbon fiber composites provide great potential in achieving coupled structural and electrical properties for their applications in aircraft, unmanned aircraft systems, and spacecraft. Proper optimization of tensile and electrical properties offers benefits early in the design and continuous operational safety phases to obtain coupled multifunctional properties. In this paper, fused filament fabrication additive manufacturing (AM) technique was used to fabricate continuous carbon fiber solid laminated composites test coupons. The proposed new method characterizes the electrical conductivity's coupled effects on the tensile properties, including the failure …

Additive Manufacturing Of Stainless Steel -- Copper Functionally Graded Materials Via Inconel 718 Interlayer, Xinchang Zhang, Lan Li, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The joining of dissimilar materials is becoming increasingly prevalent to integrate different material properties to enhance design flexibility and overall performance. This study introduced an innovative approach to additively manufacture copper on 316L stainless steel (SS316L) via Inconel 718 interlayers using directed energy deposition (DED). The novel multi-material structure was studied both experimentally and theoretically. The microstructure, tensile properties, microhardness, and thermal performance of the structure were characterized. Residual stress distribution over the structure was revealed by experimental-validated numerical modeling. The result exhibits that defect-free structures with excellent interfacial bonding can be achieved by introducing Inconel 718 interlayers. The bonding …

A Novel Laser-Aided Machining And Polishing Process For Additive Manufacturing Materials With Multiple Endmill Emulating Scan Patterns, Mohammad Masud Parvez, Sahil Patel, Sriram Praneeth Isanaka, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In additive manufacturing (AM), the surface roughness of the deposited parts remains significantly higher than the admissible range for most applications. Additionally, the surface topography of AM parts exhibits waviness profiles between tracks and layers. Therefore, post-processing is indispensable to improve surface quality. Laser-aided machining and polishing can be effective surface improvement processes that can be used due to their availability as the primary energy sources in many metal AM processes. While the initial roughness and waviness of the surface of most AM parts are very high, to achieve dimensional accuracy and minimize roughness, a high input energy density is …

A Kinematic Error Controller For Real-Time Kinematic Error Correction Of Industrial Robots, Mitchell R. Woodside, Joseph Fischer, Patrick Bazzoli, Douglas A. Bristow, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Industrial robots are being used more and more for manufacturing applications that require accuracy beyond what can be obtained from joint measurement. While offline calibration techniques such as volumetric error compensation can be used to correct robot kinematic error, these methods are unable to compensate for robot deformations caused by changing tool loads during the manufacturing operation. This paper explores the use of a real-time robot kinematic error compensation technique where an external high-precision feedback sensor (in this case a laser tracker) directly measures the robot kinematic error and corrections are implemented during processing. A robot kinematic error model is …

Three-Dimensional Laser-Assisted Printing Of Structures From Nanoparticles, Heng Pan, Chinmoy Podder, Wan Shou, Xiaowei Yu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A method for manufacturing a component comprising bombarding nanoparticles in a dispersion with a laser to transform the ligand and cause the nanoparticles to drop out of the dispersion and deposit onto a substrate; and bombarding additional nanoparticles in the dispersion with the laser to transform the ligand and cause the nanoparticles to drop out of the dispersion and deposit onto the nanoparticles previously deposited out of the dispersion.

Oxidation Polymerization Additive Manufacturing, Jonghyun Park, Tazdik Patwary Plateau, Hiep Pham

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Various processes for producing three dimensional electrically conductive polymer structures, such as three dimensional structures of poly(3,4-ethylenedioxythiophene), are described as well as materials produced by these processes.

Development Of In-Situ Radiometric Inspection Methods For Quality Assurance In Laser Powder Bed Fusion, Cody S. Lough

Doctoral Dissertations

“Laser Powder Bed Fusion (LPBF) metal Additive Manufacturing (AM) fabricates 3D metal parts layer-by-layer. The process enables production of geometrically complex parts that are difficult to inspect with traditional methods. The LPBF parts experience significant geometry driven thermal variations during manufacturing. This creates microstructure and mechanical property inhomogeneities and can stochastically cause defects. Mission critical applications require part qualification by measuring the defects non-destructively. The layer-to-layer nature of LPBF permits non-intrusive measurement of radiometric signals for a part’s entire volume. These measurements provide thermal features that correlate with the local part health. This research establishes Optical Emission Spectroscopy (OES) and …

Fabrication Of Silicon Nitride Parts By Ceramic On-Demand Extrusion Process, Sachin Choudhary

Masters Theses

“Ceramic On-Demand Extrusion (CODE) is a patented solid freeform fabrication method for manufacturing high-density monolithic ceramic parts. In the past 5-6 years, the technology has been successfully implemented to fabricate alumina and zirconia parts. The mechanical characterizations also show CODE’s high potential in achieving desired structural properties. The present study covers the fabrication of silicon nitride parts by CODE process, which entailed the design of paste formulation for achieving rheology suitable for dimensional control in fabricated parts and determining firing temperature and the content of sintering additives for silicon nitride green bodies fabricated by CODE. The density, hardness, and fracture …

Research And Development Of A Laser Hot Wire Deposition Process, Christopher Croft

Masters Theses

“Laser hot wire directed energy deposition (DED) is an increasingly popular method for improving deposition rates and overall reduction of build times in DED processing. While there is clear benefit, it is important to fully understand the impact of preheating the wire. This work focuses on developing a model that describes bead geometry output using all factors including the wire preheat. The model was fit with over 150 data points that explored a large range of each factor. The resulting model was then leveraged to evaluate a process control variable. The technique chosen used feedback from the hot wire system …

3d-Printed Biomimetic Bioactive Glass Scaffolds For Bone Regeneration In Rat Calvarial Defects, Krishna C. R. Kolan, Yue-Wern Huang, Julie A. Semon, Ming-Chuan Leu

Biological Sciences Faculty Research & Creative Works

The pore geometry of scaffold intended for the use in the bone repair or replacement is one of the most important parameters in bone tissue engineering. It affects not only the mechanical properties of the scaffold but also the amount of bone regeneration after implantation. Scaffolds with five different architectures (cubic, spherical, x, gyroid, and diamond) at different porosities were fabricated with bioactive borate glass using the selective laser sintering (SLS) process. The compressive strength of scaffolds with porosities ranging from 60% to 30% varied from 1.7 to 15.5 MPa. The scaffold's compressive strength decreased significantly (up to 90%) after …

Hydrokinetic Turbine Composite Blades And Sandwich Structures: Damage Evaluation And Numerical Simulation, Mokhtar Fal

Doctoral Dissertations

“Composite materials are gaining interest due to their high strength to weight ratio. This study deals with both experimental and numerical approaches to cover the aspects of the failure of composite materials in hydrokinetic turbine applications. In Part I, the location and magnitude of failure in the horizontal axis water turbine carbon fiber-reinforced polymer (CFRP) composite blades with different laminate stacking sequences were investigated. Two lay-up orientations were adopted for this work ([0⁰]₄ and [0⁰/90⁰]_2s). A finite element analysis model was generated to examine the stresses along the blade. Five angles were introduced to study the effect …

Influence Of Input Energy On Mechanical Properties Of Laser Powder Bed Fused Aisi 304l Stainless Steel, Tan Pan

Masters Theses

“Powder Bed Fusion process with selective laser melting technique is popularly adopted in additive manufacturing area on account of its layer by layer manufacturing fashion capable of fabricating components with complex internal and external geometries and structures. However, the process-property map is unique and vital for different materials and AM configurations used for fabrication. The process parameter is identified as a significant factor that heavily influences the properties and performances of the printed materials.

Current work aimed to extend the existing knowledge on Laser Powder Bed Fusion fabricated AISI 304L by accessing the influence of varying energy input on the …

Additive Manufacturing Of Customized Lithium-Ion Batteries: Process Fundamentals And Applications, Xiaowei Yu

Doctoral Dissertations

“In the pasting decades, considerable efforts have been spent in developing the next-generation lithium-ion batteries (LIBs), from advanced active materials to new manufacturing methods. The development of additive manufacturing (AM) has brought new opportunities to LIBs. In this work, two AM methods are introduced for fabricating electrodes of LIBs. The first method is aerosol printing, which is a solvent-based wet additive method. Whereas the second method is a solvent-free, dry printing method. The commonly used materials for current collectors and active materials (including cathodes and anodes) of LIBs are aerosol printed and the electrochemical functionalities of the printed materials are …

In-Situ X-Ray Imaging Of The Selective Laser Melting Process, Meelap M. Coday

Masters Theses

"Fusion-based metal additive manufacturing (AM) has garnered much interest in recent decades. Despite the popularity of fusion-based AM technologies such as selective laser melting (SLM), there are still fundamental questions and uncertainties that need to be addressed. In this work, we focus on the understanding of the undercooling in the SLM process and the uncertainties induced by the laser beam size, power, and scan speed. First, we report the estimation of undercooling in the SLM process from the solidification rate measured by in-situ high-speed synchrotron x-ray imaging, based on the dendrite growth velocity model. The undercooling changes as a function …

Combining Laser Aided Ablation And Polishing To Minimize Surface Roughness Of Additively Manufactured Aluminium Components, Sahil Bipinkumar Patel

Masters Theses

“The surface roughness of additively manufactured parts is much higher than the acceptable range for most applications, thus post-processing is needed to qualify these parts for use. Laser polishing can be used to bring the surface roughness in an admissible range, but if the initial roughness is very high then the energy density for the polishing process needs to be very high to achieve a significant reduction in roughness. This high energy density can produce many process defects. Also, laser polishing alone cannot get rid of high wavelength asperities. Any waviness in the part can be linked with initial waviness …

A Framework For A Successful Additive Repair System, Todd E. Sparks

Doctoral Dissertations

“The goal of this research is to generate a revolutionary improvement to the usability and usefulness of additive repair technology by integrating a set of tools into a seamless work flow. Insufficient automation in the current repair process is a huge hurdle in achieving cost-effective, reliable repairs. Many opportunities have been missed due to inconsistency, quality issues and lack of robustness and flexibility. The present work addresses deficiencies in preparatory steps such as 2D and 3D geometry processing, parameter estimation, and path planning as well as on-machine execution of the path plan. The bulk of the effort is focused on …

Frequency Inspection Of Additively Manufactured Parts For Layer Defect Identification, Aimee Allen, Kevin Johnson, Jason R. Blough, Andrew Barnard, Troy Hartwig, Ben Brown, David Soine, Tristan Cullom, Douglas A. Bristow, Robert G. Landers, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Additive manufactured (AM) parts are produced at low volume or with complex geometries. Identifying internal defects is difficult as current testing techniques are not optimized for AM processes. The goal of this paper is to evaluate defects on multiple parts printed on the same build plate. The technique used was resonant frequency testing with the results verified through Finite Element Analysis. From these tests, it was found that the natural frequencies needed to detect the defects were higher than the excitation provided by a modal hammer. The deficiencies in this range led to the development of other excitation methods. Based …

Effective Elastic Properties Of Additively Manufactured Metallic Lattice Structures: Unit-Cell Modeling, Okanmisope Fashanu, David Murphy, Myranda Spratt, Joseph William Newkirk, K. Chandrashekhara, Ben Brown, John Porter

Materials Science and Engineering Faculty Research & Creative Works

Lattice structures are lightweight materials, which exhibit a unique combination of properties such as air and water permeability, energy and acoustic absorption, low thermal conductivity, and electrical insulation. In this work, unit-cell homogenization was used to predict the effective elastic moduli of octet-truss (OT) lattice structures manufactured using selective laser melting (SLM). OT structures were manufactured using a Renishaw AM 250 SLM machine with various relative densities. Compression test was carried out at strain rate 5 x 10^-3 m^-1 using an MTS frame. Finite element analysis was used in the determination of the OT’s effective elastic properties. Results …

In-Situ Local Part Qualification Of Slm 304l Stainless Steel Through Voxel Based Processing Of Swir Imaging Data, Cody S. Lough, Xin Wang, Robert G. Landers, Douglas A. Bristow, James A. Drallmeier, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper demonstrates the potential for qualification through local part property prediction of 304L stainless steel parts manufactured by Selective Laser Melting (SLM). This is accomplished through voxel based processing of SWIR imaging data measured in-situ. Thermal features are extracted from time-series SWIR imaging data recorded from layer-to-layer to generate 3D point cloud reconstructions of parts. The voxel based data is indexed with localized measurements of SLM part properties (light-to-dark microstructural feature ratio, microhardness, μCT data) to demonstrate the correlations. Various features are extracted from the thermal history for comparison of their respective abilities to predict the resulting local part …

Comparison Of Fatigue Performance Between Additively Manufactured And Wrought 304l Stainless Steel Using A Novel Fatigue Test Setup, M. M. Parvez, Y. Chen, Joseph William Newkirk, Frank W. Liou

Materials Science and Engineering Faculty Research & Creative Works

In this research, a novel adaptive controlled fatigue testing machine was designed for bending type high cycle fatigue test. A unique dual gauge section Krouse type mini specimen was designed for simply supported transverse bending. Displacement controlled fatigue tests were implemented using an electromechanical actuator. The variation in the control signal and load observed during the test provides unique insights into realizing the deterioration of the specimen due to fatigue. These analyses were utilized to compare the fatigue performance of wrought and additively manufactured 304L stainless steel. The influence of the build direction on fatigue performance was also investigated by …

Application Of Schlieren Technique In Additive Manufacturing: A Review, R. Bharadwaja, Aravind Murugan, Yitao Chen, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Additive manufacturing has gained a lot of attention in the past few decades due to its significant advantages in terms of design freedom, lower lead time, and ability to produce complex shapes. One of the pivotal factors affecting the process stability and hence the part quality is the shielding gas flow in additive manufacturing. As extremely beneficial for the process, the shielding gas flow is often set at maximum supply to achieve enough gas cover over the substrate. This causes excessive quantity of shielding gas to be unutilized. Realizing the importance of shielding gas, various studies have been carried out …

Applications Of Supervised Machine Learning Algorithms In Additive Manufacturing: A Review, M. S. Joshi, Aaron Flood, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Additive Manufacturing (AM) simplifies the fabrication of complex geometries. Its scope has rapidly expanded from the fabrication of pre-production visualization models to the manufacturing of end use parts driving the need for better part quality assurance in the additively manufactured parts. Machine learning (ML) is one of the promising techniques that can be used to achieve this goal. Current research in this field includes the use of supervised and unsupervised ML algorithms for quality control and prediction of mechanical properties of AM parts. This paper explores the applications of supervised learning algorithms - Support Vector Machines and Random Forests. Support …

Simulated Effect Of Laser Beam Quality On The Robustness Of Laser-Based Am System, Aaron Flood, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In many metal AM techniques, a laser is used as the heat source and in some applications, it can be advantageous to work off of the focal plane. When operating outside of focus, the beam quality of the laser can have drastic impacts on the ability to manufacture quality parts. This study investigates the effect of the beam quality and distance from the focal plan on the ability to deposit Ti-64, aluminum, and steel through the simulation of the blown powder process.

Compressive And Bending Performance Of Selectively Laser Melted Alsi10mg Structures, D. Murphy, O. Fashanu, Myranda Spratt, Joseph William Newkirk, K. Chandrashekhara, H. Misak, D. Klenosky

Materials Science and Engineering Faculty Research & Creative Works

Selective laser melting (SLM) is a widely used additive manufacturing technique that effectively manufactures complex geometries such as cellular structures. However, challenges such as anisotropy and mechanical property variation are commonly found due to process parameters. In a bid to utilize this method for the commercial production of cellular structures, it is important to understand the behavior of a material under different loading conditions. In this work, the behavior of additively manufactured AlSi10Mg under compression, bending, and tension loads was investigated. Vertical and horizontal build directions are compared for each type of loading. Specimens were manufactured using the reduced build …