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Articles 1 - 19 of 19
Full-Text Articles in Engineering
An Investigation Into Applications Of Canonical Polyadic Decomposition & Ensemble Learning In Forecasting Thermal Data Streams In Direct Laser Deposition Processes, Jonathan Storey
Theses and Dissertations
Additive manufacturing (AM) is a process of creating objects from 3D model data by adding layers of material. AM technologies present several advantages compared to traditional manufacturing technologies, such as producing less material waste and being capable of producing parts with greater geometric complexity. However, deficiencies in the printing process due to high process uncertainty can affect the microstructural properties of a fabricated part leading to defects. In metal AM, previous studies have linked defects in parts with melt pool temperature fluctuations, with the size of the melt pool and the scan pattern being key factors associated with part defects. …
Characterization Of Interlayer Laser Shock Peening During Fused Filament Fabrication Of Polylactic Acid (Pla), Fabien Denise
Characterization Of Interlayer Laser Shock Peening During Fused Filament Fabrication Of Polylactic Acid (Pla), Fabien Denise
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
The field of additive manufacturing (AM) has gained a significant amount of popularity due to the increasing need for more sustainable manufacturing techniques and the adaptive development of complex product geometries. The problem is that AM parts routinely exhibit flaws or weaknesses that affect functionality or performance. Over the years, surface treatments have been developed to compensate certain flaws or weaknesses in manufactured products. Combining surface treatments with the modularity of additive manufacturing could lead to more adaptable and creative improvements of product functions in the future. The current work evaluates the feasibility of pursuing a new research axis in …
Damage Detection With An Integrated Smart Composite Using A Magnetostriction-Based Nondestructive Evaluation Method: Integrating Machine Learning For Prediction, Christopher Nelon
Damage Detection With An Integrated Smart Composite Using A Magnetostriction-Based Nondestructive Evaluation Method: Integrating Machine Learning For Prediction, Christopher Nelon
All Dissertations
The development of composite materials for structural components necessitates methods for evaluating and characterizing their damage states after encountering loading conditions. Laminates fabricated from carbon fiber reinforced polymers (CFRPs) are lightweight alternatives to metallic plates; thus, their usage has increased in performance industries such as aerospace and automotive. Additive manufacturing (AM) has experienced a similar growth as composite material inclusion because of its advantages over traditional manufacturing methods. Fabrication with composite laminates and additive manufacturing, specifically fused filament fabrication (fused deposition modeling), requires material to be placed layer-by-layer. If adjacent plies/layers lose adhesion during fabrication or operational usage, the strength …
Upcyclying Of Polyethylene Terephtalate By Addition Of Thermoplastic Elastomer, Diego Francisco Bermudez
Upcyclying Of Polyethylene Terephtalate By Addition Of Thermoplastic Elastomer, Diego Francisco Bermudez
Open Access Theses & Dissertations
Continual overconsumption of single-use plastics has generated challenges of solid waste management across the United States. Common plastic waste management solutions, such as landfill, have caused the migration of contaminants into the environment consequently affecting not only the health of wildlife, but also that of human beings. Alternative strategies for the handling of single-use plastic such as polyethylene terephthalate (PET), used in the food packaging industry, can ultimately help mitigate the noxious consequences of single-use plastics affecting entire ecosystems. This study demonstrates a potential avenue of materials upcycling by studying the effects of coupling PET with the thermoplastic elastomer styrene-ethylene-butylene-styrene …
Predicting Thermoelectric Power Factor Of Bismuth Telluride During Laser Powder Bed Fusion Additive Manufacturing, Ankita Agarwal, Tanvi Banerjee, Joy Gockel, Saniya Leblanc, Joe Walker, John Middendorf
Predicting Thermoelectric Power Factor Of Bismuth Telluride During Laser Powder Bed Fusion Additive Manufacturing, Ankita Agarwal, Tanvi Banerjee, Joy Gockel, Saniya Leblanc, Joe Walker, John Middendorf
Computer Science and Engineering Faculty Publications
An additive manufacturing (AM) process, like laser powder bed fusion, allows for the fabrication of objects by spreading and melting powder in layers until a freeform part shape is created. In order to improve the properties of the material involved in the AM process, it is important to predict the material characterization property as a function of the processing conditions. In thermoelectric materials, the power factor is a measure of how efficiently the material can convert heat to electricity. While earlier works have predicted the material characterization properties of different thermoelectric materials using various techniques, implementation of machine learning models …
Investigation Of Oleic Acid As A Dispersant For Hydroxyapatite Powders For Use In Ceramic Filled Photo-Curable Resins For Stereolithography, Brendan Kennedy, Eamonn De Barra, Stuart Hampshire, Maura Kelleher
Investigation Of Oleic Acid As A Dispersant For Hydroxyapatite Powders For Use In Ceramic Filled Photo-Curable Resins For Stereolithography, Brendan Kennedy, Eamonn De Barra, Stuart Hampshire, Maura Kelleher
Articles
Stereolithography allows production of porous hydroxyapatite scaffolds for bone regeneration but is limited by the challenging rheology of ceramic filled resins. Oleic acid, a natural fatty acid, was applied in concentrations of 0.0–0.3 wt% to improve the rheological properties of HAp resins for the fabrication of solid cylinders and scaffolds by digital light processing (DLP) printing in a wiperless system. Bonding by chemisorption was confirmed by FTIR analysis. The powders were then incorporated into a photo-curable resin of 1–6 hexanediol diacrylate at 18–30 vol%. The shear viscosity and sedimentation rates of photocurable resins containing HAp powder decreased with increasing concentration …
Material Extrusion-Based Additive Manufacturing: G-Code And Firmware Attacks And Defense Frameworks, Haris Rais
Material Extrusion-Based Additive Manufacturing: G-Code And Firmware Attacks And Defense Frameworks, Haris Rais
Theses and Dissertations
Additive Manufacturing (AM) refers to a group of manufacturing processes that create physical objects by sequentially depositing thin layers. AM enables highly customized production with minimal material wastage, rapid and inexpensive prototyping, and the production of complex assemblies as single parts in smaller production facilities. These features make AM an essential component of Industry 4.0 or Smart Manufacturing. It is now used to print functional components for aircraft, rocket engines, automobiles, medical implants, and more. However, the increased popularity of AM also raises concerns about cybersecurity. Researchers have demonstrated strength degradation attacks on printed objects by injecting cavities in the …
Compact Dual-Band Rectangular T E10 Mode To Circular Tm01 Mode Converter For Telemetry/Telecommand Applications In Satellite Communication: Design, Equivalent Circuit Modeling, Mode Level Measurement Technique And 3d Printed Manufacturing, Esra Alkin, Ceyhan Türkmen, Mustafa Seçmen
Compact Dual-Band Rectangular T E10 Mode To Circular Tm01 Mode Converter For Telemetry/Telecommand Applications In Satellite Communication: Design, Equivalent Circuit Modeling, Mode Level Measurement Technique And 3d Printed Manufacturing, Esra Alkin, Ceyhan Türkmen, Mustafa Seçmen
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, the design of a dual-band mode converter, which provides transition from rectangular waveguide T E10 mode to circular waveguide TM01 mode and operates simultaneously in telemetry/telecommand (TT&C) frequencies, is presented along with its equivalent circuit and a mode level measurement technique. This dual-band converter is designed to uniformly excite TT&C slot antennas used in satellite communication with symmetric circular TM01 mode. The structure can work as a transceiver due to having one common rectangular waveguide feed. As a Ku-band application, a converter giving high purity TM01 mode at circular waveguide at 11.75 GHz/TX …
Enabling Nanoimprint Lithography Techniques Across Multiple Manufacturing Processes, Vincent Einck
Enabling Nanoimprint Lithography Techniques Across Multiple Manufacturing Processes, Vincent Einck
Doctoral Dissertations
Advanced nanooptics in the areas of flat lenses, diffractive elements, and tunable emissivity require a route to high throughput manufacturing. Nanooptics are often demanding of high refractive index materials, nanometer precision and ease of fabrication. Nanoimprint lithography (NIL) is a low-cost, high throughput manufacturing technique beginning to be realized in commercial industry.1,2 The NIL process is an ideal manufacturing candidate due to its ability to have a fast process time, efficient use of materials, repeatability and high precision while also having wide diversity of potential structures and material choices. Appling NIL techniques to other facets of manufacturing enable the …
Towards An Instant Structure-Property Prediction Quality Control Tool For Additive Manufactured Steel Using A Crystal Plasticity Trained Deep Learning Surrogate, Yuhui Tu, Zhongzhou Liu, Luiz Carneiro, Caitriona M. Ryan, Andrew C. Parnell, Sean B. Leen
Towards An Instant Structure-Property Prediction Quality Control Tool For Additive Manufactured Steel Using A Crystal Plasticity Trained Deep Learning Surrogate, Yuhui Tu, Zhongzhou Liu, Luiz Carneiro, Caitriona M. Ryan, Andrew C. Parnell, Sean B. Leen
Research Collection School Of Computing and Information Systems
The ability to conduct in-situ real-time process-structure-property checks has the potential to overcome process and material uncertainties, which are key obstacles to improved uptake of metal powder bed fusion in industry. Efforts are underway for live process monitoring such as thermal and image-based data gathering for every layer printed. Current crystal plasticity finite element (CPFE) modelling is capable of predicting the associated strength based on a microstructural image and material data but is computationally expensive. This work utilizes a large database of input–output samples from CPFE modelling to develop a trained deep neural network (DNN) model which instantly estimates the …
A Highly Conductive, Flexible, And 3d-Printable Carbon Nanotube-Elastomer Ink For Additive Bio-Manufacturing, Andy Shar, Phillip Glass, Daeha Joung Ph.D.
A Highly Conductive, Flexible, And 3d-Printable Carbon Nanotube-Elastomer Ink For Additive Bio-Manufacturing, Andy Shar, Phillip Glass, Daeha Joung Ph.D.
Undergraduate Research Posters
The synthesis of a highly conductive, flexible, 3D-printable, and biocompatible ink has been of great interest in the field of bio-based additive manufacturing. Various applications include ultra-sensitive, microscale tactile sensors, patient-customizable scaffolds for cardiac and nerve tissue regeneration, and flexible electrocardiogram (ECG) electrodes. Here, a novel elastomeric carbon nanocomposite is presented consisting of amino-functionalized carbon nanotubes (CNT-NH2) homogenously dispersed in a one-part room-temperature vulcanizing (RTV) silicone matrix. The use of acetone as a swelling solvent aids in electrical percolation through the elastomer matrix. CNT-NH2 ratios can be tuned to fit various needs; higher tensile strength is favored …
Investigation And Statistical Modeling Of The Mechanical Properties Of Additively Manufactured Lattices, Derek G. Spear, Anthony N. Palazotto
Investigation And Statistical Modeling Of The Mechanical Properties Of Additively Manufactured Lattices, Derek G. Spear, Anthony N. Palazotto
Faculty Publications
This paper describes the background, test methodology, and experimental results associated with the testing and analysis of quasi-static compression testing of additively manufactured open-cell lattice structures. The study aims to examine the effect of lattice topology, cell size, cell density, and surface thickness on the mechanical properties of lattice structures. Three lattice designs were chosen, the Diamond, I-WP, and Primitive Triply Periodic Minimal Surfaces (TPMSs). Uniaxial compression tests were conducted for every combination of the three lattice designs, three cell sizes, three cell densities, and three surface thicknesses. In order to perform an efficient experiment and gain the most information …
Effect Of Heat Treatment On Microstructure And Hardness Of A Worn Rail Repaired Using Laser Powder Deposition, Ershad Mortazavian, Zhiyong Wang, Hualiang Teng
Effect Of Heat Treatment On Microstructure And Hardness Of A Worn Rail Repaired Using Laser Powder Deposition, Ershad Mortazavian, Zhiyong Wang, Hualiang Teng
Mechanical Engineering Faculty Research
The frequent replacement of worn rails on tracks brings an immense economic burden on the railroad industry, and also causes significant interruptions to railroad operation. Restoration of worn rails via laser powder deposition (LPD) can considerably reduce the associated maintenance costs. This study was focused on the use of LPD to repair the worn profile of a standard U.S. rail. The microstructure of the 304L stainless steel deposits with a minimum hardness of 85 HRB was composed of austenite, δ-ferrite, and sigma. Micropores were dispersed throughout the deposit, and microcracks were found at the rail-deposition interface. The pearlitic rail substrate …
Texture-Driven Image Clustering In Laser Powder Bed Fusion, Alexander H. Groeger
Texture-Driven Image Clustering In Laser Powder Bed Fusion, Alexander H. Groeger
Browse all Theses and Dissertations
The additive manufacturing (AM) field is striving to identify anomalies in laser powder bed fusion (LPBF) using multi-sensor in-process monitoring paired with machine learning (ML). In-process monitoring can reveal the presence of anomalies but creating a ML classifier requires labeled data. The present work approaches this problem by printing hundreds of Inconel-718 coupons with different processing parameters to capture a wide range of process monitoring imagery with multiple sensor types. Afterwards, the process monitoring images are encoded into feature vectors and clustered to isolate groups in each sensor modality. Four texture representations were learned by training two convolutional neural network …
Texture-Driven Image Clustering In Laser Powder Bed Fusion, Alexander H. Groeger
Texture-Driven Image Clustering In Laser Powder Bed Fusion, Alexander H. Groeger
Browse all Theses and Dissertations
The additive manufacturing (AM) field is striving to identify anomalies in laser powder bed fusion (LPBF) using multi-sensor in-process monitoring paired with machine learning (ML). In-process monitoring can reveal the presence of anomalies but creating a ML classifier requires labeled data. The present work approaches this problem by printing hundreds of Inconel-718 coupons with different processing parameters to capture a wide range of process monitoring imagery with multiple sensor types. Afterwards, the process monitoring images are encoded into feature vectors and clustered to isolate groups in each sensor modality. Four texture representations were learned by training two convolutional neural network …
Increasing The Functionality Of Additive Manufacturing Through Atmospheric Microplasma And Nanotechnology, Alexander Jon Ulrich
Increasing The Functionality Of Additive Manufacturing Through Atmospheric Microplasma And Nanotechnology, Alexander Jon Ulrich
Doctoral Dissertations
Additive Manufacturing (AM) has been changing the manufacturing landscape for the last 20 years. As the interest and demand for both polymer and metal-based 3D printing has grown, the materials and machines used have increased in capabilities. Despite the growth and advancement, there are still a large number of improvements that can be made to add functionality to 3D printers. Metal AM, a subcategory of 3D printing, has garnered much attention among industrial applications with large companies such as General Electric trying to implement the technology to increase innovative designs for motors. Some of the limitations on AM have to …
Experimental Laser Powder Bed Fusion System For Difficult To Process Metallic Materials, Syed Zia Uddin
Experimental Laser Powder Bed Fusion System For Difficult To Process Metallic Materials, Syed Zia Uddin
Open Access Theses & Dissertations
The focus of this research was twofold, such as development of defect free fabrication parameters for laser powder bed fusion (LPBF) processing of crack prone or difficult to process metallic materials, and study of the temperature dependence of emissivity for some commonly used metal alloy powders in LPBF process. The later objective extends to the implementation of multiwavelength (MW) pyrometer technology for in situ true surface temperature measurement in LPBF process. LPBF is an additive manufacturing (AM) process capable of layer-by-layer manufacturing by successive laser melting of each layer according to CAD data. AM manufacturing has the inherent advantages of …
Cellulose Nanofiber-Reinforced Impact Modified Polypropylene: Assessing Material Properties From Fused Layer Modeling And Injection Molding Processing, Jordan Elliott Sanders
Cellulose Nanofiber-Reinforced Impact Modified Polypropylene: Assessing Material Properties From Fused Layer Modeling And Injection Molding Processing, Jordan Elliott Sanders
Electronic Theses and Dissertations
The purpose of this research was to investigate the use of cellulose nanofibers (CNF) compounded into an impact modified polypropylene (IMPP) matrix. A IMPP was used because it shrinks less than a PP homopolymer during FLM processing. An assessment of material properties from fused layer modeling (FLM), an additive manufacturing (AM) method, and injection molding (IM) was conducted. Results showed that material property measurements in neat PP were statistically similar between IM and FLM for density, strain at yield and flexural stiffness. Additionally, PP plus the coupling agent maleic anhydride (MA) showed statistically similar results in comparison of IM and …
Does Material Choice Drive Sustainability Of 3d Printing?, Jeremy Faludi, Zhongyin Hu, Shahd Alrashed, Christopher Braunholz, Suneesh Kaul, Leulekal Kassaye
Does Material Choice Drive Sustainability Of 3d Printing?, Jeremy Faludi, Zhongyin Hu, Shahd Alrashed, Christopher Braunholz, Suneesh Kaul, Leulekal Kassaye
Dartmouth Scholarship
Environmental impacts of six 3D printers using various materials were compared to determine if material choice drove sustainability, or if other factors such as machine type, machine size, or machine utilization dominate. Cradle-to-grave life-cycle assessments were performed, comparing a commercial-scale FDM machine printing in ABS plastic, a desktop FDM machine printing in ABS, a desktop FDM machine printing in PET and PLA plastics, a polyjet machine printing in its proprietary polymer, an SLA machine printing in its polymer, and an inkjet machine hacked to print in salt and dextrose. All scenarios were scored using ReCiPe Endpoint H methodology to combine …