Mechanical Engineering Commons^™

Cobalt Chromium In Biomedical Applications And The Development Of A Pspp Map, Nouralhouda Jamal

BCoE Publications

During the world wars, Cobalt-Chromium (Co-Cr) alloys gained prominence for their use in aircraft engine components, where they exhibited high temperature strength and durability. They are used in a wide range of industries due to their unique set of qualities, particularly strength, corrosion resistance, and biocompatibility. They have emerged as versatile materials with a broad spectrum of applications, from aerospace and automotive components to biomedical implants.

This paper presents a thorough analysis of its composition, processing techniques, microstructure, mechanical properties, and performance characteristics. The primary goal of this project is to develop a PSPP (Process, structure, properties, and performance) map …

Design And Implementation Of Laser Beam Measurements At The Extents Of The Build Platform: Impact Of Beam Location On Melt Pool Geometry, Alexandra Hernandez

Open Access Theses & Dissertations

Laser powder bed fusion (LPBF) is a form of metal additive manufacturing that enables the development of complex parts that cannot readily be made with traditional manufacturing methods. The process utilizes a tightly focused laser beam to selectively melt and fuse layers of powdered metal to create a 3-D part.LPBF is a promising technology, but there are barriers to its adoption in most industries. Mainly, it is difficult to qualify these parts for use, since they are prone to processing defects and part-to-part variation. One source of this is part position on the building plane, especially for multi-part builds where …

Exploration Of Advanced Scan Strategy Capabilities On A Commercial Lpbf System Using Intervector Power Ramping, Antonio York

Open Access Theses & Dissertations

Lack of confidence in the quality of materials produced with metal AM has hinged on the unaddressed defects inherent to the process. Studies have worked to determine defect formation mechanisms and provide adjustments to key process controls. However, these advances have typically been developed in-house on research systems which offer increased and transparent control to the operator. A research gap exists in applying changes in approach of scan strategies to existing commercial systems, which can incentivize adoption while furthering development. The focus of this study is the implementation of inter-vector power ramping on a commercial laser powder bed fusion system …

Laser Assisted Direct Writing Of Liquid Metal For Microprinting Applications, Olga Vargas Cruz

Theses and Dissertations

This paper presents a research study for potential printing of a Liquid Metal (LM) Eutectic Gallium Indium alloy (EGaIn) through the applications of the innovative additive manufacturing technology LIFT (Laser Induced Forward Transfer). LIFT is a precise printing technology that allows to create small, detailed printing. The liquid metal in study, EGaIn, has demonstrated great potential for microelectronics applications due to its minimum toxicity and high conductivity. Throughout this research different printing parameters are studied to comprehend the behavior of EGaIn printing with LIFT technique, these include laser energy, laser pulse, receiver material substrate, donor layer thickness, and …

An Investigation Into The Challenges Of Contemporary Additive Manufacturing: Insights Into The Metallurgical Response Of Materials And Relevant Solution, Huan Ding

LSU Doctoral Dissertations

Additive Manufacturing (AM) has gained attention in recent years due to its unique capabilities in the fabrication of complex parts. As with any new research, there is still a lack of sufficient understanding in the field of additive manufacturing, and further investigation is needed to solve existing problems. Ultimately, the aim is to enable the widespread use of AM components across various industries.

Chapter One provides a brief introduction to the background and current bottlenecks of additive manufacturing technology. Chapter two focuses on the development of high-strength 7075 aluminum alloy (Al7075) for Fused Deposition Modeling and Sintering (FDMS) technology. Al7075 …

Additive Manufacturing For Medical Education, Michael Noon

College of Engineering Summer Undergraduate Research Program

A growing body of evidence is suggesting that anatomical knowledge, the keystone of many medical specialties, is suffering among new graduates. While a host of reasons are provided, one common thread that many point to is the decline of cadaver dissections in the classroom. Many virtual audio-visual tools are used to address this gap, yet evidence has shown their ineffectiveness. Given this gap, the high degree of flexibility found in additive manufacturing (AM), and the many uses AM has already found in the medical field, we propose its use to fill this gap, allowing for students to learn with touch …

Optimizing Mn-Al Permanent Magnet Performance Through Control Of The Phase Transformation, Ternary Element Addition, And Advanced Processing, Thomas R. Keller

Dartmouth College Ph.D Dissertations

The growing need for electrical power in machines and vehicles brings with it a growing need for critical materials. The current high-performance permanent magnets (PMs) based on rare-earth (RE) elements Nd and Sm cannot escape the problem of raw material cost, geographic scarcity in the earth’s crust, and lack of circular global supply chains. This poses a problem of industrial ecology: can PMs be made from inexpensive, more abundant materials while still meeting sufficient performance criteria? PMs based on the magnetic τ phase of Mn-Al offer a possible alternative to REPMs. However, years of innovation have not yet achieved real-world …

Additive Manufacturing Of Stretchable Strain Sensors: Fabrication, Optimization And Application, John Nady Shihat Bastawrous

Theses and Dissertations

In this project, a novel strain sensor design is fabricated employing different additive manufacturing techniques. The spring sensor's primary material is PLA-Like resin with a nanocomposite encapsulation layer as the functional material. The main principle of Straining the sensors results in a change in resistivity as the distances among the conductive carbon particles change according to the strain applied.

Sensor fabrication consists of two parts: spring manufacturing and development of nanocomposite encapsulation The nanocomposite matrix is developed through the dispersion of Graphene and Carbon nanotubes in Thermoplastic Polyurethane through sonication and magnetic hotplate stirring. While the spring itself is manufactured …

Damage Identification In 3d Printed Metal Parts Using Deep Learning, Romaine Byfield, Alireza Modir, Ibrahim Tansel, Raniero Plaza

Florida Conference on Recent Advances in Robotics

An active Structural Health Monitoring (SHM) method called Surface Response to Excitation (SuRE), is used in this study to detect and quantify the damages created by a milling operation on additively manufactured metal plates. This method entails bonding two piezoelectric disks to the test specimens, one to excite it with surface waves from one end of the plate, and the other to sense the dynamic response to excitation at the other end. A sweep sine wave with a duration of 1 ms, ranging from 50-120 kHz is used as the excitation signal. Five stainless steel plates of identical size (195×54×2.5 …

Cycle Time Reduction In Additive Manufacturing Using Peltier Thermoelectric Cooling Devices, Trevor Carlton

Honors College Theses

Thermoelectric cooling and the Peltier effect were discovered in 1834, over 188 years ago. Additionally, the first iterations of additive manufacturing (i.e., 3D printing) began in the early 1980s, more than 40 years ago. Despite these technologies’ age and years of advancements, the application of Peltier cooling-based devices in additive manufacturing has not yet been realized. These devices can be used for the active thermal management of print beds in 3D printers. Developing a mechanism to heat and cool a print bed can reduce the cycle time to manufacture a part. In 3D printing, waiting for the heated bed to …

A Value-Based Sequential Optimization Framework For Efficient Materials Design Considering Uncertainty And Variability, Maher Alghalayini

All Dissertations

Many problems in engineering and science can be framed as decision problems in which we choose values for decision variables that lead to desired outcomes. Notable examples include maximizing lift in airplane wing design, improving the efficiency of a power plant, or identifying processing protocols resulting in structural materials with desired mechanical properties. These problems typically involve a significant degree of uncertainty about the often-complex underlying relationships between the decision variables and the outcomes. Solving such decision problems involves the use of computational models or physical experimentation to generate data to make predictions and test hypotheses. As a result, both …

A Method For Measuring The Spectral Emissivity Of Metal Powders At Different Temperatures And Applications In Laser Powder Bed Fusion, Emmanuel Levario

Open Access Theses & Dissertations

Radiation thermometry monitoring methods used in powder bed fusion additive manufacturing (PBF-AM) are becoming increasingly more popular for quality assurance and repeatability. The dynamic nature of the PBF process and a lack of accuracy of metrics being captured for temperature monitoring lend great difficulty in the successful implementation of in-situ monitoring. There is currently no data on the emissivity, a metric used in non-contact temperature measurements, for metal powders used in AM. This work describes a method for measuring the spectral emissivity for metal powder sizes commonly used in AM using a multi-wavelength (MW), FMPI SpectroPyrometer, calibrated within the spectral …

An Experimental Study On The Mechanical Properties And Chemical Composition Of Lcd 3d Printed Specimens, Sebastian Gomez

College of Graduate Studies: Theses & Dissertations

Additive manufacturing technologies have been enhanced throughout the years yet have surprised the manufacturing industry due to their high-end surface finish and dimensional accuracy. Different experiments have been done to identify a specific phenomenon known in the vat-polymerization field. Distortion and dimensional inaccuracy tend to affect the overall properties of the process, either physical or chemical. This approach allows the understanding of how the physical properties have been affected and how to study the chemical properties to avoid this type of phenomenon. The chemical reaction between polymer and UV light has been studied and experimented with to the point that …

Investigation Of Manufacturing Techniques For Magnetorheological Elastomers To Expand Feasibility In A Diverse Array Of Applications, Austin S. Robbins

College of Graduate Studies: Theses & Dissertations

Magnetorheological elastomers, or MREs, are smart composite materials with controllable physical and mechanical properties when introduced to an external stimulus of a magnetic field. The controllability of these properties is highly tunable by the selection of the elastomeric matrix, concentration of magnetically permeable particles, introduction of additives, and the alignment of the constituents during the curing process. The fabrication of MREs typically calls for a mold that is filled with an MRE mixture to create the final desired geometry after curing. These molds are frequently placed under a magnetic field which orients the micron sized magnetic particles along the magnetic …

An Active Voice Coil Negative Stiffness Vibration Isolator With Application To Mobile 3d Printing, Lucas M. Schloemp

Dissertations, Master's Theses and Master's Reports

Equipment whose performance degrades when exposed to base vibration is often deployed in vibration-rich environments. Using 3D printers in mobile applications, such as vehicles and ships, are typical examples where the extruder and bedplate are easily excited by base vibration. A versatile active vibration isolator is considered in this thesis constructed using a voice coil actuator and a laser displacement feedback sensor to achieve a wide range of dynamic response characteristics, including negative stiffness. This approach permits transmissibility shaping to meet band-limited base isolation requirements without active damping vibration control. A combination of simulation and hardware validation is used to …

Effect Of Size And Shape Parameters On Microstructure Of Additively Manufactured Inconel 718, Showmik Ahsan

Browse all Theses and Dissertations

Additive Manufacturing (AM) methods are promising in applications where complex part geometries, exotic materials and small lot sizes are required. Aerospace manufacturing stands to use AM methods extensively in the future, and frequently requires temperature- and corrosion-resistant alloy materials such as Inconel 718. However, the microstructural evolution of Inconel 718 during additive manufacturing is poorly understood and depends on part size and shape. We studied the microstructure of Inconel 718 parts manufactured by Laser Powder Bed Fusion in order to further elucidate these dependencies. Microstructural analysis, SEM imaging, EBSD scans and Microhardness testing were performed.

Accelerating Manufacturing Decisions Using Bayesian Optimization: An Optimization And Prediction Perspective, Taofeeq Olajire

Graduate Theses, Dissertations, and Problem Reports (ETD)

Manufacturing is a promising technique for producing complex and custom-made parts with a high degree of precision. It can also provide us with desired materials and products with specified properties. To achieve that, it is crucial to find out the optimum point of process parameters that have a significant impact on the properties and quality of the final product. Unfortunately, optimizing these parameters can be challenging due to the complex and nonlinear nature of the underlying process, which becomes more complicated when there are conflicting objectives, sometimes with multiple goals. Furthermore, experiments are usually costly, time-consuming, and require expensive materials, …

Analysis Of The Effect Of Surface Roughness In Additive Manufacturing On Thermo-Hydraulic Performance By Ml Models Supported By Physics-Based Modeling, Kaylen A. Platt

Graduate Research Theses & Dissertations

Heat exchangers (HX) are crucial components of thermal control systems which facilitate proper transfer of heat in systems such as nuclear reactors. This research focuses on the heat transfer-enhancing effect associated with turbulence in fluid flowing conduits. Turbulence can be induced at low flow rates when surface roughness is present on channel walls. Rough surfaces are typically regarded as a flawed product of the Additive Manufacturing (AM) process during the construction of Heat Exchangers. Machining surface finishes onto AM parts is a typical post-processing method used to remove the roughness. Thorough investigations have not yet been published on the effects …

Characterization And Improvement Of Powder Properties Through Plasma Spheroidization For Use In The Laser Powder Bed Fusion Process, M. Hossein Sehhat

Doctoral Dissertations

"This research was conducted to characterize the powder properties using different characterization techniques to enhance the powder behavior in the Laser Powder Bed Fusion (LPBF) process. One of the shortcomings of LPBF process is the high cost of gas-atomized powder feedstock. To overcome this downside, the cheaper water-atomized powder was characterized and used in LPBF process, and its performance was compared with those of gas-atomized powder. Also, the plasma spheroidization process was used to improve the powder characteristics; if the spheroidized powder could function as well as the virgin powder, plasma spheroidization process could be applied to the used powders …

Direct Ink Write And Thermomechanical Characterization Of Thermoset Composites, Sergio Dante Favela

Open Access Theses & Dissertations

This research will be divided into two sections. The first section discusses direct ink writing and thermomechanical characterization for thermoset composites. The thermoset ink is prepared with fillers aiding the printing process by modifying the rheology of the ink and geometry retention by allowing for the part to have an initial UV cure step. Three specimen formulations with different weight percentages were printed by material extrusion in the shape of tensile specimens following ASTM standard D638 to characterize the mechanical properties at room temperature, 100â?? and 200â??. Furthermore, the ink resin was characterized through DSC, TGA, and rheology testing. The …

Prediction Of Meltpool Depth In Laser Powder Bed Fusion Using In-Process Sensor Data, Part-Level Thermal Simulations, And Machine Learning, Grant King

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The goal of this thesis is the prevention of flaw formation in laser powder bed fusion additive manufacturing process. As a step towards this goal, the objective of this work is to predict meltpool depth as a function of in-process sensor data, part-level thermal simulations, and machine learning. As motivated in NASA's Marshall Space Flight Center specification 3716, prediction of meltpool depth is important because: (1) it can serve as a surrogate to estimate process status without the need for expensive post-process characterization, and (2) the meltpool depth provides an avenue for rapid qualification of microstructure evolution. To achieve the …

A Machine Learning Approach To Robotic Additive Manufacturing Of Uv-Curable Polymers Using Direct Ink Writing, Luis A. Velazquez

LSU Master's Theses

This thesis presents the design and implementation of a robotic additive manufacturing system that uses ultraviolet (UV)-curable thermoset polymers. Its design considers future applications involving free-standing 3D printing by means of partial UV curing and the fabrication of samples that are reinforced with fillers or fibers to manufacture complex-shape objects.

The proposed setup integrates a custom-built extruder with a UR5e collaborative manipulator. The capabilities of the system were demonstrated using Anycubic resin formulations containing fumed silica (FS) at varying weight fractions from 2.8 to 8 wt%. To fully cure the specimens after fabrication, a UV chamber was used. Then, measurements …

Minimax Registration For Point Cloud Alignment, Zhaohui Geng, Mauro Garcia, Bopaya Bidanda

Manufacturing & Industrial Engineering Faculty Publications

The alignment, or rigid registration, of three-dimensional (3D) point clouds plays an important role in many applications, such as robotics and computer vision. Recently, with the improvement in high precision and automated 3D scanners, the registration algorithm has become critical in a manufacturing setting for tolerance analysis, quality inspection, or reverse engineering purposes. Most of the currently developed registration algorithms focus on aligning the point clouds by minimizing the average squared deviations. However, in manufacturing practices, especially those involving the assembly of multiple parts, an envelope principle is widely used, which is based on minimax criteria. Our present work …

The Effect Of Heat Treatment On Mechanical Properties Of Additively Manufactured 17-4 Ph Stainless Steel, Nicholas Aaron Hopkins

Theses and Dissertations

Additive manufacturing (AM) is used to create geometries otherwise impossible to machine. Topology optimization, microstructural texture control, and the use of lattices could be created through AM to increase performance of systems. Currently research focuses on solution aging of printed 17-4 PH, while other heat treatments are not as heavily studied. This study identifies different heat treatments applied to additively manufactured 17-4 precipitation hardened (PH) and the effects on mechanical properties. This study used quasi-static tension, quasi-static compression, and Charpy V-notch testing to analyze the effects of heat treatment as well as the effectiveness of additive manufacturing compared to traditional …

Mobile 3d Printing Of Rail Track Surface For Rapid Repai, Ershad Mortazavian

UNLV Theses, Dissertations, Professional Papers, and Capstones

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 additive manufacturing, i.e., 3D printing, can considerably reduce the associated maintenance costs.The scope of this dissertation is to utilize metal additive manufacturing (AM) technology to repair worn rails that are used in the U.S. railway transportation system (e.g. 75-lb/yd light transit rails, or 136-lb/yd heavy freight rails). More specifically, this study aims to understand the interactive mechanisms between the deposited materials and the high-carbon rail steel to identify and alleviate …

Large Area Projection Sintering Of Semicrystalline Polymers And Part Analysis Of The Printed Specimens, Taranjot Kaur

USF Tampa Graduate Theses and Dissertations

As the requirements posed to products have increased in recent years. The trend towards individualized serial products steps up the need for respective manufacturing techniques to be more and more flexible. Conventional techniques of serial production, such as injection molding, are unable to fully meet the requirements of this trend. Additive manufacturing techniques generate components directly from a CAD data set while requiring no specific mold, producing minimal waste, and reaching satisfactory geometric accuracy. This is how, as opposed to conventional techniques, they comply with these increased demands to processing technology. Over the last two decades, the research community has …

Grey-Taguchi Approach To Optimize Fused Deposition Modeling Process In Terms Of Mechanical Properties And Dimensional Accuracy, Md Asif Bin Syed, Qausar Rhaman, Hasan Md Shahriar, Mohammad Muhshin Aziz Khan

Graduate Student Scholarship

Fused Deposition Modeling (FDM) is a process that allows for the rapid production of functional parts through the deposition of fused material layers in a sequential manner. FDM has flexibility and the potential to create complicated parts. This study aims to optimize the FDM process parameters in terms of tensile strength, flexural strength, and longitudinal shrinkage using the Grey-Taguchi approach. The input parameters chosen to study the effects on dimension and mechanical properties are layer thickness, the raster angle, fill density, the number of contours, printing temperature, and printing speed. The Taguchi L27 orthogonal array is used as the statistical …

Suitability Of Low-Cost Additive Manufacturing For Polymer Electrolyte Fuel Cells, David Alexander

Open Access Theses & Dissertations

The purpose of this dissertation is to study the feasibility of low-cost additive manufacturing to fabricate polymer electrolyte fuel cell bipolar plate materials. Traditional manufacturing techniques include molding, milling, hollow embossing, hydro-forming, rolling, and electromagnetic forming. These processes are employed when a design has been selected due to higher costs at low volumes. The combination of high initial costs and bipolar plates being the most expensive component of the polymer electrolyte fuel cell creates incentive to mitigate this obstacle. The feasibility of low-cost additive manufactured bipolar plates will be proven by fabrication, post-processing, and characterization of printed test specimen. The …

All-In-One Multi3d System: Exploring Potential Of 5-Axis Material Extrusion Additive Manufacturing, Angel Vega

Open Access Theses & Dissertations

Additive Manufacturing (AM) has experienced consistent growth since its inception across its seven process categories, especially Material Extrusion (MEX) with systems that can be seen in commercial and industrial settings. As MEX evolves, innovation can be traced in the growing variety of available process materials and new system capabilities leading to greater interest in the technology across various industries including automotive, aerospace and even nuclear weapons. This has created an increasing demand for end-use parts from MEX systems leading to more complex machines with additional Degrees of Freedom (DoF), specialized workflows, and expanded post processing that address the drawbacks of …

Material Synthesis And Machine Learning For Additive Manufacturing, Jaime Eduardo Regis

Open Access Theses & Dissertations

The goal of this research was to address three key challenges in additive manufacturing (AM), the need for feedstock material, minimal end-use fabrication from lack of functionality in commercially available materials, and the need for qualification and property prediction in printed structures. The near ultraviolet-light assisted green reduction of graphene oxide through L-ascorbic acid was studied with to address the issue of low part strength in additively manufactured parts by providing a functional filler that can strengthen the polymer matrix. The synthesis of self-healing epoxy vitrimers was done to adapt high strength materials with recyclable properties for compatibility with AM …