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In Situ Process Monitoring And Machine Learning Based Modeling Of Defects And Anomalies In Wire-Arc Additive Manufacturing, Eduardo Miramontes

Masters Theses

Wire Arc Additive Manufacturing (WAAM) has made great strides in recent years however, there remain numerous persistent challenges still hindering more widespread adoption. Defects in the parts produced degrade their mechanical performance. Inconsistency in the geometry of the weld beads or undesirable anomalies such as waviness, or humps can lead to loss of geometric accuracy and in extreme cases, when anomalies propagate to subsequent layers, build failure. Such defects can be mitigated by a controls framework, which would require a model that maps undesirable outcomes to information about the process that can be obtained in real time. This thesis explores …

Assessing Mechanical Performance Of Dissimilar Steel Systems Made Via Wire-Arc Additive Manufacturing, Obed Daniel Acevedo

Masters Theses

Hot stamping is part of a specific type of metalworking procedure widely used in the automotive industry. This research seeks to help make hot stamp tooling component production more cost-effective by using large-scale additive manufacturing. Additive manufacturing can produce dissimilar steel components that can be more cost-effective and time-efficient and allow for complex geometries to be made. A dissimilar steel system consisting of 410 martensitic stainless steel and AWS ER70S-6 mild steel is proposed to make hot stamps, making them more cost-efficient. However, the material interface's mechanical behavior in 410SS-mild steel additively manufactured material systems is not well understood. This …

Design Of A Cable-Driven Manipulator For Large-Scale Additive Manufacturing, Phillip Chesser

Masters Theses

Additive manufacturing of concrete is a growing field of research, yet current motion platforms do not offer viable routes towards large scale deployable systems. This thesis presents the design and analysis of a novel cable-driven robot for use in large scale additive manufacturing. The system developed, termed SkyBAAM, is designed to be easily deployable to a construction site for on-site additive manufacturing of buildings and other large structures. The design philosophy behind this system is presented. Analysis of this system first explores the kinematics, and stiffness as a function of cable tension. Analysis of the workspace and singularities is also …

Evaluating The Effects Of Scan Strategy On Am Annealed Fe-3si Steel Through Understanding Of Solidification Conditions And Thermal Stresses, Michael P. Haines

Masters Theses

Soft magnetic steels have seen recent adoption in additive manufacturing (AM) due to the prospect of reducing eddy currents and hysteresis losses through leveraging of complex geometries and microstructural control. An annealing step will be a significant step for these alloys produced in AM to increase grain size and further reduce hysteresis losses. In this study, thin wall Fe-3Si samples were produced using laser powder bed fusion (L-PBF) using two different scan strategies, with a subset of samples annealed at 1200°C for 5 minutes. The effects of the two different scan strategies on microstructure in the as-built and annealed samples …

Application Of Artificial Neural Nets To A Selective Laser Sintering Additive Manufacturing Process For Fault Detection, Benjamin Terry

Masters Theses

The purpose of this paper is to report recent results demonstrating feasibility of active monitoring and fault probability estimation in the Selective Laser Melting (SLM) process in a Renishaw AM250 machine, through analysis of layer-by-layer surface profile data of Fe3Si powder. The data was collected in-situ during the metal additive manufacturing of a Heat Exchanger section, comprised of a series of conformal channels. Specifically, a shallow artificial neural net (ANN) was trained with high-resolution powder bed surface height data from a laser profilometer and then linked to post-print CT scans which provided the truth-data labelling of each site as faulty …

The Use Of Optical In-Situ Data Of Tensile Samples To Model Porosity For Part Qualification Of Am 316l, Caitlin Hensley

Masters Theses

Additively manufactured parts often contain porosity that forms during the building process. These defects can affect the part quality and make individual part qualification difficult. In this study, pores were purposefully designed within tensile samples in combinations of three diameters (200m, 350m, and 500m) and three volume percentages (1%, 3%, and 5%) for a total of nine combinations. Each combination was built twice in order to compare the ability of hot isostatic pressing (HIP) and solution annealing (SA) to mitigate pore effects and produce a part that achieves acceptable tensile properties. Two control samples with no purposeful porosity included were …

Investigation Of Selective Laser Melting Fabricated Internal Cooling Channels, Colin Jack

Masters Theses

Channels where coolant is run to cool a system are common in injection mold tooling. Conventionally, these channels are machined into the mold. This has limited the design of mold cooling systems to the constraints of traditional machining processes, where straight circular channels machined from cast material are typical. The transfer of heat away from the part cavity into these cooling channels has a large effect on the cooling time of the injection mold cycle. In this investigation, laser powder bed fusion processes were used to create non-circular cooling channels. To compare cooling performance, elliptical and circular channels of equal …

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 …

Performance Evaluation Of Alsi10mg Fabricated By A Selective Laser Melting Process, David Michael Murphy

Masters Theses

“Selective laser melting is becoming a widely used additive manufacturing technique that melts metal powder in a layer by layer process in order to build a desired part or geometry. Like many additive processes, selective laser melting allows for fabrication of parts with complex geometries. In order to fabricate a fully dense part there are a number of variables to take into account including: powder characteristics, laser parameters, and environmental parameters. Each of these variables can affect the microstructure and thus the mechanical performance of an additively manufactured part. In this work, the aluminum alloy AlSi10Mg was investigated. AlSi10Mg is …

3d Printing Reinforced Concrete Structures, Bryce Tyler Tafolla

Masters Theses

"This study aims to investigate a 3D printing method to directly incorporate continuous reinforcement into concrete structures. The ability to design and produce complex structures with optimized topographical configuration can be used to reduce potential material waste while maintaining the required structural strength. Furthermore, the ability to actively incorporate reinforcement into printed members substantially reduces potential labor requirements and eliminates the need to set up formwork.

The study began its initial approach with a manual extrusion process containing reinforcement to observe the necessary constraints required to achieve a printing system with this functionality. The second stage of development was designing …

Rationalization Of Crystallographic Texture Evolution In High Gamma Prime Ni-Based Superalloys During Laser Powder Feed Directed Energy Disposition, Kevin Michael Smith

Masters Theses

Single-crystal nickel superalloy components are widely used in high temperature aerospace applications due to their excellent high temperature strength and creep resistance. Mechanical properties of single-crystal nickel superalloys are affected by chemical composition and the method of manufacture. Production of these components is costly and repair offers opportunity to sustain system performance while reducing costs. Additive Manufacturing by Laser Powder Feed Directed Energy Deposition (DED) is a promising method for repair due to selective application of material and the ability to tailor heat input. However, laser processing of these materials presents several challenges due to the high potential for cracking …

Automatic Error Detection And Correction In Laser Metal Wire Deposition - An Additive Manufacturing Technology, Adeola Idowu Adediran

Masters Theses

Additive manufacturing (AM) technology involves building three-dimensional objects by adding material layer-upon-layer under computer control. Metal additive manufacturing offers new possibilities, not only in design, but also in the choice of materials. However, the additive process remains at a lower maturity level compared to the conventional subtractive processes such as milling, drilling and machining among others. Scientifically, there is a safety concern relating to the accuracy of the AM process, how printed products will perform over time and the consistency of their quality. Process accuracy and eventual part quality is compromised due to errors introduced by each of the building …

Approach To Qualification For Electron Beam Powder Bed Fusion In Ti-6al-4v, Sean Lucas Yoder

Masters Theses

Recent developments in additive manufacturing (AM) show promise for using AM manufactured components in a production setting. However, a crucial step for mass producing AM components is to certify these parts for use. One common method for certifying parts is to manufacture tensile coupons alongside any parts. These coupons are characterized and the results are related to the parts. This causes many researchers to focus on the process-material interactions while neglecting build setup. Another issue related to certification of AM parts is the lack of knowledge in the software calculations for a given process. Original equipment manufacturers (OEM), such as …

The Effect Of Hydrogen On Gas Porosity In Laser Powder Bed Fusion Of Alsi10mg, Travis A. Mcfalls

Masters Theses

The density of components built using selective laser melting systems are greatly affected by pore formation during rapid solidification. By limiting the hydrogen content of the AlSi10Mg powder and the solidification through build parameters, gas porosity can be reduced. In this study, three types of porosity were characterized in AlSi10Mg samples built by both SLM and Concept Laser systems. Trends relating to energy input and pore type were established for gas, keyhole, and lack of fusion. The physical mechanisms for each type of pore formation were rationalized relative to solidification parameters such as, thermal gradient and solidification front velocity. Areal …

Metal-Polymer Adhesive Bond Characterization In An Additive Manufacturing Environment, Daniel Seth Elkins

Masters Theses

Recently, the aerospace industry has turned the focus of its manufacturing efforts towards additive methods. For many aerospace applications, however, hybrid materials are preferred for their ability to combine optimal properties from various material sets, and these materials are not yet compatible with large-scale additive manufacturing. To fix this lack of compatibility, new additive methods must be developed that can print dissimilar hybrid materials on one print bed at a large scale, which will require a reliable dissimilar material joining method.Among current joining techniques, one of the most promising for this application is adhesive bonding. Typically, adhesive bonding requires optimizing …

Laser-Aided Additive Manufacturing Of Glass, John Michael Hostetler

Masters Theses

“This thesis presents various approaches for the laser-aided additive manufacturing of glass. First, a technique is investigated to create free-form, low to zero coefficient of thermal expansion structures out of silica-gel. A CO₂ laser was coupled through a gantry system and focused onto a binder-free silica-gel powder bed (15-40 μm particles). Prior to writing each layer, powder is dispensed by sifting it onto the build platform as opposed to a conventional wiper system, avoiding contacting and potentially damaging sensitive parts. After deposition, the parts are annealed in a furnace to increase their strength. The influence of various process parameters …

Designed Extrudate For Ceramic Additive Manufacturing, Devin Mcmillen

Masters Theses

"The objective of this thesis work was to design ceramic paste systems that assist in achieving a high theoretical density ( > 95%) after deposition by a novel additive manufacturing process, i.e. Ceramic On-Demand Extrusion (CODE). The work is encompassed in five main sections: Sections 1 and 2 provide an introduction and literature review of relevant topics for the following sections of experimentation. Section 3 provides an analysis of a reaction chemistry to identify three discrete materials that could be combined via CODE and result in zirconium diboride (ZrB₂) post-sintering. Section 4 describes the development of a high solids …

3d Printed Electronics, Mwamba Bowa

Masters Theses

Additive manufacturing is revolutionizing the way we build and produce a plethora of products spanning many industries. 3D printing, a subset of additive manufacturing, has shown strong potential in reduced energy use, sustainability and cost effectiveness. Exploring avenues that this technology can be utilized is key to improve productivity and efficiency in various applications; for example electronic systems and devices manufacturing.Electronic systems and sub-systems are built using a variety of materials and processes, which require a large carbon footprint, significant waste products and high production time. We have seen experiments of printed electronics using inkjet printing technology to provide a …

Monitoring The Metal Additive Manufacturing Process Through Thermographic Data Analysis, Jacob B. Raplee

Masters Theses

Metal Additive Manufacturing (AM) is the formation of a solid metal part through the layer-wise melting of metal powder, wire, or thin sheets using various heat sources or other bonding methods. This manufacturing method provides nearly limitless complexity with decreased waste, energy needs, and lead time. However, the process faces challenges in part consistency and validation especially for high precision fields such as aerospace and defense. Research has sought to implement robust process monitoring techniques to increase consistency and the reliability of the AM process and detect vital information about the part such as microstructural development, and porosity formation so …

In-Situ Control Of Substrate Temperature In Additive Manufacturing To Homogenize Micro-Hardness Of Laser Clad Deposits Using Thermo-Electric Cooling, Raghu Ram Kolla

Masters Theses

”Nickel hard-surfacing alloys are replacing hard Chromium coatings due to their excellent wear and corrosion-resistant properties. In laser cladding of these alloys, however, these properties can vary across the height of the deposit due to an accumulation of excess heat generated in the deposit during the process. This may result in uneven wear of the clad parts which can be detrimental for practical purposes. The research objective is to develop an in-situ cooling system that works in line with the laser deposition system to extract the excess heat buildup and reduce the variation in the hardness of the Ni-based clad …

Error Mapping Of Build Volume In Selective Laser Melting, Ninad Kulkarni

Masters Theses

“Selective laser melting is one of the commonly used additive manufacturing processes employed for production of functional part. Therefore, quality aspects such as dimensional accuracy have become a point of great interest. Like all of the other additive manufacturing processes selective laser melting process suffers from the issue if having wide range of process parameters making the process control a complex task. Additionally, issues specific to the selective laser melting process such as position dependency of accuracy of the part, makes it difficult to predict the resulting dimensional inconsistencies in the part manufactured by this processes. This research is an …

A Haptic Surface Robot Interface For Large-Format Touchscreen Displays, Mark Price

Masters Theses

This thesis presents the design for a novel haptic interface for large-format touchscreens. Techniques such as electrovibration, ultrasonic vibration, and external braked devices have been developed by other researchers to deliver haptic feedback to touchscreen users. However, these methods do not address the need for spatial constraints that only restrict user motion in the direction of the constraint. This technology gap contributes to the lack of haptic technology available for touchscreen-based upper-limb rehabilitation, despite the prevalent use of haptics in other forms of robotic rehabilitation. The goal of this thesis is to display kinesthetic haptic constraints to the touchscreen user …

Effect Of Build Parameters On Mechanical Properties Of Ultem 9085 Parts By Fused Deposition Modeling, Krishna Prasanth Motaparti

Masters Theses

"Additive manufacturing is a fabrication technique that is used to build components by depositing material in a layer-by-layer manner. Fused Deposition Modeling (FDM) is one of the additive manufacturing techniques which is widely used for prototyping and production applications of thermoplastic components. In load bearing applications, the flexural and compression forces often coexist. In order to avoid failure under these loads, it is essential to study the mechanical properties of the components fabricated by FDM. The main focus of this research is to study the mechanical properties of the fabricated components and to comprehend their dependence on various build parameters. …

Freeze-Form Extrusion Fabrication Of Boron Carbide, Aaron Scott Thornton

Masters Theses

"Boron carbide is a safe, alternative to beryllium as a material for aerospace structures since it is also light-weight and exhibits high strength. This paper discusses a study of the Freeze-form Extrusion Fabrication (FEF) process to fabricate parts from boron carbide. Process parameters and hardware were modified to fabricate boron carbide specimens free of printed defects. Four-point bending tests were performed to measure the flexural strength of fabricated specimens. Observations of the presence of voids caused by ice crystals in fabricated parts led to further development and characterization of the boron carbide paste used with the FEF process. Additives were …

Performance Metrics For Powder Feeder Systems In Additive Manufacturing, Venkata Sivaram Bitragunta

Masters Theses

"In blown powder Direct Metal Deposition (DMD) process, parts are built by adding metal powder on the melt pool created by the laser system. At low feed rates powder feeder systems have perturbations. The study focused on relationship between the perturbation frequencies by inherent powder feeder designs and its impact on deposition quality. Performance metric determine the relation between perturbations in the powder flow and quality of the deposit. To determine performance metric, various powder feeder designs were analyzed. Perturbation frequencies were introduced to the disk feeder design. The quality of the deposit was determined by the surface roughness of …

Numerical Analysis Of Thermal Stress And Deformation In Multi-Layer Laser Metal Deposition Process, Heng Liu

Masters Theses

"Direct metal deposition (DMD) has gained increasing attention in the area of rapid manufacturing and repair. It has demonstrated the ability to produce fully dense metal parts with complex internal structures that could not be achieved by traditional manufacturing methods. However, this process involves extremely high thermal gradients and heating and cooling rates, resulting in residual stresses and distortion, which may greatly affect the product integrity. The purpose of this thesis is to study the features of thermal stress and deformation involved in the DMD process. Utilizing commercial finite element analysis (FEA) software ABAQUS, a 3-D, sequentially coupled, thermo-mechanical model …

Additive Manufacturing Laser Deposition Of Ti-6al-4v For Aerospace Repair Application, Nanda Kumar Dey

Masters Theses

"Parts or products machined from high performance metals are very expensive, partly due to the processing complexities during manufacturing. Therefore, many high performance metal parts users, such as the aerospace industry, mold/die casting industry, heavy machinery consumers etc., extend the service of these damaged parts by employing repair or remanufacturing technology. The research objective is to use laser deposition and machining processes to repair titanium parts.

This thesis discusses a new way of approach for developing a repair process for Ti-6Al-4V for the aerospace industry using Laser Metal Deposition (LMD). The repairs were conducted in a multi-axis hybrid manufacturing systems …

Characterization Of 304l Stainless Steel By Means Of Minimum Input Energy On The Selective Laser Melting Platform, Ben Brown

Masters Theses

"Developing parameter sets for new materials on the Selective Laser Melting (SLM) platform has traditionally been done through the use of single line processing windows and a basic design of experiments (DOE) which would include varying machine parameters to maximize density. This study expands the traditional method by determining the main effects statistically for density, allowing for a more in depth analysis wherein the experimental results are statistically correlated to the variable machine parameters used. With this analysis, parameter optimization with respect to achieving near full density, while also considering build rates, can be performed. New parameters for 304L stainless …

Parameter Optimization For Controlling Aluminum Loss When Laser Depositing Ti-6al-4v, Richard Charles Barclay

Masters Theses

"The ability to predict the mechanical properties of engineering materials is crucial to the manufacturing of advanced products. In the aerospace industry, Ti-6Al-4V is commonly used to build structures. Any deviation from the alloy's standard properties can prove detrimental. Thus, the compositional integrity of the material must be controlled. The ability to directly build and repair large, complicated structures directly from CAD files is highly sought after. Laser Metal Deposition (LMD) technology has the potential to deliver that ability. Before this process can gain widespread acceptance, however, a set of process parameters must be established that yield finished parts of …