Engineering Commons^™

Comparison Of Additively Manufactured And Wrought 17-4 Ph Stainless Steels In Ultra Low Cycle Fatigue, Timothy Strasser

Graduate Theses and Dissertations

Additive manufacturing (AM) processes allow for creation of complex geometries that are otherwise impractical to fabricate with traditional subtractive methods. AM technology has potential to improve the optimization of seismic lateral force resisting components which dissipate seismic energy through large plastic strains; however, the ultra low-cycle fatigue performance of AM metals are not yet well understood. Void formation during the AM fabrication process has potential to affect performance. This study compares the performance of heat-treated and non-heat-treated AM and wrought 17-4PH stainless steel in Ultra Low Cycle Fatigue. To understand ULCF performance differences between the AM and wrought specimens, post …

Improvement Of Labyrinth Seal Leakage Rates Using Additive Manufacturing, Austin L. Gasbarra

Master's Theses

The growing popularity of additive manufacturing in commercial applications has al- lowed for new ideas and new ways of thinking when designing components. Further optimization at the component level is possible, though powder metallurgy is in its infancy. This study explores the possibility of using additive manufacturing to develop better labyrinth seals in turbomachinery. Labyrinth seals have a torturous fluid path with high losses, thus limiting the amount of fluid leakage. These types of seals can be non-rotating, allowing them to better take advantage of the additive manufacturing process due to the absence of rotating stresses. Labyrinth seal performance is …

Study On The Viability Of Preparing Plaster Molds For Rapid Prototyping Of Complex Ceramic Parts Using The Lost Pla Method, Shelton F. Fowler Iv

Honors College Theses

In the field of metal casting, cast parts often require an internal cavity to be made to meet design requirements. Frequently, these interior surfaces are not manufacturable through standard machining processes, and even when possible, they would most likely involve expensive and time-consuming operations. In order to avoid these machining costs, expendable ceramic or sand cores are manufactured and placed into the mold to allow the direct casting of complex internal geometries. This research seeks to use relatively inexpensive plastic 3D printing technology and the lost PLA casting process for the production of low-cost and rapidly producible ceramic cores. A …

Design, Validation, And Verification Of The Cal Poly Educational Cubesat Kit Structure, Nicholas B. Snyder

Master's Theses

In this thesis, the development of a structure for use in an educational CubeSat kit is explored. The potential uses of this kit include augmenting existing curricula with aspects of hands on learning, developing new ways of training students on proper space systems engineering practices, and overall contributing to academic capacity building at Cal Poly and its collaborators. The design improves on existing CubeSat kit structures by increasing accessibility to internal components by implementing a modular backplane system, as well as adding the ability to be environmentally tested. Manufacturing of the structure is completed with both additive (Fused Deposition Modeling …

Additive Manufacturing And How 3d Printing Is Fighting Covid-19, Raghavan Srinivasan, Ahsan Mian, Joy Gockel, Laura M. Luehrmann

Mechanical and Materials Engineering Faculty Publications

This is the fourth installment in the Shelter in Place (SiP) Lecture series. This installment covers the creative ways that 3D printing has supported efforts to combat the pandemic. It covers the basics of what 3D printing is, some of the various creative projects that have used 3D printing to combat the pandemic, among other topics and questions by the pandemic.

Improvement Of Geometric Quality Inspection And Process Efficiency In Additive Manufacturing, Yu Jin

Graduate Theses and Dissertations

Additive manufacturing (AM) has been known for its ability of producing complex geometries in flexible production environments. In recent decades, it has attracted increasing attention and interest of different industrial sectors. However, there are still some technical challenges hindering the wide application of AM. One major barrier is the limited dimensional accuracy of AM produced parts, especially for industrial sectors such as aerospace and biomedical engineering, where high geometric accuracy is required. Nevertheless, traditional quality inspection techniques might not perform well due to the complexity and flexibility of AM fabricated parts. Another issue, which is brought up from the growing …

Thermal Modeling Of Additive Manufacturing Using Graph Theory: Validation With Directed Energy Deposition, Jordan Severson

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

Metal additive manufacturing (AM/3D printing) offers unparalleled advantages over conventional manufacturing, including greater design freedom and a lower lead time. However, the use of AM parts in safety-critical industries, such as aerospace and biomedical, is limited by the tendency of the process to create flaws that can lead to sudden failure during use. The root cause of flaw formation in metal AM parts, such as porosity and deformation, is linked to the temperature inside the part during the process, called the thermal history. The thermal history is a function of the process parameters and part design.

Consequently, the first step …

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 …

Providing Rational For Further Funding Additive Manufacturing Efforts In The Air Force, Trever J. Braunberger

Theses and Dissertations

Extremely long lead times for legacy aircraft replacement parts often exceed 120 days and cost 3 to 4 times the original price drives a search for alternative manufacturing methods such as additive manufacturing. Currently, the method to procuring a legacy replacement for aircraft such as the C-130 is daunting and at times, impossible. Through a comprehensive knowledge collection of organizational data the Air Force body of knowledge increases and provides actionable data to decision makers which has the potential of dramatically decreasing part wait times and procurement. The proposed, intuitive decision analysis framework mapped out in this research provides relevant …

Correlating In-Situ Monitoring Data With Internal Defects In Laser Powder Bed Fusion Additive Manufacturing, Andrew J. Harvey

Browse all Theses and Dissertations

The presence of defects within laser powder bed fusion (LPBF) parts can lead to reduced mechanical properties and life of components. Because of this, the ability to detect these defects within the parts is critical before the part is subject to its intended loading. Normally the parts are subjected to a quality analysis once they are completed however, this process is typically expensive and time consuming. A solution for these problems is to sense the creation of defects and pores in the parts in-situ, while the part is being fabricated. One proposed method of in-situ monitoring is visible spectroscopy to …

Multi-Wavelength Pyrometry For Emissivity Mapping And Accurate Surface Temperature Measurement In Powder Bed Fusion Systems, Md Moinuddin Shuvo

Open Access Theses & Dissertations

Accurate surface temperature measurement within powder bed fusion (PBF) systems during fabrication remains elusive for many reasons, despite the importance of knowing temperature for improving part quality, process control, repeatability and reproducibility, simulation capabilities, and more. Multi-wavelength (MW) pyrometry has been used previously to measure off-axis temperatures of a small region (~2.6mm in diameter) within an electron beam PBF (EBPBF) system. While this small region measurement makes it difficult to get a full field temperature map of the powder bed, it also allows for inline (on-axis) with laser temperature measurements for laser PBF (LPBF) systems. The MW pyrometry technique determines …

Primary Processing Parameters And Their Influence On Porosity And Fatigue Life Of Additively Manufactured Alloy 718, Luke C. Sheridan

Browse all Theses and Dissertations

In many structural applications void-like defects cause significant performance debits which call for component redesign or post-processing to account for or remove the defects. For laser powder bed fusion (LPBF) processes, it has been shown that many of these features and their size and shape characteristics are controllable through LPBF process parameter manipulation. For design efforts, however, it is necessary to understand the direct influences of processing on the formation of porosity and the role that individual pores and porosity distributions have on the properties and performance of AM components. Additionally, design criteria must be established to facilitate implementation of …

Development Of Recepticals And Joints For Embedded Electronic Components Inserted During Print Via Hybrid Thermoplastic-Based Additive Manufacturing, Leonardo Isaac Gutierrez Sierra

Open Access Theses & Dissertations

The use of hybrid additive manufacturing (AM) systems is a novel approach in the fabrication of multi-functional parts. 3D printed electronics are an example of multi-functional parts fabricated using the Foundry Multi3D System, a hybrid AM system. Previous research has demonstrated the capabilities of the system by manufacturing RF antennas and satellite panels with embedded electronics, to name a few. However, research to identify design clearances and establish a manufacturing process plan had not been performed. The purpose of this manuscript is to determine the correct clearances for foreign components to be inserted unto a partially printed substrate. Besides this …

Mechanical Performance Of Ebm Ti-6al-2sn-4zr-2mo Influenced By The Effects Of Different Hot Isostatic Pressing Treatments, Miguel Lopez

Open Access Theses & Dissertations

Electron Beam Melting (EBM) is an additive manufacturing process that presents a lower level of internal defects in comparison to Selective Laser Melting (SLM). Pairing Hot Isostatic Pressing (HIP) with Additive Manufactured metal parts, sub-surface voids can be eliminated through high pressure and temperature. This significantly improves fatigue life, impact toughness, creep, rupture strength, and tensile ductility. In this investigation, Ti-6Al-2Sn-4Zr-2Mo samples manufactured in the Arcam's Q20 system will be tested as per ASTM E8 Standard Test Methods for Tension Testing of Metallic Materials. Different variants of Hot Isostatic Pressing (HIP) treatments were analyzed and compared. Tensile testing was performed …

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 …

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 …

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 …

Designing New Generations Of Bcc Lattice Structures And Developing Scaling Laws To Predict Compressive Mechanical Characteristics And Geometrical Parameters, Hasanain Abdulhadi

Browse all Theses and Dissertations

Lattice structures (LSs) have been exploited for wide range applications including mechanical, thermal, and biomedical structures because of their unique attributes combining the light weight and relatively high mechanical properties. The first goal of this research is to investigate the effect of strut orientation and length on the compressive mechanical characteristics of body centered cubic (BCC) LS subjected to a quasi-static axial compressive loading using finite element analyses (FEA). In this study, two lattice generations were built and analyzed in commercial finite element (FE) software, ABAQUS/CAE 2016 using “smart procedure”, a meshing technique which was developed for this research to …

Food Printing: Evolving Technologies, Challenges, Opportunities, And Best Adoption Strategies, Sharmin Attarin, Mohsen Attaran

Journal of International Technology and Information Management

3D printing is a process of making three-dimensional objects using additive processes where layers are laid down in succession to create a complete object. Companies across the globe are actively piloting and leveraging the inherent benefits of 3D printing technology. Today, 3D printing can revolutionize food innovation and production through better creativity, customizability, and sustainability. This article highlights 3D printing evolving technologies and trends and identifies its applications and implementation challenges. In this paper, we conducted a literature review to explore 3D printing's current technologies and applications in the food industry, including its advantages, its potential implications, and its obstacles …

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 …

Development Of Lightweight Materials By Meso- And Microstructure Control, Myranda Shea Spratt

Doctoral Dissertations

”In this work, two lightweight structures – lattice structures and metal matrix syntactic foams (MMSF) – were studied. Honeycomb lattices were manufactured by powder bed selective laser melting (SLM) from 304L stainless steel. The wall thicknesses of these structures ranged from 0.2 to 0.5 mm. Surface roughness was the primary cause of dimensional mismatch between the expected and as-built structures with an average wall thickness increase of 0.12 mm. The strength of the honeycombs increased with increasing wall thickness. A feature of the SLM microstructure, the melt pool boundary, was also studied as a part of this work. 3D models …

Development Of A Process For Thermal And Mechanical Modelling Of Screw-Driven Pellets Extrusion, Kaixiang Shi

Master’s Theses

The overall goal of the thesis project is to develop a process for thermal and mechanical modelling of the screw-driven pellets extrusion process, and applying the model results to design extruder temperature and flow rate controllers.

The proposed extruder is designed for metal 3D printing. The device demonstrates great potential in tackling some of the major issues faced by the metal additive manufacturing community. It eliminates the use of metal powder for workplace and workers safety. It is able to produce end-use parts with industrial grade mechanical and microstructural properties. It utilizes low cost metal-loaded polymer pellets as feedstock. However, …

Characterization Of Directed Energy Deposition Additively Manufactured Grcop-42 Alloy, Scott Landes

Electronic Theses and Dissertations

GRCop is an alloy family constructed of copper, chromium, and niobium and was developed by NASA for high heat flux applications. The first of its kind, GRCop-84, was specifically designed for the environments seen by channel cooled main combustion chamber liners. To further increase thermal conductivity while maintaining material strength characteristics, the percentage of alloying elements were cut in half and GRCop- 42 was developed. In recent years, NASA has successfully additively manufactured GRCop with comparable material characteristics to wrought GRCop using a Laser Powder Bed Fusion (L-PBF) process. Benefits of this process include fabrication of intricate cooling channels as …

Sustainability-Based Expert System For Additive Manufacturing And Cnc Machining, Josage Chathura Pamuditha Perera

Graduate Theses, Dissertations, and Problem Reports

The development of technologies which enable resource efficient production is of paramount importance for the continued advancement of the manufacturing industry. In order to ensure a sustainable and clean energy future, manufacturers should be able to contrast and validate existing manufacturing technologies on a sustainability basis. In the post COVID-19 era of enterprise management, the use of artificial intelligence to simulate human expert decision making abilities will open new doors to achieving heightened levels of productivity and efficiency. The introduction of innovative technologies such as CNC machining and 3D printing to production systems has redefined the manufacturing landscape in a …