Engineering Commons^™

Recycled Printer Filament, Charlotte Hyland, Troy D. Molinar

Williams Honors College, Honors Research Projects

The purpose of this research is to examine the effects of recycling PLA filament for 3D printing on its material properties. After examining these effects, PLA and carbon fiber additives were mixed with recycled PLA pellets in different ratios to attempt to regain material properties lost in the recycling process. To complete these findings, an experiment was design and executed.

The research found that tensile strength during multiple iterations of recycling remained mostly unaffected, however, the strain degraded exponentially. In the PLA additive study, high ratios of PLA additive were able to increase the strength and strain properties of the …

The Study Of 3d Micro-Fluid Printing In Aqueous Two-Phase System, Mian Huang

Dissertations and Theses

Aqueous two-phase system (ATPS) is a technology that allows phase separation in an aqueous environment. This technology can be used for the separation, extraction and purification of a variety of biomolecules and thus gained great attention in industry and academia. This thesis is a combination of ATPS, 3D printing, and microfluidics technologies and realizes the printing of biocompatible aqueous structures in another aqueous matrix. The objectives of this thesis include 1) customizing a regular thermal extrusion 3D printer for printing 3D aqueous structures, 2) printing 3D aqueous structure in an aqueous matrix, and 3) studying the stability of the printed …

Application Of Sla 3d Printing For Polymers, Taylor Wilson

Williams Honors College, Honors Research Projects

Stereolithography is a type of 3D printing that allows liquid photopolymer resin to be cured into layers that make up a 3D object. Creation of such resins for these purposes can require a significant amount of time to test and develop, and commercial resins also require some amount of testing for printer settings before use. This paper reviews how stereolithography works, the materials used, and experimentation done to compare the resin properties to the determined curing times. Using several commercially available resins, varying base exposure and layer exposure times were used to determine the lowest possible curing time that gave …

Strategies To Improve Shrinkage Resistance Of Cement-Based Materials For Extrusion-Based 3d Printing, Kavya Vallurupalli

Doctoral Dissertations

"The main objective of this study is to develop new generation of shrinkage-resistant 3D printable mortar mixtures. To this end, the research work was carried out to: i) identify key material and processing parameters that affect printability; ii) investigate the influence of water-to-cement ratio, superplasticizer dosage, and welan gum content on mortar printability; iii) propose a “printability window” where rheological properties and desorptivity can secure successful printing; iv) investigate effect of shrinkage mitigation materials (expansive agent (EA), pre-saturated lightweight sand (LWS), superabsorbent polymers (SAP), and shrinkage reducing admixture) on printability and shrinkage performance of mortar; and v) evaluate the effect …

Thermal And Mechanical Numerical Modeling Of Extrusion-Based 3d Printed Reinforced Polymers For Selecting Manufacturing Process Parameters, Sunil Bhandari

Electronic Theses and Dissertations

Extrusion-based 3D printing of thermoplastic polymer composites manufactures parts that have nonhomogenous, orthotropic, and process-dependent macro-scale material properties. As a part of the dissertation, research works were carried out to: • improve the interlayer mechanical properties and reduce the orthotropy, • use experimentally homogenized orthotropic material properties to numerically model the mechanical behavior of the non-homogenous orthotropic 3D printed parts, • create an efficient numerical thermal model to predict the process-dependent thermal history of the 3D printed part, and • aid the manufacturing process by selecting a suitable set of processing parameters based on a simplified sequentially coupled thermomechanical model. …

Identifying An Optimization Technique For Maker Usage To Address Covid-19 Supply Shortfalls, Michael J. Wilson

Doctoral Dissertations

Fused Deposition Modeling (FDM) can be purchased for under five hundred dollars. The availability of these inexpensive systems has created a large hobbyist (or maker) community. For makers, FDM printing is used numerous uses.

With the onset of the COVID-19 pandemic, the needs for Personal Protective Equipment (PPE) skyrocketed. COVID-19 mitigation strategies such as social distancing, businesses closures, and shipping delays created significant supply shortfalls. The maker community stepped in to fill gaps in PPE supplies.

In the case of 3DP, optimization remains the domain of commercial entities. Optimization is, at best, ad-hoc for makers. With the need to PPE …

Additive Manufacturing Of Soil Using Bio-Cementation, Christina Childress

Graduate Theses and Dissertations

Microbially Induced Calcite Precipitation (MICP) is an emerging soil treatment technique that is proven to increase strength, decrease erosion, reduce liquefaction risk, enhance slope stability, decrease compressibility, decrease swelling potential, and overall create a more competent soil. The benefits and applications of MICP are broad, and this research seeks to broaden them further by developing a single-phase additive manufacturing application with no treatment time delay. This is done by analyzing layering behaviors of five USCS soil classifications (100 % Ottawa sand, sand clay mixtures, and 100% lean clay) which provides insight into process variables such as the solution volume and …

Magnetorheological Cementitious Inks For 4d Printing Of Origami Inspired Auxetic Concrete Elements, Aparna Shashikant Deshmukh

Theses and Dissertations

Existing concrete technology relies on the use of considerable volumes of raw materials, large energy consumption and so associated with severe corresponding environmental impacts. This impact is the driving force for the development of sustainable concrete including a wide range of concrete with supplementary cementitious materials and advanced manufacturing. Recent developments in the field are further inspired by the digital concrete based on 3D printing (3DP) technology which require tailor-made concrete mixtures. The main challenge for 3D printing of concrete is to develop printable ink material, thus this research focuses on characterisation of cementitious materials based on smart materials-materials that …

Materials And Process Design For Ceramic Fused Filament Fabrication (Cf3) Of Hydroxyapatite., Kavish Sudan

Electronic Theses and Dissertations

Ceramic fused filament fabrication (CF3) enables the fabrication of highly customizable ceramic parts at relatively lower costs compared to other AM technologies. Advanced ceramics, having specific or niche applications, call for a high level of accuracy to meet the performance requirements. For achieving the desired level of accuracy in any manufacturing process, it is important to know the effect of involved parameters at different stages of fabrication. CF3 has been around for a while but there has been a severe lack of literature dealing with understanding the effect of process parameters on the final part properties. In this study, Hydroxyapatite …

Characteristics Analysis Of Electrochemical Impedance Spectroscopy (Eis) For Different Electrode Patterns, Shanzida Kabir

Theses and Dissertations

Electrochemical impedance spectroscopy (EIS) is a rapidly developing technique used in characterizing materials and interfaces. Using equivalent circuits as models can determine the electrical properties of heterogeneous systems like membranes or electrolytes. Different electrochemical processes like the electron transfer rate of a specific reaction or the capacitive behavior of the system, or even the diffusion-limited response can coincide. EIS is applicable to determine different electrochemical processes that can happen simultaneously. The purpose of this research is to find the optimal operating range for other AC electrokinetic mechanisms. Analysis of EIS can be helpful in both fundamental examinations of electrokinetic transport …

Exploring Fused Deposition Modeling (Fdm) Three-Dimensional Printing Tablet Design Options For Pharmaceutical Dosage Forms, Guluzar Gorkem Buyukgoz

Dissertations

This dissertation examines the use of Fused Deposition Modeling (FDM) based three-dimensional (3D) printing approach for developing patient-specific dosage forms and addressing related technical challenges in such drug delivery systems. The first main objective is to explore pharmaceutical tablet design options using novel FDM 3D printing technology as the drug delivery platform such that drug form and tablet properties are tailored by considering patient age-specific formulations and dissolution control. Of the five different design options, two proposed options meet the main objective of providing similar drug release, whereas the popular option of fixed drug concentration but differing tablet size could …

3d Printing Technology Applied In Lithium Metal Batteries: From Liquid To Solid., Xuejie Gao

Electronic Thesis and Dissertation Repository

Li-metal batteries are strongly considered to be one of the most promising candidates for high energy density energy storage devices in our modern society. However, the state-of-the-art Limetal batteries are still limited by several challenges including 1) low energy/power density; 2) Li dendrite growth; 3) low coulombic efficiency, and 4) safety concerns within the liquid electrolyte. This thesis mainly focuses on addressing these challenges by using a 3D printing technique to realize high energy/power density Li-metal batteries.

A self-standing high areal energy density cathode for Li-S battery was developed by the 3D printing method in the first part. The optimized …

Highly Integrated And Miniaturized 3d Printed Serial Dilution Microfluidic Devices For Dose-Response Assays, Jose Luis Sanchez Noriega

Theses and Dissertations

The ability to generate a range of concentrations of various solutions rapidly and conveniently is an ongoing need in biotechnology. In this thesis we demonstrate how we took advantage of the full process control afforded by our recent custom high resolution 3D printer and resin advances to realize highly integrated and miniaturized microfluidic components for simultaneous on-chip serial dilution for dose-response assays. With judicious selection of mixed layer thicknesses and pixel-by-pixel dose control, we show that the diameter of 3D printed membrane valves can be reduced from 300 µm to 46 µm. We further introduce an entirely new kind of …

Pseudo-Ductile 3d Printed Fiber Reinforced Polymer Composites, Shreya Vemuganti

Civil Engineering ETDs

The use of fiber-reinforced polymer (FRP) composite materials is continuously growing in civil infrastructure owing to its high strength, low weight, and manufacturing flexibility. However, FRP is characterized by sudden failure and lacks ductility. When used in construction, gradual failure of FRP components is desired to avoid catastrophic structural collapse. Due to its mechanical orthotropy, the behavior of FRP relies significantly on fiber orientation and stacking sequence. In this research proposal, investigations showed that novel multi-angled glass fiber reinforced polymer (GFRP) composites with varying fiber orientation angles, stacking sequence, and thickness of laminas can be designed and fabricated using 3D …

3d Printed Polypyrrole Scaffolds For Ph Dependent Drug Delivery With Applications In Bone Regeneration, Matthew T. Lawrence

Electronic Thesis and Dissertation Repository

Areas of large bone loss are typically healed using autologous bone grafts, seen as the gold standard of care. These materials have a complication rate of 10–40% during harvesting and are limited by the quantity available; therefore the use of 3D printed polymer scaffolds as bone graft alternatives are proposed. Polypyrrole (PPy) is a biocompatible electroactive polymer that has metal-like electrical properties that can be harnessed to hold and release charged drug molecules, triggered by a change in pH. pH fluctuations are seen inside the human body in areas of bone regrowth, which would act as the triggering mechanism for …

Flow Visualization Of Bolus Microcapsule Delivery Through 3d Printed Microneedles, Sophie Quisling, Leana Vestal, Alexis Enstrom

Bioengineering Senior Theses

Microneedle arrays are an emerging technology that offers a novel drug delivery system to treat a variety of skin wounds and diseases. The needles deliver therapeutics to the epidermis layer of the skin and therefore establish advantageous qualities over the standard hypodermic needle as they are non-invasive, efficient in biologic absorption, and can be self-administered. This project investigates a custom 3D-printed hollow microneedle device created by a Santa Clara University Senior Design team in 2018 for microencapsulated cell extrusion to be applied for accelerated wound healing. The goal of our project is to operate in the therapeutic range for flowrate …

Blds Pressure Belt, Hailey Earnest, Sean Casteel, Benjamin Bons, Biren Rama

Mechanical Engineering

Dr. Westphal has a Boundary Layer Data System (BLDS) that is used to take pressure measurements on the surface of the aircraft. Our team has created a design and manufacturing method for producing the corresponding pressure belt that attaches to Dr. Westphal's system to obtain pressure data.

3d Printing Of Hybrid Architectures Via Core-Shell Material Extrusion Additive Manufacturing, Robert Cody Pack

Doctoral Dissertations

Biological materials often employ hybrid architectures, such as the core-shell motif present in porcupine quills and plant stems, to achieve unique properties and performance. Drawing inspiration from these natural materials, a new method to fabricate lightweight and stiff core-shell architected filaments is reported. Specifically, a core-shell printhead conducive to printing highly loaded fiber-filled inks, as well as a new low-density syntactic foam ink, are utilized to 3D-print core-shell architectures consisting of a syntactic epoxy foam core surrounded by a stiff carbon fiber-reinforced epoxy composite shell. Effective printing of test specimens and structures with controlled geometry, composition, and architecture is demonstrated …

3d Printing Of High Viscosity Fluids And Its Application In 3d Printing Of Prosthetic Teeth., Abhilash Aditya

Open Access Theses & Dissertations

The advancement in technology has brought forward non-conventional manufacturing methods that are efficient and advantageous for specific applications. 3D printing is one such outcome, whose applications stretch from biomedical applications to daily products. 3D printing is a rapidly growing technology, and innovative research developments have proven versatility in creating physical objects. Simplification and constant improvement in Fused Deposition Modeling (FDM) operation result from decades of research. However, 3D printing is material-specific and contributes to shortcomings in the technology. The build-material dictates the extrusion parameters, including the material discharge rate and head speed for a continuous flow. Customization being the prime …

3d Printable And Computational Models Of The Bone Marrow Mechanical Environment, Alexander Regner

Boise State University Theses and Dissertations

Aged individuals and astronauts experience bone loss despite rigorous physical activity. Bone mechanoresponse is in part regulated by mesenchymal stem cells (MSCs). We reported that daily low intensity vibration (LIV) restores MSC proliferation in senescence and simulated microgravity models, suggesting reduced mechanical signal delivery to MSCs likely contributes to declining bone mechanoresponse. To this end, we have developed a 3D bone marrow analog which controls trabecular geometry, marrow mechanics and external stimuli.

Finite element (FE) models of hydrogels, representing bone marrow, were generated using instantaneous compression (1000% strain/s, 20% strain) and relaxation experiments (100s) of both gelatin and hyaluronin-based hydrogels. …

Theory And Application Of Dielectric Rod Antennas And Arrays, Gabriel Saffold

USF Tampa Graduate Theses and Dissertations

Dielectric rods have been used for many years as waveguides and radiators. Their low loss as a transmission line and tendency to radiate at discontinuities have proven useful in applications ranging from fiber optic cables to naval fire control radar. Although this technology is well es- tablished, advances in additive manufacturing techniques and associated materials combined with the ubiquity of wireless communications and their shift to higher frequencies have generated re- newed interest in dielectric rods. Dielectric rod antennas have moderate gain and less conductive loss at higher frequencies. Similar to other surface wave antennas, they can achieve broadband performance.This …

Decision Model For Additive Versus Conventional Construction In Remote Locations, Matthew R. Nicholson

Theses and Dissertations

Additive construction is a potential game changing innovative alternative to conventional methods with regards to structural integrity, timeliness, and waste reduction, especially in remote locations. While there have been numerous studies into the material science, additive construction will not be a viable alternative until a cost analysis is performed. This paper details the cost elements for both methods. Breaking down the key variables of material, logistics and transportation, and labor costs garner a better understanding of the cost difference between the two construction methods.

Study Of Recyclable And Repairable Dynamic Covalent Polymers For Sustainable 3d Printing Development, Mingyue Zheng

Electronic Thesis and Dissertation Repository

3D printing technology with valuable features, including cost-saving, easy access, and unlimited structure design, has attracted significant attention and been employed for production use. This technology has also been considered as a sustainable manufacturing method and quickly developed in recent years. However, the development of sustainable 3D printing is still facing challenges, especially in waste management. Thanks to the flexibility of 3D printing and diversified printing mechanisms, the big step forward can be approachable by the transformation from materials. This dissertation presents a variety of strategies designed for sustainable 3D printing development based on the combination of dynamic covalent chemistry …

Metallization Process For 3d Printed Electronics: From I3dp Ii To 3d Co-Printing Technology, Junfeng Xiao

Electronic Thesis and Dissertation Repository

3D printing has emerged as a powerful additive manufacturing technique and becomes as a viable alternative to conventional manufacturing processes in an increasing number of applications. Thus, the development of printable materials also continues to expand, while polymers are still the most utilized materials in 3D printing. There is a great advance for developing polymers with versatile mechanical and chemical properties. However, the end-use products are demanding various functions. It is imperative to develop functional 3D printed polymeric materials to achieve enhanced functionalities.

Usually, one polymer can meet one specific application. This has considerably limited the capability of 3D printing …

Design And Evaluation Of The 3d Printed Electromagnetic Absorber Built With Conductive Carbon-Filled Filament, Rui Mi

Masters Theses

"This research presents an application of the resistive frequency selective surface (FSS) fabricated with a 3D printed conductive material as an electromagnetic absorber for the EMI-reducing door. This solution allows to reduce radiated emissions of a router system. The resistive frequency selective surface has a three-layer structure. The top layer is a 3D printed FSS pattern, the middle layer is an air gap, and the bottom layer is a metal plane.

The first paper presents the methodology for manufacturing a frequency selective surface using the 3D printing technology, including the material characterization, design, fabrication, and evaluation.

The unpublished content presents …

Quantifying Mafenide Release From 3d Printed Phenylalanine-Coumarin Copolyester Scaffolds, Jacob Seeh

Williams Honors College, Honors Research Projects

This project addressed burn wound healing through controlled release of the antibacterial drug mafenide encapsulated by a copolyster into 3D printed scaffolds. Scaffolds were printed at 25^oC and 0.77-1 bar in a cross-hatch pattern with uniform thickness, distance between parallel layers, and diameter then photo-crosslinked. The number of scaffolds available for testing was limited by the amount of polymer that could be synthesized. A high-performance liquid chromatography method was developed specifically for this experiment and used to determine daily release of mafenide from the scaffold into a 2-mL phosphate buffer solution. During the first 24 hours a large …

Development And Application Of A Computational Modeling Scheme For Periodic Lattice Structures, Abdalsalam Fadeel

Browse all Theses and Dissertations

Sandwich structures are widely used for aerospace, marines and other applications due to their light-weight, strength, and strain energy absorption capability. The cores of the sandwich structure are typically fabricated by using high strength cellular materials such as aluminum and titanium alloys, or polymer foams, and honeycombs. Lattice cell structures (LCS) of different configurations such as body centered cubic (BCC), tetrahedron and pyramidal are being investigated as core material due to their design freedom and periodic nature. Due to the recent advent of additive manufacturing (AM), new research is being sought in the areas of designing and developing application-specific LCS …

Development Of Novel Inks And Approaches For Printing Tissues And Organs, Shen Ji

Dissertations

Tissue engineering is a multidisciplinary field that investigates and develops new methods to repair, regenerate and replace damaged tissues and organs, or to develop biomaterial platforms as in vitro models. Tissue engineering approaches require the fabrication of scaffolds using biomaterials or fabrication of living tissues using cells. As the demands of customized, implantable tissue/organs are increasing and becoming more urgent, conventional scaffold fabrication approaches are difficult to meet the requirements, especially for complex large-scale tissue fabrication. In this regard, three-dimensional (3D) printing attracted more interest over the past decades due to its unrivaled ability to fabricate highly customized tissues or …

Leveraging Biomimicry And Additive Manufacturing To Improve Load Transfer In Brittle Materials, Ana Paula Bernardo

Graduate Theses and Dissertations

With the emergence of Additive Manufacturing (i.e., 3D printing) in construction, new strategically designed shapes can be created to improve load transfer through structural members and foundations. Cross-sections can be optimized to carry load using less material, or even using weaker constituent materials, like soils, which are cheap and abundant. The goal of this research is to investigate the benefits of using cellular patterns which leverage biomimicry in civil engineering applications, since nature has perfectly engineered materials and patterns which carry loads with the least amount of material possible. Most of the periodic cellular work to date has focused on …

Multilayered Transmission Lines, Antennas And Phased Arrays With Structurally Integrated Control Electronics Using Additive Manufacturing, Merve Kacar

USF Tampa Graduate Theses and Dissertations

This dissertation presents high-performance transmission lines, antennas, and phased arrays with novel packaging techniques by harnessing design flexibilities of additive manufacturing (AM). AM enables realizing multilayered RF electronics with complex geometrical structures that are not practical using conventional fabrication methods. Design flexibilities offered by AM as customized dielectric shapes/thicknesses, dielectric properties, metallization on conformal surfaces, and structural packaging are harnessed for multilayered RF applications. Although several works demonstrated the viability of AM for antenna realizations, its capability for addressing the needs of wideband, high radiation efficiency antenna systems packaged with active RF circuit components remains relatively unexplored. The first major …