Engineering Commons^™

Digital Design And Thermomechanical Process Simulation For 3d Printing With Abs And Soyhull Fibers Reinforced Abs Composites., Saleh Khanjar

Electronic Theses and Dissertations

Recent demonstrations with fused filament fabrication (FFF) 3D printing have shown to produce prototypes as well as production components. Additionally, due to the FFF process platforms being low-cost and readily available there has been a high-demand to produce on-demand parts for various applications in automotive, in-space manufacturing and electronic industries. However, current limitations such as limited availability of advanced composites materials, and guidelines for design-for-manufacturing make the process prone to trial-and-error experiments both at the materials development, product design and manufacturing stage. In this work, new thermomechanical process simulations platform, Digimat-AM has been evaluated to address and demonstrate digital design …

An Investigation Into Energy-Material Properties Interaction In Additive Manufacturing Of Polymers., Pu Han

Electronic Theses and Dissertations

Additive manufacturing (AM), known as three-dimensional (3D) printing, is a fabrication process to build 3D objects layer by layer based on computer aided design (CAD) model or digital 3D model. Fused filament fabrication (FFF) has become a preferred method for additive manufacturing due to its cost-effectiveness and flexibility. However, the parts built using FFF process suffer from lower mechanical strength compared to that fabricated using traditional method and rough surface finish. With this motivation, this dissertation aims to develop and implement a novel in-process laser assisted technique on FFF to heal the microstructure of FFF built objects by enhancing reptation …

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 …

Additive Manufacturing Using Robotic Manipulators, Fdm, And Aerosol Jet Printers., Alexander Curry

Electronic Theses and Dissertations

Additive manufacturing has created countless new opportunities for fabrication of devices in the past few years. Advances in additive manufacturing continue to change the way that many devices are fabricated by simplifying processes and often lowering cost. Fused deposition modeling (FDM) is the most common form of 3D printing. It is a well-developed process that can print various plastic materials into three-dimensional structures. This technology is used in a lot of industries for rapid prototyping and sometimes small batch manufacturing. It is very inexpensive, and a prototype can be created in a few hours, rather than days. This is useful …

Atomistic Investigation Of Phase Stability And Sodium Ion Conduction In Sulfide Electrolytes., Sabina Zakhidovna Chertmanova

Electronic Theses and Dissertations

In this thesis, we employ a combination of density functional theory (DFT) calculations, and ab initio molecular dynamics (AIMD) simulations to identify the effect of chemical doping on (a) thermodynamic phase stability, and (b) Na-ion conduction in Na₃SbS₄ (NSS) solid-state electrolytes. We found that (a) Se doped electrolytes, namely, Na₃SbS_exS_4-x undergo a tetragonal-to-cubic structural phase transition at x > 3 (Se-rich), and (b) the size, valence, and electronegativity of chemical dopants that substitute Na in Na₃SbS₄ have a cumulative profound impact on Na-ion conductivity. Specifically, substituting Na with higher valence …

Design Of A 300cm2 Pemfc Stack With Force And Cfd Simulation To Optimize Flow Channels, Gasket Design, And Clamping Forces., Robert M. Ench

Electronic Theses and Dissertations

Proton exchange membrane fuel cells are important to the future of green energy as hydrogen can be made with green technologies and store energy for later use. Fuel cells can efficiently convert the hydrogen to electricity as needed. This study uses Solidworks simulation to make design improvements to the fuel cell before the prototype build stage of testing; this saves money and time by reducing the prototype builds needed.

In this study, a multi-channel serpentine design with two outlets versus a single outlet is evaluated using CFD to investigate pressure drop. Lower pressure drops are desirable as less energy input …

Rapid Annealing Of Perovskite Solar Cell Thin Film Materials Through Intense Pulse Light., Amir Hossein Ghahremani

Electronic Theses and Dissertations

Perovskite solar cells (PSCs) have garnered a great attention due to their rapid efficiency improvement using cheap and solution processable materials that can be adapted for scalable high-speed automated manufacturing. Thin film perovskite photovoltaics (PVs) are typically fabricated in an inert environment, such as nitrogen glovebox, through a set of deposition and annealing steps, each playing a significant role on the power conversion efficiency (PCE), reproducibility, and stability of devices. However, atmospheric processing of PSCs would achieve lucrative commercialization. Therefore, it is necessary to utilize materials and methods that enable successful fabrication of efficient PSCs in the ambient environment. The …

Electrical Characterization Of Phytoplankton Suspensions Using Impedance Spectroscopy., Margaret R Jett

Electronic Theses and Dissertations

Phytoplankton are closely monitored because of their important environmental role, and the impacts they have on their local ecosystems. Some phytoplankton respond to stress by producing lipids, which can be harvested for biofuels and other chemicals. Microfluidic devices have been important in improving the portability and throughput of phytoplankton characterization methods, increasing their potential for in situ use. This study utilized a small sample of phytoplankton suspended in a stagnant medium and measured the impedance response using a lab-on-chip and impedance analyzer. The individual cell characteristics were derived from the impedance response of the group. The goal was to characterize …

Image Analysis Of Charged Bimodal Colloidal Systems In Microgravity., Adam J. Cecil

Electronic Theses and Dissertations

Colloids are suspensions of two or more phases and have been topics of research for advanced, tunable materials for decades. Stabilization of colloids is typically attributed to thermodynamic mechanisms; however, recent studies have identified transport or entropic mechanisms that can potentially stabilize a thermodynamically unstable colloidal system. In this study, suspensions of silsesquioxane microparticles and zirconia nanoparticles were dispersed in a nitric acid solution and allowed to aggregate for 8-12 days in microgravity aboard the International Space Station. The suspensions were subsequently imaged periodically at 2.5x magnification. Due to the inadequacy of existing image analysis programs, the python package “Colloidspy” …

Simulation Of Fracture Strength Improvements Of A Human Proximal Femur Using Finite Element Analysis., Waleed Ebraheem Alim

Electronic Theses and Dissertations

The most common hip fracture in the elderly occurs as a result of a fall to the side with impact over the greater trochanter resulting in a fracture of the proximal femur. The fracture usually involves the femoral neck or the intertrochanteric region. It has recently been determined that the fracture crack of a hip fracture typically initiates on the superior-lateral cortex of the femoral neck and then propagates across the femoral neck, resulting in a complete fracture. The strength of the superior-lateral cortex of the femoral neck is likely determined by the combined properties of the generally thin cortex …

Design For Metal Fused Filament Fabrication (Dfmf3) Of Ti-6al-4v Alloy., Mohammad Qasim Shaikh

Electronic Theses and Dissertations

Additive manufacturing (AM) offers unmatchable freedom of design with the ability to manufacture parts from a wide range of materials. The technology of producing three-dimensional parts by adding material layer-by-layer has become relevant in several areas for numerous industries not only for building visual and functional prototypes but also for small and medium series production. Among others, while metal AM technologies have been established as production method, their adoption has been limited by expensive equipment, anisotropy in part properties and safety concerns related to working with loose reactive metal powder. To address this challenge, the dissertation aims at developing the …