Mechanical Engineering Commons^™

Insulating Tunneling Contact For Efficient And Stable Perovskite Solar Cells, Jinsong Huang, Xiaopeng Zheng, Qi Wang, Yang Bai, Qingfeng Dong

Department of Mechanical and Materials Engineering: Faculty Publications

Perovskite-based photoactive devices, such as solar cells, include an insulating tunneling layer inserted between the perovskite photoactive material and the electron collection layer to reduce charge recombination and concomitantly provide water resistant properties to the device.

Beyond The Toolpath: Site-Specific Melt Pool Size Control Enables Printing Of Extra-Toolpath Geometry In Laser Wire-Based Directed Energy Deposition, Brian T. Gibson, Bradley S. Richardson, Tayler W. Undermann, Lonnie J. Love

Department of Mechanical and Materials Engineering: Faculty Publications

A variety of techniques have been utilized in metal additive manufacturing (AM) for melt pool size management, including modeling and feed-forward approaches. In a few cases, closed-loop control has been demonstrated. In this research, closed-loop melt pool size control for large-scale, laser wire-based directed energy deposition is demonstrated with a novel modification, i.e., site-specific changes to the controller setpoint were commanded at trigger points, the locations of which were generated by the projection of a secondary geometry onto the primary three-dimensional (3D) printed component geometry. The present work shows that, through this technique, it is possible to print a specific …

Disposable Fluidic Self-Propelling Robot For Traversing A Tubular Passage, Carl Nelson, Benjamin Terry, Abolfazl Pourghodrat, Hossein Dehghani, Dmitry Oleynikov, Prithviraj Dasgupta

Department of Mechanical and Materials Engineering: Faculty Publications

A probe for traversing a tubular passage includes an introducer to be supported at an entrance to the tubular passage. The probe also includes a probe tip to traverse the tubular passage, and a tube with an inflatable tube segment. In some embodiments, the inflatable tube segment is storable in the probe tip. The inflatable tube segment is configured to be inflated to push the probe tip away from the introducer toward an end on the tubular passage. In some embodiments, the probe includes a sealing mechanism, whre the sealing mechanism can be positioned between the inflatable tube segment of …

Mechanical Stresses Associated With Flattening Of Human Femoropopliteal Artery Specimens During Planar Biaxial Testing And Their Effects On The Calculated Physiologic Stress-Stretch State, Majid Jadidi, Anastasia Desyatova, Jason N. Mactaggart, Alexey Kamenskiy

Department of Mechanical and Materials Engineering: Faculty Publications

Planar biaxial testing is commonly used to characterize the mechanical properties of arteries, but stresses associated with specimen flattening during this test are unknown. We quantified flattening effects in human femoropopliteal arteries (FPAs) of different ages, and determined how they affect the calculated arterial physiologic stress-stretch state. Human FPAs from 472 tissue donors (age 12-82 years, mean 53±16 years) were tested using planar biaxial extension, and morphometric and mechanical characteristics were used to assess the flattening effects. Constitutive parameters for the invariant-based model were adjusted to account for specimen flattening, and used to calculate the physiologic stresses, stretches, axial force, …

Correlation Microanalysis Of Localized Molecular Structure And Nano-Mechanical Property Of Pvdf Based Copolymer, Wen Qian, Shuo Sun, Charles Nguyen, Stephen Ducharme, Joesph A. Turner

Department of Mechanical and Materials Engineering: Faculty Publications

Poly (vinylidenefluoride) (PVDF) and its copolymers, are well-recognized electroactive polymers. The PVDF polymer can crystallize in a quasi-hexagonal close-packed “β-phase” structure with the dipoles of all chains aligned with maximum spontaneous polarization [1-3]. Due to the limited availability of quantitative methods for nanoscale molecular structure and mechanical analysis, the polymer organization has not been fully optimized. For such ferroelectric polymers, the influence of nanoscale molecular structure on mechanical response is not well understood. In this paper, we demonstrate nanoscale characterization and measurement techniques, by comprehensive integrating atomic force microscopy (AFM), X-ray diffraction (XRD), nano-infrared (nanoIR) spectroscopy, nanoindentation, chemical nanoIR mapping, …

Mechanical Characterizations Of 3d-Printed Plla/Steel Particle Composites, Hozhabr Mozafari, Pengfei Dong, Haitham Hadidi, Michael P. Sealy, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

The objective of this study is to characterize the micromechanical properties of poly-L-lactic acid (PLLA) composites reinforced by grade 420 stainless steel (SS) particles with a specific focus on the interphase properties. The specimens were manufactured using 3D printing techniques due to its many benefits, including high accuracy, cost effectiveness and customized geometry. The adopted fused filament fabrication resulted in a thin interphase layer with an average thickness of 3 μm. The mechanical properties of each phase, as well as the interphase, were characterized by nanoindentation tests. The effect of matrix degradation, i.e., imperfect bonding, on the elastic modulus of …

Hemodynamic Interference Of Serial Stenoses And Its Impact On Ffr And Ifr Measurements, Siyeong Ju, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

The hemodynamic interference of serial stenoses poses challenges for identifying the functional severity using the fractional flow reserve (FFR) method. The instantaneous wave-free ratio (iFR), i.e., the distal-to-proximal pressure ratio at 75% of diastole, was recently proposed to overcome the disadvantages of the FFR. However, the underlying mechanism remained ambiguous due to the lack of quantitative definition of hemodynamic interference. The objective of this study is to quantitatively define the hemodynamic interference and then examine its role on the FFR and iFR measurements. Pressure distributions, velocity fields, and Q-criterion which identifies vortices, were obtained through the computational fluid dynamics (CFD) …

Hemodynamics And Wall Mechanics After Surgical Repair Of Aortic Arch: Implication For Better Clinical Decisions, Siyeong Ju, Ibrahim Abdullah, Shengmao Lin, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Graft repair of aortic coarctation is commonly used to mimic the physiological aortic arch shape and function. Various graft materials and shapes have been adopted for the surgery. The goal of this work is to quantitatively assess the impact of graft materials and shapes in the hemodynamics and wall mechanics of the restored aortic arch and its correlation with clinical outcomes. A three-dimensional aortic arch model was reconstructed from magnetic resonance images. The fluid–structure interaction (FSI) analysis was performed to characterize the hemodynamics and solid wall mechanics of the repaired aortic arch. Two graft shapes (i.e., a half-moon shape and …

Interface Facilitated Reorientation Of Mg Nanolayers In Mg-Nb Nanolaminates, Y. Chen, Mingyu Gong, N. A. Mara, Jian Wang

Department of Mechanical and Materials Engineering: Faculty Publications

Mg/Nb nanolaminates synthesized through vapor deposition techniques exhibit high flow strength without conventional twinning in Mg. In this work, we investigated the influence of laminated microstructures on deformation mechanisms of Mg nanolayers. Using molecular dynamics simulations, we explored that (0001)-oriented Mg layers transform or re-orient to {10¯10}-oriented Mg layers through nucleation and growth of {10¯12} twins by atomic shuffling, instead of conventional {10¯12} twinning shear. Such a reorientation accommodates in-plane compressive strain and out-of-plane tensile strain when Mg/Nb laminates are subjected to compression parallel to the Mg/Nb interfaces. The nucleation of {10¯12} twins is promoted at the Mg/Nb interface due …

Predictive Peridynamic 3d Models Of Pitting Corrosion In Stainless Steel With Formation Of Lacy Covers, Siavash Jafarzadeh, Florin Bobaru, Ziguang Chen

Department of Mechanical and Materials Engineering: Faculty Publications

In this work, the peridynamic corrosion model is used for 3D simulation of pitting corrosion in stainless steel. Models for passivation and salt layer formation are employed to predict detailed characteristics of pit growth kinetic in stainless steels, such as lacy cover formation on top of the pit, and the diffusion-controlled regime at the pit bottom. The model is validated against an experimentally grown pit on 316L stainless steel in NaCl solution. Lacy covers in this model are formed autonomously during the simulation process. They are remarkably similar to the covers observed on top of the real pits.

Predictive Peridynamic 3d Models Of Pitting Corrosion In Stainless Steel With Formation Of Lacy Covers, Siavash Jafarzadeh, Florin Bobaru, Ziguang Chen

Department of Mechanical and Materials Engineering: Faculty Publications

In this work, the peridynamic corrosion model is used for 3D simulation of pitting corrosion in stainless steel. Models for passivation and salt layer formation are employed to predict detailed characteristics of pit growth kinetic in stainless steels, such as lacy cover formation on top of the pit, and the diffusion-controlled regime at the pit bottom. The model is validated against an experimentally grown pit on 316L stainless steel in NaCl solution. Lacy covers in this model are formed autonomously during the simulation process. They are remarkably similar to the covers observed on top of the real pits.

Energy Efficiency Evaluation Of Blower Heater Non-Purge Compressed Air Dryers, Alexandra M. Botts

Graduate Theses, Dissertations, and Problem Reports (ETD)

There are several compressed air dryers available for industrial use including, refrigerant, desiccant, and membrane. This research focuses on twin tower regenerative closed loop desiccant dryers, specifically: blower heater non-purge (BHNP) with and without cooling water pumps, Compressed-air Heater Purge (CHP), Blower Heater Purge (BHP), and Pressure Swing Heaterless (PSH). These styles of dryers are used mainly in industries that require extremely dry air such as, food manufacturing, medical air, or sensitive technology manufacturers. The research was conducted by collecting and analyzing real time current draw data on air compressors and associated dryers at eight different facilities (13 compressor systems) …

Comparison Of Drag Area Estimation Using Natural Coast Down And Constant Speed Test Methods, Cem Baki Mr

Graduate Theses, Dissertations, and Problem Reports (ETD)

Currently in US, more than 26 percent of the total GHG emissions comes from transportation and mostly from heavy duty vehicles. Similarly, the European Council stated that 25 percent of the emissions comes from heavy duty transportation and they expect it to be further increased in the future. However, with the new coming regulations US EPA and European Council aiming to reduce the emissions by 80 percent in US and 60 percent in EU. In order to keep track and control the emissions, both authorities published new regulations and testing methods for certifying the new vehicles.

Aerodynamic testing is one …

Design Of Experiment And Analysis Techniques For Fuel Consumption Data Using Heavy-Duty Diesel Vehicles And On-Road Testing, Sarah Ann Mills

Graduate Theses, Dissertations, and Problem Reports (ETD)

Chassis dynamometer and on-road testing are usually employed to test vehicle operation. Testing on a chassis dynamometer reduces data variability compared to on-road testing due to the controlled environment but it does not account for other important variables that affects real-world vehicle operation. This study used on-road testing to investigate the differences between two test fuels under real-world conditions. Three heavy-duty diesel vehicles were driven on different routes for a period of three months. Each vehicle was instrumented with flow meters to gather fuel consumption data, which was then compared to the fuel rate broadcasted by the engine control unit …

Evaluating The Approach Of Using Nox Control Performance Tracking For On-Board Diagnostics Of Heavy-Duty Diesel Vehicles, Renata Castiglioni

Graduate Theses, Dissertations, and Problem Reports (ETD)

egulatory agencies have taken several measures to ensure proper regulation of engine exhaust in response to a yearly rise in urban pollution levels. This is due in no small part to vehicular traffic and resulting air pollution from exhaust.

This study evaluates the NOx Control Performance Tracking (NCPT) Onboard Diagnostic (OBD) parameter proposed by the California Air Resources Board (CARB) as a tool to assess in-use heavy-duty vehicle performance. It also assesses the various criteria prescribed in the NCPT approach for applicability to real-world vehicle data.

In order to analyze the data, the study also investigated the effect of various …

Compositional Analysis Of Cerium And Cesium In Rapid Setting Cement As An Immobilization Agent For Nuclear Waste, Riyadh M. Motny

Theses and Dissertations

A feasibility of rapid setting cement (RSC) as an agent of immobilization for certain elements such as fission products or radioactive materials was explored. Cerium (Ce) and cesium (Cs) have been selected as a surrogate for U and/or Pu and fission products, respectively, in this study in three phases. In Phase I, RSC was evaluated for physical properties (e.g., porosity, density, pH values, etc.) using two groups methods—the cement powder at different concentrations of Ce (2 – 10 wt%) with deionized water (DIW) and artificial seawater (ASW). The results showed that the final setting time and compressive strength of RSC …

Differential Mobility Classifiers In The Non-Ideal Assembly, Thamir Alsharifi

Theses and Dissertations

The differential mobility classifier (DMC) is one of the core components in electrical mobility particle sizers for sizing sub-micrometer particles. Designing the DMC requires knowledge of the geometrical and constructional imperfection (or tolerance). Studying the effects of geometrical imperfection on the performance of the DMC is necessary to provide manufacturing tolerance and it helps to predict the performance of geometrically imperfect classifiers, as well as providing a calibration curve for the DMC. This thesis was accomplished via studying the cylindrical classifier and the parallel plate classifier. The numerical model was built using the most recent versions of COMSOL Multiphysics^{® …}

Reduction Of Nox Emissions In A Single Cylinder Diesel Engine Using Sncr With In-Cylinder Injection Of Aqueous Urea, Anthony Timpanaro

UNF Graduate Theses and Dissertations

The subject of this study is the effect of in-cylinder selective non-catalytic reduction (SNCR) of NO_x emissions in diesel exhaust gas by means of direct injection of aqueous urea ((NH₂)₂CO) into the combustion chamber. A single cylinder diesel test engine was modified to accept an electronically controlled secondary common rail injection system to deliver the aqueous urea directly into the cylinder during engine operation.

Direct in-cylinder injection was chosen in order to ensure precise delivery of the reducing agent without the risk of any premature reactions taking place. Unlike direct in-cylinder injection of neat water, …

Virtual Morphology As A Method Of Robotic Control, Conner Todd Castle

Graduate Theses, Dissertations, and Problem Reports (ETD)

This thesis presents Virtual Morphology (VM), a method that explores a different perspective on the design of robot autonomy using inspiration from morphological computing and programmed computation. Morphological computation offers physical solutions that solve complex tasks, like robotic grasping of unknown objects, with relative ease. Unfortunately, these physical solutions are difficult to adjust post-development, and are usually designed to complete only one or a few specific tasks. Programmed computational approaches are more flexible because they can be implemented and adjusted through software, but unfortunately, these approaches can become rather complex as tasks become more difficult. This thesis explores the potential …

Remotely Controlled Industrial Robotic Arm And Simulation Of Automated Thermal Furnace, Prince Mehandi Ratta

Dissertations, Master's Theses and Master's Reports

The right execution of controllers ensures the correct analysis of information, generating efficient results and better optimizing the system. In this report, two controllers were designed. Firstly, a remotely controlled robotic arm, since there are no such type commercially available controllers. Moreover, robotic platforms are costly, so students and researchers are often unable to learn the concepts of programming industrial robots. This project makes a non-destructive, remotely-controlled robotic arm to better teach students and researchers about programming and control of robotic arms. Secondly, simulation of an automated thermal furnace for ArcelorMittal on SIMULINK, which is used for the annealing process …

Design And Development Of Personal Protective Equipment Products To Reduce The Impacts Of Machete Injuries For Indigenous Ngäbe Subsistence Farmers In Bocas Del Toro, Panama, Micah Koller

Dissertations, Master's Theses and Master's Reports

Design and development of personal protective equipment products for workers using machetes (MPPE) is considered in the specific context of indigenous Ngäbe subsistence farmers in a small, rural community in Bocas del Toro, Panama where the author spent two years as a Peace Corps volunteer from 2017-2019. People in this community regularly suffer significant health and economic impacts due to accidents with machetes, which are essential tools in their farm work and daily lives. The history, criticisms, and recent frameworks related to product design and development in resource-poor markets is examined, and specific details of the problem of machete injuries …

Ultraviolet Imager Application For A Cube Satellite, Jason Grillo, Troy Hajjar, Brady Hill

Mechanical Engineering

This document serves as the final design review (FDR) report for the 2018 Cal Poly CubeSat Ultraviolet Imager senior project, sponsored by UC Berkeley Space Sciences Laboratories (SSL). SSL wants to monitor the ionosphere above Earth to gain a better understanding of its properties and particle interactions. Far Ultraviolet (FUV) imaging is a good way to obtain high quality images of the ionosphere and the Earth's auroras, and advancement in optic technologies have made cube satellites (CubeSats) an ideal vessel for a FUV imager, as they are relatively low-cost, lightweight, and can be repeatedly deployed. These CubeSat FUV imagers could …

Furnace System Improvements, Kenji K. Anzai, Ethan Fedor, Patrick Zailaa

Mechanical Engineering

This Final Design Review (FDR) documents the work done by the group to manufacture the system to deliver improvements to the furnace in the Cal Poly microfabrication laboratory (better known as the cleanroom). The document describes the material covered in the Scope of Work (SOW), including background research, customer needfinding, and the problem statement, material associated with concept development and selection for Preliminary Design Review (PDR), material detailing the design and manufacturing plan of the system for Critical Design Review (CDR), and new material detailing the manufacture of the system for FDR.

Research done for the SOW resulted in a …

Reinventing The Wheel, Esther K. Unti, Ahmed Z. Shorab, Patrick B. Kragen, Adam M. Menashe

Mechanical Engineering

Reinventing the Wheel selected tires and designed wheels for the 2018 Cal Poly, San Luis Obispo Formula SAE combustion vehicle. Available tire options were evaluated for steady-state and transient performance as well as vehicle integration. A single-piece composite wheel with hollow spokes was designed to meet stiffness, strength, and tolerance requirements. A detailed study of wheel loading and geometric structural efficiency was performed. Finite element analysis was used to iterate the geometry and laminate. A two-piece male mold was designed and machined to manufacture the wheel. Removable silicone inserts were used to create the hollow spokes.

All-Terrain Storage Surfboard Carts, Ben M. Kennedy, Danny Riedeman, Roberto Gonzalez

Mechanical Engineering

All Terrain Storage consists of three mechanical engineering students: Roberto Gonzalez, Ben Kennedy, and Danny Riedeman. The goal of All Terrain Storage is to design and create two portable storage devices for the non-profit organization AmpSurf. AmpSurf helps veterans, people with disabilities, and anyone else who could be helped through adaptive surfing and other outdoor activities. Their current method of storing and transporting equipment for events is carrying it from the trailer in the parking lot through the sand onto the beach. This document will provide: a more thorough introduction to AmpSurf and the project, the objectives, background information, the …

Daimscale — 1:14th Tractor-Trailer For Testing Driver Assistance Technology, Christopher Marrale, Jase Sasaki, Devin Bodmer

Mechanical Engineering

Active driver assistance systems are becoming increasingly wide-spread throughout the automotive industry due to their potential for safer roads and decreased costs of transportation, but testing these systems on real trucks can be time consuming, dangerous, and costly. Testing these systems on a small-scale tractor-trailer combination will lead to faster and more efficient development of driver assistance systems and can be used by both engineers and students, leading to a larger field of experienced developers to improve these systems.

Our goal will be to design, manufacture, and build a scale 6x2 model of the tractor portion of a Daimler semi-truck …

System And Methods For Ventilation Through A Body Cavity, Mark A. Borden, Benjamin S. Terry

Department of Mechanical and Materials Engineering: Faculty Publications

A system and methods for the delivery of oxygen through a body cavity of a subject using oxygen microbubbles . Through circulation of oxygen microbubbles through the body cavity , oxygen and carbon dioxide exchange may occur . Overall improvement in extending survival rate time during emergency situations caused by pulmonary or similar oxygen - intake restricting injury and / or failure may be achieved through use of the invented system and methods .

Finite Element Failure Analysis Of Lattice Structures, Behzad Bahrami Babamiri, Andrew Minor

Von Braun Symposium Student Posters

No abstract provided.

Liquid Jet Penetration And Breakup In A Free Supersonic Gas Jet, Hansen Jones

LSU Master's Theses

In the testing of today’s rocket engines, both on large scale vertical test stands and smaller subscale horizontal component testing stands, it is extremely important to be able to accurately quantify and mitigate the thermal and acoustic loads the engines will generate on test stand infrastructure. Due to the large number of parameters that must be considered for many cases, development of a multi-phase computational code is under way to properly analyze and design water spray cooling systems used at NASA’s Stennis Space Center (SSC) and across other NASA centers. As such, a small-scale experiment has been conducted at Louisiana …

Hemodynamics And Pathology Of An Enlarging Abdominal Aortic Aneurysm Model In Rabbits, Hongmei Chen, Yonghua Bi, Siyeong Yu, Linxia Gu, Xiaoyan Zhu, Xinwei Han

Department of Mechanical and Materials Engineering: Faculty Publications

Hemodynamics may play an essential role in the initiation and progression of abdominal aortic aneurysm (AAA). We aimed to study the mechanism of self-healing process by the changes of hemodynamics and pathology in an enlarging AAA in rabbits. Seventy-two rabbits were randomly divided into three groups. Rabbits underwent extrinsic coarctation and received a 10-minute elastase incubation in Group A and Group B. Absorbable suture used in Group A was terminated by balloon dilation at week 4. Diameter was measured after 1, 3, 5, and 15 weeks, computational fluid dynamics analysis was performed at week 3 and week 15. Rabbits were …