Mechanical Engineering Commons^™

Base Vibration Effects On Additive Manufactured Part Quality: A Study Of 3d Printing Onboard U.S. Navy Ships, Nick Jensen

Dissertations, Master's Theses and Master's Reports

The current landscape of manufacturing is evolving because of technology like additive manufacturing (AM). The mobility and compactness of AM are what make it desirable for many industry sectors. The U.S. Navy has shown interest in deploying AM on ships as it could alleviate their dependency on off-route docking to recharge supplies. However, the U.S. Navy's aspiration is currently hindered due to harsh ship-borne environments that degrade AM part quality.

This thesis focuses on vertical base vibration effects on AM part quality. An introduction is first given in Chapter 1 to familiarize the reader with the U.S. Navy's predicament. The …

Novel New Modeling Procedure For Industrial Machinery With Nonlinear Connections, Steven Whitican

Dissertations, Master's Theses and Master's Reports

Given current timelines for rolling out production at volume, the ability to model portions of the production process is of paramount importance. To model production, high-fidelity models of production assets must be obtained. The production assets are comprised of linear and nonlinear structures. The linear structures are well understood and defined. Significant work has, and is, being done to understand the nonlinear components. This work focuses on developing and correlating a model of a nonlinear component. The component studied and modeled is a linear guide. Linear guides are bearings which facilitate translational motion of machine axes. An accurate model of …

Experimental Evaluation And Simulation Of Torque Transmissibility Frequency Response Functions Of Vibration Isolators And Absorbers For Drivetrain Applications, Luke Jurmu

Dissertations, Master's Theses and Master's Reports

Four studies involving torsional vibration isolation performance of automotive drivetrain components, make up this dissertation. One study features a prototype planetary torsional vibration absorber, a unique device that targets low frequency torsion modes in automotive drivetrains. Two studies feature experiments on several torque converters, clutch locked and open, to validate models of the hardware. The last study details experiments on a centrifugal pendulum absorber in a torque converter, to characterize the viscous friction while submerged in automatic transmission fluid (ATF). The enclosed studies improve the state of the art of drivetrain vibration absorbers and isolators, by introducing a new vibration …

Development Of A Method To Model An Enclosed, Coaxial Carbon Nanotube Speaker With Experimental Validation, Suraj Prabhu

Dissertations, Master's Theses and Master's Reports

Carbon nanotube (CNT) speakers operate on heat as compared to conventional loudspeakers that operate on vibration. CNT speakers are extremely lightweight, stretchable, flexible, and have high operating temperatures. Due to these advantages, CNT speakers are being considered as a viable replacement option for conventional loudspeakers. One such application is automotive exhaust noise control. The goal of this research is to design an enclosed, coaxial CNT speaker and to develop a modeling method to model this speaker using COMSOL Multiphysics.

As part of this research, an enclosed, coaxial CNT speaker was designed and manufactured for automotive exhaust noise control. The first …

Development Of The Carbon Nanotube Thermoacoustic Loudspeaker, Troy Bouman

Dissertations, Master's Theses and Master's Reports

Traditional speakers make sound by attaching a coil to a cone and moving that coil back and forth in a magnetic field (aka moving coil loudspeakers). The physics behind how to generate sound via this velocity boundary condition has largely been unchanged for over a hundred years. Interestingly, around the time moving coil loudspeakers were first investigated the idea of using heat to generate sound was also known. These thermoacoustic speakers heat and cool a thin material at acoustic frequencies to generate the pressure wave (i.e. they use a thermal boundary condition). Unfortunately, when the thermoacoustic principle was initially discovered …

Development Of Autonomous Vehicle Motion Planning And Control Algorithm With D* Planner And Model Predictive Control In A Dynamic Environment, Somnath Mondal

Dissertations, Master's Theses and Master's Reports

The research in this report incorporates the improvement in the autonomous driving capability of self-driving cars in a dynamic environment. Global and local path planning are implemented using the D* path planning algorithm with a combined Cubic B-Spline trajectory generator, which generates an optimal obstacle free trajectory for the vehicle to follow and avoid collision. Model Predictive Control (MPC) is used for the longitudinal and the lateral control of the vehicle. The presented motion planning and control algorithm is tested using Model-In-the-Loop (MIL) method with the help of MATLAB® Driving Scenario Designer and Unreal Engine® Simulator by Epic Games®. Different …

Application Of Carbon Nanotube Thermophones As Duct Noise Cancelling Speakers: Using New Technology With Old Theories, Stephania M. Vaglica

Dissertations, Master's Theses and Master's Reports

Certain materials can produce sound through heat fluctuations. In recent times, the material capable of this was discovered to be Carbon Nanotubes (CNT). The idea is to create a flexible speaker that can be made into any shape or form to create sound. Once a speaker has been created, an active noise control system can be designed to cancel loud sounds in building and pipe ducts. This technology, similar to noise cancelling headphones, allows a user to create a modular system to mitigate noise in everyday life. Thus, the purpose of this research is to illustrate the abilities of a …

Sliding Mode Control Of A Nonlinear Wave Energy Converter Model, Tania Demonte Gonzalez

Dissertations, Master's Theses and Master's Reports

The most accurate wave energy converter models for heaving point absorbers include nonlinearities, which increase as resonance is achieved to maximize energy capture. The efficiency of wave energy converters can be enhanced by employing a control scheme that accounts for these nonlinearities. This project proposes a sliding mode control for a heaving point absorber that includes the nonlinear effects of the Froude-Krylov force. The sliding mode controller tracks a reference velocity that matches the phase of the excitation force to ensure higher energy absorption. This control algorithm is tested in regular linear waves and is compared to a complex-conjugate control …

Defect Detection Using Dynamic Analysis For Additive Manufactured Metals, Gita Deonarain

Dissertations, Master's Theses and Master's Reports

Additive manufacturing (AM) has the ability to produce parts with complex geometries and internal features, however, for demanding applications such as the automotive and aerospace industries, it is crucial that the parts can meet the demanding functional and geometric requirements. Quality control for AM parts focuses on nondestructive methods of testing, but many of the current methods are expensive and time-consuming. The research presented in this report explores various methods of nondestructive evaluation (NDE) using dynamic analysis on stainless steel parts produced with selective laser melting (SLM). Methods include, but are not limited to, frequency response functions (FRF), impedance-based measurements, …