Mechanical Engineering Commons^™

Release Of Large Water Droplets, Jeffrey N. Fonnesbeck

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Water is familiar to all human beings and water droplets are an integral part of our daily lives. From irrigation sprinklers to waterfalls we can observe the formation of water droplets. For most, the droplets are so common and mundane that no thought is given to how the droplets form. Scientists have spent many decades detailing the processes that lead to droplet formation. Current theories and experiments agree quite well for specific cases such as pendant drop formation and jet breakup, but in regards to large volumes of free falling liquid there is very little experimental work to confirm the …

R/C Baja: Drivetrain, Connor T. Donovan

All Undergraduate Projects

The Central Washington University Mechanical Engineering Technology Department hosts an annual R/C Baja competition in which R/C cars fabricated by student teams are put through a series of courses and tests to determine which team's vehicle is best. The goal of this project was to create a functioning drivetrain that conveys power from the battery to the wheels and provides control of the vehicle. A list of requirements for the drivetrain was created to ensure that the vehicle will not only function, but that it will actually succeed in the competition. These requirements included that the vehicle must achieve a …

Development, Classification And Biomedical Applications Of Nano Composite Piezoresponsive Foam, Aaron Jake Merrell

Theses and Dissertations

This dissertation focuses on the development of and applications for Nano-Composite Piezoresponsive Foam (NCPF). This self-sensing foam sensor technology was discovered through research in a sister technology, High Deflection Strain Gauges (HDSG), and was subsequently developed with some of the same base materials. Both technologies use nano and micro conductive additives to provide electrically responsive properties to materials which otherwise are insulative. NCPF sensors differ from HDSGs in that they provide a dual electrical response to dynamic and static loading, which is measured through an internally generated charge, or a change in resistance. This dissertation focuses on the development of …

Heterogeneous Flow Structure And Gas-Solid Transport Of Riser, Jun You

Dissertations

This study aims to understand physical mechanisms of gas-solid transport and riser flow, investigate heterogeneous flow structures of gas-solid transport and their formation mechanism of the in riser flows, both in axial and radial directions. It provides sound interpretation for the experimental observation and valuable suggestion to riser reactor design. Chemical reaction is also coupled with flow hydrodynamics to board the industrial applications. This study mainly focuses on mathematical modeling approach based upon physical mechanism, and endeavor to validate model prediction against available experimental data.

First of all, most important physical mechanisms including inter-particle collision force, gas/solid interfacial force and …

Mitigation Of Impact Vibrations Using Impedance Mismatch In Cylindrical Structures, Sachiko Sueki

UNLV Theses, Dissertations, Professional Papers, and Capstones

The focus of this work is to study the phenomenon of material impedance mismatch to determine its effect on the mitigation of high frequency accelerations in projectile and long bar structures within linear ranges of materials. In this study, the acceleration responses of structures with various materials and material combinations were studied experimentally, numerically and by the Finite Element Analysis (FEA). Air-gun tests conducted by the US Army Research Laboratory were modeled using FEA to simulate the acceleration pulse and shock waves experienced by artillery components during a launch. After the prototype of projectile was selected, further studies were conducted …

The Effect Of Variable Gravity On The Cooling Performance Of A Partially-Confined Fc-72 Spray, Travis Edward Michalak

Browse all Theses and Dissertations

This thesis discusses the effects of a variable-gravity environment on the performance of a subcooled partially-confined spray. An experiment, consisting of a test chamber, the associated flow loops, and instrumentation, was fabricated and flown on the NASA Reduced-Gravity Testing Platform. This modified KC-135 aircraft followed a parabolic flight path to provide various acceleration levels. The spray chamber contained two opposing nozzles spraying onto Thick Film Resistor (TFR) heaters, which were mounted on insulating glass pedestals. Only the upward facing heater was used during this testing. Thermocouples under the heater in the glass pedestal were used to determine the heater surface …

A Compliant Threshold Acceleration Sensor Integrated With Radio Frequency Identifiable Tags, Benjamin L. Todd

Theses and Dissertations

Fully compliant bistable mechanisms have been proposed to be used as threshold accelerometers. The advantages to using these devices are that they require no external power to operate and maintain their sensing state. Using this characteristic the devices can be integrated with passive radio frequency identification tags (RFID). This allows for the sensing package to lay dormant with no maintenance needed until the sensor is read by the RFID reader. This thesis presents a successfully fabricated and integrated threshold accelerometer with a passive RFID tag. This in turn has been successfully read with an RFID reader and shown to act …

Characterizing The Three-Dimensional Behavior Of Bistable Micromechanisms, Brian B. Cherry

Theses and Dissertations

Compliant bistable micromechanisms have been proposed for use in applications such as switches, relays, shutters, and sensing arrays. Unpublished laboratory testing suggests that off-axis forces may affect the bistable nature of fully compliant bistable micromechanisms (FCBMs). The actuation forces required to snap the FCBM from one stable equilibrium position to another can be altered if the off-axis forces are applied to the mechanism during transition between stable positions. Understanding the three-dimensional characteristics of these mechanisms and the effect of eccentric loading conditions would be helpful in design and analysis of FCBMs. Two 3-D FEA models were developed for analysis and …

Settling-Time Improvements In Positioning Machines Subject To Nonlinear Friction Using Adaptive Impulse Control, Tim Hakala

Theses and Dissertations

A new method of adaptive impulse control is developed to precisely and quickly control the position of machine components subject to friction. Friction dominates the forces affecting fine positioning dynamics. Friction can depend on payload, velocity, step size, path, initial position, temperature, and other variables. Control problems such as steady-state error and limit cycles often arise when applying conventional control techniques to the position control problem. Studies in the last few decades have shown that impulsive control can produce repeatable displacements as small as ten nanometers without limit cycles or steady-state error in machines subject to dry sliding friction. These …