Mechanical Engineering Commons^™

Development Of A Virtually Calibrated Projection Moire Interferometry Technique Capable Of Inaccessible Surface Measurements, Mark Lee Kimber

Theses and Dissertations

Optical-based techniques have found merit in measuring displacement and strain for decades. These techniques are commonly used in numerous applications ranging from large displacements in wind tunnel experiments to displacement measurements on the submicron scale. Projection Moiré Interferometry (PMI) is an out-of-plane displacement measurement technique, and consists of capturing reference and deformed images of a grid pattern projected on the test object. By differencing the reference and deformed images of the projected grid pattern, a fringe pattern is generated from which the displacement field can be extracted. This computation requires calibration procedures that analyze a number of fringe patterns from …

Variation Simulation Of Fixtured Assembly Processes For Compliant Structures Using Piecewise-Linear Analysis, Michael L. Stewart

Theses and Dissertations

While variation analysis methods for compliant assemblies are not new, little has been done to include the effects of multi-step, fixtured assembly processes. This thesis introduces a new method to statistically analyze compliant part assembly processes using fixtures. This method, consistent with the FASTA method developed at BYU, yields both a mean and a variant solution. The method, called Piecewise-Linear Elastic Analysis, or PLEA, is developed for predicting the residual stress, deformation and springback variation in compliant assemblies. A comprehensive, step-by-step analysis map is provided. PLEA is validated on a simple, laboratory assembly and a more complex, production assembly. Significant …

The Benefit Of Using Simulation To Improve The Implementation Of Lean Manufacturing Case Study: Quick Changeovers To Allow Level Loading Of The Assembly Line, Jack J. Mcclellan

Theses and Dissertations

In today's competitive manufacturing environment, companies are constantly looking for ways to improve. Because of this, many companies are striving to become "lean" by implementing lean manufacturing, which is a difficult process. To aid in the implementation of lean manufacturing, simulation was used to reduce the trial-and-error period of lean manufacturing and find to optimum approach to implement the lean manufacturing principle. In this research, a case study of implementing level loading of the production schedule for BullFrog International, L.C. will be examined. To make it possible to implement level loading, the thermo-former machine at the beginning of the operations …

A Review Of Setup Practices And Procedures For Creating Ieee 802.11 Wireless Community Networks, Jae M. Theobald

Theses and Dissertations

IEEE 802.11 wireless networking equipment has made it possible to bridge the last mile for new broadband internet service providers. Inexpensive wireless networking equipment and high gain antennas enable high speed internet delivery at a fraction of the cost of installing or upgrading land lines for cable or DSL services. Based on this research, a guide of general practices and procedures is proposed for designing, installing, and maintaining a reliable wireless community area network. Included tests have provided performance results for several types of wireless antennas (including wire grid parabolic dishes, Yagi and Vagi styles, and echo backfire), wireless bridges, …

Numerical Simulations In Electro-Osmotic Flow, Joseph S. Tenny

Theses and Dissertations

The developing flow field in a parallel plate microchannel, induced by wall motion, has been modeled numerically. This type of flow simulates the physical driving mechanism that exists in electro-osmotically generated flow with large channel diameter-to-Debye length ratios (Z). The physics of the flow field were compared between the moving wall model (MWM) and electro-osmotic flow (EOF) at Reynolds numbers of 1 and 1800, and Z > 2500. Also, Z-values between 50 and 500 were studied to investigate the accuracy of the MWM. Results show that for Z-values greater than 100 the MWM shows good agreement with EOF.

The dynamics of …

An Open Architecture For Versatile Machine And Actuator Control, Michael Scott Baxter

Theses and Dissertations

Automatic control technology increases usability, reliability and productivity in manufacturing, transportation, and climate control. There are many additional areas of modern life that could benefit through automatic control; however, current automation components are too expensive or aren't sufficiently flexible. For example, the cost of current commercial motion control components precludes their use in an average home. This thesis describes an automatic control methodology that is low cost and is flexible enough for a wide variety of control applications. Typical applications could include:

- Home lighting, security and appliances

- Commercial building heating, ventilation and air conditioning

- Industrial machine tool …

Electrostatic Radio Frequency (Rf) Microelectromechanical Systems (Mems) Switches With Metal Alloy Electric Contacts, Ronald A. Coutu Jr.

Theses and Dissertations

RF MEMS switches are paramount in importance for improving current and enabling future USAF RF systems. Electrostatic micro-switches are ideal for RF applications because of their superior performance and low power consumption. The primary failure mechanisms for micro-switches with gold contacts are becoming stuck closed and increased contact resistance with increasing switch cycles. This dissertation reports on the design, fabrication, and testing of micro-switches with sputtered bi-metallic (i.e., gold (Au)-on-Au-(6.3at%)platinum (Pt)), binary alloy (i.e., Au-(3.7at%)palladium (Pd) and Au-(6.3at%)Pt), and ternary alloy (i.e., Au-(5at%)Pt-(0.5at%)copper (Cu)) contact metals. Performance was evaluated, in-part, using measured contact resistance and lifetime results. The micro-switches with …

A Tightly-Coupled Ins/Gps Integration Using A Mems Imu, Jonathan M. Neu

Theses and Dissertations

Micro-Electro-Mechanical Systems (MEMS) technology holds great promise for future navigation systems because of the reduced size and cost of MEMS inertial sensors relative to conventional devices. Current MEMS devices are much less accurate than standard inertial sensors, but they can still be useful. In this thesis, data was recorded from an inexpensive MEMS inertial measurement unit and integrated with GPS measurements using a tightly-coupled Kalman filter. The overall goal of this research is to investigate the usefulness of MEMS sensors for a small, real-time, low-cost INS/GPS integration. A golf cart was used to collect dynamic data, along with a commercial …

Fully Compliant Tensural Bistable Mechanisms (Ftbm) With On-Chip Thermal Actuation, Daniel L. Wilcox

Theses and Dissertations

The Fully compliant Tensural Bistable Mechanism (FTBM) class is introduced. The class consists of fully compliant linear bistable mechanisms that achieve much of their displacement and bistable behavior through tension loading of compliant segments. Multiple topologies of designs arising from the FTBM class were designed using a finite element analysis (FEA) model with optimization. In a coupled design approach, thermal actuators were optimized to the force and displacement requirements of the bistable mech-anisms, and selected FTBM devices were combined in switching systems with the result-ing Thermomechanical In-plane Microactuators (TIMs) and Amplified Thermomechanical In-plane Microactuators (ATIMs). Successful on-chip actuation was demonstrated. …

Flexible Machine Tool Control For Direct, In-Process Dimensional Part Inspection, Tyler Addison Davis

Theses and Dissertations

For some time now coordinate measuring machines have been an integral part of the shop floor. The goal has been to make coordinate measuring machines (CMMs) into tools that can easily be used by machinists to improve their manufacturing capabilities. The value of a CMM as a quality control tool is undisputed. Now efforts are being made to further reduce the time and cost of measurement by reducing the physical distance between machining and measuring processes. The ability to reduce that distance to zero and measure a part directly on the chip-making machine has been a goal for many years. …

The Development Of An Accelerated Testing Facility For The Study Of Deposits In Land-Based Gas Turbine Engines, Jared Wilfred Jensen

Theses and Dissertations

Turbine engine efficiency modeling depends on many parameters related to fluid dynamics and heat transfer. Many of these parameters change dynamically once the engine enters service and begins to experience surface degradation. This thesis presents a validation of the design and operation of an accelerated testing facility for the study of foreign deposit layers typical to the operation of land-based gas turbines. It also reports on the use of this facility in an effort to characterize the change in thermal resistance on the surface of turbine blades as deposits accumulate. The facility was designed to produce turbine deposits in a …

Effects Of Friction Stir Processing On The Microstructure And Mechanical Properties Of Fusion Welded 304l Stainless Steel, Colin J. Sterling

Theses and Dissertations

Friction stir processing (FSP) has been utilized to locally process regions of arc weldments in 304L stainless steel to improve the microstructure and mechanical performance. The cast microstructure and coarse delta-ferrite has been replaced with a fine-grained wrought microstructure. Furthermore, twins were introduced throughout the friction stir processed region. Although sub-surface sigma and carbides were introduced during FSP, their presence is not expected to adversely affect the resulting mechanical or corrosion properties of friction stir processed 304L arc welds. The resulting mechanical properties of FS processed weldments were also an improvement over as-welded arc welds. FSP resulted in an increase …

Modeling And Control Of Surface Micromachined Thermal Actuators, Robert K. Messenger

Theses and Dissertations

A model that accurately describes the transient and steady-state response of thermal microactuators is desirable to provide guidance for design and operation. However, modeling the full response of thermal actuators is challenging due to the temperature-dependent material properties and nonlinear deformations that must be included to obtain accurate results. To meet these challenges a three-dimensional multi-physics nonlinear finite-element model was developed using commercial code. The Thermomechanical Inplane Microactuator (TIM) was chosen as a candidate application to validate the model. TIMs were fabricated using the SUMMiT V™ process and their response was measured using a high-speed camera. The TIMs were modeled …

Numerical Modeling Of Friction Stir Welding: A Comparison Of Alegra And Forge3, Alma H. Oliphant

Theses and Dissertations

The objective of this research was to evaluate the capabilities of ALEGRA, a Sandia National Labs hydrocode, and Forge3, a Transvalor S.A. product, to accurately model the Friction Stir Welding Process. ALEGRA and Forge3 are discussed in light of the inherent challenges of modeling Friction Stir Welding, and a rotational boundary condition is added to ALEGRA. Results are presented from Friction Stir Welding modeling outputs from both ALEGRA and Forge3. ALEGRA is shown to be incapable of modeling the Friction Stir Welding process, in large part due to its focus on shock propagation, which causes extremely small time steps. Forge3 …

Coordinated Uav Target Assignment Using Distributed Calculation Of Target-Task Tours, David H. Walker

Theses and Dissertations

This thesis addresses the improvement of cooperative task allocation to vehicles in multiple-vehicle, multiple-target scenarios through the use of more effective preplanned tours. Effective allocation of vehicles to targets requires knowledge of both the team objectives and the contributions that individual vehicles can make toward accomplishing team goals. This is primarily an issue of individual vehicle path planning --- determining the path the vehicles will follow to accomplish individual and team goals. Conventional methods plan optimal point-to-point path segments that often result in lengthy and suboptimal tours because the trajectory neither considers future tasks nor the overall path. However, cooperation …

A Comprehensive Model For Technology Push Product Development, Gregory Loren Bishop

Theses and Dissertations

Successful product development has been a fundamental part of many of today's companies and their continued prosperity depends on continuing to develop new products in the future. There are many models of product development. The two most common classes of development are market pull (MP) and technology push (TP). TP product development differs from MP in that the development begins with a specified technology rather than a specified customer. Because TP development is generally considered more difficult and challenging, most of the product development research has focused on MP development and many researchers and practitioners favor MP development over TP …

The Contextable: Building And Testing An Intelligent, Context-Aware Kitchen Table, Daniel Matthew Hoopes

Theses and Dissertations

The purpose of this thesis was to design and evaluate The ContexTable, a context-aware system built into a kitchen table. After establishing the current status of the field of context-aware systems and the hurdles and problems being faced, a functioning prototype system was designed and built. The prototype makes it possible to explore established, untested theory and novel solutions to problems faced in the field.

High-Torque Capacity Compliant Centrifugal Clutches, Ryan G. Weight

Theses and Dissertations

This thesis developed high-torque-capacity floating opposing arm clutches that are manufactured with standard economical manufacturing processes, while maintaining critical performance characteristics. Contact engagement speed and torque capacity models were created for the Hoffco-Comet, floating-opposing-arm (FOA), and floating 1 (F1) clutches. Sensitivity analyses were performed to identify key design parameters. A robust compliant FOA clutch was designed by minimizing the tolerance for both contact engagement speed and torque capacity. The robust design insures that the clutch will operate within the prescribed application constraints. Additional modeling showed that using a layered clutch would significantly tighten the contact engagement speed and torque performance …

Percolation Paths Of Three-Dimensions In Sensitized Stainless Steel, Alisa Jean Henrie

Theses and Dissertations

The study of three-dimensional percolation paths through materials is important in its contribution to understanding defect sensitive properties of materials. This work shows the importance of grain boundary character in modeling defect sensitive boundaries. Also presented are trends of percolation of sensitized grain boundaries in 304 stainless steel (304SS). Of particular interest is how open paths form in a three-dimensional model created through serial sectioning. Evidence is presented that triple or quadruple points that contain typically two boundaries with special character that intersect the percolation path break up the path. Some grains with no known special qualities (i.e., CSL) have …

Thin Film Encapsulation Of Radio Frequency (Rf) Microelectromechanical Systems (Mems) Switches, Eric D. Marsh

Theses and Dissertations

Microelectromechanical systems (MEMS) radio frequency (RF) switches have been shown to have excellent electrical performance over a wide range of frequencies. However, cost-effective packaging techniques for MEMS switches do not currently exist. This thesis involves the design of RF-optimized encapsulations consisting of dielectric and metal layers, and the creation of a novel thin film encapsulation process to fabricate the encapsulations. The RF performance of several encapsulation designs are evaluated with an analytical model, full wave electromagnetic simulation, and laboratory testing. Performance degradation due to parasitic and reflection losses due to the package is considered, and RF feed-throughs of the transmission …

Demonstrating Optothermal Actuators For An Autonomous Mems Microrobot, Francis R. Szabo

Theses and Dissertations

There are numerous applications for microrobots which are beneficial to the Air Force. However, the microrobotics field is still in its infancy, and will require extensive basic research before these applications can be fielded. The biggest hurdle to be solved, in order to create autonomous microrobots, is generating power for their actuator engines. Most present actuators require orders of magnitude more power than is presently available from micropower sources. To enable smaller microrobots, this research proposed a simplified power concept that eliminates the need for on-board power supplies and control circuitry by using actuators powered wirelessly from the environment. This …

Effects Of Friction Stir Welding On Polymer Microstructure, Seth R. Strand

Theses and Dissertations

This work establishes the relationships between several key Friction Stir Welding process parameters and the resulting microstructural and flexural properties of the welded joint. A series of four single parameter experiments were run. The parameters investigated were pin diameter, feedrate, shoe temperature, and pressure time. Butt welds were made in 6 mm thick stress-relieved extruded polypropylene sheet. Three-point bend tests were used to determine the ultimate flexural strength and coincident strain. The maximum bend angle before failure was used to label the welds as "good or bad." An optical microscope capable of cross polarization was used to examine and photograph …

Evaluation Of The Flail Space Model Utilizing Event Data Recorder Technology, Douglas John Gabauer

Theses and Dissertations

Developed in the early 1980's, the flail space model has become the standard method for estimating occupant risk in full-scale crash tests involving roadside safety features. The widespread availability of airbags and increased seat belt usage rates in today's vehicle fleet, however, raise serious questions regarding the validity of the model. Recent implementation of Event Data Recorder (EDR) technology in a number of late model vehicles presents a different perspective on the assessment of the validity of occupant risk based on the flail space model. EDRs are capable of electronically recording data such as vehicle speed, brake status and throttle …

Establishing A Quantitative Foundation For Exactly Constrained Design, Alisha M. Hammond

Theses and Dissertations

Exactly constrained (EC) design is a robust design method which can be used for mechanical assemblies. It entails using the minimum number of constraints to eliminate all desired motion.

While found by some engineers in industry to have many benefits (including robust assembly, no binding or play, ease of assembly, and the ability to tolerate the wear of parts), EC designs remain somewhat unrecognized by academia. One reason for this minimal exposure may be the lack of a quantitative foundation for such designs. This thesis describes the history and current background for EC designs, and it also begins to develop …

Selecting Appropriate Product Concepts For Manufacture In Developing Countries, Danielle Johnson

Theses and Dissertations

There is a noticeable lack of production of indigenously engineered and manufactured products in Less Developed Countries (LDC's). Few products developed in these LDC's could be viable in competitive markets or even sold as components and supplies to other manufacturers of competitive goods. Assumintg that these less developed countries do not innovate and manufacture because they cannot, the next logical question to ask is why can they not?

This thesis looks at the problems of manufacture and design in LDC's from the standpoint of Product Development. It begins by looking at development theories, namely top down and bottom up and …

Evaluation Of Event Data Recorders In Real World Crashes And Full-Scale Crash Tests, Lewis Thomas Clayton Jr.

Theses and Dissertations

With the advent of advanced safety systems in U.S. passenger vehicles, there has been increased interest shown by automakers in recording crash related parameters that ultimately lead to the deployment of these safety systems in what are known as Event Data Recorders (EDRs). Since the only other record of these parameters, specifically crash pulse, comes from staged crash tests in a controlled environment, the advent of the EDR has become increasingly important to crash researchers. The purpose of this study is to quantify the performance of EDRs in full-scale crash tests and real world crashes.

Comparison of EDRs with staged …

Modeling The Transient Response Of A Thermosyphon, James Kirk Storey

Theses and Dissertations

Thermosyphon transient operation was numerically modeled. The numerical model presented in this work overcame the limitations of previous studies by including transient conduction in the vessel wall, shear stress between the rising vapor and the falling film in the thermosyphon, the influence of the mass in the liquid pool in the evaporator, and by using a more refined and accurate numerical grid. Unique to this model was the accounting for temporal changes in the effective length of the vapor space due to the expanding and contracting of non-condensable gases in the vapor space. The model assumed quasi-steady one-dimensional vapor flow, …

A Closed-Form Dynamic Model Of The Compliant Constant-Force Mechanism Using The Pseudo-Rigid-Body Model, Cameron Boyle

Theses and Dissertations

A mathematical dynamic model is derived for the compliant constant-force mechanism, based on the pseudo-rigid-body model simplification of the device. The compliant constant-force mechanism is a slider mechanism incorporating large-deflection beams, which outputs near-constant-force across the range of its designed deflection. The equation of motion is successfully validated with empirical data from five separate mechanisms, comprising two configurations of compliant constant-force mechanism. The dynamic model is cast in generalized form to represent all possible configurations of compliant constant-force mechanism. Deriving the dynamic equation from the pseudo-rigid-body model is useful because every configuration is represented by the same model, so a …

Predicting Drag Polars For Micro Air Vehicles, Mark Elden Luke

Theses and Dissertations

Drag polars for three Micro Air Vehicles (MAVs) were measured at Reynolds numbers of 70,000, 50,000, 30,000, and 10,000 and compared to predictions generated using the classical approach. The MAVs tested had different configurations and aspect ratios varying from 1.2 to 1.6 and ratios of wetted surface area to planform area from 2.6 to 3.9.

A force balance was used to measure the lift and drag on the MAVs at angles of attack ranging from -5 degrees (or -10 degrees) to 10 degrees. The force balance allowed the MAVs to rotate in the pitching axis. The MAV angle of attack …

School Bus Idling And Mobile Diesel Emissions Testing: Effect Of Fuel Type And Development Of A Mobile Test Cycle, Jason Scott Hearne

Theses and Dissertations

The New Jersey Department of Transportation (NJDOT) is currently sponsoring a research study at Rowan University to develop strategies for reducing diesel emissions from mobile sources such as school buses and class 8 trucks (classified as a heavy-duty truck of more than 33,000 lbs.). This thesis presents the results of an investigation performed to measure school bus idle emissions in a controlled environmental chamber. This thesis also presents the results of mobile school bus testing that has been performed to quantify the emission reduction capabilities of various alternative fuels, such as biodiesel, ultra low sulfur diesel, and a blend of …