Mechanical Engineering Commons^™

New Constant-Force Mechanism Configurations, Bart D. Frischknecht, Dr. Larry L. Howell

Journal of Undergraduate Research

In machine design it is often desirable to correlate output force with displacement. Incorporating a translational spring into the design creates a linear relationship between force and displacement. In contrast, if a constant output force is desired independent of displacement, solutions include pneumatic or hydraulic systems or complicated systems of weights or springs. A simple lightweight mechanical device that exhibits constant-force output over a significant displacement would have the potential of replacing complicated current systems. It could also provide an improved solution for systems where a constant-force output is desirable but has not yet been proven feasible.

Behavior Of Stacked Ortho-Planar Springs In Cvt’S, Marc P. Christenson, Dr. Robert H. Todd

Journal of Undergraduate Research

Compliant mechanisms are mechanical devices that achieve their motion from the deflection of flexible members rather than rigid links and moveable joints. One such mechanism using compliant design is an ortho-planar spring.

Fatigue Testing A Laminated Compliant Clutch, Daniel Brown, Dr. Robert H. Todd

Journal of Undergraduate Research

Compliant mechanisms derive motion from flexible segments, rather than from joints. A BYU student, Nathan Crane, used compliant design concepts to develop a prototype centrifugal clutch.1 Manufacturing considerations led to a design incorporating many layers rather than a single solid piece.2 Further testing verified the engagement RPM and torque capacity of the clutch.3

Nasa Msfc Summer Internship 2013 5.5m Composite Cryotank Sump Door Fabrication, Markus Murdy

Von Braun Symposium Student Posters

No abstract provided.

The Effect Of Pre-Service Turbine Blade Surface Roughness On The Formation Of Deposits, John Pettitt, Dr. Jeffrey P. Bons

Journal of Undergraduate Research

Land based Gas Turbine (GT) engines are used very widely in power generation plants. The performance of the turbine blades greatly influences the engine’s overall efficiency and service life. As turbine engines operate, the life and performance of the blades are degraded by the deposition of material. Deposits can come from dirty fuels or eroded components or from airborne particles in the environment.1 Filters have been created for GT engines in an effort to screen out such particles. When particles are ingested into the GT engine and infiltrate these filters they become molten and stick to the turbine blade surfaces. …

Flexible Residential Test Facility: Impact Of Infiltration And Ventilation On Measured Heating Season Energy And Moisture Levels, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

Perhaps no residential topic has been discussed as much among building scientists as air infiltration and required mechanical ventilation. Usually, envelope tightening is recommended as an efficiency strategy for retrofitting an existing home. In humid climates, reducing infiltration can reduce summer moisture loads. However, during drier weather when the air conditioner is not running, lower infiltration can lead to potential condensation. Even though severe cold weather is rare in the Deep South, the prevalence of single-pane windows can lead to condensation events.

The Development Of Updated And Improved Slw Model Parameters And Its Application To Comprehensive Combustion Predictions, John T. Pearson

Theses and Dissertations

Accurate modeling of radiative heat transfer through combustion gases has received considerable attention in recent years. The spectral line weighted-sum-of-gray-gases (SLW) model was developed based on detailed line-by-line spectral data of gases. A critical element of the SLW model is the absorption line blackbody distribution function (ALBDF). This function was designed to utilize the spectral properties of gases in an efficient and compact manner. However, there are several limitations of the ALBDF in its original form. First, the valid ranges of temperature and pressure are not large enough to include important applications, such as oxy-combustion, where temperatures can exceed 2500 …

Fault Detection And Diagnosis For Air Conditioners And Heat Pumps Based On Virtual Sensors, Woohyun Kim

Open Access Dissertations

The primary goal of this research is to develop and demonstrate an integrated, on-line performance monitoring and diagnostic system with low cost sensors for air conditioning and heat pump equipment. Automated fault detection and diagnostics (FDD) has the potential for improving energy efficiency along with reducing service costs and comfort complaints. To achieve this goal, virtual sensors with low cost measurements and simple models were developed to estimate quantities that would be expensive and or difficult to measure directly.

A virtual refrigerant charge sensor (VRC) was extended with three approaches for determining refrigerant charge for equipment having variable-speed compressors and …

Scalable Autonomous Operations Of Unmanned Assets, Sunghun Jung

Open Access Dissertations

Although there have been great theoretical advances in the region of Unmanned Aerial Vehicle (UAV) autonomy, applications of those theories into real world are still hesitated due to unexpected disturbances. Most of UAVs which are currently used are mainly, strictly speaking, Remotely Piloted Vehicles (RPA) since most works related with the flight control, sensor data analysis, and decision makings are done by human operators. To increase the degree of autonomy, many researches are focused on developing Unmanned Autonomous Aerial Vehicle (UAAV) which can takeoff, fly to the interested area by avoiding unexpected obstacles, perform various missions with decision makings, come …

Semiconductor Nanomaterial Development For Photovoltaic And Thermoelectric Applications, Liangliang Chen

Open Access Dissertations

Today's world is frequently going through fossil energy shortage and environmental consequences brought by the over-emission of greenhouse gas from burning fossil fuels. Therefore, it is urgent now more than ever to discover or develop clean and sustainable power generation approaches. Among various approaches, photovoltaics and thermoelectrics have been more and more attentive both in academia and industry. Photovoltaic power generators can significantly decrease carbon dioxide emission by directly converting sunlight into electricity, and thermoelectric power generators can increase energy use efficiency by recycling waste heat into electricity. This research seeks to gain a better understanding of the mechanism that …

Micro Solar Thermal Energy Development And Use For Mems Power Applications, Emmanuel Ogbonnaya

Doctoral Dissertations

Increasing focus on alternative energy sources has produced significant progress across a wide variety of research areas. One particular area of interest has been solar energy. The sun represents sustainable and renewable energy source capable of meeting present energy needs without compromising the ability of future generations to meet theirs. Energy from the sun can be utilized in multiple ways. Direct rise in modern power generation typically involves either photovoltaic systems or large-scale solar thermal energy installations. While large-scale solar thermal energy generation is well advanced, there has been comparatively little research on smaller scale thermal energy collection and application. …

Hybrid Opto-Electrokinetic Technique For Micro/Nanomanipulation: Towards Application Of A Novel Non-Invasive Manipulation Technique In Microbiological Assay, Jae-Sung Kwon

Open Access Dissertations

This dissertation explores various physical mechanisms of the Rapid Electrokinetic Patterning (REP) technique suggested for rapid and precise on-chip manipulation of colloids and fluids, and bio-compatibility of the technique for biological applications. REP is a hybrid opto-electrokinetic technique that is driven by the simultaneous application of an AC electric field and a heating source. It can not only effectively transport and manipulate a fluid but also concentrate and pattern particles suspended in the fluid through the combined effect of an electrohydrodynamic flow, electrostatic colloidal interactions and an electrothermal microfluidic flow. These capabilities make REP a promising tool which can provide …

Identification And Quantification Of Nonlinear Behavior In A Disbonded Aluminum Honeycomb Panel Using Single Degree-Of-Freedom Models, Eric Richard Dittman

Open Access Dissertations

There is not a complete understanding of how damage mechanisms in composite materials react to nondestructive testing inputs. A deeper understanding of composite damage mechanisms and their responses to external vibratory excitation is sought using nonlinear modeling of damping and stiffness characteristics related to the damage. Different types of damping and stiffness single degree-of-freedom models are presented with analysis of their behavior at specific harmonics of the primary resonance of the system. After an understanding of the approximate behaviors of the models is obtained, experimental tests on a damaged specimen are conducted. An aluminum honeycomb sandwich panel is damaged by …

Formulation To Predict Lower Limb Muscle Forces During Gait, Gil Serrancolí, Jonathan P. Walter, Allison Kinney, A. Barjau, Benjamin J. Fregly, Josep M. Font-Llagunes

Mechanical and Aerospace Engineering Faculty Publications

The human body has more muscles than Degrees of Freedom (DoF), and that leads to indeterminacy in the muscle force calculation. This study proposes the formulation of an optimization problem to estimate the lower-limb muscle forces during a gait cycle of a patient wearing an instrumented knee prosthesis. The originality of that formulation consists of simulating muscle excitations in a physiological way while muscle parameters are calibrated. Two approaches have been considered. In Approach A, measured contact forces are applied to the model and all inverse dynamics loads are matched in order to get a physiological calibration of muscle parameters. …

Bridging The Gap Between Engineering Design And Pk-12 Curriculum Development Through The Use The Stem Education Quality Framework, Margaret Pinnell, James Rowley, Sandi Preiss, Rebecca P. Blust, Rebecca Beach, Suzanne Franco

Mechanical and Aerospace Engineering Faculty Publications

This paper will describe a unique partnership among the Department of Teacher Education and School of Engineering at the University of Dayton (UD) and the Dayton Regional STEM Center (DRSC). This partnership resulted in the development of the STEM Education Quality Framework (SQF), a tool to guide educators in teaching, learning and refining STEM education. The SQF resulted in a variety of educational tools, including a STEM curriculum template, that was implemented in the DRSCs teacher professional development and curriculum development program entitled the STEM Fellow Program. The STEM Fellow program was later modeled in a unique, NSF sponsored six …

A Novel Fluid Structure Interaction And Thermal Model To Predict The Cylinder Block / Valve Plate Interface Performance In Swash Plate Type Axial Piston Machines, Marco Zecchi

Open Access Dissertations

The cylinder block / valve plate interface represents one of the most critical design element in the rotating kit of axial piston machines. The thin film of lubricant between cylinder block and valve plate has to fulfill simultaneously a bearing and a sealing function under dynamic load conditions; on the other hand, it represents an important source of power losses due to viscous friction and leakage flow.

An accurate prediction of the time changing characteristics of the interface, in terms of fluid film thickness, dynamic pressure field, load carrying ability and energy dissipation is necessary to generate more efficient and …

A Dynamic Magnetic Equivalent Circuit Model For Design And Control Of Wound Rotor Synchronous Machines, Xiaoqi Wang

Open Access Dissertations

Recently, a new magnetic equivalent circuit (MEC) model was developed to support automated multi-objective design of wound-rotor synchronous machines (WRSMs). In this research, the MEC model and its application have been enhanced. Initial enhancement has focused on using the MEC model to explore machine design and control as a unified problem. Excitation strategies for optimal steady-state performance have been developed. The optimization is implemented in two phases. First, stator and field excitation at rated power is obtained as part of a WRSM design in which the objectives are to minimize machine mass and loss. Second, a map between current and …

Synthesis Of Graphene Nanomaterials And Their Application In Electrochemical Energy Storage, Guoping Xiong

Open Access Dissertations

The need to store and use energy on diverse scales in a modern technological society necessitates the design of large and small energy systems, among which electrical energy storage systems such as batteries and capacitors have attracted much interest in the past several decades. Supercapacitors, also known as ultracapacitors, or electrochemical capacitors, with fast power delivery and long cycle life are complementing or even replacing batteries in many applications. The rapid development of miniaturized electronic devices has led to a growing need for rechargeable micro-power sources with high performance. Among different sources, electrochemical micro-capacitors or micro-supercapacitors provide higher power density …

Propagation Of Sound In The Vicinity Of Rigid Porous Interfaces, Hongdan Tao

Open Access Dissertations

Propagation of sound in the vicinity of rigid porous interfaces is investigated systematically to facilitate the acoustical characterization of sound absorption materials for noise reduction applications. Various rigid porous interfaces are considered: (1) a semi-infinite porous layer; (2) a porous hard-backed surface; and (3) a porous impedance-backed layer. A closed-form solution and numerical methods are derived with respect to each rigid porous interface condition.

A modified saddle-point method is exploited to investigate the sound field emanating from a monopole source above and below a rigid porous interface. The solutions can be expressed in a form that resembles the classical Weyl-Van …

Mechanisms Of Microstructure Formation Under The Influence Of Ultrasonic Vibrations, Milan Rakita

Open Access Dissertations

Positive effects of ultrasound on crystallization have been known for almost 90 years. Application of ultrasound has been very successful in many industries, most notably in chemistry, creating a new branch of science - sonochemistry. However, ultrasonication has not found wide commercial application in the solidification processing. The reason for that is the complexity of underlying phenomena and the lack of predicting models which correlate processing parameters with the properties of a product. The purpose of this study is to give some contribution toward better understanding of mechanisms that lead to changes in the solidifying microstructure. It has been found …