Mechanical Engineering Commons^™

Shaken Baby Syndrome: Retinal Hemorrhaging. A Biomechanical Approach To Understanding The Mechanism Of Causation, Steven Alex Hans

Mechanical & Aerospace Engineering Theses & Dissertations

Shaken Baby Syndrome (SBS) is a form of abuse where typically an infant, age six months or less, is held and shaken. There may or may not be direct impact associated with this action. Further, there is very little agreement on the actual mechanism of SBS. Clinical studies are limited in showing the exact mechanism of injury and only offer postulations and qualitative descriptions. SBS has received much attention in the media, has resulted in a great deal of litigation and can be the source of unfounded accusations. Therefore, it is necessary to try to quantify the forces that may …

Using Basic Computer Aided Drafting And Design Courses At The Freshman Level To Improve Technology Students Competitiveness In Obtaining Early Academic Career Internships, Anthony Dean, Mustafa Moustafa, Julie Moustafa

Engineering Technology Faculty Publications

Many students have the desire to have internships and part-time employment during their academic careers. Often students in their freshman and sophomore years in four year engineering and technology programs find it difficult to be competitive against more senior students for these positions. This paper discusses how students, in the Mechanical Engineering Technology (MET) program at ________________University, through taking CAD and Solid Modeling courses early in their academic careers are well suited to be competitive in obtaining internships and part time employment. This paper discusses the MET programs first two years’ curriculum and how it prepares the students to enter …

Micro Synthetic Jets As Effective Actuator, Mehti Koklu

Mechanical & Aerospace Engineering Theses & Dissertations

Synthetic jets have previously been studied as actuators for external macroflow control and recently been proposed for internal microflow applications. Despite the wide variety of the potential applications of synthetic jet actuators, the majority of the studies have been done at macro scales. Furthermore, there has not been any design methodology that addresses the effectiveness of the micro synthetic jet actuators. Bearing these needs in mind, a micro synthetic jet configuration is considered in a microscale environment where Kn number is less than 0.1 and more than 0.001. Flowfields are simulated by solving the compressible Navier-Stokes equations. The wall boundary …

Plasma Treatment Of Bulk Nb Surface In The Ar/Cl2 Discharge, M. Rašković, L. Vuskovic, S. Popovic, A.-M. Valente-Feliciano, L. Phillips

Physics Faculty Publications

The preparation of the cavity walls has been one of the major challenges in the superconducting radio-frequency (SRF) accelerator technology. Therefore, constant research and development effort is devoted to develop surface preparation processes that will improve roughness and lower the level of impurities, like hydrogen or oxygen, embedded in bulk Nb, having in the same time reasonable etching rates. Plasma based surface modification provides an excellent opportunity to achieve these goals. We present Ar/Cl₂ discharge treatment of bulk Nb where we achieved etching rates comparable to the rates obtained with the electropolishing method without introducing impurities in Nb. The …

Load Characteristics For An Aluminum Alloy Friction Stir Weld, Lewis T. Henderson

Mechanical & Aerospace Engineering Theses & Dissertations

A process was developed to modify a vintage 1960's milling machine to allow axial load measurements to be taken and to allow automated control of the plunging stage during the friction stir welding process. The installation of a load cell in the housing of the mill machine was accomplished by way of modifying internal machine parts and introducing new external hardware. Successful post removal inspections and operational checks show that the conversion of a vintage 1960's milling machine to allow axial load measurements is feasible. The automation of the plunge process during friction stir welding was proven feasible by the …

A Study Correlating Entropy Generation To Parameters Characterizing Thermal Comfort In A Conditioned Room, Sai Shrinivas Sreedharan

Mechanical & Aerospace Engineering Theses & Dissertations

Although significant advances have been made to analyze and study a room as an open thermodynamic system experiencing indoor airflow and heat exchanges with surroundings, studies incorporating entropy generation in the analysis have been sparse. This study focuses on correlating indoor thermal comfort with entropy generation, which hopefully will result in efficient utilization of energy supplied to the system. The problem that this thesis attempts to solve involves calculation of entropy production in conditioned space and its correlation to parameters that characterize thermal comfort. Thermal comfort in a conditioned space is governed by many thermal, mechanical and psychrometric parameters. The …

Most Probable Point-Based Design Optimization, Akhil R. Tipnis

Mechanical & Aerospace Engineering Theses & Dissertations

Modem products ranging from simple components to complex systems should be designed to be optimal and reliable. The challenge of modem engineering is to ensure that manufacturing costs are reduced and design cycle times are minimized while achieving requirements for performance and reliability. If the market for the product is competitive, improved quality and reliability can generate very strong competitive advantages. Reliability based design optimization plays a very important role in designing almost any kind of product. This investigation focuses on the development of the hybrid PMNRIA approach which uses the active-in-reliability concept for reliability based design optimization. The efficiency …

Unsteady Numerical Analysis Of A 2-Dimensional, Hydrogen Fueled, Air-Breathing Dual Mode Scramjet Engine, Nathan John Luetke

Mechanical & Aerospace Engineering Theses & Dissertations

Upstream interaction in a transient two-dimensional dual-mode scramjet engine is examined. This research is performed to compare completed and verified steady results with unsteady results in order to have a better understanding of the flow field. The flow is solved numerically with a Mach 2.5 free stream and sonic normal injection of hydrogen fuel emanating from facing walls while no symmetry assumptions were made. The free stream is modeled as vitiated air in order to produce comparable flight enthalpies and stagnation properties at the combustor inlet during flight conditions of approximately Mach 7. The vitiated stream consists of water vapor …

Life Cycle Impact Assessment Method For Early Design Phase Of Industrial Products, Harpreet Singh Multani

Mechanical & Aerospace Engineering Theses & Dissertations

The objective of this thesis is to develop a simplified life cycle impact assessment method that can reliably and quickly provide the values of Eco-indicator 99 single score, the Eco-indicator damage categories score (human health, ecosystem quality, resource depletion), environmental impacts like global warming, ozone depletion, acidification, eutrophication, photochemical oxidants potential of the product/process, which could be used in the initial design stages for alternative design comparisons and product improvements, thus leading towards green manufacturing.

To achieve this, a variety of products have been chosen and the life cycle inventory data is gathered from the environmental product declarations that are …

Statistical Interpretation Of Mohr-Coulomb Theory As Applied To Fracture In Brittle Materials Containing Cracks, Mudit J. Monsi

Mechanical & Aerospace Engineering Theses & Dissertations

Fracture in brittle materials containing pre-existing cracks was studied. The probability of of crack growth under both shear and tensile stresses was determined for an arbitrary distribution of crack sizes. Two different crack orientation distributions, random and uniform, as well as friction were also taken into account. The material's reliability was assumed to depend on the number of active cracks at a particular stress level, and this was expressed as an arbitrary 2-parameter Weibull distribution. Two new and efficient methods for calculating crack growth probabilities based on spherical triangles and spherical caps were developed. They utilized normalized stress coordinates and …

Micron-Level Actuator For Thermal-Fluid Control In Microchannels, Nurhak Erbas

Mechanical & Aerospace Engineering Theses & Dissertations

Effectiveness of an actuator is investigated for thermal-flow control in microchannels. First, simulations of a single actuator in a quiescent external medium are performed in order to study the parameters characterizing the synthetic jet flow from the actuator. For this purpose, a simplified, two-dimensional configuration is considered. The membrane motion is modeled in a realistic manner as a moving boundary in order to accurately compute the flow inside the actuator cavity. The geometric and actuation parameters of the actuator are investigated to define the effectiveness of the jet flow. The study is done initially at macro scales. Then, the flow …

Mechanical Properties And Durability Of A Composite Material At Cryogenic Temperatures, Ray Walton Grenoble

Mechanical & Aerospace Engineering Theses & Dissertations

Several issues relevant to the use of a high-performance graphite-epoxy material in hydrogen storage tank applications have been examined. The tensile properties of IM7/977-2 were evaluated as a function of test temperature and thermal-mechanical load history. The temperature dependent coefficient of thermal expansion (CTE) of unidirectional specimens of the same material was measured between -200°C and 0°C. The effects of test temperature, mechanical loading, and damage state on the leak rate of hydrogen gas through IM7/977-2 laminates were evaluated using a novel test system. Finally, the mechanical properties of several commercially available polymer films, which might prove useful as leak-resistant …

Process And Product Optimization Techniques - A Comparative Analysis Using Optimization Of Surface Roughness, Amol Suresh Sonje

Mechanical & Aerospace Engineering Theses & Dissertations

Robust design improves the fundamental function of the product or process considering noise factors in DOE. G. Taguchi has made significant advances in the use of experimental design. Taguchi methods are criticized on the basis of failure to deal with interactions, use of SIN ratio and lack of sequential nature of investigation. Response Surface Methodology deals with designing models that represents response in terms of various factors affecting it. Optimization of surface finish is achieved using both Taguchi Methods and Response Surface Methodology.

Dual response approach is a combination of Taguchi methods and RSM techniques in which primary response is …

Computational Aerodynamics Study Of Ahmed Body Car Model, Rajat Trehan

Mechanical & Aerospace Engineering Theses & Dissertations

Vehicle Aerodynamics has been the focus of study by researchers for centuries. This interest can be owed to increasing demand on fuel efficiency, vehicle top speed and acceleration performance. Interior aerodynamics, such as engine cooling, air conditioning, wind noise, stability, and cross wind sensitivity play key role in customer satisfaction. Hence a complete understanding of flow around the vehicle is prerequisite to achieve any of the above parameters. Aerodynamic development of motor vehicle is expensive. Much capital must be invested in test facilities such as wind tunnels and climate tunnels. The models are costly and at the beginning of a …

Strategy For Product Reusability Based On Technical And Economic Model, Srikanth Uppuluri

Mechanical & Aerospace Engineering Theses & Dissertations

Reusing old components is considered the most profitable End-of-Life strategy in the modern day scenario of sustainable manufacturing. Though there is increasing pressure on the product designers worldwide to make reuse possible, the functionality of the products and the economic feasibility have been the main considerations for manufacturers in evaluating the reuse strategy. The quality level of the used product and mainly the economic aspect of disassembling the product have been the main uncertainties confronting the industries to move towards the product recovery strategies like reuse and disassembly. The profitability factor in designing and implementing the technology for disassembly of …

Passive And Active Nonlinear Control Of Ship Roll Motions Using U-Tube Tanks, Thongchai Phairoh

Mechanical & Aerospace Engineering Theses & Dissertations

A U-tube water tank is first designed to roll a ship floating on still water. The 6-degree of freedom (DOF) dynamic model of U-tube tank is derived and the effects of its parameters on ship roll motion are studied. Numerical simulations show that the U-tube tank is an effective stimulator to roll the ship on still water. For a rolling ship, the U-tube tank can be used as a damper to reduce ship roll motion quickly.

Active control of ship roll motion with a proportional and derivative (PD) controller, linear quadratic regulator (LQR), generalized predictive control (GPC), and deadbeat predictive …

Fixture Design For Load Measurement In Friction Stir Welding, Shekhar S. Kulkarni

Mechanical & Aerospace Engineering Theses & Dissertations

In the Friction Stir Welding Process a vertical force is required for plunging the pin or probe of the tool into the workpiece specimen material, and maintaining contact between the shoulder and the substrate. In addition to the vertical force, Friction Stir Welding Process also involves a horizontal force, which is instrumental for the advancement of the tool as the weld progresses. The essential objective of the thesis was to design, manufacture and test a fixture that can be utilized to measure the vertical force as well as the horizontal force. The designing of the fixture was concerned with various …

Boundary Interference Assessment And Correction For Open Jet Wind Tunnels Using Panel Methods, Wael Ahmed Mokhtar

Mechanical & Aerospace Engineering Theses & Dissertations

The presence of nearby boundaries in a wind tunnel can lead to aerodynamic measurements on a model in the wind tunnel that differ from those that would be made when the boundaries of the moving fluid were infinitely far away. The differences, referred to as boundary interference or wall interference, can be quite large, such as when testing aircraft models developing high lift forces, or whose wingspan is a large fraction of the wind tunnel width, or high drag models whose frontal area is a large fraction of the tunnel cross section. Correction techniques for closed test section (solid walled) …

Unsymmetrical And Symmetrical Sparse Iterative Algorithm With Multiple Right-Hand-Sides Strategies, D. T. Nguyen, A. P. Honrao, G. Hou, O. Akan, O. Baysal

Civil & Environmental Engineering Faculty Publications

Unified unsymmetrical and symmetrical iterative solvers for handling multiple right-hand-side vectors are examined in this work. Efficient computer implementation strategies (to reduce computational time and in-core memory requirements) are proposed. In-core, out-of-core, linear, multiple right hand side (RHS) vectors, non-linear, symmetrical, and unsymmetrical capabilities of the developed software are demonstrated by solving variety of problems selected form different engineering disciplines. Results indicate that the developed algorithm and software is reliable and efficient.

Using Rfid Technology In Collaborative Design Of The Assembly Systems, Stevan Stankovski, Gordana Ostojić, Vukica Jovanović, Branislav Stevanov

Engineering Technology Faculty Publications

Modern production conditions require the application of the concept of distributing production. This approach means coordinative production in a number of small and middle size companies. Multiplex products, consisting of a number of parts, components, and modules are assembled in one function unit in one company, but they may not be manufactured in one place. Huge factory and production complex, which existed in our country, comprised all phases of product lifecycle, from the development of a concept solution to the assembly. Technology of product manufacturing, resource logistics, quality control, product testing and verification of product function characteristics all represented activities …

Rfid Technology Use In Assembly And Disassembly Processes, Gordana Ostojić, Milovan Lazarević, Vukica Jovanović, Stevan Stankovski, Ilija Ćosić

Engineering Technology Faculty Publications

Modern production conditions demand the application of the concept of distributed production. Today companies are specialized for partial technology processes. Hundreds, sometimes even thousands, of collaborative processes depend on workers’ interaction and communication in product assembly and disassembly phases. RFID technologies can be really helpful in identifying objects in terms of sustainable development, regarding disassembly, recycling and reuse. In this paper we presented VCDE system architecture and the realization method of RFID technology as well as the data acquisition using RFID technology during the product lifecycle from the design process, production, assembly, usage, and an special example is given regard- …

Processing And Characterization Of High Performance Structural Nanocomposites, Dennis C. Working

Mechanical & Aerospace Engineering Theses & Dissertations

Carbon nanotubes are considered to be a revolutionary material breakthrough due to their unique combination of properties. While many applications for SWCNTs have been projected, realization of these potential uses have been hampered by the high cost of limited supplies of high quality SWCNTs and the difficulty in the development of a suitable processing method that does not damage the filler thus diminishing the desirable properties of this material. In spite of these technical challenges, their potential to enable the fabrication of multifunctional materials is being investigated in earnest. The goal of this thesis is to investigate the feasibility of …

Robustness And Control Of A Magnetically Levitated Transportation System, Grzegorz Oleszczuk

Mechanical & Aerospace Engineering Theses & Dissertations

Electromagnetic suspension of Magnetic Levitation Vehicles (Maglev) has been studied for many years as an alternative to wheel-on rail transportation systems. In this work, design and implementation of control systems for a Maglev laboratory experiment and a Maglev vehicle under development at Old Dominion University are described. Both plants are modeled and simulated with consideration of issues associated with system non-linearity, structural flexibility and electromagnetic force modeling. Discussion concerning different control strategies, namely centralized and decentralized approaches are compared and contrasted in this work. Different types of electromagnetic non-linearities are considered and described to establish a convenient method for modeling …

Gauss-Hermite Integration For Reliability Calculation And Sensitivity Analysis, Nilesh K. Borade

Mechanical & Aerospace Engineering Theses & Dissertations

In the real world, many applications are subjected to uncertainty. A simple illustration would be a structure like a bridge where magnitude and the speed of the loads acting on it are continuously changing. Therefore it becomes essential to study this stochastic or random nature. The thrust of this research is to develop an efficient reliability and sensitivity technique based on stochastic response surfaces (polynomial chaos expansions) constructed using Gauss-Hermite integration. The focus is on calculating the uncertainty propagation using less number of function evaluations since the stochastic response surface needs to be reconstructed at each design cycle. Using the …

Validation Of Finite Element Beam Models, Pavan R. Madhineni

Mechanical & Aerospace Engineering Theses & Dissertations

Finite Element (FE) methods these days are becoming very popular to predict the responses of structures in industries, such as the aerospace and automobile industries. When there is a new design or modification of an existing design, the product must be tested to fulfill the criterion projected by the industry or external agencies before it can be launched. The product must be checked for each and every aspect, and every minute detail of each of the external forces. Hence, it becomes very important to carry out the model validation on the product.

This thesis describes validation of finite element (FE) …

Shape And Size Sensitivity Analysis Of Geometrically Nonlinear Laminated Composite Plates, Nitin R. Mane

Mechanical & Aerospace Engineering Theses & Dissertations

Since major applications of composite laminates involve large deformation, the nonlinear strain-displacement relation in the Von Karman sense has been incorporated here with the first order shear deformation to study bending analysis of composite laminated panels. The finite element model constructed here is an extension of the MIN3 element which is a displacement based element developed by Hughes and Tessler. The element avoids shear locking in the thin bending regime and achieves computational efficiency. The resultant nonlinear matrix equation is solved for analysis of composite panels by using the Newton-Raphson iterative method. Based upon the nonlinear matrix equation, the shape …

Computational Analysis And Validation Of The Hans Head And Neck Support, Kapil Tyagi

Mechanical & Aerospace Engineering Theses & Dissertations

One of the major causes of racing fatalities is basilar skull fracture from excessive head motions and neck loading in a frontal impact. There are many head/neck restraints available in the market but HANS head and neck support has proved to be the most efficient one in sled testing. This paper evaluates and compares the performance of the HANS device in MAthematical DYnamic MOdel (MADYMO) software with the sled testing. The tests were conducted for the frontal impact motions, with a crash pulse of 45 G's.

The goal of the tests was to evaluate the performance of HANS without the …

Conjugate Gradient Method For Solving System Of Nonlinear Equations, Abhijit Prakash Honrao

Mechanical & Aerospace Engineering Theses & Dissertations

In this thesis, the conjugate gradient method will be extended to solve symmetric and non-symmetric nonlinear equations. Several variations of the conjugate gradient method are introduced and investigated. To extend the conjugate gradient method for nonlinear problems, there are four methods discussed; the pre-conditioning conjugate gradient method, the pre-conditioning conjugate gradient method for better initial guess, the fixed point conjugate gradient method and the fixed point conjugate gradient method for better initial guess. The four methods are discussed in detail and tested on various numerical examples. The linear numerical examples include a two dimensional structural frame problem, a Hilbert matrix …

An Analysis Of A Finite Element Human Brain In Low Speed Rear Impact Automobile Collision Comparison, Model Development And Study Using Tno Rear Impact Dummy, Mangesh S. Kadam

Mechanical & Aerospace Engineering Theses & Dissertations

According to the National Safety Council, rear-end collisions are the most common types of collisions with approximately two and a half million cases reported every year. Crash tests indicate a change of vehicle velocity of 4km/h (2.5 mph) may produce occupant symptoms. Vehicle damage may not occur until 14-15km/h (8.7 mph) (Davis CG, 1998). Occupants, in rear-end vehicle impacts sustain a motion associated with whiplash, where the head snaps backwards quickly, resulting in linear and/or angular acceleration forces acting on the brain. This angular motion tends to subject the brain to shear deformations from rapid rotation. This study is a …

Complexity Measure Of A Product Or Process By Application Of Fuzzy Multi-Attribute Utility Theory, Shrikant Chandrakant Nagpure

Mechanical & Aerospace Engineering Theses & Dissertations

During the early phases of design, the development cost of complex products or systems is very difficult to obtain because of the uncertainties related to their work breakdown structures and the wide choice of manufacturing technologies with no historical data specific to these products. This thesis presents a method to derive a complexity index to capture the non-additive property and inherent uncertainty, i.e. fuzziness, of the technologies that could be used for complex objects. This complexity index can then be used as a cost index for comparing various candidate manufacturing processes.

Macros are written in Microsoft Excel to establish a …