Mechanical Engineering Commons^™

Plastic Dissipation Energy In Mixed-Mode Fatigue Crack Growth On Ductile Bimaterial Interfaces, Jeremy S. Daily

Browse all Theses and Dissertations

A new theory of fatigue crack growth in ductile solids has recently been proposed based on the total plastic energy dissipation per cycle ahead of the crack. This and previous energy-based approaches in the literature suggest that the total plastic dissipation per cycle can be closely correlated with fatigue crack growth rates under Mode I loading. The goal of the current study is to extend the dissipated energy approach to steady-state crack growth under mixed-mode loading conditions, with application to cyclic delamination of ductile interfaces in layered materials. The total plastic dissipation per cycle is obtained by 2-D elastic-plastic finite …

Multidimensional, Time-Accurate Cfd Simulation Of Adsorption/Desorption In A Carbon Canister, Xingyan Bai, Kakkattukuzhy M. Isaac, D. Klein, R. Banerjee, J. Edson, W. Breig, L. Oliver

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Computational fluid dynamics simulations of fixed-bed adiabatic adsorption/desorption processes are presented in this paper. Linear driving force model is used for heat and mass transfer rates. a two-dimensional cylindrical canister and three-dimensional automotive production canister geometry are used to study the adsorption/desorption processes of carbon dioxide in helium carrier gas on Norit B4 activated carbon. the two-dimensional results compare well with the results of Hwang et al. [1]. Computational results as breakthrough curve, adsorption amount and temperature profiles are provided. Results show that non-adiabatic model should be used to fully utilize the activated carbon bed capacity prior to breakthrough. Copyright …

Development Of An Aggregation Methodology For Risk Analysis In Aerospace Conceptual Vehicle Design, Trina Marsh Chytka

Engineering Management & Systems Engineering Theses & Dissertations

The growing complexity of technical systems has emphasized a need to gather as much information as possible regarding specific systems of interest in order to make robust, sound decisions about their design and deployment. Acquiring as much data as possible requires the use of empirical statistics, historical information and expert opinion. In much of the aerospace conceptual design environment, the lack of historical information and infeasibility of gathering empirical data relegates the data collection to expert opinion.

The conceptual design of a space vehicle requires input from several disciplines (weights and sizing, operations, trajectory, etc.). In this multidisciplinary environment, the …

Numerical Study Of Two-Dimensional Secondary Injection Into A Mach 3.5 Freestream, Stephen C. Coghill

Mechanical & Aerospace Engineering Theses & Dissertations

Upstream interaction within a dual-mode scramjet engine is investigated numerically. The upstream interaction is investigated by increasing the freestream-to-injector pressure ratio. The constant area duct and sudden expansion geometries are used to achieve these results. Analysis using the symmetry boundary condition is compared to the full boundary condition for the constant area duct. Numerical analysis of the Mach 3.5 freestream is conducted using normal sonic injection of nitrogen gas to create the upstream interaction. Comparisons, where applicable, are made to experimental results. Due to the high speed of the flowfield, oblique shockwaves are present causing numerical convergence difficult to achieve. …

Effect Of Combined Metal-Carbon Additions On The Microstructure And Structure Of Sm2fe17, B. E. Meacham, Jeffrey E. Shield

Department of Mechanical and Materials Engineering: Faculty Publications

The effect of combined alloying additions on the structure and scale of rapidly solidified Sm–Fe alloys was investigated. Transition metal additions tend to promote the formation of the disordered TbCu₇-type structure in Sm₂Fe₁₇ alloys, as determined by monitoring the long-range order parameter. Essentially no order was observed for M = Ti, Zr, V, or Nb. Thus, the structure was close to the prototypical TbCu₇-type structure. With M = Si, a large amount of order was observed (S = 0.62), resulting in a structure closer to the well-ordered Th₂Zn₁₇-type. The …

Recent Advances In Solid Hydrogen Storage Systems, B. S. Chao, R. C. Young, V. Myasnikov, Y. Li, F. Gingl, Patrick D. Ferro, V. Sobolev, S. R. Ovshinsky

Mechanical Engineering Faculty Scholarship

Hydrogen energy offers great promise as an energy alternative. Hydrogen technologies can reduce and eliminate the release of carbon dioxide from fossil-fuel combustion, the main cause of global warming. One of the main challenges is hydrogen storage. Storing hydrogen in the solid-state hydride form holds a volumetric advantage over compressed and liquid hydrogen states. Solid hydrogen storage systems also have features of low-pressure operation, compactness, safety, tailorable delivery pressure, excellent absorption /desorption kinetics, modular design for easy scalability, and long cycle life.

In this paper, solid hydrogen storage systems (such as portable power canisters, lightweight fiber wrapped vessels, and aluminum …

Experimental Investigation Of Cavitation Signatures In An Automotive Torque Converter Using A Microwave Telemetry Technique, Carl L. Anderson, L. Zeng, P. O. Sweger, Amitabh Narain, Jason R. Blough

Department of Mechanical and Aerospace Engineering Publications

A unique experimental investigation of cavitation signatures in an automotive torque converter under stall conditions is reported. A quantitative criterion is proposed for predicting early and advanced cavitation in terms of suitable nondimensional pump speeds. The dimensionless pump speed that marks early cavitation is obtained by relating this parameter to the appearance of charge-pressure–dependent pressure fluctuations in the differential pressure transducer readings. The differential pressure transducers were mounted at well-defined locations in the pump passage of a torque converter. The data were transmitted by a wireless telemetry system mounted on the pump housing. Data were received and processed by a …

Finite Element Analysis And Testing Of An Inkjet Cartridge Die, Dylan Ryan

Theses

This project investigates the application of finite element and experimental analysis in the design and testing of silicon based semiconductor components. In a thermal inkjet printer the ink cartridge contains a print head (or die), the head fires numerous droplets simultaneously to form pixels and letters. The inkjet cartridge die consists of a thin film layer, containing the integrated circuits that make up the thennal inkjets, mounted on a polysilicon substrate structure.

A number of incremental changes to the design and manufacturing processes related to the manufacture of these inkjet cartridge dies is made. In past instances when changes were …

The Transcendental Eigenvalue Problem And Its Application In System Identification, Kumar Vikram Singh

LSU Doctoral Dissertations

An accurate mathematical model is needed to solve direct and inverse problems related to engineering analysis and design. Inverse problems of identifying the physical parameters of a non-uniform continuous system based on the spectral data are still unsolved. Traditional methods, for the system identification purpose, describe the continuous structure by a certain discrete model. In dynamic analysis, finite element or finite difference approximation methods are frequently used and they lead to an algebraic eigenvalue problem. The characteristic equation associated with the algebraic eigenvalue problem is a polynomial. Whereas, the spectral characteristic of a continuous system is represented by certain transcendental …

Indirect Evaporative Cooling Potential In Air-Water Systems In Temperate Climates, Ben Costelloe, Donal Finn

Articles

Recent developments have prompted a review of evaporative cooling technology as an effective means of cooling modern deep plan buildings. Prominent among these developments is the success of high temperature sensible cooling systems, particularly, chilled ceilings, which require a supply of cooling water at 14–18 °C. Crucial to the success of evaporative cooling technology, as a significant means of cooling in modern applications, is the ability to generate cooling water, in an indirect circuit, at a temperature which closely approaches the ambient adiabatic saturation temperature (AST) or wet bulb temperature (WBT). Recent experimental research has demonstrated that it is technically …

The Design And Evaluation Of A Plc-Based Model Predictive Controller For Application In Industrial Food Processes, Bryan T. Griffen

Dissertations and Theses @ UNI

Model Predictive Control (MPC) is a viable control strategy for industrial processes that display relatively large variations in the process variable, have complex process variable interactions, or display a large amount of process deadtime. The objective of using MPC in manufacturing is to reduce overall process variability, the result being an increase in process accuracy, precision and efficiency. This study focused on the implementation of model predictive control techniques on an industrial sugar cooking process. The goal was to implement a successful MPC solution directly on a programmable logic controller (PLC) rather than on a personal computer (PC). Although there …

Air Intake Cooling Motor Vehicle Performance Enhancement, James Brunton, David Kennedy, John D. Kelleher

Articles

This research examined the practical effects of cooling the intake air, on the combustion characteristics of a modern motor vehicle operating under simulated road conditions as well as its subsequent impact on the environment. The cooling effect was achieved by taking a typical air conditioning rig as fitted to a modern motor vehicle and incorporating it into the induction system of the car. The test vehicle used was a 1993 Renault Safrane 2.0Vi standard passenger car that was modified as part of the research to facilitate the extraction of the required test information. A series of tests were conducted using …

Manufacturing And Analysis Of A Liga Heat Exchanger For The Surface Of A Tube: A Cooling Simulation Of The Leading Edge Region Of A Turbine Blade, Christophe Marques

LSU Doctoral Dissertations

Fabricating nickel micro heat exchangers directly on planar or non-planar metal surfaces has been demonstrated using the LIGA micromachining process. These heat exchangers can effectively control the temperature of surfaces in high heat flux applications. Of particular interest is the temperature control of gas turbine engine components. The locations in the gas turbine engine where improved, efficient cooling is required includes gas turbine blades, stator vanes, the turbine disk, and the combustor liner. In this dissertation, the primary application of interest is the use of such heat exchangers to cool airfoils such as turbine blades. In the first part of …

Production Of Fine Nd-Fe-B Alloy Powder By Pulsed Plasma Atomization, Jeffrey E. Shield, S. Christensen, R. W. Kincaid, F. D. Witherspoon

Department of Mechanical and Materials Engineering: Faculty Publications

Extremely fine (<10 >μm) Nd-Fe-B powder was generated by pulsed plasma atomization processing. The number average was just over 3 μm, as determined by computer-assisted scanning electron microscopy analysis of almost 3000 particles. Despite the fine particle size, alloys of stoichiometric Nd₂Fe₁₄B resulted in the properitectic formation of α-Fe, deleteriously affecting the magnetic properties. Nevertheless, this work shows the possibility of generating extremely fine, isotropic powder for bonded and hybrid magnet applications.

Alloy States In Dilute Gaas1-XNX Alloys (X<1%), X. D. Luo, Jinsong Huang, Z. Y. Xu, C. L. Yang, J. Liu, W. K. Ge, Y. Zhang, A. Mascarenhas, H. P. Xin, C. W. Tu

Department of Mechanical and Materials Engineering: Faculty Publications

A set of GaAs_1-xN_x samples with small nitrogen composition (x<1%) were investigated by continuous-wave photoluminescence (PL), pulse-wave excitation PL, and time-resolved PL. In the PL spectra, an extra transition located at the higher-energy side of the commonly reported N-related emissions was observed. By measuring the PL dependence on temperature and excitation power, the PL peak was identified as a transition of alloy band edge-related recombination in GaAsN. The PL dynamics further confirms its intrinsic nature as being associated with the band edge rather than N-related bound states.

Nonlinear H Infinity Missile Longitudinal Autopilot Design With Θ-D Method, Ming Xin, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, a new nonlinear control synthesis technique, the theta- D method, is employed to design a missile longitudinal autopilot. The θ-D technique yields suboptimal solutions to nonlinear optimal control problems in the sense that it provides approximate solution to the Hamilton-Jacobi-Bellman (HJB) equation. Semi-global asymptotic stability can be achieved by manipulating the perturbation terms which are added to the cost function in developing a series solution. Furthermore, this method can be used to provide an approximate closed-form solution to the state dependent Riccati equation. The particular θ-D methodology adopted in this paper is referred to as θ-D H …

Mapping Function To Failure Mode During Component Development, Irem Y. Tumer, Robert B. Stone

Mechanical and Aerospace Engineering Faculty Research & Creative Works

When designing aerospace systems, it is essential to provide crucial failure information for failure prevention. Failure modes and effect types of analyses and prior engineering knowledge and experience are commonly used to determine the potential modes of failures a product might encounter during its lifetime. When new products are being considered and designed, this knowledge and information is expanded upon to help designers extrapolate based on their similarity with existing products and the potential design tradeoffs. in this work, we aim to enhance this process by providing design-aid tools which derive similarities between functionality and failure modes. Specifically, this paper …

Experimental Studies Assessing The Repeatability Of A Functional Modeling Derivation Method, Mark A. Kurfman, Michael E. Stock, Robert B. Stone, Jagan Rajan, Kristin L. Wood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents the results of research attempts to substantiate repeatability and uniqueness claims of a functional model derivation method following a hypothesis generation and testing procedure outlined in design research literature. Three experiments are constructed and carried out with a participant pool that possesses a range of engineering design skill levels. the experiments test the utility of a functional model derivation method to produce repeatable functional models for a given product among different designers. in addition to this, uniqueness of the functional models produced by the participants is examined. Results indicate the method enhances repeatability and leads designers toward …

New Approaches To Gortler And Tollmien-Schlichting Boundary-Layer Instabilities, Vijay Kalburgi

Mechanical & Aerospace Engineering Theses & Dissertations

A detailed understanding of the physical processes that lead to instability and transition in the external viscous boundary layers of airfoils has been the goal of researchers for decades. This study seeks to enhance our understanding of Gortler and Tollmien-Schlichting instabilities through a critical review of prior theoretical methodology and fundamental experiments, the development of dimensionally consistent disturbance equations, and novel interpretation of the resulting flow physics revealed by their solutions to explain the process of transition.

Gortler vortices arise in boundary layers along concave surfaces due to centrifugal effects and these vortices in combination with other instabilities play an …

Comparison Of 3-, 5-, And 6-Phase Machines For Automotive Charging Applications, B. Zhang, Hua Bai, Walter Eversman, Ronald J. Krefta, Duane J. Buening, Steven Pekarek, Gregory R. Holbrook

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, the performance of a 5-phase claw-pole machine/converter system is compared with those of 3-phase and 6-phase systems of the same volume. It is shown that the acoustic output of the 5-phase machine compares favorably with that of the 6-phase machine and is much lower than that of the 3-phase machine over a majority of the operating range. In addition, the output current produced by the 5-phase machine Is, in general, 6-8% higher than those of the 3-phase and 6-phase machines. These results suggest that for maximizing power density while minimizing cost and acoustic noise, 5-phase machines provide …

Approximate Dynamic Programming Based Optimal Neurocontrol Synthesis Of A Chemical Reactor Process Using Proper Orthogonal Decomposition, Radhakant Padhi, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The concept of approximate dynamic programming and adaptive critic neural network based optimal controller is extended in this study to include systems governed by partial differential equations. An optimal controller is synthesized for a dispersion type tubular chemical reactor, which is governed by two coupled nonlinear partial differential equations. It consists of three steps: First, empirical basis functions are designed using the "Proper Orthogonal Decomposition" technique and a low-order lumped parameter system to represent the infinite-dimensional system is obtained by carrying out a Galerkin projection. Second, approximate dynamic programming technique is applied in a discrete time framework, followed by the …

Hierarchical Optimal Control Of A Turning Process - Linearization Approach, Anand Dasgupta, B. Pandurangan, Robert G. Landers, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Machining process control technologies are currently not well integrated into machine tool controllers and, thus, servomechanism dynamics are often ignored when designing and implementing process controllers. In this paper, a hierarchical controller is developed that simultaneously regulates the servomechanism positions and cutting forces in a lathing operation. The force process and servomechanism system are separated into high and low levels, respectively, in the hierarchy. The high level goal is to maintain a constant cutting force to maximize productivity while not violating a spindle power constraint. This goal is systematically propagated to the lower level and combined with the low level …

Proper Orthogonal Decomposition Based Modeling And Experimental Implementation Of A Neurocontroller For A Heat Diffusion System, Prashant Prabhat, S. N. Balakrishnan, Dwight C. Look, Radhakant Padhi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Experimental implementation of a dual neural network based optimal controller for a heat diffusion system is presented. Using the technique of proper orthogonal decomposition (POD), a set of problem-oriented basis functions are designed taking the experimental data as snap shot solutions. Using these basis functions in Galerkin projection, a reduced-order analogous lumped parameter model of the distributed parameter system is developed. This model is then used in an analogous lumped parameter problem. A dual neural network structure called adaptive critics is used to obtain optimal neurocontrollers for this system. In this structure, one set of neural networks captures the relationship …

Proper Orthogonal Decomposition Of Hartmann Wavefront Sensor Data For A Plane Mixing Layer, Peter J. Szyjka

Mechanical Engineering ETDs

The ''snapshot" proper orthogonal decomposition (POD) was used to analyze the turbulent characteristics of a plane mixing layer. A two-dimensional (2-D) Hartmann wavefront sensor measured optical tilt propagation through a flow field downstream of a splitter plate. The velocity difference across the splitter plate produced roller vortices via the Kelvin-Helmholtz instability. Refractive-index fluctuations were produced by slightly heating the flow on the low-speed side of the splitter plate. The Hartmann sensor detects gradients in refractive index (and thus temperature) in directions perpendicular to its direction of propagation. The measured field of two-dimensional tilt (or optical deflection) is proportional to the …

Optimal Feedback Control For Ship Roll Motion Under Sea States, Anusit Anmanatarkul

Mechanical & Aerospace Engineering Theses & Dissertations

The primary influences of ship motion are roll motion. The purpose of this dissertation is to discuss a means to reduce the roll amplitude of ship motion in the case of zero forward speed using the roll mitigation device known as the flume tank, or U-tube, tank. Passive control and active control are studied. Optimal feedback control is the designated algorithm for activated roll mitigation device. The assumed model in this study is a submarine chaser. The linear coupled equation of swaying, rolling, and yawing motion of this assumed model is studied. The roll motion of this vessel is investigated …

Generalized Predictive Control Of Ship Coupling Motions Using Active Flume Tanks, Abdulkarim Mohammed Alotaiwi

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation uses the Generalized Predictive Control (GPC) approach to design a control system for a ship rolling motion coupled with the sway and yaw using an activated flume tank. GPC is a strategy based on system output prediction over finite horizon known as the prediction horizon. GPC controller is designed from the coefficients of the Autoregressive model with exogenous input (ARX) that are computed directly from input and output data. It computes the future control input based on the cost function with weighted input and output. System identification approach is implemented on the system to find the ARX coefficients …

An Air-Filter Sensor For Home-Used Air Conditioners, Cheng Y. Lin, Gary R. Crossman, Alok K. Verma

Engineering Technology Faculty Publications

This paper presents a successful senior project of instrumentation developed in a Mechanical Engineering Technology senior capstone course. Students were encouraged to approach the problem of designing an air-filter sensor and to propose an optimum and practical solution for the problem. Work includes conceptual design and analysis, implementation, tests and modifications. When an air filter is used in a home air conditioner, inhabitants often forget when to replace it until the cooling or heating capacity is obviously reduced. If the filter remains in service, the efficiency of the cooling/heating system will continue decreasing while the electricity bill will significantly increase. …

Advanced Turbulence Modeling For Industrial Flows, Raymond Michael Jones

LSU Doctoral Dissertations

This dissertation deals with the development of an improved two-equation turbulence model and its application to various flows. Six different conventional turbulence models were initially tested for predicting the flow inside of an unbaffled stirred tank reactor (STR), and the results are compared with experimental LDV data. Each of the models use low Reynolds number corrections. Results indicate that the radial velocity component in the impeller discharge region is overpredicted by each of the models. The tangential velocity component in the impeller discharge region is predicted well by the models, but is underpredicted near the shaft. The low Reynolds number …

Large Eddy Simulations Of Complex Turbulent Flows, Mayank Tyagi

LSU Doctoral Dissertations

In this dissertation a solution methodology for complex turbulent flows of industrial interests is developed using a combination of Large Eddy Simulation (LES) and Immersed Boundary Method (IBM) concepts. LES is an intermediate approach to turbulence simulation in which the onus of modeling of “universal” small scales is appropriately transferred to the resolution of “problem-dependent” large scales or eddies. IBM combines the efficiency inherent in using a fixed Cartesian grid to compute the fluid motion, along with the ease of tracking the immersed boundary at a set of moving Lagrangian points. Numerical code developed for this dissertation solves unsteady, filtered …

Design, Development, And Analysis Of A Twin-Fluid Fire Suppression Atomizer And Characterization Of Electrostatically Charged Droplet Sprays, Chad Everett Moore

LSU Master's Theses

A twin-fluid water mist fire suppression atomizer is designed, developed, and analyzed. Of primary interest is the development of a twin-fluid atomizer that produces a large droplet diameter and velocity distribution and also produces a mist with sufficient cone angle to be effective in fire suppression applications. Spray characterization experiments are conducted utilizing Phase Doppler Particle Analysis (PDPA). The effect of atomizer nozzle geometry on internal two-phase flow and resulting spray pattern is investigated. National Fire Protection Association (NFPA) Standard 750 characterization experiments are conducted to verify that the sprays produced by the developed atomizer are classified as a water …