Mechanical Engineering Commons^™

Setpoint Tracking Predictive Control In Chemical Processes Based On System Identification, Sinchai Chinvorarat

Mechanical & Aerospace Engineering Theses & Dissertations

A Kraft recovery boiler in a pulp-paper mill provides a means for recovery of the heat energy in spent liquor and recovery of inorganic chemicals while controlling emissions. These processes are carried out in a combined chemical recovery unit and steam boiler that is fired with concentrated black liquor and which produces molten smelt. Since the recovery boiler is considered to be an essential part of the pulp-paper mill in terms of energy resources, the performance of the recovery boiler has to be controlled to achieve the highest efficiency under unexpected disturbances.

This dissertation presents a new approach for combining …

A New Reflection Free Boundary In Uniform Flow Using Mapped Infinite Wave Envelope Elements, Walter Eversman, Indranil Danda Roy

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Variable order mapped infinite wave envelope elements are developed for finite element modeling of acoustic radiation in a uniformly moving medium. These elements can be used outside of the near field as a non-reflecting boundary condition for computations on an infinite domain in which a radiating body is immersed in a moving medium. Mapped infinite wave envelope elements provide a boundary condition equivalent to stiffness, mass, and damping matrices appended to the inner mesh. A demonstration of the characteristics of the mapped infinite wave envelope elements is given in the context of acoustic radiation from a turbofan inlet for which …

Design, Optimization, And The Prototyping Of A Small Tuning-Fork Ultrasonic Piezoelectric Linear Motor, Daniel S. Stutts, James R. Friend

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The design, optimization, and properties of a prototype small traveling-wave ultrasonic piezoelectric linear motor design are described. A method for optimizing the geometry of the motor to maximize its mechanical output for a given electrical input is described, as is the inherent properties of the design to maximize the motors durability and utilization of the piezoelectric material. Results from testing the motor demonstrate the design and indicate a maximum speed of 2.5 cm/s with a preload of 16 g due to an applied voltage of 80 V/RMS/ at an applied current of 15 mA.

Adaptive Critic Based Neural Networks For Control-Constrained Agile Missile Control, Dongchen Han, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We investigate the use of an `adaptive critic' based controller to steer an agile missile with a constraint on the angle of attack from various initial Mach numbers to a given final Mach number in minimum time while completely reversing its flightpath angle. We use neural networks with a two-network structure called `adaptive critic' to carry out the optimization process. This structure obtains an optimal controller through solving Hamiltonian equations. This approach needs no external training; each network along with the optimality equations generates the output for the other network. When the outputs are mutually consistent, the controller output is …

Environmental Performance Analysis Of Solid Freedom Fabrication Processes, Yanchun Luo, Zhiming Ji, Ming-Chuan Leu, R. J. Caudill

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a method for analyzing the environmental performance of solid freeform fabrication (SFF) processes. In this method, each process is divided into life phases. Environmental effects of every process phase are then analyzed and evaluated based on the environmental and resource management data. These effects are combined to obtain the environmental performance of the process. The analysis of the environmental performance of SFF processes considers the characteristics of SFF technology, includes material, energy consumption, processes wastes, and disposal. Case studies for three typical SFF processes: stereolithography (SL); selective laser sintering (SLS); and fused deposition modeling (FDM) are presented …

Computational Modeling Of Airborne Noise Demonstrated Via Benchmarks, Supersonic Jet, And Railway Barrier, Moumen Idres

Mechanical & Aerospace Engineering Theses & Dissertations

In the last several years, there has been a growing demand for mobility to cope with the increasing population. All kinds of transportation have responded to this demand by expanding their networks and introducing new ideas. Rail transportation introduced the idea of high-speed trains and air transportation introduced the idea of high-speed civil transport (HSCT). In this expanding world, the noise legislation is felt to inhibit these plans. Accurate computational methods for noise prediction are in great demand.

In the current research, two computational methods are developed to predict noise propagation in air. The first method is based on the …

Skin-Stiffener Separation In Buckled Composite Plates And Shallow Shells, Mark Edward Robeson

Mechanical & Aerospace Engineering Theses & Dissertations

The development of an approximate analysis for predicting stresses in the skin-stiffener interface region of composite plates and shallow shells is presented. The analysis determines interlaminar normal stress and transverse shear stresses in the direction of the stiffener axial coordinate and the direction of the inplane coordinate perpendicular to the stiffener axis. The analysis accounts for skin-stiffener interfaces with nonzero thickness and for curvature in the skin and stiffener. The interlaminar normal stress and transverse shear stresses at the interface are applied to the lower face of the skin and the upper face of the stiffener flange as unknown functions, …

Design Optimization Of Magnetic Bearings And Magnetic Suspension Systems, V. Dale Bloodgood Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

Magnetic suspension systems were first demonstrated as practical by Holmes and Beams in the 1930's. Since then, numerous academic researchers have worked with various types of these systems. Commercial applications have largely been limited to magnetic bearings for rotating machinery. Other applications that have held considerable promise include wind tunnel model suspensions, space payload pointing and vibration isolation systems, satellite momentum storage and control devices and electromagnetic launch systems. However, none of these have progressed significantly beyond the prototype stage. Maglev trains have not reached serious commercial service but are being aggressively developed in Germany and Japan.

Design methods for …

Electro-Mechanical Fatigue Behavior Of A Quasi-Isotropic Laminate With An Embedded Piezoelectric Actuator, Tse Lin Hsu

Theses and Dissertations

This study primarily investigated the electro-mechanical fatigue behavior of the embedded piezoelectric actuators in graphite/epoxy laminate with a lay-up of 0 | ± 45 | 90s. A secondary focus was the investigation of the mechanical fatigue effects of the 0 | 0 | ± 45 | 0 | 0 | 90s laminate with embedded PZT under tensile loading. All the fatigue tests were conducted with a triangular loading waveform which had a frequency of 10 Hz and with R=0. 1. In the electro-mechanical testing, the embedded actuator was excited by a -10 V to -100 V or a 10 V …

Design Methodology For Low Speed High Altitude Long Endurance Unmanned Aerial Vehicles, Aaron Altman

Mechanical and Aerospace Engineering Faculty Publications

High Altitude Long Endurance (HALE) Unmanned Aerial Vehicles (UAV's) are increasingly being considered to perform a wide range of tasks. Recent years have seen greater value of UAV's in the military reconnaissance arena, first in the Persian Gulf war, with the use of small UAV's, and more recently over Bosnia with medium sized UAV's.

The NASA ERAST program uses HALE UAV's for environmental sensing and monitoring. The military has investigated using HALE UAV's for Theater Ballistic Missile defense, as well as general battlefield reconnaissance. Proposals have been made to use HALE UAV's for communications relay, long term surveillance (with a …

Development And Experimental Validation Of An Underwater Manipulator Hydrodynamic Model, Timothy W. Mclain, Stephen M. Rock

Faculty Publications

Hydrodynamic forces can be large and hence have a significant effect on the dynamic performance of underwater manipulation systems. this paper investigates these forces for a cylindrical single-link arm undergoing motions that are characteristics of a robotic manipulator. Based on flow visualization, theoretical analysis, and experimental measurements, a new model is developed that describes these forces. This model differs from previous models in that the drag and added-mass coefficients are state-dependent functions that depend on the distance traveled by the arm. A factor of four improvement in accuracy is demonstrated over standard constant-coefficient models.

Vortex Wake And Exhaust Plume Interaction, Including Ground Effect, Ihab Gaber Adam

Mechanical & Aerospace Engineering Theses & Dissertations

Computational modeling and studies of the near-field wake-vortex turbulent flows, far-field turbulent wake-vortex/exhaust-plume interaction for subsonic and High Speed Civil Transport (HSCT) airplane, and wake-vortex/exhaust-plume interaction with the ground are carried out. The three-dimensional, compressible Reynolds-Averaged Navier-Stokes (RANS) equations are solved using the implicit, upwind, Roe-flux-differencing, finite-volume scheme. The turbulence models of Baldwin and Lomax, one-equation model of Spalart and Allmaras and two-equation shear stress transport model of Menter are implemented with the RANS solver for turbulent-flow modeling.

For the near-field study, computations are carried out on a fine grid for a rectangular wing with a NACA-0012 airfoil section and …

Design Of The Guidance, Navigation, And Control Subsystem For The Proposed Firebird Spacecraft, Erin Robinson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Firebird spacecraft is a space mission to gather scientific and physical data on the effects of atmospheric deceleration, commonly called aerobraking. The objective of the Firebird mission is to measure specified aerobraking parameters over a range of reentry velocities to provide a database sufficient to construct and validate mathematical models of such aerobraking mission maneuvers. The Firebird senior design team designed the first spacecraft in the mission series to look at aerobraking at an altitude of 160 kilometers above the surface of the Earth. This paper looks specifically at the design of the subsystem that provides the guidance, navigation, …

Research And Design Of A High L/D Aircraft, Blake Ashby, Gregory Nielson

Undergraduate Honors Capstone Projects

This senior design team, consisting of Blake Ashby, Shelly Barlow, Greg Nielson, Deryl Snyder, and Chris Wright, designed, built, and flew an airplane that met the requirements of the Cessna/ONR Student Design/Build/Fly Competition sponsored by AIAA. This radio-controlled airplane was designed to fly the most laps around a course in seven minutes using only 2.5 pounds of NiCad batteries. A total of three senior design teams from Utah State University designed separate airplanes. Though all three teams designed, built, and tested complete airplanes, each emphasized a different aspect of a successful entry. This team emphasized theoretical and numerical analysis in …

Hydrogen On-Orbit Storage And Supply: A Spacecraft Bus Design, Roy Gladden

Undergraduate Honors Capstone Projects

Spacecraft designers have two options when developing spacecraft for a particular mission. The bus, which is the primary structure and support system for the spacecraft, can be designed from an existing layout or a new design may be developed to meet specific mission needs. In recent years, the trend in small satellite design has been to employ a previously designed spacecraft bus in order to reduce cost and development time. However, these structures sometimes provide greater capability than is required for smaller, simple missions at a higher price. Therefore, it may be preferable to custom design a bus to meet …

Reduction Of Thermal Deflection And Random Response Of Composite Structures With Embedded Shape Memory Alloy At Elevated Temperature, Zhiwei Zhong

Mechanical & Aerospace Engineering Theses & Dissertations

A feasibility study on the reduction of thermal deflection and random response of the composite structures using shape memory alloys (SMA) at elevated temperatures is presented in this dissertation. The characteristics of SMA are introduced and the structural problems, static and dynamic, of SMA fiber reinforced composites are investigated. The stress-strain relations are developed for a composite lamina with embedded SMA fibers. The finite element system equations including shape memory effect are derived. A consistent two-step solution procedure is developed for solving the static and dynamic problems of composite structures with embedded SMA fibers subjected to combined acoustic and thermal …

Analysis And Testing Of Plates With Piezoelectric Sensors And Actuators, Jeffrey S. Bevan

Mechanical & Aerospace Engineering Faculty Publications

Piezoelectric material inherently possesses coupling between electrostatics and structural dynamics. Utilizing linear piezoelectric theory results in an intrinsically coupled pair of piezoelectric constitutive equations. One equation describes the direct piezoelectric effect where strains produce an electric field and the other describes the converse effect where an applied electrical field produces strain. The purpose of this study is to compare finite element analysis and experiments of a thin plate with bonded piezoelectric material. Since an isotropic plate in combination with a thin piezoelectric layer constitutes a special case of a laminated composite, the classical laminated plate theory is used in the …

The Restoration Of A Wwii Avenger Provides Projects For Wpi Students, Donald N. Zwiep, William W. Durgin, Nathan H. Mayo

Office of the Provost Scholarship

In 1970 WPI completely revised its traditional approach to engineering education. The resulting program, the WPI Plan, emphasized the use of projects as a distinctive process for achieving educational goals. Every student, as a degree requirement, had to successfully complete two major projects: one in a student's major field, the Major Qualifying Project (MQP) and the second, the Interactive Qualifying Project (IQP), which related science and technology to societal issues.

The IQP's related to the restoration of the WWII Avenger at Mayocraft, Inc. for the Collings Foundation in Stow, Massachusetts enabled the students working with the authors as advisors to …

Battery-Operated Atomic Force Microscope, Burford J. Furman, J. Christman, M. Kearny, F. Wojcik, M. Tortonese

Faculty Publications, Mechanical Engineering

The design of a battery-operated atomic force microscope (AFM) using a piezoresistive cantilever is described. The AFM is designed so that all power to drive the scanning tube and detection electronics comes from a self-contained battery. The prototype AFM uses a 6 V, Ni–Cd, camcorder battery, however, any battery that supplies between 6 and 12 V may be used. Scanner control and data acquisition are implemented using commercially available software running on an external computer. The prototype AFM achieves a scan area of 53 by 53 μm, consumes 1.8 W of power, and can scan continuously for about 7 h …

A Class Of Modified Hopfield Networks For Control Of Linear And Nonlinear Systems, Jie Shen, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a class of modified Hopfield neural networks (MHNN) and their use in solving linear and nonlinear control problems. This class of networks consists of parallel recurrent networks which have variable dimensions that can be changed to fit the problems under consideration. It has a structure to implement an inverse transformation that is essential for embedding optimal control gain sequences. Equilibrium solutions are discussed. Numerical results for a motivating aircraft control problem (linear) are presented. Furthermore, we formulate the state-dependent Riccati equation method (SDRE) for a class of nonlinear dynamical system and show how MHNN provides the solution. …

Cell Mapping Based Fuzzy Control Of Car Parking, Tea-Quin Kim, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper describes the development of a near-optimal fuzzy controller for maneuvering a car in a parking lot. To generate the rules of the fuzzy controller, a cell mapping method is utilized to systematically generate near-optimal trajectories for all possible initial states in the parking lot. Based on the input-output relations of these trajectories, which represent the states and controls of the corresponding cells, a set of fuzzy rules are generated automatically. In order to result in a small number of fuzzy rules from the large amount of numerical information generated by cell mapping, grouping of trajectories is proposed and …

Printer Carriage Motion Control Experiment, Burford Furman

Faculty Research, Scholarly, and Creative Activity

No abstract provided.

Robustness Analysis Of Hopfield And Modified Hopfield Neural Networks In Time Domain, Jie Shen, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A variant of the Hopfield network, called the modified Hopfield network is formulated. This network which consists of two mutually recurrent networks has more free parameters than the well-known Hopfield network. Stability analysis of this network is presented. The analysis is carried out in the time domain with an application of the Lyapunov method and robust control Lyapunov function. The current flow in the network is treated as a "control". This "controller" is shown to guarantee "a practically stabilizing control". Analysis of the Hopfield network is also included for completion.

The Effect Of A Baffle On Acoustic Radiation Directivity, Walter Eversman, Indranil Danda Roy

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An investigation is made of the effect of an artificial baffle introduced in Finite Element modeling of acoustic radiation from turbofan inlets. The purpose of the baffle is to limit the extent of the computational domain in order to maximize the efficiency of the scheme. However, the possibility exists that the baffle, if improperly oriented, will generate spurious reflections which interfere with the true radiated acoustic field. A generic example of a turbofan inlet, including typical geometry and non-uniform potential flow in and around the nacelle, is modeled with a baffle as typically introduced limiting the angular extent of the …

Aerodynamic Interference For Hypersonic Missiles At Low Angle Of Attack, Harlan F. Nelson, Derek G. Hillstrom

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A Euler code is used to predict the flow field over a hypersonic missile and to determine the carryover factors KW(B), fin lift in the presence of the body, and KB(W), lift produced by the body in the presence of the fins. The missile is assumed to have cruciform, delta fins in the + orientation and an aspect ratio of 1.529. Results are presented as a function of fin span at Mach 6, 8, and 10, for a 2-deg angle of attack. Two ratios of specific heats, 1.4 and 1.3, are considered to partially account for vibrational excitation effects. Both …

An Integrated Approach To Determining The Sequence Of Machining Operations For Prismatic Parts With Interacting Features, Alan C. Lin, Shou Yee Lin, Das Diganta, Wen F. Lu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper proposed a framework for integrating artificial intelligence (AI) techniques and mechanistic models in the task of generating process plans for prismatic parts. The main issue of process planning addressed in this paper is the determination of the operation sequence for mechanical parts containing interacting features where machining of one feature might adversely affect the surface quality of other features. The informed graph-search strategy in AI is used to achieve the function of operation sequence planning. The search graph is built by considering alternative machining operations in converting a blank stock into the final part configuration. Several heuristic functions …

Placement Of Piezoelectric Actuators For Active Control Of Vibration Using Modal Parameters, Xuegeng Zhu

Mechanical & Aerospace Engineering Theses & Dissertations

An equation is derived to model the piezoelectric actuators incorporation with flexible structures. This equation permits the comparison of the performance indices over the entire structure for a piezoelectric actuator with constant area, which is unachievable if the Finite Element Method is used for complicated structures.

An index has been developed for placement of piezoelectric actuator for control of vibration of a flexible structure. This index is derived from the definition of H2norm. Computation of the proposed index requires only the natural frequencies and corresponding mode shapes of the structures of interest. The method is well suited to large …

Effects Of Liquid Transpiration Cooling On Heat Transfer To The Diverging Region Of A Porous-Walled Nozzle, Daniel J. Schieb

Theses and Dissertations

This research effort investigated the effects of evaporation of water on the heat transferred to the wall of the diverging portion of a porous walled nozzle The AFIT High Pressure Shock Tube was used with a two-dimensional Mach 3 nozzle. One flat surface of the nozzle was fitted with a layer of porous stainless steel from the nozzle throat to the exit. This porous material was saturated with water to simulate liquid transpiration cooling. Surface temperature data was taken in this region using fast response coaxial thermocouple. Heat transfer was determined from the surface temperature history. Data was taken for …

Experimental Investigation Of Water Spray Cooling Characteristics Of A Solid Heated Surface, Rainer F. Ponzel

Masters Theses

Water spray cooling characteristics of a solid heated surface were investigated to better understand the physical phenomenon of nucleate boiling heat transfer for full cone sprays. An experimental test loop was developed to conduct the spray cooling experiments. A uniform heat flux condition was assumed, and the liquid flow rate and nozzle orifice diameter were selected as the main variables. Two water temperatures were chosen to perform the study. Saturated water spray was utilized to measure the wall superheat temperature. Subcooled water spray was applied to investigate the effect of water spray in the single-phase regime.

Experiments conducted using the …

Flow Due To A Moving Pressure Distribution Over Free-Surface With Finite-Depth Bottom, Noriaki Okita

Masters Theses

Two-dimensional, steady-state and time-dependent analysis of wave making phenomenon due to a moving pressure distribution in sub-critical Froude number was performed. The domain is consisted of undisturbed free-surface at y=0, flat bottom at y=-h, and it is unbounded in horizontal direction. The pressure distribution was treated as an ideal model of an air-cushioned-vehicle (ACV). Ideal flow theory and linearized boundary conditions were used. Numerical integration algorithm was developed to evaluate the analytical solution. The surface elevation, bottom pressure profiles, and wave resistance were analyzed as functions of speed and depth.

The steady-state wave resistance calculated from the surface elevation profile …