Mechanical Engineering Commons^™

Combustion Of Aerosolized Spherical Aluminum Powders And Flakes In Air, Binu Zacharia Eapen

Theses

Combustion rates and completeness of aerosolized spherical aluminum powders and flakes are compared using constant volume explosion experiments. The comparison of particles and flake sizes was made based on their specific surface areas determined using the Brunauer-Emmett-Teller (BET) method and respective "BET diameters". It is observed that the rates of pressure rise and rates of flame propagation were higher for aluminum powders with BET diameters of about 2 to 5 μm compared to aluminum flakes for which the BET diameters were under 1 μm In agreement with the flame propagation rates, the overall completeness of combustion was also higher for …

Characterization Of Aluminum Powder Ignition, Salil Mohan

Theses

Heating rate effect and particle size effect on ignition temperature of Al powder were studied to collect data for development of a possible Al powder ignition model. Aluminum ignition is associated with a highly accelerated burn rate and high combustion enthalpy. A new ignition model, which can adequately interpret these conditions, is needed to develop better propulsion fuels, explosives and incendiaries that use Al as an additive. This experimental program was focused on preparing framework for characterization of ignition kinetics of Al powder by determining the ignition temperature for different, systematically varied, heating rates and particle size. The experimental setup …

Magneto-Rheological Fluid Orthosis For Suppressing Tremor, Hyoung-Joo Yeo

Theses

Tremor is a common movement disorder that occurs with specific neurological conditions. This condition may seriously impact daily living activities. The aim of the present study is to evaluate the possibility of the development of a wearable technology that is capable of exerting torques at a user's joints for suppressing tremor.

This thesis is based on the concept of "smart structures" which are made of Magneto-Rheological (MR) fluid that can dynamically alter its viscosity under magnetic field. The wearable tremor suppressing orthosis needs several conditions. It should be safe, light weight, simple and small in structure, and easily attachable. An …

Synthesis Of Nano/Micro Particles Using Supercritical Method And Particle Characterization, Abhijit Aniruddha Gokhale

Theses

The thesis work consists of the two parts, jet behavior of solvents (ethanol and acetone) and the particle formation using SAS method. In the first part, the study of the effects of process parameters like temperature, pressure, injection velocity and internal diameter of nozzle on liquid jets are studied. The critical pressure for which liquid jet of solvents changes to gas - like jet, is investigated.

In the second part, the experiments are done to study the process of the particle formation using SAS method. Effects of process parameters like pressure, injection velocity of solution, the inner diameter of nozzle …

Theoretical And Experimental Studies Of The Field-Induced Phenomena In Flowing Suspensions, Nikolai Markarian

Dissertations

The present work describes results of experimental and theoretical studies of the behavior of dilute suspensions subject to high gradient AC electric fields. When a spatially non-uniform electric field is applied to a suspension, in which the particles and the suspending fluid have different dielectric permittivities andlor conductivities, the particles migrate towards the regions of high or low electric field strengths depending on the sign of their polarization. This phenomenon, referred to as dielectrophoresis, has found numerous applications for the control and manipulation of the particle motions.

Presented in Chapter 3 are the results of studying the field -induced motion …

Experimental Study Of Ignition Of Mechanical Alloy And Pure Metal Powders, Ruslan Mudryy

Theses

Mechanical alloys of Al Mg, AI Zr, Al Ti, Al Li, Al C, Al Mg H, B Mg, B Al, and B Ti were produced and tested for possible applications as high energy density additives to fuels, propellants, explosives, and incendiaries. These new materials are metastable, supersaturated, nanocrystalline solid solutions that include a base metal as a solvent and another component (metal or gas, e.g. hydrogen) as a solute. Phase changes occurring in such materials during ignition and combustion are expected to significantly affect both ignition and bum rates. This experimental program focused on the characterization of ignition kinetics of …

Direct Simulation Of Electrorheological Suspensions Subjected To Pressure Driven Flow And Spatially Non-Uniform Electric Field, Arun Thankamony John Kadaksham

Theses

A numerical method based on the distributed Lagrange Multiplier method is developed for direct simulation of electrorheological (ER) suspensions subjected to pressure driven flows and spatially non-uniform electric fields. The flow inside particle boundaries is constrained to be rigid body motion by the distributed Lagrange multiplier method and the point-dipole approximation is used to model the electrostatic forces acting on the polarized particles. Simulations show that the particles move to the regions of high electric field when the value of β, the Clausius-Mossotti factor is positive and they move to the regions of low electric field when the value of …

Analysis Of Random Packing Of Uniform Spheres Using The Monte Carlo Simulation Method, Sai S. Tulluri

Theses

The study of random packing of spheres has had a long history. It particularly interests many researchers because randomly packed hard spheres exhibit some features of the properties of simple liquid, e.g. the packing density and the radial distribution. Many researchers have studied random packing both experimentally and also by using computer simulation.

Monte Carlo simulation method was used to generate random loose packing of hard spheres. Packing characteristics like packing density, radial distribution function, co-ordination, angular distribution and fabric tensor have been computed for this packing system.

The packing density for a system of 8000 particles with a diameter …

Addition Of A Chain-Cell Search Method And A Van Der Waals Force Model To A Particle Dynamics Code, Michael J. Sweetman

Theses

This project studies the implementation of a computational time saving technique and adds an additional force model into a discrete element method simulation code. Both aspects of the project are focused on increasing the versatility of an existing particle dynamics code by increasing the execution speed and available force models for simulation.

The first portion of the project consisted of adding a function to the collision detection mechanism to hash the particles into a spatial grid. This hashing function allows a search for near neighbor particles to be restricted to the space immediately adjacent to the particle of interest, thereby …

Discrete Element Simulation And Nonlinear Dynamic Analysis Of Particles In A Simple Lattice Structure, Liam E. Buckley

Theses

The study of particles interacting in lattice structures allows for insight into the complex interactions of granular flow, and the adaptation of such structures to mechanical apparatuses to handle the separation of bulk particulate matter. Applying methods of computer analysis to the interactions taking place within the particle-lattice system provides a particle level methodology to the study of the phenomenon taking place, as well as a stepping stone for future design of related devices.

A two prong approach is presented to the study of such particle-lattice systems. The first approach is composed of adapting an existing discrete element computer code …

Acoustical Characterization And Parameter Optimization Of Polymeric Noise Control Materials, Emile N. Homsi

Dissertations

The sound transmission loss (STL) characteristics of polymer-based materials are considered. Analytical models that predict, characterize and optimize the STL of polymeric materials, with respect to physical parameters that affect performance, are developed for single layer panel configuration and adapted for layered panel construction with homogenous core. An optimum set of material parameters is selected and translated into practical applications for validation.

Sound attenuating thermoplastic materials designed to be used as barrier systems in the automotive and consumer industries have certain acoustical characteristics that vary in function of the stiffness and density of the selected material. The validity and applicability …

Numerical And Experimental Investigation Of Dry Particle Coating, Ajit Mujumdar

Dissertations

Dry particle coating is an emerging field in the industries that deal with particulate products and powder processing. Compared to the widely reported experimental studies of the dry particle coating, the theoretical modeling of such processes is found to be less comprehensive. The work presented in this thesis is an attempt to fill this gap.

The first part of the dissertation aims at the numerical investigation of the hybridization system (Nara Machinery, Tokyo, Japan). The flow behavior of different materials processed in this device is analyzed using three-dimensional Discrete Element Method (DEM) as well as the computational fluid dynamics (CFD) …

Evaporating Crossflow Sprays In Gas-Solid Flows, Guangliang Liu

Dissertations

Injection of evaporating sprays into gas-solid flows is encountered in many engineering processes such as energy production industry and chemical industry. The phenomenon involves phase change, three-phase interactions, heat and mass transfer. All of these characteristics control the process efficiency, pollutant production and product quality. However, very limited studies are available on the evaporating spray jets in gas-solid flows, especially on the spray evaporation rate within a gas-solid medium. A combined study of experiments and theoretical analysis has been carried out here to investigate the fundamental mechanism of evaporating Crossflow spray jets in gas-solid flows.

In this study, in addition …

Numerical Study Of Pneumatic Conveying Of Powders, Muhammad Mushahid Rafique Quereshi

Theses

The dense phase mode may be advantageous over the dilute phase mode, for some pneumatic conveying problems, because it causes less erosion of the pipeline, less attrition of the material, requires less dust collection and is effective even for smaller pipe diameters. The objective of this study is to numerically determine the parameters that govern the formation slugs in dense phase conveying. The distributed Lagrange multiplier/fictitious domain method (Glowinski et al. 1998 and Singh et al. 2000) is used to perform direct simulations of the motion of solid and gas phases in pipes with rectangular cross-sections. In this approach the …

Electrohydrodynamical Manipulation Of Particles Based On Dielectrophoresis, Oleksii Vasylyschuk

Theses

The movement of matter in a non-uniform electric field, termed dielectrophoresis, is of interest to scientists of various branches: physics, chemistry, engineering, and life science. To chemists and physicists it is a science of many varied phenomena. To engineers it is a source of new and useful techniques for separating materials or improving materials’ behavior. To ecologists it provides a major means of minimizing pollution. To life scientists it offers new ways to study and manipulate cells and their subparticles, and to help unravel the nature of living systems.

The purpose of this thesis is to concentrate on some aspects …

Implementation Of A Two-Dimensional Discrete Element Method To Describe Granular Materials Composed Of Elliptical Cohesionless Particles, Juan Jose Martinez Alvez

Theses

This work is aimed at developing a discrete element simulation that models the contact between elliptical grains or particles in granular materials. The goal is to implement an algorithm to carry out collision detection between ellipses as well as ellipsoidal objects. The practical issue here is that the real shape of macroscopic grains can be approximated better using elliptical curves than using spherical curves. In addition, the simulation model will also be valid for spheres, since these objects are special cases of ellipsoids.

An accurate contact detection algorithm was investigated by means of two different formulations. The first formulation determines …

Computer Simulation Of Automotive Disc Brake Noise, Vadims Milovs

Theses

Disc brake noise continues to be a major concern throughout the automotive industry despite efforts to reduce its occurrence. Many articles are written on this subject, but there still is no agreement on what exactly causes disc brake noise and what part of the braking system is responsible for it.

The goal of current research was to build a simplified but inclusive mathematical model of a disc brake system and investigate it using Matlab software. The twodimensional model including damping, Stribeck effect and stick-slip friction was built.

The model is unique in a way that all the similar models have …

Atomic Force Microscopy Used To Determine The Young's Modulus Of Vascular Smooth Muscle Cells, Samuel C. Lieber

Theses

The Young's modulus of cultured mouse and rat vascular smooth muscle cells (VSMC) was measured with an atomic force microscope (AFM). The AFM can image the three-dimensional structure of biological cells in a physiological environment enabling real-time biochemical and physiological processes to be monitored at a resolution similar to that obtained for the electron microscope (EM). Cellular mechanical properties were determined by indenting the cell's body, and analyzing the indentation data with classical infinitesimal strain theory. This calculation was accomplished by modeling the AFM probe as a cone. as well as a blunted cone. The blunted cone geometry fits the …

Destructive Disassembly Of Bolts And Screws Using Impact, Kyung Geun Pak

Dissertations

Disassembly, the process of separating parts or components at the end of their useful life is complex due to a variety of fastener shapes and variability in their damage during use. As a natural solution, mechanical impact has been suggested as a cost-effective method for destructive disassembly of joining elements.

The objective of this research is to improve the efficiency of impact disassembly process by studying the characteristics of elastic waves caused by impact. This research presents a new method for increasing the shear stress applied on the bolt head without increasing the energy input invested on launching striker. The …

Development Of Icejet-Based Surface Processing Technology, Dimitri V. Shishkin

Dissertations

The objective of the proposed work is to acquire knowledge needed for the development and deployment of manufacturing processes utilizing the enormous technological potential of water ice. Material removal by blasting with ice media such as particles, pellets and slugs was investigated. The ice media was accelerated by entrainment in a fluid stream (air, steam, liquid water, supercritical C0₂), impact of rotating blades, fluid expansion, etc. The ice-airjet has to replace sand blasting and the ice-waterjet has to replace the abrasive waterjet. Based on these results, technical approaches for surface processing and machining will be improved. A primary …

Concurrent Evaporating Spray Jets In Dilute Gas-Solid Pipe Flows, Xiaohua Wang

Dissertations

Evaporating spray jets into gas-solids suspensions are encountered in many industrial applications. The rapid evaporation of spray jets has significant effects on the gas-solids mixing near the jet nozzle regions, including non-uniform solids concentration dilution, gas/solids temperature reduction, and gas/solids velocity acceleration. Furthermore, the jet structure is altered by the change of solids loading, jet mass flow rate and initial droplet size distribution. These interactions of gas, solids and evaporating droplets dominate the process efficiency and product quality. There is an urgent need for exploring fundamental mechanisms of the multi-phase interactions with heat and mass transfer as there are few …

Experiments With A Galton Board, Christopher Oshman

Theses

Galton boards have been used for over a half-century as a tool to illustrate the formation of Gaussian shaped distributions as well as the Central Limit Theorem. Here, the Galton board was used to study the spontaneous percolation of a particle through an ordered array of rigid scatterers. The apparatus that was designed and fabricated provided a means to release 1/8" diameter spheres one at a time in a controlled and precise manner at any location on the board. The three experimental variables used in these experiments were the particle material, the release height, and the board tilt. angle. The …

Current Requirements By Electro Hydrodynamic Filter Systems Under Shipboard Operation Conditions, Ravi Shankar Attri

Theses

An experimental study was performed to determine the current required by an ElectroHydrodynamic (EHD) filter system to clean contaminants from Diesel Engine Lubrication Oil under normal shipboard operation conditions. The amount of current at a set predetermined voltage, which together means Power, was needed in order to anticipate the power required to perform a Shipboard Site Test Evaluation of the EHD filter.

The filter uses the effect of dielectrophoresis to separate contaminants from the lubrication oil. The filter operates at two thousand volts (2KV ac-rms) and thus requires substantial current to energize its electrodes. This type of Power is not …

Flexible Manufacturing System Utilizing Computer Integrated Control And Modeling, Yahia Mohammed Al-Smadi

Theses

In today's fast-automated production, Flexible Manufacturing Systems (FMS) play a very important role by processing a variety of different types of workpieces simultaneously. This study provides valuable information about existing FMS workcells and brings to light a unique concept called Programmable Automation.

Another integrated concept of programmable automation that is discussed is the use of two feasibility approaches towards modeling and controlling FMS operations; the most commonly used is programmable logic controllers (PLC), and the other one, which has not yet implemented in many industrial applications is Petri Net controllers (PN). This latter method is a unique powerful technique to …

Numerical Simulation Of Mechanofusion System For Dry Particle Coating Process, Wenliang Chen

Dissertations

A numerical simulation of the Meclianofusion device for dry particle coating is carried out using Discrete Element Method (DEM) technique. In dry particle coating, tiny sub-micron guest particles are coated onto larger micron sized host particles by using mechanical forces, which the Mechanofusion device provides. It consists of a rotating cylindrical chamber that contains the powder mixture, a stationary inner piece (which has a cylindrical surface at the end), and a fixed scraper blade, which prevents powder from caking against the chamber wall. The simulation studies are performed on two scales: system scale to investigate the particle-particle and particle system …

Experimental And Numerical Study Of Flow Characteristics And Segregation In Flow Enhanced Systems, Gregory James

Dissertations

In the study of granular materials, two major topics of importance are powder flow enhancement mechanisms and the flow characterization. This dissertation is involved with both of these topics. With respect to the powder flow enhancement, this study involves investigation of two types of flow enhancement methods. The first flow enhancement method examined is a novel method called the Magnetically Assisted Powder Flow (MAPF) method. In the MAPF, small magnetic particles and powders are placed in a test hopper. A mesh is placed at the bottom of the hopper to hold the magnetic particles while the powder is discharged through …

Computation And Control Of Flow-Induced Noise Behind A Circular Cylinder Using An Acoustic Analogy Approach, Sirivit Taechajedcadarungsri

Dissertations

The computational aeroacoustics (CAA) research, which focuses on predicting acoustics by means of advanced numerical techniques, has recently gained a great deal of progress. In most applications, the prediction of both the sound source and its far-field propagation is necessary as required by regulations. Recently, powerful computers and reliable algorithms have allowed the prediction of far-field noise through the use of Computational Fluid Dynamics (CFD) data as near-field sound sources. One of the most useful analytical methods, used for the computation of noise, is Lighthill's acoustic analogy. The latter will be used in the present study.

Lighthill's acoustic analogy, combined …

Buckling Of Composite Conical Shells Under Combined Axial Compression, External Pressure, And Bending, Youngjin Chung

Dissertations

Conical shells are extensively used in space crafts, robots, shelters, domes, tanks, and in machinery or devices (e.g. as Belleville washers). Thus, the design of minimum weight, maximum strength, stiffened conical (and cylindrical) shells under combined loads has long been of interest to designers. The objective of this study is to improve the strength of conical shells and reduce the weight of the structure. Buckling of composite conical shells subjected to combined axial loading, external pressure, and bending is investigated using energy and finite element methods. The conical shells have single and multiple layers, different cone angle, length, and radius. …

Integration Of E-Business Strategy For Multi-Lifecycle Production Systems, Yanchun Luo

Dissertations

Internet use has grown exponentially on the last few years becoming a global communication and business resource. Internet-based business, or e-Business will truly affect every sector of the economy in ways that today we can only imagine. The manufacturing sector will be at the forefront of this change. This doctoral dissertation provides a scientific framework and a set of novel decision support tools for evaluating, modeling, and optimizing the overall performance of e-Business integrated multi-lifecycle production systems. The characteristics of this framework include environmental lifecycle study, environmental performance metrics, hyper-network model of integrated e-supply chain networks, fuzzy multi-objective optimization method, …

Dynamic Friction Of Uhmwpe Angular Compliant Bearing For Joint Implants And Machinery, Max Roman

Theses

The feasibility of a unique design of orthopedic- joint implant is investigated. The work focuses on the dynamic friction characteristics of a new joint. This unique design can be also useful in machinery involving oscillating motion similar to that of the hip joint during walking. An elastomeric layer bonded behind the rigid acetubular cup can be beneficial in improving the durability of prosthetic implants. Angular compliance offered by the elastomeric layer reduces relative sliding between the surfaces, lowers contact stresses by distributing pressure more evenly, and reduces the possibility of incongruent loading conditions caused by misalignment. The application of a …