Mechanical Engineering Commons^™

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 …

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 …

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 …

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 …

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 …

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 …

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 …

Analytical And Fea Analysis Of Silicon Micro-Machined Capacitive Pressure Sensor, Eoghan O'Donoghue

Theses

This thesis is concerned with the electro-mechanical characterisation of MEMS capacitive pressure sensors and the determination of models to describe their behaviour.

The finite element software package ANSYS is validated as a tool for the examination of the electro-mechanical behaviour of capacitive pressure sensors. It is then used to incorporate the effects of applied load, voltage and residual stress into a model of the sensor structure. The capacitive pressure sensor is modelled both in 3D and also in 2D axis-symmetric modes. The error between the 2D and 3D models is quantified.

The behaviour of structures under electrostatic actuation is investigated. …

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 …

Thermal Assessment Of Silicon-Based Composite Materials Used In Photovoltaics, Pavlos K. Bataglannis

Theses

Photovoltaics are devices that convert sunlight directly to electricity. It is well established that the conversion efficiency of mono and poly-crystalline silicon-based photovoltaic modules is inversely related to their temperature. Substantial improvements in operational performance can thus be achieved if the thermal energy accumulating in the material can be effectively dissipated.

Accurate modelling of modules would allow possible methods of thermal dissipation to be evaluated, and as a crucial component of the model, the thermal properties of the constituent materials of PV modules needed to be known. Special consideration needed to be given to the interfaces between dissimilar materials and …