Engineering Commons^™

An Experimental And Analytical Investigation On The Production Of Microfibers Using A Single Hole Melt Blowing Process, Bryan David Haynes

Doctoral Dissertations

An extensive experimental investigation was undertaken to study the influence of the processing variables on the production of microfibers using a single hole melt blowing process. included: The processing variables that were investigated air jet exit velocity, polymer throughput, die air gap, die setback, polymer and air temperatures, polymer melt viscosity as expressed by ASTM Melt Flow Rate (MFR), and collection distance. Polypropylene was used for the investigation. In addition to the experimental investigation, a one dimensional single hole melt blowing analytical model was developed.

The air jet exit velocity and polymer throughput had the most influence on the average …

Investigations Of The Mechanical Behavior Of Graphite/Peek (Apc-2) Composits, Kyun Lee

Doctoral Dissertations

The purpose of this research is to investigate the effects of two phenomena that are specific to thermoplastic resin composites. The phenomena are:

(a) the significant nonlinear creep, that occurs especially at high temperatures, which affects the residual thermal stresses in a geometrically constrained structure.

(b) the spatially nonuniform transverse crystallinity which develops in some fiber-reinforced thermoplastic composites, which introduces spatial variability and nonlinearity in the stiffness of the composite.

The first part of the dissertation is related to the former phenomenon. It presents a computational scheme for the optimal temperature path for APC-2 composite laminate, modeled as nonlinear, thermorheologically …

Cryogenic Line Quench Experiment In Microgravity, Kanishkan Sathasivam

Masters Theses

This experiment was designed to provide a visual understanding of the nature of saturated liquid nitrogen flow boiling in a microgravity environment. This was undertaken by obtaining visual records of the flow patterns on film, and qualitatively analyzing them to form a definitive picture of the flow. An experimental apparatus was designed and built to obtain these visual records in microgravity. Liquid nitrogen was supplied from a dewar to an accumulator, from which it was then delivered to a test section. The accumulator was home-built and made of stainless steel. It contained a metal bellows vessel within it. Gaseous helium …

Inverse Dynamics And Control For Nuclear Power Plants, Riza C. Berkan

Doctoral Dissertations

A new nonlinear control technique was developed by reformulating one of the “inverse Problems” techniques in mathematics, namely the reconstruction problem. The theory identifies an important concept called inverse dynamics which is always a known property for systems already developed or designed. Accordingly, the paradigm is called “reconstructive inverse dynamics” (RID) control. The standard state-space representation of dynamic systems constitutes a sufficient foundation to derive an algebraic RID control law that provides solutions in one step computation. The existence of an inverse solution is guaranteed for a limited dynamic space. Outside the guaranteed range, existence depends on the nature of …

Studies Of Mathematical Modelling And Experimental On-Line Measurement For The Tubular Film Blowing Process, Cheng-Chien Liu

Masters Theses

An experimental and analytical study of the process of blown film extrusion was carried out. On-line measuring techniques were used to follow the dynamics and temperature profiles occurring in the process. The applicability of a mathematical model which includes a non-isothermal crystallization rate equation was tested. Subsequently, a new simplified model derived from a modified force balance was proposed and examined.

Linear low density polyethylene, LLDPE, (melt flow index 1.0) provided by Dow Chemical Company was used in the experimental part of the study. On-line measurements for radius, thickness, velocity and temperature as a function of distance from the extrusion …