Masters Theses

Keywords and Phrases

Coaxial nozzles; Shielding gas; Laser aided manufacturing process (LAMP); Metallic powder

Abstract

"Laser aided deposition process involves the supply of metallic powders into a laser-heated spot where the powder is melted and forms a melt puddle which quickly solidifies into a bead. Analysis of metallic powder flow in the feeding system is of particular significance to researchers in the laser aided deposition process. Powder flow modeling holds a critical role in understanding flow. phenomenon so as to ensure proper design and sound functionality of the coaxial nozzle.

The first part of the thesis aims to understand the flow structure of coaxial nozzle used in laser aided material deposition process and be able to control focused particle stream by switching shielding gas ratio and outer shielding gas inclination angle. This investigation reports on the results obtained through simulation conducted by commercial software FLUENT and experiments using prototyped coaxial nozzles. It is found that the best particle concentration mode can be achieved using a lower inclination angle and an optimal gas velocity ratio.

The second part proposes a stochastic model, which considers particle shape effects, to quickly simulate realistic powder flow and also meet the practical requirement for design optimization of the coaxial nozzle. The comparison of the proposed stochastic model with direct 3-D rigid body simulation results suggested that the new model is sufficiently accurate in the prediction of irregular bouncing behavior at a much lower cost of computation time. The validity of the model was also demonstrated through comparison with experiment"--Abstract, page iv.

Advisor(s)

Liou, Frank W.

Committee Member(s)

Landers, Robert G.
Stephenson, Richard Wesley

Department(s)

Mechanical and Aerospace Engineering

Degree Name

M.S. in Manufacturing Engineering

Publisher

University of Missouri--Rolla

Publication Date

Summer 2004

Journal article titles appearing in thesis/dissertation

  • Numerical and experimental study of shielding gas orientation effects on particle stream concentration mode in coaxial laser aided material deposition process
  • Numerical simulation of metallic powder flow in coaxial nozzle for laser aided deposition process

Pagination

x, 59 pages

Note about bibliography

Includes bibliographical references (pages 57-58)

Rights

© 2004 Heng Pan, All rights reserved.

Document Type

Thesis - Restricted Access

File Type

text

Language

English

Subject Headings

Rapid prototyping

Thesis Number

T 8482

Print OCLC #

56474012

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