Doctoral Dissertations

Zhiqiang Fan

Keywords and Phrases

Free surface fluid flow with surface tension; Laser metal deposition; Numerical modeling; Solidification phase change

Abstract

"Laser metal deposition is an additive manufacturing technique which allows quick fabrication of fully-dense metallic components directly from Computer Aided Design (CAD) solid models. A self-consistent three-dimensional model was developed for the laser metal deposition process by powder injection, which simulates heat transfer, phase changes, and fluid flow in the melt pool, The governing equations for solid, liquid and gas phases in the calculation domain have been formulated using the continuum model. The free surface in the melt pool has been tracked by the Volume of Fluid (VOF) method, while the VOF transport equation was solved using the Piecewise Linear Interface Calculation (PLIC) method. Surface tension was modeled by taking the Continuum Surface Force (CSF) model combined with a force-balance flow algorithm. Laser-powder interaction was modeled to account for the effects of laser power attenuation and powder temperature rise during the laser metal deposition process.

The governing equations were discretized in the physical space using the finite volume method. The advection terms were approximated using the MUSCL flux limiter scheme. The fluid flow and energy equations were solved in a coupled manner. The incompressible flow equations were solved using a two-step projection method, which requires a solution of a Poisson equation for the pressure field. The discretized pressure Poisson equation was solved using the ICCG (Incomplete Cholesky Conjugate Gradient) solution technique. The energy equation was solved by an enthalpy-based method. Temperature-dependent thermal-physical material properties were considered in the numerical implementation. The numerical model was validated by comparing simulations with experimental measurements"--Abstract, page iv.

Advisor(s)

Liou, Frank W.

Committee Member(s)

Newkirk, Joseph William
Chandrashekhara, K.
Homan, Kelly
Du, Xiaoping

Department(s)

Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2013

Pagination

xi, 104 pages

Note about bibliography

Includes bibliographical references.

Rights

© 2013 Zhiqiang Fan, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Injection molding of metals -- Mathematical modelsPowder injection molding -- Mathematical modelsHeat -- TransmissionHeat exchangers -- Fluid dynamics

Thesis Number

T 10498

Electronic OCLC #

883202979

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