Doctoral Dissertations


Wei Li


"Pre-mixed powder is frequently-used powder supply to fabricate Functional Gradient Material (FGM) by Laser 3D printing, which is also called Laser Metal Deposition (LMD). The deposited FGM composition is expected to be similar or same as supplied powder mixture. However, because pre-mixed powder has different particle densities and particle sizes, the caused particle acceleration differences can result in the separation in powder mixture. Up to now, there was no study focused on pre-mixed powders' flow behavior in LMD. The current research aims to investigate the flow behaviors of pre-mixed powder supplied for LMD through both experimental and modeling approaches. In this dissertation, four research achievements are introduced in detail as follows. First of all, an effective experimental method is utilized to investigate the powder fluid behaviors in powder mixture during flow in powder feeder pipe. Secondly, a comprehensive CFD-DEM model is built to simulate the powder mixture fluid behaviors and particle trajectory. This model can provide an effective method to analyze the powder separation phenomenon, the processing parameters' effects on the separation, etc. Thirdly, the effect of argon gas flow rate on the powder separation is studied through the CFD-DEM model and validated by the experiment results. Finally, based on the particle acceleration theory, a novel particle size optimization idea is introduced in the research. This optimization idea can control the powder separation and keep almost uniform powder mixture composition. The main contribution of this research is to solve the composition ratio deviation of pre-mixed powder in fabricating FGM through LMD process, in order to enhance the quality of FGM"--Abstract, page iv.


Liou, Frank W.

Committee Member(s)

Midha, A. (Ashok)
Pan, Heng
Chen, Lianyi
He, Xiaoming


Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering


Laser Aided Manufacturing Processes (LAMP) Laboratory
Missouri University of Science and Technology Intelligent Maintenance Systems


Missouri University of Science and Technology

Publication Date

Fall 2018

Journal article titles appearing in thesis/dissertation

  • Investigation and eliminating powder separation in pre-mixed powder supply for laser metal deposition
  • Numerically simulating the separation of pre-mixed powder flow supplied for laser metal deposition and experimental validation
  • Modeling analysis of argon gas flow rate's effect on pre-mixed powder separation in laser metal depostion and experimental validation
  • CFD-DEM modeling analysis of particle size optimization's effect on controlling pre-mixed powder flow separation in laser metal deposition


xi, 93 pages

Note about bibliography

Includes bibliographic references.


© 2018 Wei Li, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 11431

Electronic OCLC #