Doctoral Dissertations


Lei Yan

Keywords and Phrases

Blown Powder; Coolant Residue; Finite Element Analysis; Hybrid Additive Manufacturing; Ti-6Al-4V; Transient Thermal History


“Till now, laser metal deposition (LMD) has been developed with the capability of near-net shape high-performance metal parts fabrication, especially complicated titanium alloys, nickel alloys, and aluminum alloys. However, LMD processed parts usually do not meet end-use requirements without post treatments. In-process part quality inspection and inner features machining are impossible within a single LMD process. Hybrid additive manufacturing (HAM), which integrates additive and subtractive manufacturing in one process, has been proposed to increase the feasibility of complex parts fabrication. This dissertation aims to improve the applications of Ti-6Al-4V parts fabricated via a HAM technique. The first research topic is to investigate the build strategy using the HAM process of correlating yield strength of final parts to processing parameters from both additive and subtractive processes for Ti-6Al-4V structures. The second research topic focuses on coolant residue cleaning methods, where effective cleaning methods have been generated on both oil- and water-based coolant. To reduce trial-and-error efforts and optimize large-scale parts fabrication using HAM, thermal control has become an essential factor that directly relates to the final distortion and residual stress. Hence, the third research topic is conducted on the fast prediction of thermal history in large-scale parts fabrication via a HAM process. This dissertation leads to new knowledge for the effective fabrication of metallic components via a HAM process. Moreover, the research results of the dissertation could benefit a wide range of industries”--Abstract, page iv.


Liou, Frank W.

Committee Member(s)

Chandrashekhara, K.
Pan, Heng
Newkirk, Joseph William
Zhou, Caizhi


Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering


This project was supported by The Boeing Company through the Center for Aerospace Manufacturing Technologies (CAMT), National Science Foundation Grants #CMMI-1547042 and CMMI-1625736, and the Intelligent Systems Center (ISC) at Missouri S&T.

Research Center/Lab(s)

Intelligent Systems Center


Missouri University of Science and Technology

Publication Date

Spring 2019

Journal article titles appearing in thesis/dissertation

  • Build strategy investigation of TI-6AL-4V produced via a hybrid manufacturing process
  • Investigation of machining coolant residue cleaning methods for TI6AL4V part fabrication through hybrid manufacturing process
  • Fast prediction of thermal history in large-scale parts fabrication via a laser metal deposition process


ix, 57 pages

Note about bibliography

Includes bibliographic references.


© 2019 Lei Yan, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 12065

Electronic OCLC #