Doctoral Dissertations

Keywords and Phrases

Additive Manufacturing; Aerospace engineering; Mechanical engineering; Process control

Abstract

"Powder based additive manufacturing (AM) exhibits tremendous uncertainties, where variations in build quality is present despite utilizing similar build processing parameters. First, this work reports the features and formation mechanisms of five unique types of spatter during the LPBF process by in-situ high-speed, high-energy x-ray imaging. The unique physical characteristics of spatter are determined. The effect of laser scan speed and laser power on spatter formation, ejection, and mitigation are determined. Second, this work addresses the uncertainty challenge by identifying the sources of uncertainty in SLM by in-situ characterization due to variations from the additive manufacturing processing parameters needed for Ti6Al4V. Second, this work addresses the uncertainty challenge by identifying the sources of uncertainty in SLM by in-situ characterization due to variations from the additive manufacturing processing parameters needed for Ti6Al4V. We show that small variations in the laser beam size, power, scan speed, and powder bed thickness results in significant changes in the SLM dynamics. Third, this work focuses on identifying the uncertainty due to particle size distribution (PSD) on the resulting Ti6Al4V powder’s flowability. More specifically, we showed that the PSDs effect on flowability is not linear, rather the PSD near local high packing densities cause significant reductions in overall dynamic flowability and affect the finalized part’s SLM dynamics. The understanding and control of these uncertainties are vital for increasing the capabilities and reliability of AM produced parts"--Abstract, p. iv

Advisor(s)

Chen, Lianyi
Bristow, Douglas A.

Committee Member(s)

Liou, Frank W.
Go, Yijia
Midha, A. (Ashok)

Department(s)

Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2021

Pagination

xii, 103 pages

Note about bibliography

Includes_bibliographical_references_(pages 26, 63, 96)

Rights

© 2021 Zachary Young, All Rights Reserved

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12223

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