Doctoral Dissertations


Haythem Gaja

Keywords and Phrases

Acoustic Emission; Artificial Neural Network; Deposition Defects Detection; Depth of Cut Detection; Laser Metal Deposition; Machine Learning


"The approach of hybrid manufacturing addressed in this research uses two manufacturing processes, one process builds a metal part using laser metal deposition, and the other process finishes the part using a milling machining. The ability to produce complete functioning parts in a short time with minimal cost and energy consumption has made hybrid manufacturing popular in many industries for parts repair and rapid prototyping. Monitoring of hybrid manufacturing processes has become popular because it increases the quality and accuracy of the parts produced and reduces both costs and production time. The goal of this work is to monitor the entire hybrid manufacturing process. During the laser metal deposition, the acoustic emission sensor will monitor the defect formation. The acoustic emission sensor will monitor the depth of cut during milling machining. There are three tasks in this study. The first task addresses depth-of-cut detection and tool-workpiece engagement using an acoustic emission monitoring system during milling machining for a deposited material. The second task, defects monitoring system was proposed to detect and classify defects in real time using an acoustic emission (AE) sensor and an unsupervised pattern recognition analysis (K-means clustering) in conjunction with a principal component analysis (PCA). In the third task, a study was conducted to investigate the ability of AE to detect and identify defects during laser metal deposition using a Logistic Regression Model (LR) and an Artificial Neural Network (ANN)"--Abstract, page iv.


Liou, Frank W.

Committee Member(s)

Chandrashekhara, K.
Kinzel, Edward C.
Pan, Heng
Cudney, Elizabeth A.


Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering


U.S. National Science Foundation
Product Innovation and Engineering, LLC
Missouri University of Science and Technology Intelligent Systems Center
Missouri University of Science and Technology Manufacturing Engineering Program


This research was supported by the National Science Foundation grants IIP1345240, CMMI-1301414, and CMMI-1547042.

Research Center/Lab(s)

Intelligent Systems Center


Missouri University of Science and Technology

Publication Date

Summer 2018

Journal article titles appearing in thesis/dissertation

  • Automatic detection of depth of cut during end milling operation using acoustic emission sensor
  • Defects monitoring of laser metal deposition using acoustic emission sensor
  • Defects classification of laser metal deposition using logistic regression and artificial neural networks for pattern recognition


xiii, 102 pages

Note about bibliography

Includes bibliographic references.


© 2018 Haythem Gaja, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 11374

Electronic OCLC #