Date of Award

12-2017

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

Sudarsanam S. Babu

Committee Members

Ryan R. Dehoff, Chad E. Duty, William R. Hamel

Abstract

Metal Additive Manufacturing (AM) is the formation of a solid metal part through the layer-wise melting of metal powder, wire, or thin sheets using various heat sources or other bonding methods. This manufacturing method provides nearly limitless complexity with decreased waste, energy needs, and lead time. However, the process faces challenges in part consistency and validation especially for high precision fields such as aerospace and defense. Research has sought to implement robust process monitoring techniques to increase consistency and the reliability of the AM process and detect vital information about the part such as microstructural development, and porosity formation so that eventually the proper control systems can be created to control the desired outcome. The research performed in this thesis seeks to utilize one of the more promising monitoring techniques for the metal PBF processes (selective laser sintering and electron beam melting), infrared (IR) thermography. However, little research has been performed using the technology, and therefore few monitoring applications for AM have been developed. The methods and results in this research will show two potential applications for the use of IR thermography to monitor AM materials: microstructural monitoring and porosity detection. The research will also discuss an algorithmic method for calibrating IR signals for in-situ emissivity change of the material to obtain a more accurate temperature history of a part during the build and direction for future work that needs to be addressed to advance the technology further.

Comments

Chapters 4 and 5 of this document contain results and discussion that was previously published in Scientific Reports

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