Date of Award

2018-01-01

Degree Name

Master of Science

Department

Metallurgical and Materials Engineering

Advisor(s)

David A. Roberson

Abstract

To enable the advancement of large-scale additive manufacturing processes, it is necessary to establish and standardize methodologies to characterize the mechanical properties of printed test coupons. Due to the large size of the print beads, conventional test standards are inadequate. The focus of this study was to determine the feasibility of using Digital image correlation (DIC) technology as a key enabler for robust data collection of strain measurements of large 3D printed parts. To incorporate the DIC measurements, a novel method was developed to prepare large 20 wt.% glass filled ABS test coupons for adequate contrast. Through this technique, Poisson's ratio and elastic modulus were measured and stress strain curves were generated. The data produced by DIC collaborated well with failure analysis performed on spent test coupons. Additionally, fracture surface analysis of the specimens revealed poor adhesion among the ABS matrix and glass fibers. This matrix/fiber debonding demonstrated the need for improved printing parameters to maximize tensile strength. Finally, critical length analysis of the fibers revealed them to be dimensionally inadequate, prompting a need for extrusion parameters to be optimized. The bead neck growth study conducted on 20 wt.% carbon fiber filled ABS provided insight on the screw speed limitation at which this material could be processed. The work presented here establishes the framework for future characterization of BAAM fabricated components.

Language

en

Provenance

Received from ProQuest

File Size

65 pages

File Format

application/pdf

Rights Holder

Kevin Schnittker

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