Date of Award

3-2024

Document Type

Thesis

Degree Name

Master of Science

First Advisor

John S. Brewer, PhD

Abstract

This study evaluates the yield behavior of additively manufactured Ti-6-4 specimens in combined loading. Specimens were probed for yield across multiple load combinations along a given yield surface, holding pin one mode while applying load increments in the other mode until yield was detected. In combined loading, the yield surfaces across varied print parameters showed statistically significant, but negligible differences. This research sought to characterize the yield behavior across print parameters with the goal of increasing manufacturability. Ultimately, the benefits of the smaller print powder did not outweigh the increased manufacturing time. Furthermore, the comparison of material behavior in subsequent yield surfaces was observed with varied modes of plasticity. Plasticity was imparted in both pure tensile and pure shear to reach subsequent yield surfaces. This behavior was evaluated between both plastic modes, as well as across the varied layer heights. The material response to plasticity was observed to behave as expected for smaller layer heights. The larger layer heights indicated a small susceptibility to plasticity, though the magnitude of the differences is concluded as negligible.

AFIT Designator

AFIT-ENY-MS-24-M-201

Comments

An embargo was observed for posting this thesis on AFIT Scholar.  Approved for Public Release, Distribution Unlimited. PA case number 88ABW-2025-0647

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