Date of Award

2024

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Trisha Sain

Committee Member 1

Gregory Odegard

Committee Member 2

Susanta Ghosh

Abstract

The advent of additive manufacturing (AM), commonly known as 3D printing, has revolutionized the production of metallic components across various industries. This technology, which builds objects layer by layer, has shifted paradigms in manufacturing, allowing for unprecedented design freedom, material efficiency, and rapid prototyping. Metal additive manufacturing, in particular, has shown remarkable promise due to its ability to produce complex geometries that are difficult or impossible to achieve with traditional subtractive methods. In addition, additively manufactured (AM) materials are gaining popularity in thanks to their often superior and controllable properties in comparison to their wrought counterparts. In the present work, a computational model is developed to predict the complex ductile fracture behaviors of AM metallic alloys. AM metals exhibit anisotropic ductility similar to that of cold-rolled metals, while the failure mechanisms are uniquely anisotropic due to the manufacturing methods. The Hill yield function is employed in combination with the phase-field (PF) fracture model to predict crack growth in these materials. In the proposed formulation, the phase-field smears the propagating crack over a length scale parameter. In this way, the displacement jump created by the crack is approximated as a smooth transition. The development of the crack surface is solved by minimizing the Galerkin-type weak form of the total energy expressed in terms of a regularized crack surface. A work threshold is utilized to control the point at which stored energies may begin to contribute to the crack growth. We model the constitutive behavior by considering the additively manufactured metal as homogenized, having an isotropic elastic response combined xviii with an anisotropic plastic yield criterion. The model is implemented using finite elements and the parameters are calibrated from experimental results found in literature. The model is validated utilizing a variety of test cases obtained from the existing literature.

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