ORCID Identifier(s)

0000-0002-1541-4041

Graduation Semester and Year

2018

Language

English

Document Type

Thesis

Degree Name

Master of Science in Mechanical Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Robert M Taylor

Abstract

A design of experiments approach has been used to analytically determine a low cycle fatigue (LCF) constraint for use in design optimization of 3D printed structures. In context of metal additive manufacturing, the process of melting, solidification and consolidation of metal powder introduces very high temperature gradient field within the build which in turn results in high compressive stresses at the core and tensile stresses at the outer surface of the part after it has cooled down to room temperature post build. An approach of finite element modeling in ANSYS Additive has been used to develop a residual stress profile throughout the build in bridge shaped specimens, keeping the build boundary temperature considerably less than melting temperature of the metal. The effect of these stresses on the fatigue life is predicted using Coffin Manson’s model based on plastic strain state produced by high residual stresses superimposed with external loading. Furthermore, equations were developed using linear regression to generate a response surface as a function of span and thickness of the models which could be used for any range of values of these dimensions to represent the fatigue life as well as distortions. With consideration of structural response shown by the specimens, the current work demonstrates a method in using the developed equations for shape optimization of the printed parts.

Keywords

3D printing, Fatigue, Optimization

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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