Megha Tangri

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

Ashfaq Adnan

Abstract

Recently, additive manufacturing, or 3D printing as it is more commonly called, has taken a big leap in the manufacturing industry. This technology is rapidly moving from prototyping to manufacturing using metals, polymers, concrete and even composites. Unlike subtractive methods of manufacturing, additive manufacturing can be used to manufacture parts with highly directional mechanical properties. This research focuses on predicting tensile failure of 3D printed polymer structures in different raster orientations using composites lamination theory. Previously it was found experimentally that tensile strengths of 3D printed specimens decrease when raster orientations changes from 0° to 90°. The proposed model developed confirms the experimental trends observed for ULTEM 9085. The samples comprise of 14 laminae with varying volumes of 0° and 90° raster orientation. It is discussed how geometry of a printed structure creates a difference in strength variation of 3D printed structures. It is also found that stacking sequence affects failure strength. Finite Element Analysis has been conducted to compare the analytical and experimental studies to find a co-relation of failure force corresponding to the first ply failure of the laminate samples. The latter part of the research explores the fracture and flexure strengths of the ABS resin. Experiment was designed to manufacture number of straight bar specimens with variation in initial crack length and size, and specimen thickness to study the behavior of crack growth. The experiments helped establish a co-relation between bending and fracture energies and how they varied with thickness and crack length of specimens.

Keywords

Additive manufacturing, 3D printing, Composite lamination theory, FEA, Fracture, Flexure

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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