Date of Award

Winter 12-30-2019

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

Advisor

Masoud Rais-Rohani

Second Committee Member

Brett Ellis

Third Committee Member

Keith Berube

Abstract

As additive manufacturing (AM) grows in popularity, the need for better simulation tools to predict the process-structure-property relationships of AM parts becomes ever more necessary to employ the technology in design of functional parts with varying degrees of complexity and performance requirements. Many simulation tools and techniques have been developed that aim to achieve this goal, and the main purpose of this research is to explore how well different simulation tools and modeling approaches can capture various AM-specific features such as inter-raster and end-of raster voids, and residual stresses induced by dissimilar rates of thermal expansion. Process simulation of fused filament fabrication (FFF) through FEA-based code (ABAQUS) and affiliated programs combined with performance simulation through a nonlinear user-material model (GENOA) to predict the tensile and bending properties of Polylactic Acid (PLA) samples. Following the examination of different process parameters such as rate of extrusion per distance travel, fan speed, and nozzle temperature through a multi-factor design of experiments, an optimal setting was identified and used to explore the effect of raster architecture on tensile response of dog-bone specimens based on ASTM D638 standard, and bending response of rectangular beam specimens based on ASTM D790 standard. Comparison of the experimental data from nearly 300 tests with the simulation-based results indicate that the Young’s modulus, ultimate tensile strength, and bending strength predictions are very sensitive to how FFF-induced voids and temperature effects are modeled, and that it is possible to achieve reasonably good agreements (

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