Date of Award

Fall 12-15-2021

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Civil Engineering

Advisor

Roberto A. Lopez-Anido

Second Committee Member

Douglas J. Gardner

Third Committee Member

William G. Davids

Additional Committee Members

Senthil S. Vel

Bashir Khoda

Abstract

Extrusion-based 3D printing of thermoplastic polymer composites manufactures parts that have nonhomogenous, orthotropic, and process-dependent macro-scale material properties. As a part of the dissertation, research works were carried out to: • improve the interlayer mechanical properties and reduce the orthotropy, • use experimentally homogenized orthotropic material properties to numerically model the mechanical behavior of the non-homogenous orthotropic 3D printed parts, • create an efficient numerical thermal model to predict the process-dependent thermal history of the 3D printed part, and • aid the manufacturing process by selecting a suitable set of processing parameters based on a simplified sequentially coupled thermomechanical model. The dissertation presents four studies that improve the understanding of the mechanical behavior and aid the manufacturing process of the 3D printed thermoplastic polymer composites. Three journal publications that resulted from the research work carried out are listed below: • Bhandari, S., Lopez-Anido, R. A., & Gardner, D. J. (2019). Enhancing the interlayer tensile strength of 3D printed short carbon fiber reinforced PETG and PLA composites via annealing. Additive Manufacturing, 30, 100922. iii • Bhandari, S., Lopez-Anido, R.A., Wang, L. et al. (2020). Elasto-Plastic Finite Element Modeling of Short Carbon Fiber Reinforced 3D Printed Acrylonitrile Butadiene Styrene Composites. JOM 72, 475– 484. • Bhandari, S.; Lopez-Anido, R.A. (2020). Discrete-Event Simulation Thermal Model for Extrusion-Based Additive Manufacturing of PLA and ABS. Materials, 13, 4985.