Date Approved

2-1-2021

Embargo Period

2-2-2021

Document Type

Thesis

Degree Name

M.S. Mechanical Engineering

Department

Mechanical Engineering

College

Henry M. Rowan College of Engineering

First Advisor

Miri, Amir K.

Second Advisor

Zhu, Cheng

Third Advisor

Zhang, Hong

Keywords

hydrogels, bioprinting, extrusion manufacturing, discrete element modeling, forces

Subject(s)

Hydrocolloids

Disciplines

Materials Science and Engineering | Mechanical Engineering

Abstract

Hydrogels are widely used in extrusion bioprinting as bioinks. Understanding how the hydrogel microstructure affects the bioprinting process aids researchers in predicting the behavior of biological components. Current experimental tools are unable to measure internal forces and microstructure variations during the bioprinting process. In this work, discrete element modeling was used to study the internal interactions and the elastic deformation of the molecular chains within hydrogel networks during the extrusion process. Two-dimensional models of hydrogel extrusions were created in Particle Flow Code (PFC; Itasca Co., Minneapolis, MN). For our model's calibration, hydrogel compression testing was used in which a cluster of particles is pushed in the vertical direction with a confined load similar to the uniaxial compression test. The parameter sensitivity study was performed using a set of parameters, e.g., coefficient of friction, restitution coefficient, and stiffness. Force distribution among the particles during the extrusion process was then predicted using the results of the study. Using this model, we analyzed the distribution of internal forces.

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