Date of Award

Spring 5-13-2017

Level of Access

Open-Access Thesis

Language

English

Degree Name

Master of Science (MS)

Department

Civil Engineering

Advisor

Roberto A. Lopez-Anido

Second Committee Member

William G. Davids

Third Committee Member

Douglas J. Gardner

Abstract

This thesis presents a novel combined experimental and numerical mechanics approach for characterizing 3D printed thermoplastic materials by the fused deposition modeling process for thermoforming thermoplastic composites. The implications of this work are:

  1. a methodology for model-based performance evaluation of 3D printed structural parts, and
  2. an improved design of 3D printed molds for composites manufacturing, which has potential for material innovations and scaled-up applications in additive manufacturing.

The thesis formulates basic criteria for selection of thermoplastic polymer used for the 3D printed mold based on forming temperatures. The thesis creates a lattice and shell finite element model of the 3D printed part to characterize its linear elastic mechanical properties and validates this model by mechanical experiments on 3D printed coupons. The thesis studies the thermomechanical and creep properties of a 3D printed polymer and implications of these behaviors on mold making. The thesis creates an idealized orthotropic solid finite element model for the lattice internal structure of 3D printed parts. The mechanical properties of this orthotropic solid are obtained from the virtual experiments carried out on the lattice and shell finite element model. This orthotropic solid finite element model is validated through mechanical experiment on 3D printed molds subjected to forming pressures. Finally, an optimization technique is outlined to create and optimal internal structure for the 3D printed polymer part.