07/18/2022
By Sokny Long

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a Doctoral dissertation defense by Robert G. Lahaie on “Fused Deposition Manufacturing of Polymer Composites via Dynamic Co-extrusion."
Ph.D. Candidate: Robert G. Lahaie
Defense Date: Monday, August 1st, 2022
Time: 3 – 5 p.m.
Location: This will be held in Southwick 240 as well as virtually via MS Teams. Those interested in attending should contact Robert_lahaie@student.uml.edu and committee advisor, Christopher_Hansen@uml.edu, at least 24 hours prior to the defense to request access to the meeting.
Committee Chair (advisor): Christopher Hansen, Associate Professor and Chair, Mechanical Engineering, UMASS Lowell
Committee Members:
David Kazmer, Professor, Plastics Engineering, UMASS Lowell
Scott Stapleton, Associate Professor, Mechanical Engineering, UMASS Lowell
Jo Ann Ratto, Research Engineer & Deputy Director DEVCOM – HEROES

Brief Abstract:
Multi-material 3D printing has been largely adopted by industry and researchers for the capability to quickly manufacture prototypes and fixtures. This work will present a novel hot end that enables dynamic co-extrusion from two filaments, allowing for heterogenous material within a deposited road. The hot end will investigate a spiral flow and a multi-runner flow geometry to achieve an axisymmetric flow of an outer shell of material around the core material. An axisymmetric flow increases stability of the co-extrudate being deposited from the hot end. Validation of the novel hot end has been performed through simulation work and cross-sectional analysis of printed roads.

In addition to the development of a novel hot end, the parameters that affect material transition times will be investigated. Currently, switching between materials leads to waste of material and longer print times. Two geometric flow paths with two different wall shear stresses are printed by co-extrusion to investigate how wall shear stresses will influence material transition time. The temperature, volumetric flow rate, and the melt volume within the hot end are investigated.

All interested are invited to attend.