09/17/2021
By Sokny Long

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a Ph.D. proposal defense by Robert G. Lahaie on “Fused Deposition Manufacturing of Multiple Materials.”

Ph.D. Candidate Name: Robert G. Lahaie
Defense Date: Thursday September 30, 2021
Time (from/to): Noon – 2 p.m. EST
Location: This will be a virtual defense via MS Teams. Those interested in attending should contact the student 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, Mechanical Engineering, UMass Lowell

Committee Members:
David Kazmer, Professor, Plastics Engineering, UMASS Lowell
Scott Stapleton, Associate Professor, Mechanical Engineering, UMASS Lowell
Jo Ann Ratto, Deputy Director (HEROES), DEVCOM Soldier Center

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, cross-sectional analysis of printed roads, and through mechanical properties testing.

In addition to the development of a novel hot end, the aspects that affect material transition times will be investigated. Currently, switching between materials is a waste of material and time. The two geometric flow paths being investigated for co-extrusion have been designed with two different wall shear stresses to investigate how wall shear stresses will affect material transition time. The temperature, volumetric flow rate, and the melt volume within the hot end will be the investigated aspects. By understanding the underlying phenomena, higher performance products can be more quickly produced.

All interested students and faculty members are invited to attend the online defense via remote access.