Yehansa I Herath Dissanayake Mudiyans
Pronouns: she/her
Research Mentor(s): Kimberlee Kearfott
Research Mentor School/College/Department: NERS/BME / Engineering
Program:
Authors: Yehansa I Dissanayake, Hythem H Beydoun, Callissa L Clarkson, Caleb M Bush, Jordan D Noey, Kimberlee Kearfott
Session: Session 5: 2:40 pm – 3:30 pm
Poster: 27
Abstract
Machining complex shapes involving lead and tungsten can be challenging and expensive, with material costs amplified for common subtractive manufacturing processes that result in material waste. Additive Manufacturing (AM) allows for more complex geometry while preserving material. Fused Filament Fabrication (FFF), a highly accessible type of AM, allows for use of various thermoplastics for three-dimensional printing (3DP). FFF is characterized by the direct extrusion of plastic filament through a heated nozzle, depositing material onto the print bed in sequential layers. Prints designed to contain shielding pellets can be cost-effective but have unavoidable air gaps. Finite pellet dimensions present difficulties for tapered and thin parts. Filament properties can be modified with carbon fibers, metals, and other additives, such as 75% tungsten powder by mass-filled Polyethylene Terephthalate Glycol (PETG-W). Combining the attenuation properties of tungsten with PETG 3DP, customizable shielding becomes easy to fabricate. FFF’s restrictions mainly include tolerances, overhangs, and dimensions. PETG strength, workability, and self-adhesion than some filaments, but requires an enclosed printer and heated bed. This research applies PETG-W prints on Bambu Labs X1 Carbon printers for radiation applications. The filament manufacturer’s specifications determined initial parameters, including print temperatures and cooling. Test prints, including a progressively steeper overhang, tolerance tests, and “Benchy the Boat” for practical and aesthetic qualities were performed, determining adjustments for printer variations. 100%-fill PETG-W sheets with varying thicknesses were produced for attenuation experiments in an existing rig. Ba-133, Co-57, Co-60, Cs-137, Mn-54, Na-22, and Sr-90 point sources were used to evaluate PETG-W’s absorption characteristics. Various collimators, scatter-rejection grids, and pinhole arrangements were created. Future work includes experiments with various radiation sources, different detectors, and comparing material-filled and PETG-W prints. Although the density of PETG-W is not comparable to pure metal, FFF with PETG-W shows promise for solving several radiation collimation and scatter-rejection problems.
