Session: 04-15-01: Nanoengineered, Nano Modified, Hierarchical, Multi-Scale Materials and Structures

Paper Number: 146102

146102 - Nanomodifications and Experimental Investigations of Process Induced Effects on Mode 1 Fracture Behavior of Veropurewhite Material System in Polyjet Additive Manufacturing Setup 

This investigation explores the Mode I fracture behavior of VeroPureWhite Material System integrated with VeroPureWhite and Carbon Nanofibers (CNF) resin blend in Polyjet Additive Manufacturing Setup. The study leverages the unique capabilities of PolyJet printing to fabricate complex structures and examines the influence of process parameters on fracture behavior and material characteristics, particularly through the integration of CNF to enhance mechanical properties. Employing a novel two-step method, the research introduces a tailored nanocomposite system into the printed specimens. This approach utilizes the Air injection feature of PolyJet printing to create voids without the infusion of support material, thereby maintaining the purity of the nanocomposite blend. The nanocomposite, consisting of Carbon Nanofiber mixed with VeroPureWhite base resin, is uniformly dispersed using bath sonication, ensuring a consistent distribution of nanofibers within the resin. Specimens for fracture testing were designed to include voids for nanocomposite infusion and printed using optimized process parameters in the GrabCAD interface. Cylindrical voids are created for samples with crack front oriented parallel to material deposition direction and cubical voids are created for samples with crack front oriented perpendicular to the material deposition direction. This allowed for the precise introduction of the VeroPureWhite-CNF blend at location of voids in the printing process, enhancing the specimens' fracture resistance. Fracture toughness tests conducted in accordance with ASTM D5045 standards revealed significant improvements in mechanical properties, attributable to the CNF infusion. The test results showed a marked increase in the mechanical performance of CNF-infused specimens. For samples with crack fronts parallel to the material deposition direction, peak loads varied between 822 N and 953 N, with Mode 1 fracture toughness (K_1C) values averaging 1.493 MPa^0.5. The critical strain energy release rates (G_1C) for these samples ranged from 1294 J/m² to 1571 J/m², highlighting a significant energy absorption capacity. Conversely, specimens with crack fronts perpendicular to the deposition direction demonstrated enhanced mechanical strength, with peak loads ranging from 1431 N to 1531 N and an average K_1C value of 2.500 MPa_0.5. The G_1C values for these samples showed a wider variation, from 1730 J/m² to 2036 J/m², indicating differences in energy absorption at the fracture point, possibly due to variations in nanocomposite distribution or the architecture of the voids. Fractographic analysis of the fracture surfaces revealed microscale toughening mechanisms such as fiber pull-out and bridging in CNF-infused areas, correlating with the observed improvements in fracture toughness and energy absorption. These findings underscore the efficacy of CNF integration in enhancing the structural properties of 3D printed components, showcasing the potential of nanocomposite materials in additive manufacturing for producing materials with customized mechanical properties.

Presenting Author: Vishwanath Khapper North Carolina Agricultural and Technical State University

Presenting Author Biography: Vishwanath Khapper was born on January 7, 1985, in the Kalaburagi district of Karnataka, India. He completed his undergraduate studies in mechanical engineering at B.V. Bhoomaraddi College of Engineering and Technology in Hubballi, India, in 2007. He then earned his master's degree in Heat Power Engineering from the Visvesvaraya National Institute of Technology in Nagpur, India, in 2013. Before starting his Ph.D., Vishwanath spent seven years teaching mechanical engineering courses in India, where he was actively involved in setting up a hydraulics and pneumatics lab. He also has experience in the service industry as a technical writer, where he contributed to creating maintenance manuals for aircraft braking systems. His current research interests include digital twins and Lean Six Sigma in additive manufacturing,

Authors:

Vishwanath Khapper North Carolina Agricultural and Technical State University
Ram Mohan North Carolina Agricultural and Technical State University