2023 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2023): Applications: Lattices and Cellular IV
Program Organizers: Joseph Beaman, University of Texas at Austin
Wednesday 8:00 AM
August 16, 2023
Room: Salon B
Location: Hilton Austin
Session Chair: Richard Crawford, University of Texas Austin
8:00 AM
Deformation Pattern of Cellular Mechanical Interface in a Bi-material Structure Fabricated by Material Extrusion Additive Manufacturing: Sumit Paul1; Li Yang1; 1University of Louisville
This research focuses on the investigation of the deformation behavior and mechanical response of the cellular structure-based mechanical interlocking interface designs for bi-material structures fabricated by material extrusion additive manufacturing (AM). Three different cellular designs, including auxetic, body centered cubic (BCC), and octahedral, were investigated. In addition, the effects of build orientation and interface polarity were also included in the study. Utilizing both finite element analysis and experimental characterization, the deformation characteristics and fracture patterns of these structures were investigated. The results show that the failure of the interlocking interface is significantly influenced by geometry design, printing orientation and the intrinsic material interfacial bonding strength. In particular, the choice of interface geometry design appears to be related to the intrinsic material interfacial bonding strength between the two materials, indicating design flexibility with this design concept.
8:20 AM
Comparison of tensile and compressive behavior of triply periodic minimal surface lattices fabricated by laser powder bed fusion: Bharath Ravichander1; Shweta Hanmant Jagdale1; Akib Jabed1; Golden Kumar1; 1University of Texas at Dallas
Fabrication of sheet-based triply periodic minimal surface (TPMS) lattices was carried out using laser powder bed fusion, employing 316L stainless steel. The dimensional accuracy and printing defects of various unit cell types (diamond, gyroid, fischer, IWP, and primitive) were assessed using scanning electron microscopy. The tensile and compressive behaviors of TPMS structures were examined, including elastic modulus, yield strength, and energy absorption. Results demonstrated that these properties exhibited similar dependence on the lattice topology for both compression and tension. Notably, the fischer structure displayed superior mechanical performance compared to the previously studied sheet-based diamond TPMS lattice, exhibiting remarkable compressive and tensile properties, which are reported here for the first time in relation to metallic materials. Most sheet-based TPMS structures exhibited high stiffness and plateau stress, indicating deformation dominated by stretching. However, the primitive structure exhibited lower resistance to deformation, likely due to a significant contribution from bending. Understanding the mechanical properties of TPMS lattices will facilitate their selection and utilization in various potential applications.
8:40 AM
A Review on the Joining Mechanisms of Multiple Materials using Additive Manufacturing: Sumit Paul1; Li Yang1; 1University of Louisville
Multi-material manufacturing imposes various challenges due to the difference between the properties of constituent materials. With the advancement of additive manufacturing (AM), the use of multiple materials opens up more application spaces due to the enhanced design freedom with materials. With unique process principle, AM multi-material structures often exhibit unique joining/bonding mechanisms between multiple constituent materials. In addition, the geometry design flexibility with AM also enables new joining concepts. This paper attempts to provide a brief review about joining/bonding mechanisms during multi-material AM from both the perspectives of process principles and structural types. The discussion also attempts to summarize some rather novel multi-material bonding/joining mechanisms that are uniquely enabled by AM. This paper aims to provide some additional insights into the technological challenges of multi-material AM as well as future research opportunities.
9:00 AM
3D Printed Intelligently Graded Functional Stiffness Foam for Sturdier Multi Stiffness Materials: Brett Emery1; Daniel Revier1; Masa Nakura1; Vivek Sarkar1; Jeffrey Lipton2; 1University of Washington; 2Northeastern University
Foams are ubiquitous, being used in applications such as padding, insulation, and noise isolation. Bonding different density foams together produces undesired stress concentrations and boundary effects. Creating controlled gradients in foam properties has been a challenge for traditional and AM processes. Here we show how to use a form of material extrusion called viscous thread printing (VTP) to produce foams with multiple stiffnesses and continuous gradients between different stiffnesses. We do so by varying the path speed during extrusion to control the production of microstructures. We compare the process of producing discrete components and those with gradients, showing that those with gradients have higher strength in plane during tension, have no discontinuities in out of plane stiffness, and are less prone to forming cracks at the boundaries. We demonstrate the process in thermoplastic polyurethane (TPU).