2023 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2023): Applications: Techniques for End Use Parts
Program Organizers: Joseph Beaman, University of Texas at Austin
Wednesday 1:10 PM
August 16, 2023
Room: 410
Location: Hilton Austin
Session Chair: Timothy Phillips, University of Texas Austin
1:10 PM
Guided Manual Design for Additive Manufacturing of Topologically Optimized Legacy Tooling Parts: Hannah Luben1; Nicholas Meisel1; 1Pennsylvania State University
While some of the choices made in Design for Additive Manufacturing (DFAM) become second nature to seasoned AM designers, inexperienced designers may not know the nuances involved in what is still a developing manufacturing technology. Topology Optimization (TO) in particular can result in organic shapes that may not be immediately conducive to printing through AM. This paper proposes a comprehensive workflow tool to guide a designer, no matter their level of experience, through the decision-making process inherent to DFAM. The tool helps the designer manually edit a legacy tooling design into a topologically optimized part that is readily manufacturable through AM. Several case studies follow the outline of the design tool to exemplify its use. After the best possible TO part is generated, the flowchart culminates with a guide to choosing the best part between the original legacy design, the raw TO part, and the redesigned TO part.
1:30 PM
Hybrid Electromagnetics: Printed RF Sensitive Structures, Circuits, and Sensors Integrated with Non-traditional Electromagnetic Substrates: Lucas Unger1; Christopher Molinari1; Basil Vanderbie1; Samuel Fedorka1; Gary Walsh2; Corey Shemelya1; 1University of Massachusetts Lowell; 2U.S. Army DEVCOM Soldier Center
Nonprinted, nontraditional substrates have seen increasing use in printed RF electronics applications. However, these substrates present significant design challenges to overcome, such as coarse surfaces, flexibility, and multilayer designs. For example, the performance of RF structures printed upon textiles or multilayer laminates are limited by uneven ink deposition, “bleeding” effects, poor ink adhesion, and poor component adhesion. This work demonstrates solutions to many of these problems including methods for blind, multilayer fabrication, extrudable RF encapsulants, printable surface wetting materials, and reliable adhesion and alignment devices for RF ICs. As a case study, we demonstrate an encapsulated RF sensing circuit printed directly atop a polyethylene fiber laminate using direct-write printing methods, alongside a multi-layer frequency selective surface embedded within an RF radome laminate. Our work can offer innovative ideas for how additively manufactured RF circuits and ICs can be integrated “on-demand” to meet new and novel goals.
1:50 PM
3D Printing of Complex Wire Geometries for Tailored Resistance Response: Timothy Phillips1; Jared Allison1; Joseph Beaman1; 1University of Texas Austin
Additive manufacturing (AM) is a rapidly growing field that enables production of complex geometries without tooling. AM has gained traction as a method of producing complex electronic circuits not possible using traditional techniques. The method explored in this manuscript involves post-build infiltration of conductive inks into complex channels to create resistive elements with tunable properties. A Polyjet printer is used to enable high-precision multi-material components with custom mechanical properties. Further, the conductive pathway geometry can be designed to achieve different resistive responses. These properties allow for decoupling of the stress-strain response and resistance-strain response to produce custom strain gauges with engineered properties.
2:10 PM
Additive Compliant Mechanisms for Deployable Space Structures: Christine Gebara1; Savannah Sunez1; 1NASA Jet Propulsion Laboratory
Over the past decade, additive manufacturing (AM) has matured and been infused into numerous spaceflight missions. Simultaneously, deployable structures have become more common on spacecraft. These structures seek to maximize packing efficiency using complex systems that challenge traditional manufacturing methods. An example is the spring mechanisms developed for the NISAR satellite antenna. The mechanism required high torque and was severely volume constrained. This resulted in the use of high aspect ratio rectangular cross-section torsion springs. These springs represented the state of the art for manufacturing. Significant testing, development, and rework was needed for the traditional springs to meet requirements.These issues can now be avoided using AM. By additively manufacturing torsion springs embedded in the mechanism structure, novel geometries are possible. Thus, increasing performance while decreasing complexity and part count. JPL will present on the latest research to monolithically print compliant mechanisms for spaceflight applications.
2:30 PM
Process and Design Strategies for Fluid Wicking in Additively Manufactured Inconel 718 for Monolithic Heat Pipes: Cameron Noe1; Zachary Goode1; Dhruv Bhate1; 1Arizona State University
The ability to integrate heat pipes into monolithic structures using additive manufacturing is a promising avenue for advanced thermal management. A monolithic heat pipe structure is a geometry where the part, heat pipe walls, and the fluid wicking structure are all fabricated as one integrated component. In this work we examine the use of the laser powder bed fusion process for creating wicking structures out of Inconel 718 for use in heat pipes. Specifically, three different approaches are studied for their fluid wicking performance: structured, rastered and sintered, which use design and process strategies for creating porous wicks. The wicks are evaluated based on their porosity, manufacturability, and fluid rate of rise, using X-ray tomography, SEM, mass measurements, IR thermal imaging and CFD simulations for the investigation. Results include a discussion of the advantages and disadvantages of the three strategies as well as on their potential for future system integration.
2:50 PM Break
3:20 PM
Additively Manufactured Inconel718-Methanol Heat Pipe: Fabrication and Low Temperature Thermal Testing: Adnen Mezghani1; Abdalla Nassar2; Corey Dickman3; Edward Reutzel3; Douglas Wolfe3; 1The Pennsylvania State University; 2John Deere; 3The Applied Research Laboratory
Effective thermal management is crucial in hypersonic flight (Mach > 5) due to extremely high aerodynamic heating located at leading edges. Historically, passive and active thermal protection systems (TPS) have been used to achieve this purpose. Among passive TPS methods are two-phase thermal management systems, also known as heat pipes. Heat pipes can achieve extremely high thermal conductivity which makes them an attractive TPS solution. However, conventional fabrication methods for heat pipes and other two-phase thermal management devices require multiple manufacturing and assembly steps which limit design space. Additive manufacturing is a fabrication technology in which components are fabricated layer-by-layer to achieve net-shape geometry from CAD. AM is able to create complex geometries, incorporate internal channels, and consolidate assemblies. Hence, the ability to additively manufacture leading-edge heat pipes would bypass conventional manufacturing limitations and achieve a larger design space for lightweight, highly conductive leading-edge concepts. This presentation presents the fabrication and low-temperature thermal testing of a notional inconel718 leading edge heat pipe fabricated via laser-powder bed fusion AM and filled with methanol. This work serves as a proof of concept and precedes simulated-environment high-temperature thermal performance assessment of additively manufactured inconel718 leading-edge heat pipes filled with sodium.
3:40 PM
Mechanical and Dimensional Characterization of Polymer Powder Bed Fusion Parts for Non-assembly Mechanisms: Nava Khatri1; Johnathan Smith1; Paul Egan1; 1Texas Tech University
Polymer powder bed fusion (PBF) is promising for fabrication of non-assembly mechanisms in applications such as prosthetics needing rotational parts with mechanical strength. Here, PBF feasibility is studied for mechanical systems using a form fuse printing system with nylon 11 by printing and mechanically testing lattices, springs, and rotational mechanisms. Elastic moduli of specimens tested according to ASTM D638 type IV were about 43 MPa and demonstrated low anisotropy. BC-Cube lattices were printed at 30% and 50% relative densities with measured effective elastic moduli from 25 MPa to 55 MPa. Printed helical spring stiffness was approximately 0.2 N/mm to 16.8 N/mm for 3 mm to 7 mm wire diameters. Functional prosthetic fingers were operable for gap sizes printed within the range of 200 to 800 µm to avoid fusion of joints while enabling free rotation. Results demonstrate PBF’s feasibility for printing non-assembly parts for functional components in diverse engineering applications.
4:00 PM Cancelled
Using Solid Freefrom Fabrication to Develop and Test Unique Texture on Mecanum Wheel Rollers and the Ground for Improved Robot Position Accuracy: Indira Dwivedi1; Bharat Dwivedi1; Rajeev Dwivedi2; 1Eastlake High School; 2STEM and Robotics Academy
Mecanum wheels enable mobile robots to move omnidirectionally. The unique movement is enabled by combination of multiple wheel speeds and the friction between the rollers and surface. Variation of friction as well as wear and tear impact the accuracy of Robot navigation. We propose unique texture on the surface of the wheel rollers as well as the ground to improve the accuracy and repeatability of trajectory. Where sustaining the textures is limited, the specially textured surface is presented at specific intervals. The spacing and texture is driven by error propagation estimates. Solid Freeform fabrication is used to develop and test differnt textures.
4:20 PM
Rapid Foam Foundry: The Future of Foam Foundry: Gopal Gote1; Pushkar Kamble1; Yash Mittal1; Yogesh Patil2; Ashik Kumar Patel3; Avinash Mehta1; K. P. Karunakaran1; 1Indian Institute of Technology Bombay; 2Indian Institute of Technology; 3National Institute of Industrial Engineering
Investment casting (IC) is one of the oldest and most extensively used manufacturing processes for metals, where expendable wax patterns are transferred into metal casting. IC can produce precise and complex castings; despite this, it has limitations in large, complex, and thin castings. Along with this, the cost of the wax pattern and its dewaxing makes the IC costlier. Lost Foam Casting (LFC) overcomes these issues because of its ability to produce large near-net-shape complex castings, cheaper and lighter pattern material, and environmental friendliness. Worldwide, conventional foundries are adopting LFC technology. Lost foam foundries uses Expanded Polystyrene (EPS) foam as a pattern material which uses the molding route for pattern making. The molding route of pattern-making limits the LFC applications for mass production because of the high initial die cost and relatively less complex castings because of the manufacturability of the die. To address these difficulties, this article presents the Rapid Foam Foundry (RFF) concept, which is the synergic integration of the hybrid Foam Additive Manufacturing (FAM) machine into conventional foam foundry. In this article, the idea of "CAD to Cast" has been introduced the field of foam casting. The indigenously developed hybrid FAM machine has unique kinematics and a novel slicing approach. It realizes the part through one additive (gluing) and two subtractive (hot wire slicing and machining) processes. A Hybrid FAM machine will be add on to the conventional foam foundries, which will enhance the capacity of the conventional foam foundries by its ability to produce more complex patterns, which will be difficult to manufacture using the molding route. And it has the great potential to manufacture patterns for batch production and for a few specific parts. The present article also includes a lab-scale case study to prove the concept of RFF. In the Lab-scale case study, we created the EPS foam pattern through a hybrid FAM machine, and that foam pattern was transferred into the shell through the foam evaporation at 2500C for 15 min, followed by shell firing has been performed at 7500C for 1hr. Finally, the casting has been manufactured by pouring the LM6 aluminum alloy. Visual inspection shows no surface-casting defects. The 18µm and 25µm surface roughness has been recorded on the flat surface of the casting and foam pattern.
4:40 PM
Material Jetting of Suspension System Components: Jeffrey Lipton1; 1Northeastern University
Material Jetting has demonstrated great promise in being able to produce complex functionalities using multimaterial printing. Despite this potential material jetting has struggled to find applications in direct part production. Here we show how material jetting can be used to produce viscoelastic energy absorbers for large displacement applications in harsh environments. We generate printed components to act as the core of a suspension system on a recumbent trike. We test the printed viscoelastic dampers through large displacements and high payloads on a DMA to characterize the nonlinear performance and compared them with standard molded components. The 3D printed dampers allowed for finer control and customization of the ride experienced. Through long term exposure studies, we demonstrate that techniques and methods previously applied to the absorption of vibration in indoor power tool applications can be extended to outdoor environments.