2023 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2023): Modeling: CAD, Scan Patterns, Contouring, Slicing II
Program Organizers: Joseph Beaman, University of Texas at Austin
Tuesday 8:15 AM
August 15, 2023
Room: Salon A
Location: Hilton Austin
Session Chair: Gabriel Lipkowitz, Stanford University
8:15 AM
Demonstrating Paraflow: Interactive Fluid Dynamics Simulation with Real-time Visualization for Augmented Resin 3D Printing: Gabriel Lipkowitz1; Joseph DeSimone1; 1Stanford University
Continuous liquid interface production (CLIP), a form of vat photopolymerization (VP), affords designers unprecedented geometric complexity in their products; however, currently CLIP requires cumbersome support structures that are materially wasteful, human labor-intensive, time-consuming to remove, and damaging to part surface finish. Recent physical demonstrations suggest injection through conduits embedded within the part itself can offset suction forces during CLIP. Here we demonstrate that in addition to increasing printing speeds, such injection can alleviate the need for supports. To demonstrate such improvements, we develop a novel fluid dynamics-guided computational inverse design tool, Paraflow. Paraflow takes as input a user's arbitrary 3D model for printing, formulates the design problem as a path planning optimization problem, and computationally designs a corresponding fluidic injection network that distributes one, or potentially multiple, materials during printing. We experimentally show such networks enable printing of farther unsupported overhang geometries than can current state-of-the-art CLIP methods.
8:35 AM
Methodical Approach to Reducing Design Time by using Neural Networks in Early Stages of Concept Development: Manuel Ott1; Iryna Mozgova1; Niclas Meihöfener1; 1Paderborn University
Modern companies often face various challenges in concept development of products or systems. Design engineers prepare initial concepts and incorporate them into 3D models. These are then simulated by computational engineers. If requirements are not met, this necessitates an iterative process that runs between the design and computation departments until a concept that is valid for both sides is created. Design methods such as topology optimization are often used here. The upcoming result is then attempted to be adapted to certain manufacturing processes. These iteration loops can sometimes take a very long time, since the model construction and structural optimization generate large computational efforts. The present work shows on an example a methodical approach to solving this problem, including a description of methods and techniques, as well as possible problems in a detailed analysis concerning training data for neural networks and their abstraction capabilities.
8:55 AM
OpenVCAD: An Open Source Volumetric Multi-material Geometry Compiler: Charles Wade1; Graham Williams1; Robert MacCurdy1; 1University of Colorado Boulder
Additive manufacturing has made significant advancements in multi-material fabrication techniques that allow for site-specific control of material deposition. With these advancements, design tools have fallen behind machine capabilities in accommodating volumetric information. Traditionally design and slicing workflows have expressed multi-material objects as several single-material bodies. The intense interest in compliant mechanisms and meta-materials demands a new design workflow that can support architecting material distribution throughout an object. To address these needs, we present OpenVCAD, an open-source volumetric design compiler with multi-material capabilities. OpenVCAD provides a scriptable suite of geometric and material design methods that enable efficient representation of complex objects with hundreds of materials. Through functional grading and convolutional blending, OpenVCAD allows for material distributions to be parameterized on spatial locations to yield complex multi-material distributions that would be impossible to describe using alternative workflows. We will demonstrate applications of OpenVCAD with additively manufactured meta-materials, compliant mechanisms, and 3D-electronics.
9:15 AM
Catalog of Triply Periodic Minimal Surfaces, Equation-based Lattice Structures, and Their Homogenized Property Data: Joseph Fisher1; Simon Miller1; Joseph Bartolai1; Michael Yukish1; Timothy Simpson1; 1Pennsylvania State University
We have compiled a catalog of equation-based lattice structures that are derived from Triply Periodic Minimal Surfaces (TPMS) for which a low-order Fourier series fit is known. The Fourier series fit allows the TPMS to be modeled and manufactured. For each equation-based lattice the catalog includes images, homogenized elastic property data, an equation for implicit modeling, and CAD models. The information can help in selection and implementation of equation-based lattice structures for engineering applications. Using lattice structures in a design allows engineers to tailor the properties and response of a component independent of material and overall geometry. We discuss the methods used to generate and process the lattice property data, and provide examples of its use.
9:35 AM Cancelled
Application of Implicit CAD System to Support Subtract-additive Hybrid Manufacturing: Jaeseung Ahn1; Sang-in Park1; 1Incheon National University
Subtract-additive hybrid manufacturing systems have been developed to improve manufacturing time and cost for customized parts. However, CAD tools are limited to support design activities, such as modifying an original design for the hybrid manufacturing and detecting internal defects. In this research, we proposed an implicit CAD system and show applications to support design for additive manufacturing activities for subtract-additive manufacturing system. We considered two activities, model modification and defect detection. In the proposed CAD system, two function-fields are defined and utilized, which are signed distance and material function fields. The result shows the proposed algorithm effectively modified a CAD model to self-supported model, which can be fabricated with support structures. The proposed approach also estimates a distribution of defects as varying process parameters.
9:55 AM Break
10:25 AM
Adaptively Sampled Distance Functions: A Unifying Digital Twin Representation for Additive Manufacturing: Sam Pratt1; Tadek Kosmal2; Christopher Williams2; 1NSWCCD/Virginia Tech; 2Virginia Tech
Digital twin models for advanced manufacturing are constrained by the fundamental geometric representations that are currently used. Instead of a singular representation, mesh, voxel, and parametric surface representations all require multiple conversions along the digital design, manufacturing, and inspection processes. These conversions inherently introduce error and are time-consuming, complicate comparison of in-situ sensor data to the as-designed model, and result in a complex, fragmented process chain.We introduce a novel holistic digital twin representation based on a voxelized, GPU-accelerated, adaptively sampled distance function (ASDF). The framework enables rapid comparison of in-situ sensor data to as-designed models, provides a baseline representation of as-designed geometry for control systems, serves as a foundation for path planning tools, allows rapid comparison of sensor data to as-designed models, and as such, could enable real-time, online path planning during the manufacturing process.
10:45 AM
Depiction of Support Structures in Technical Drawings: Stefan Lammers1; Thorsten Koers1; Tobias Lieneke2; Detmar Zimmer1; Balazs Magyar1; 1Paderborn University; 2Paderborn University / Direct Manufacturing Research Center
To ensure uniform documentation of support structure information, a concept is presented that enables a standardized depiction of support structures in technical drawings based on DIN ISO 128-50. The drawing entry should contain all production-relevant support structure information and is intended to ensure a simple, clearly and safe exchange of information between business units or different companies. Therefore, the state of the art of support structures is determined first. Secondly, requirements for a useful depiction of support structures are presented. At the end a procedure to depict the support structures in technical drawings with respect to existing standards of drawing entries is defined. Different support structure types can be documented by using a specification field. The specification field gives a detailed description of the support structure type, the geometry and the connection to the part and the building platform. Also, uncommon support structure types like lattice structures can be implemented.
11:05 AM
Additive Manufacturing and the Moving NDT Target: Cole Vaughan1; Bill Hayes1; 1Waygate Technologies
For engineers and manufacturers, additive manufacturing holds an unprecedented promise. It is an engineering marvel that enables the creation of highly complex, technically intricate and customizable three-dimensional parts, while wreaking havoc on the world of NDT and the inspectors needing to validate it. An overview of typical additive defect and indications types will be presented, along with possible solutions and tools for visualizing and inspecting them. We will also highlight the many challenges that still lie ahead for the CT inspection of additive parts to meet the demanding criteria of design engineers and drawing requirements, as well as the substantiation of our NDT methods to meet these.
11:25 AM
G-Wing: A Novel Software Tool for Toolpath-Centric Design of Wings for Material Extrusion: Justin Valenti1; Joseph Bartolai1; Michael Yukish1; 1Pennsylvania State University
A novel software tool for the rapid design of a small aircraft wing to be fabricated with material extrusion is presented. The tool, named GWing, uses rapid design algorithms based on lifting line theory to determine the outer-mold line of the wing based on desired aerodynamic behavior. The resulting wing shape and flight-load distribution are given to a structural design algorithm to determine the internal structure of the wing based on both expected flight loads and manufacturing constraints. Finally, manufacturing instructions in the form of gcode are created directly from the wing shape and internal structure. This process removes explicit geometric modeling and slicing from the critical design path and directly converts airfoil coordinates to perimeter gcode points, minimizing the introduction of geometric error. This process has been used to design and fabricate multiple small aircraft wings that have successfully flown.
11:45 AM
Transmitting G-Code with Geometry Commands for Extrusion Additive Manufacturing: Alex Roschli1; Michael Borish1; Liam White1; Cameron Adkins1; Celeste Atkins1; Abigail Barnes1; Brian Post1; Zac DiVencenzo2; Charlie Dwyer2; Gaven Rudiak2; Brian Zellers2; 1Oak Ridge National Laboratory; 2Juggerbot3D
G-code refers to text-based commands used to instruct a 3D printer how to construct an object. G-code is generated to represent each toolpath during the slicing process. Each toolpath is represented as a list of points that define the trajectory of the path to be printed. Additional commands are included to define the motion velocity and extrusion rate, called the feeds and speeds. These toolpaths and commands must be generated specific to the machine, material, and calibration settings that will be used during the print. This paper outlines a new approach for the slicing and g-code creation process that eliminates the need for outputting feeds and speeds in the slicing process. Instead, the slicer outputs g-code that defines the desired bead geometry as printed. The 3D printer can then read this geometry data and calculate the necessary feeds and speeds based on internal calibration data to successfully print the object.