Design of a Cable-Driven Manipulator for Large-Scale Additive Manufacturing

Additive manufacturing of concrete is a growing field of research, yet current motion platforms do not offer viable routes towards large scale deployable systems. This thesis presents the design and analysis of a novel cable-driven robot for use in large scale additive manufacturing. The system developed, termed SkyBAAM, is designed to be easily deployable to a construction site for on-site additive manufacturing of buildings and other large structures. The design philosophy behind this system is presented. Analysis of this system first explores the kinematics, and stiffness as a function of cable tension. Analysis of the workspace and singularities is also performed, and scaling laws for the system are examined. A prototype system that was built at ORNL is presented, and data from this system shows is suitability for large-scale printing. In order to scale this out to full-size deployment there are, however, challenges associated with scaling and workspace shape that are identified as targets for future research. However, the success of this system demonstrates the feasibility of cable-driven robots for large, deployable additive manufacturing systems

D-β-Hydroxybutyrate Is Protective in Mouse Models of Huntington's Disease

Abnormalities in mitochondrial function and epigenetic regulation are thought to be instrumental in Huntington's disease (HD), a fatal genetic disorder caused by an expanded polyglutamine track in the protein huntingtin. Given the lack of effective therapies for HD, we sought to assess the neuroprotective properties of the mitochondrial energizing ketone body, D-β-hydroxybutyrate (DβHB), in the 3-nitropropionic acid (3-NP) toxic and the R6/2 genetic model of HD. In mice treated with 3-NP, a complex II inhibitor, infusion of DβHB attenuates motor deficits, striatal lesions, and microgliosis in this model of toxin induced-striatal neurodegeneration. In transgenic R6/2 mice, infusion of DβHB extends life span, attenuates motor deficits, and prevents striatal histone deacetylation. In PC12 cells with inducible expression of mutant huntingtin protein, we further demonstrate that DβHB prevents histone deacetylation via a mechanism independent of its mitochondrial effects and independent of histone deacetylase inhibition. These pre-clinical findings suggest that by simultaneously targeting the mitochondrial and the epigenetic abnormalities associated with mutant huntingtin, DβHB may be a valuable therapeutic agent for HD

Creating Toolpaths Without Starts and Stops for Extrusion-Based Systems

Toolpath generation for extrusion-based additive manufacturing systems, called slicing, involves operations on polygonal contours that are derived from an STL file. Slicing generates multiple paths per layer (both closed-loop and open-loop) that are designed to optimally fill the space outlined by the polygon(s). In the course of printing a layer, the extruder must start and stop, the tip must be wiped, and the extruder must travel between paths without printing. Any amount of time the printer spends moving without printing is considered wasted time because the part isn’t being constructed. In addition, the start/stop point, known as the seam, is often a blemish on the surface of the part that contributes to weaker material properties. Therefore, a single path for creating multi-bead walled structures is desirable because it would save machine time and create parts with better surface finish. This paper will cover one method of modifying the CAD file and slicing engine to allow for parts to be printed without starting and stopping the extruder.Mechanical Engineerin

Changing Print Resolution on BAAM via Selectable Nozzles

Big Area Additive Manufacturing (BAAM) is an additive manufacturing (AM) technique that rapidly deposits polymer to fabricate large components. However, the increase in deposition rates leads to a decrease in resolution and a consequent decline in part surface finish. A novel technique has been developed where the nozzle diameter can be changed mid-print using a poppet nozzle selector. With this technique, a course resolution can be employed to rapidly fabricate the interior of a part, while a fine resolution can be used on the surface. This allows for improved surface quality and resolution without significantly increasing print time. This work will explain the development of the selectable nozzle and integration with the BAAM system to produce selective high-resolution surfaces on parts.Mechanical Engineerin

Reverse Engineering a Transhumeral Prosthetic Design for Additive Manufacturing

The customization and time savings additive manufacturing (AM) offers has been applied to construct prosthetics. However, prosthetics produced using AM rarely resemble the original appendage they are intended to replace. This report details the engineering of a transhumeral prosthetic design for AM. A 3D scan of a subject’s existing arm and computer-aided design (CAD) were used to create a mirrored prosthetic, which appeared aesthetically like the existing arm. The process and complexities of integrating mechanical components for basic actuation into a patient-custom prosthetic are discussed. A simple demonstration of the process is provided. The same methodology can be applied to more intricate prosthetics. This work aims to inspire subsequent research into well-functioning, custom prosthetics that can be generated relatively quickly through 3D scanning and AM.Mechanical Engineerin

Build Plate Design for Extrusion-Based Additive Manufacturing

A fundamental part of machine design for large format polymer extrusion-based additive manufacturing (AM) systems is the substrate where the object is to be constructed, often referred to as the build plate. A good build plate is imperative for a successful build as it is used for supporting and positioning the part during the entire construction. For planar 3D printing, this build plate needs to be flat and in-plane with the X/Y motion of the 3D printer. Additional functionality can include heaters for preventing delamination or warping, vacuum to help prevent warping, removable build surfaces for quick part removal, and mounting features for helping position a part for subtractive operations. This paper reviews existing build plate designs and discusses the design considerations and materials for build plate fabrication.Mechanical Engineerin

Large Format Composite Additive Manufacturing for Low-Head Hydropower

ABSTRACT: Hydropower with a small elevation change from inlet to outlet, known as “low-head” hydropower, is a relatively untapped resource for reliable green power generation. One major barrier to entry is the cost of the components needed to generate the power. Each installation site is unique, with various head levels, flow rates, and other unique site characteristics that drive up the cost of development and installation. As a result, custom-made components are necessary because the sites are intrinsically inefficient. However, customized parts are generally more expensive to manufacture than ready-made parts. Often times, the cost of custom-made components is so high that the low-head hydropower installation becomes non-viable. Additive manufacturing offers the ability to make custom components, ideal for one-off applications, at low costs that are well suited for the needs of low-head hydropower. Indirect additive manufacturing, such as making tools or dies rather than end use components, can also be used to make low-cost composite tooling as needed for these custom applications. This paper explores the use of additive manufacturing, both directly and indirectly, to produce the components of a turbine system for a low-head hydropower site. The parts were designed to form a unique modular system, which saves time for future designs and iterations. The system has operated for more than three years without failure at a test site in Wisconsin, USA. This work serves as a basis for future application of AM to low-head systems, in which the modular components can be customized for each unique hydropower installation

Wire Co-Extrusion with Big Area Additive Manufacturing

Oak Ridge National Laboratory’s Manufacturing Demonstration Facility is developing a system that will deposit and embed conductive and resistive elements within a printed bead of material. The system was implemented on a Big Area Additive Manufacturing (BAAM) system using a co-extruding nozzle. It has already been demonstrated that BAAM is useful for the tooling industry, but this could be a great improvement on an established application of BAAM parts. This system will provide the ability to control and monitor the surface of additively manufactured (AM) parts. It will also enable self-heating surfaces of AM parts, which is particularly useful in tooling applications. This system could even be used in the future for embedding other materials not found in pellet form in BAAM parts. This work will cover the development of the co-extrusion system and its integration with the dual-port nozzle and the BAAM system.Mechanical Engineerin

SkyBAAM Large-Scale Fieldable Deposition Platform System Architecture

Oak Ridge National Laboratory (ORNL) is currently developing a concrete deposition system for infrastructure-scale printed objects. This system, called SkyBAAM, uses a cable driven motion platform to manipulate the print head. This work focuses on the general aspects of the system architecture, including arrangement of the cable driven platform, general high-level control methodology, and system accuracy, along with concrete deposition methods. Results and demonstration prints will be shown.Mechanical Engineerin

Precast Concrete Models Fabricated with Big Area Additive Manufacturing

The traditional process of making precast concrete molds requires significant manual labor. The molds are made using hardwood, cost tens of thousands of dollars, and take weeks to build. Once built, a mold will last 5-10 pulls before becoming too heavily degraded to continue use. With additive manufacturing, the same mold can be built in eight hours, post-machined in eight hours, costs about $9000, and is projected to last nearly 200 pulls. Oak Ridge National Laboratory has been working with Big Area Additive Manufacturing (BAAM) to fabricate concrete molds for a new high-rise apartment complex in New York. The molded pieces will form structural window supports for the hundreds of windows in building façade. The magnitude of window molds is where additive manufacturing can shine when producing the geometry. This paper will discuss the methods and findings of using BAAM to replace conventional precast concrete pattern making.Mechanical Engineerin