Design and Fabrication of Components with Optimized Lattice Microstructures

The design and fabrication of components with optimized lattice microstructures is a new approach to creating lightweight high-performance objects. This paper introduces a unique and complete integration of design and fabrication leading to the creation of structural components with complex composite microstructures. Rather than a solid cast component with optimized outer shape this new approach leads to a component with an inner skeleton or microstructure maximizing one or more properties such as the stiffness-to-weight ratio. Three dimensional gradient materials are a natural outcome of this approach. An introduction to the design optimization and hybrid fabrication approach will be provided in addition to research progress and challenges through Spring 2004.Mechanical Engineerin

Statistical Process Control For Solid Freeform Fabrication Processes

Statistical prpcess control (SPC) has not been widely used for solid freeform fabrication (SFF) pr~cesses, primarily due to the wide diversity ofgeometries in builds. In addition, typical parts created on SFF platforms are not ofsimple, nor easy-to- measure geometries, which fVrther complicates the application ofSPC. A study is currently in progress to establisq a method to apply SPC to SFF. Three SPC test parts were studied to determine the addedIbuild cost and accuracy improvement when SPC is applied to stereolithography. In this study, SPC was applied to X & Y shrinkage, and line-widthcompensation facto~s over a period oftime. IfSPC can be effectively applied, it will alert the operator to othe~seunnoticed system changes before valuable build-time is lost.Mechanical Engineerin

Geometry and Procedure for Benchmarking SFF and Hybrid Fabrication Process Resolution

Since the advent of SFF and RP a number of SFF benchmarking geometries and methodologies have been developed and employed with some similarities but limited standardization. Minimal information has been published in regard to a standard method of measuring the resolution limits or capabilities of SFF and SFF-based hybrid processes. In an effort to benchmark resolution limits of SFF and Hybrid Fabrication processes, several benchmarking geometries were developed to capture the resolution capabilities, specifically hole size and rod size range, of multiple hybrid fabrication path steps and a hybrid path as a whole. These useful geometries are shared with the SFF community and procedures for their use are described in this paper.Mechanical Engineerin

Indirect Rapid Molds for Prototype Lost-Foam Pattern Production 506

Lost-foam (also known as Expendable Pattern Casting, EPC) is an ever-growing metalmcasting technique, capable of producing complex metal components without parting lines. Mold preparation for lost-foam casting is typically accurate, but expensive and slow. The goal of this research was to develop a new approach for producing rapid lost-foam molds. With this new approach, patterns generated by SFF technology are used to form indirect composite lost-foam molds. Ultimately, our objective is to produce these molds quickly, accurately, and inexpensively. This new approach to lost-foam mold-making will be explained as well as the results of one trial.Mechanical Engineerin

Synthesis of a Compact Tetralattice Heat Exchanger using Solid Freeform Fabrication and Comparison Testing Against a Tube Heat Exchanger

The challenge for Solid Freeform Fabrication (SFF) lies in fabricating complex parts that are not possible by conventional manufacturing means. The goal was to apply SFF techniques to complex geometry heat exchangers. The heat exchanger structure is modeled after the covalently bonded carbon atoms of a diamond. The tetrahedron diamond lattice, or Tetralattice, is a repeating lattice unit that forms a network of channels to form the heat exchanger. Electroforming methods creating Tetralattice were applied to synthesize an air-oil compact heat exchanger. After production, the heat exchanger was tested and compared with an industry standard heat exchanger for performance evaluation.Mechanical Engineerin

Geometry and procedure for benchmarking SFF and hybrid fabrication process resolution

ABSTRACT Since the advent of SFF and RP a number of SFF benchmarking geometries and methodologies have been developed and employed with some similarities but limited standardization. Minimal information has been published in regard to a standard method of measuring the resolution limits or capabilities of SFF and SFF-based hybrid processes. In an effort to benchmark resolution limits of SFF and Hybrid Fabrication processes, several benchmarking geometries were developed to capture the resolution capabilities, specifically hole size and rod size range, of multiple hybrid fabrication path steps and a hybrid path as a whole. These useful geometries are shared with the SFF community and procedures for their use are described in this paper

The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH)

The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) had a Special Observing Period (SOP) that ran from November 16, 2018 to February 15, 2019, a period chosen to span the austral warm season months of greatest operational activity in the Antarctic. Some 2200 additional radiosondes were launched during the 3-month SOP, roughly doubling the routine program, and the network of drifting buoys in the Southern Ocean was enhanced. An evaluation of global model forecasts during the SOP and using its data has confirmed that extratropical Southern Hemisphere forecast skill lags behind that in the Northern Hemisphere with the contrast being greatest between the southern and northern polar regions. Reflecting the application of the SOP data, early results from observing system experiments show that the additional radiosondes

Net Shape Composites Using SLA Tetracast Patterns

Net-shape composites have been a focus of Solid Freeform Fabrication (SFF) for a number of years. A new method to achieve net-shape composites uses hollow Stereolithography (SLA) TetraCast* patterns. The TetraCast* pattern is injected with a filler material consisting of a matrix (typically epoxy) and reinforcement fibers, flakes, andlor particles. Upon solidification ofthe injected matrix, the net-shape composite is achieved. Net-shape composites are ideal for custom manufacturing due to the virtually limitless geometry capabilities of SLA. Areas such as aerospace, medical, manufacturing, and others could someday benefit from this process. Research to date has shown this composite structure to follow the "rule ofmixtures." It has also been shown that heat-deflection, elasticmodulus, and tensile-strength can be enhanced andlor predicted in the composite material. Several areas of continuing research include: viscosity limitations, stair-step notch reduction, reinforcement combinations, shrinkage prediction, cooling methods, SLA skin removal, nextgeneration TetraCast* structures, wear-resistant coatings, process automation, and TetraCast* pattern fill methods.Mechanical Engineerin

Reduction of Complex Objects into Manufacturable Elements Using the Shell-Slice Approach

Software tools for generating a parting surface around a molded part have been available for many years and could be of use for additive fabrication of complex objects. This paper explores the use of software tools such as Materialise Magics Tooling TM and SolidWorks® software to assist in reducing complex objects, such as a lattice structure, into sub-elements free of undercuts and hidden internal geometry. The objective of the proposed Shell-Slice approach is to decompose an object into elements that can be readily machined and created via hybrid fabrication processes. The appeal of hybrid fabrication combined with an automated Shell-Slice approach, is the machinability of each sub-element parting-surface and the remarkable build-speeds and surface-finishes that may be attainable.Mechanical Engineerin

Additively Manufactured Flexible Fluidic Actuators For Precision Control in Surgical Applications

Previously, the Milwaukee School of Engineering (MSOE) demonstrated a dexterous tele-operational robotic system where actuators, joints, and linkages were fabricated simultaneously using Selective Laser Sintered Nylon 12. Primary motivation for this research was to conceive novel fluid power actuators that were inherently safe, compact, and Magnetic Resonance Imaging (MRI) compatible for surgery and rehabilitation. Although the concept of fabricating MRI compatible fluid power devices was demonstrated, further proof of precision control was needed. The design and implementation of additively manufactured flexible fluidic actuators (AMFFA) for precision control, best practices, and the comparison of these actuators with other actuation technologies are presented.Mechanical Engineerin