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Researchers Measure Stress in 3D-Printed Metal Parts

Lawrence Livermore National Laboratory researchers have developed an efficient method to measure residual stress in metal parts produced by powder-bed fusion additive manufacturing (AM).The 3D-printing process produces metal parts layer by layer using a high-energy laser beam to fuse metal powder particles. When each layer is complete, the build platform moves downward by the thickness of one layer, and a new powder layer is spread on the previous layer.While the method produces quality parts and components, residual stress is a major problem during the fabrication process. Large temperature changes near the last melt spot, and the repetition of this process, result in localized expansion and contraction.An LLNL research team, led by engineer Amanda Wu, has developed an accurate residual stress measurement method that combines traditional stress-relieving methods (destructive analysis) with modern technology: digital image correlation (DIC). The process provides fast and accurate measurements of surface-level residual stresses in AM parts.The team used DIC to produce a set of quantified residual stress data for AM, exploring laser parameters. DIC is a cost-effective, image analysis method in which a dual camera setup is used to photograph an AM part once before it’s removed from the build plate for analysis and once after. The part is imaged, removed, and then re-imaged to measure the external residual stress.SourceAlso: Learn about Design and Analysis of Metal-to-Composite Nozzle Extension Joints.

Posted in: Cameras, Imaging, Photonics, Lasers & Laser Systems, Manufacturing & Prototyping, Rapid Prototyping & Tooling, Materials, Metals, Test & Measurement, Measuring Instruments, News

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Virtual Prototyping: Visualizing the Next Generation of Products

The Department of Defense defines a virtual prototype as “A computer-based simulation of a system or subsystem with a degree of functional realism comparable to a physical prototype.” A virtual prototype is built from CAD drawings of separate assemblies that are gradually placed into the whole. Since the drawings of each subassembly are detailed and accurate, you can accurately assess their form (overall shape), fit (ease of as- sembly), and function (making sure it performs as specified). In addition to these traditional three Fs, the virtual prototype can be used for motion studies and studying interactions be- tween the machine and the humans who will use it. Once the design is complete, you can use the digital model to see whether parts interfere as you move them through their com- plete range of motion. In the past, design and analysis have been separate tasks, performed by different teams. With virtual prototyping, these functions are completely entwined.

Posted in: Manufacturing & Prototyping, White Papers

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High-Res Line Camera Measures Magnetic Fields in Real Time

Scientists have developed a high‑resolution magnetic line camera to measure magnetic fields in real time. Field lines in magnetic systems such as generators or motors that are invisible to the human eye can be made visible using this camera. It is especially suitable for industrial applications in quality assurance during the manufacture of magnets.

Posted in: Cameras, Imaging, Manufacturing & Prototyping, Sensors, Test & Measurement, Measuring Instruments, News

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3D Printing and the Future of Manufacturing

3D printing is transforming the manufacturing industry in big ways. From realized design freedom to supply chain efficiencies, 3D printing is contributing largely to the recent upswing in reshoring manufacturing in North America. Read the latest white paper from Stratasys Service Bureaus to learn how 3D printing will continue to transform the industry in the coming years.

Posted in: Manufacturing & Prototyping, White Papers

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Design and Analysis of Metal-to-Composite Nozzle Extension Joints

A design concept and subcomponent are identified that mitigate the stress associated with the coefficient-of-thermal mismatch. Marshall Space Flight Center, Alabama Analysis, design, fabrication, and testing were performed to create a new joint design for potential use in attaching a domestically available carbon-carbon (C–C) nozzle extension to the turbine exhaust manifold of a J-2X engine. Various attachment methods were investigated for a C–C-to-metallic joint, including the use of higher-thermal-expansion ceramic matrix composites both mechanically attached and also integrally fabricated to the C–C nozzle extension. The goal was to determine the advantages and disadvantages of different material and joint systems in order to converge on a design for a domestic joint and nozzle extension design that resulted in all positive margins of safety.

Posted in: Manufacturing & Prototyping, Briefs

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Modeling Laser Ablation and Plume Chemistry in a Boron Nitride Nanotube Production Rig

Langley Research Center, Hampton, Virginia The future of manned and unmanned spaceflight and exploration depends on economical access to space through multifunctional, lightweight materials. Boron nitride nanotube (BNNT) composites offer distinct advantages for enhanced survivability during long-term flights. A production technique has been developed to manufacture BNNTs that implements laser energy deposition on a boron sample in a pressurized test rig.

Posted in: Manufacturing & Prototyping, Briefs

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Damage-Free Finishing of Silicon X-Ray Optics Using Magnetic Field-Assisted Finishing

Goddard Space Flight Center, Greenbelt, Maryland Thin, segmented mirrors have been fabricated from monocrystalline silicon blocks. The material is economically viable, and is virtually free of internal stress because of its nearly perfect crystalline structure. The mirror surfaces will first be accurately figured and finished on thick silicon blocks, then sliced off at the desired thickness by wire electro-discharge machining. A finishing process has been conceived in which existing mirror-finishing processes are adapted to be capable of quickly and accurately figuring and finishing damage-free, segmented, monocrystalline silicon mirrors in a cost-efficient manner.

Posted in: Manufacturing & Prototyping, Briefs

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