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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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NASA Computer Model Reveals Carbon Dioxide Levels

An ultra-high-resolution NASA computer model has given scientists a stunning new look at how carbon dioxide in the atmosphere travels around the globe.Plumes of carbon dioxide in the simulation swirl and shift as winds disperse the greenhouse gas away from its sources. The simulation also illustrates differences in carbon dioxide levels in the northern and southern hemispheres, and distinct swings in global carbon dioxide concentrations as the growth cycle of plants and trees changes with the seasons.Scientists have made ground-based measurements of carbon dioxide for decades and in July NASA launched the Orbiting Carbon Observatory-2 (OCO-2) satellite to make global, space-based carbon observations. But the simulation — the product of a new computer model that is among the highest-resolution ever created — is the first to show in such fine detail how carbon dioxide actually moves through the atmosphere.In addition to providing a striking visual description of the movements of an invisible gas like carbon dioxide, as it is blown by the winds, this kind of high-resolution simulation will help scientists better project future climate. Engineers can also use this model to test new satellite instrument concepts to gauge their usefulness. The model allows engineers to build and operate a “virtual” instrument inside a computer.SourceAlso: Learn about the NASA Data Acquisition System (NDAS).

Posted in: Electronics & Computers, Environmental Monitoring, Green Design & Manufacturing, Greenhouse Gases, Software, Test & Measurement, Measuring Instruments, Aerospace, News

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Ocean Gliders Measure Melting Polar Ice

The rapidly melting ice sheets on the coast of West Antarctica are a potentially major contributor to rising ocean levels worldwide. Although warm water near the coast is thought to be the main factor causing the ice to melt, the process by which this water ends up near the cold continent is not well understood. Using robotic ocean gliders, Caltech researchers have now found that swirling ocean eddies, similar to atmospheric storms, play an important role in transporting these warm waters to the Antarctic coast—a discovery that will help the scientific community determine how rapidly the ice is melting and, as a result, how quickly ocean levels will rise. "When you have a melting slab of ice, it can either melt from above because the atmosphere is getting warmer or it can melt from below because the ocean is warm," explains lead author Andrew Thompson, assistant professor of environmental science and engineering. "All of our evidence points to ocean warming as the most important factor affecting these ice shelves, so we wanted to understand the physics of how the heat gets there." Because the gliders are small—only about six feet long—and are very energy efficient, they can sample the ocean for much longer periods than large ships can. When the glider surfaces every few hours, it "calls" the researchers via a mobile phone–like device located on the tail. The communication allows the researchers to almost immediately access the information the glider has collected. Like airborne gliders, the bullet-shaped ocean gliders have no propeller; instead they use batteries to power a pump that changes the glider's buoyancy. When the pump pushes fluid into a compartment inside the glider, the glider becomes denser than seawater and less buoyant, thus causing it to sink. If the fluid is pumped instead into a bladder on the outside of the glider, the glider becomes less dense than seawater—and therefore more buoyant—ultimately rising to the surface. Like airborne gliders, wings convert this vertical lift into horizontal motion. Source Also: Learn about Remote Sensing of Ice Sheets and Snow.

Posted in: Batteries, Electronics & Computers, Environmental Monitoring, Green Design & Manufacturing, Motion Control, Test & Measurement, Measuring Instruments, Monitoring, Communications, Machinery & Automation, Robotics, News

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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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Sensors Monitor Dangerous Hits on the Football Field

In football, a tackle can supply 100 Gs of force or more, well above the amount that can cause a concussion and more than 10 times the force of an F‑16 jet roll maneuver. University of Florida (UF) researchers are using the helmets of Gator football players to help measure the force of on‑field hits to better understand and prevent concussions, and treat them before they cause lasting damage.

Posted in: Sensors, Medical, Patient Monitoring, Test & Measurement, Monitoring, News

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Space-Based Instrument Monitors Plant Health

A new space‑based instrument to study how effectively plants use water is being developed at NASA's Jet Propulsion Laboratory. The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) will monitor one of the most basic processes in living plants: the loss of water through the tiny pores in leaves, or transpiration. ECOSTRESS will measure combined evaporation and transpiration, known as evapotranspiration, from the International Space Station.

Posted in: Environmental Monitoring, Green Design & Manufacturing, Greenhouse Gases, Test & Measurement, Monitoring, Aerospace, News

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Harness-Mounted Computer Improves Communication Between Dogs and Humans

North Carolina State University researchers have developed a suite of technologies that can be used to enhance communication between dogs and humans. The communication tool enables applications in search-and-rescue operations and pet training. “We’ve developed a platform for computer-mediated communication between humans and dogs that opens the door to new avenues for interpreting dogs’ behavioral signals and sending them clear and unambiguous cues in return,” says Dr. David Roberts, an assistant professor of computer science at NC State and co-lead author of a paper on the work. “We have a fully functional prototype, but we’ll be refining the design as we explore more and more applications for the platform.”The platform itself is a harness that fits comfortably onto the dog, and which is equipped with a variety of technologies.“Dogs communicate primarily through body language, and one of our challenges was to develop sensors that tell us about their behavior by observing their posture remotely,” Roberts says. “So we can determine when they’re sitting, standing, running, etc., even when they’re out of sight." A harness-mounted computer transmits data wirelessly. The technology also includes physiological sensors that monitor things like heart rate and body temperature. The sensors not only track a dog’s physical well-being, but can offer information on a dog’s emotional state, such as whether it is excited or stressed.SourceAlso: Learn about a Communication Monitoring System for Enhanced Situational Awareness.

Posted in: Electronics & Computers, Sensors, Test & Measurement, Monitoring, Communications, Wireless, News

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