Special Coverage

Applying the Dynamic Inertia Measurement Method to Full-Scale Aerospace Vehicles
Method and Apparatus for Measuring Surface Air Pressure
Fully Premixed, Low-Emission, High-Pressure, Multi-Fuel Burner
Self-Healing Wire Insulation
Thermomechanical Methodology for Stabilizing Shape Memory Alloy (SMA) Response
Space Optical Communications Using Laser Beams
High Field Superconducting Magnets

Epoxy-based Hermetic Feedthroughs Boost Switchgear Reliability

With medium-voltage switchgear, progress is being made with regard to finding alternatives to SF6 as an insulation gas. Designs that incorporate dry air or a mixture of fluoroketone, nitrogen and oxygen as the insulating gas are being explored to minimize environmental impact.

Posted in: White Papers, Aerospace, Defense, Mechanical Components, Mechanics


Lattice structure absorbs vibrations

Strong vibrations from a bus engine can be felt uncomfortably through the seats. Similarly, vibrations from the propellers or rotors in propeller aircraft and helicopters can make the flight bumpy and loud. They also lead to increased fatigue damage of the aircraft and its components. Engineers have therefore sought to prevent such vibrations in machines, vehicles, and aircraft. A new three-dimensional lattice structure developed by ETH scientists could now expand the possibilities of vibration absorption. Led by Chiara Daraio, Professor of Mechanics and Materials, the researchers made the structure with a lattice spacing of around 3.5 mm out of plastic using a 3D printer. Inside the lattice they embedded steel cubes that are somewhat smaller than dice and act as resonators. "Instead of the vibrations traveling through the whole structure, they are trapped by the steel cubes and the inner plastic grid rods, so the other end of the structure does not move," explains Kathryn Matlack, a postdoc in Daraio's group.The vibration-absorbing structure is rigid and thus can be used as a load-bearing component in rotors and propellers. It also offers another advantage. Compared to existing soft absorption materials, it can absorb a much wider range of vibrations, both fast and slow, and is particularly good at absorbing relatively slow vibrations. "The structure can be designed to absorb vibrations with oscillations of a few hundred to a few tens of thousand times per second (Hertz)," says Daraio. "This includes vibrations in the audible range. In engineering practice, these are the most undesirable, as they cause environmental noise pollution and reduce the energy efficiency of machines and vehicles."In theory, it would be possible to build such a construction out of aluminum and other lightweight metals instead of plastic, says Matlack. In principle, it would just require a combination of lightweight material, structured in a lattice geometry, and embedded resonators with a larger mass density. The geometry of the lattice structure and the resonators would need to be optimally aligned to the anticipated vibrations.The vibration absorbers are essentially ready for technical applications, says Matlack, but they are limited insofar as 3D printing technology is mostly geared toward small-scale production, and material properties, such as the load-bearing capacity, cannot yet match those of components manufactured with traditional methods. Once this technology is ready for industrial use, there is nothing standing in the way of a broader application. A further application could be in wind turbine rotors, where minimizing vibrations would increase efficiency. The technology could also conceivably be used in vehicle and aircraft construction as well as rockets.

Posted in: News, Aerospace


Carbon nanotube 'stitches' make stronger, lighter composites

The newest Airbus and Boeing passenger jets flying today are made primarily from advanced composite materials such as carbon fiber reinforced plastic – extremely light, durable materials that reduce the overall weight of the plane by as much as 20 percent compared to aluminum-bodied planes. Such lightweight airframes translate directly to fuel savings, which is a major point in advanced composites' favor.But composite materials are also surprisingly vulnerable: While aluminum can withstand relatively large impacts before cracking, the many layers in composites can break apart due to relatively small impacts – a drawback that is considered the material's Achilles' heel.Now MIT aerospace engineers have found a way to bond composite layers in such a way that the resulting material is substantially stronger and more resistant to damage than other advanced composites.The researchers fastened the layers of composite materials together using carbon nanotubes – atom-thin rolls of carbon that, despite their microscopic stature, are incredibly strong. They embedded tiny "forests" of carbon nanotubes within a glue-like polymer matrix and then pressed the matrix between layers of carbon fiber composites. The nanotubes, resembling tiny, vertically aligned stitches, worked themselves within the crevices of each composite layer, serving as a scaffold to hold the layers together.In experiments to test the material's strength, the team found that, compared with existing composite materials, the stitched composites were 30 percent stronger, withstanding greater forces before breaking apart.Roberto Guzman, who led the work as an MIT postdoc in the Department of Aeronautics and Astronautics (AeroAstro), says the improvement may lead to stronger, lighter airplane parts – particularly those that require nails or bolts, which can crack conventional composites."More work needs to be done, but we are really positive that this will lead to stronger, lighter planes," says Guzman, who is now a researcher at the IMDEA Materials Institute in Spain. "That means a lot of fuel saved, which is great for the environment and for our pockets."

Posted in: News, Aviation


Quality Driven: Automotive Display Testing

Instrumentation, information, navigation and entertainment systems have moved to fully graphical, touch-enhanced displays, and customers expect the quality of these displays to be on par with that of their consumer electronics. Makers of in-vehicle displays must keep pace with improvements in display quality, increasing screen sizes, and higher resolutions. Quality inspection of these displays faces a unique set of challenges. They will be viewed in widely varied lighting and must withstand harsh environmental conditions. Detection of subtle flaws that could worsen as a result of these circumstances is critical to ensuring a high quality display throughout the lifespan of the vehicle.

Posted in: On-Demand Webinars, Automotive, Software


Achieving Reliable Inline Measurements in Production Environments

One of the most important changes in metrology in the past few decades has been the development of portable measuring devices. This has brought inspection right to the production line, as close to the part as possible. The change—sparked by the development of portable measuring arms and the emergence of laser trackers—has turned conventional industry inspection methods completely upside down.

Posted in: White Papers, Manufacturing & Prototyping, Software, Test & Measurement


New System Allows Buildings to 'Sense' Internal Damage

Researchers at the Massachusetts Institute of Technology have developed a computational model that makes sense of the ambient vibrations that travel up a structure as trucks and other forces rumble by. By picking out specific features in the noise that give indications of a building’s stability, the model may be used to continuously monitor a building for signs of damage or mechanical stress.

Posted in: News, Data Acquisition, Detectors, Sensors


Automotive Industry Cybersecurity Assurance Testing Methods and Tools

In Conjunction with SAEIn 2015 the automotive industry began discussing the need for consistent cybersecurity testing requirements for verifying and validating that the security controls being implemented in modern automobiles are indeed providing a measurable level of cybersecurity assurance. These discussions eventually led to the formation of the Cybersecurity Assurance Testing Task Force under SAE, which is comprised of members from the automobile OEM community, suppliers, cybersecurity testing experts, government officials, and general security experts. Since inception the task force has worked diligently and has drafted multiple working documents. This 30-minute Webinar provides an overview of the working group’s activities and progress.

Posted in: On-Demand Webinars


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