Materials

Inspired by Nature, Researchers Build a Tougher Metal

Drawing inspiration from the structure of bones and bamboo, researchers have gradually changed the internal structure of metals to make stronger, tougher materials. The new metals can be customized for a wide variety of applications — from body armor to automobile parts. The research team tested the new approach in interstitial free (IF) steel, which is used in some industrial applications.If conventional IF steel is made strong enough to withstand 450 megapascals (MPa) of stress, it has very low ductility – the steel can only be stretched to less than 5 percent of its length without breaking. Low ductility means a material is susceptible to catastrophic failure, such as suddenly snapping in half. Highly ductile materials can stretch, meaning they are more likely to give people time to respond to a problem before total failure.The researchers are also interested in using the gradient structure approach to make materials more resistant to corrosion, wear, and fatigue.SourceAlso: Find more Materials tech briefs.

Posted in: Materials, Metals, Transportation, Automotive, Defense, News

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Morphable Surfaces Reduce Air Resistance

A morphable surface developed by an MIT team can change surface texture — from smooth to dimpled, and back again — through changes in pressure. When the inside pressure is reduced, the flexible material shrinks, and the stiffer outer layer wrinkles. Increasing pressure returns the surface to a smooth state. Adding golf ball-like dimples to surfaces could reduce drag and improve efficiency of vehicles.The ability to change the surface in real time comes from the use of a multilayer material with a stiff skin and a soft interior — the same basic configuration that causes smooth plums to dry into wrinkly prunes. To mimic that process, the team made a hollow ball of soft material with a stiff skin — with both layers made of rubberlike materials — then extracted air from the hollow interior to make the ball shrink and its surface wrinkle.Because the surface texture can be controlled by adjusting the balls’ interior pressure, the degree of drag reduction can be controlled at will. “We can generate that surface topography, or erase it,” said MIT’s Pedro Reis. “That reversibility is why this is pretty interesting; you can switch the drag-reducing effect on and off, and tune it.”Many researchers have studied various kinds of wrinkled surfaces, with possible applications in areas such as adhesion, or even unusual optical properties. “But we are the first to use wrinkling for aerodynamic properties,” said Reis.SourceAlso: Learn about other innovative Materials and Coatings.

Posted in: Materials, Coatings & Adhesives, Transportation, Automotive, News

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'Sensing Skin' Detects Damage in Concrete Structures

Researchers from North Carolina State University and the University of Eastern Finland have developed new “sensing skin” technology designed to serve as an early warning system for concrete structures, allowing authorities to respond quickly to damage in everything from nuclear facilities to bridges.“The sensing skin could be used for a wide range of structures, but the impetus for the work was to help ensure the integrity of critical infrastructure such as nuclear waste storage facilities,” says Dr. Mohammad Pour-Ghaz, an assistant professor of civil, construction and environmental engineering at NC State and co-author of a paper describing the work.The skin is an electrically conductive coat of paint that can be applied to new or existing structures. The paint can incorporate any number of conductive materials, such as copper, making it relatively inexpensive.Electrodes are applied around the perimeter of a structure. The sensing skin is then painted onto the structure, over the electrodes. A computer program then runs a small current between two of the electrodes at a time, cycling through a number of possible electrode combinations.Every time the current runs between two electrodes, a computer monitors and records the electrical potential at all of the electrodes on the structure. This data is then used to calculate the sensing skin’s spatially distributed electrical conductivity. If the skin’s conductivity decreases, that means the structure has cracked or been otherwise damaged.The researchers have developed a suite of algorithms that allow them to both register damage and to determine where the damage has taken place.SourceAlso: Learn about Designing Composite Repairs and Retrofits for Infrastructure.

Posted in: Electronics & Computers, Electronic Components, Electronics, Materials, Sensors, Detectors, Test & Measurement, Communications, Semiconductors & ICs, News

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New Strain Gauge Enables 'Soft Machines'

Purdue University researchers have developed a technique to embed a liquid-alloy pattern inside a rubber-like polymer to form a network of sensors. The approach may be used to produce "soft machines" made of elastic materials and liquid metals.Such an elastic technology could be used to create robots with sensory skin, as well as develop stretchable garments that interact with computers."What's exciting about the soft strain gauge is that it can detect very high strains and can deform with almost any material," said Rebecca Kramer, an assistant professor of mechanical engineering at Purdue University. "The skin around your joints undergoes about 50 percent strain when you bend a limb, so if you wanted to have sensory skin and wearable technology that tracks your movement you need to employ soft, stretchable materials that won't restrict your natural range of motion."SourceAlso: Learn about Thermal Properties of Microstrain Gauges.

Posted in: Materials, Metals, Plastics, Motion Control, Sensors, Machinery & Automation, Robotics, News

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Engineers Develop Ultrastiff, Ultralight Material

Engineers at MIT and Lawrence Livermore National Laboratory (LLNL) have developed a new ultrastiff, ultralight material. The material is based on the use of microlattices with nanoscale features, combining great stiffness and strength with ultralow density. The actual production of such materials is made possible by a high-precision 3-D printing process called projection microstereolithography.By using the right mathematically determined structures to distribute and direct the loads — the way the arrangement of vertical, horizontal, and diagonal beams do in a structure like the Eiffel Tower — the lighter structure can maintain its strength."We found that for a material as light and sparse as aerogel [a kind of glass foam], we see a mechanical stiffness that’s comparable to that of solid rubber, and 400 times stronger than a counterpart of similar density. Such samples can easily withstand a load of more than 160,000 times their own weight,” said Associate Professor Nick Fang. SourceAlso: See other Materials and Coatings tech briefs.

Posted in: Manufacturing & Prototyping, Rapid Prototyping & Tooling, Materials, Nanotechnology, News

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Thin Films Self-Assemble in One Minute

Researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) have devised a technique whereby self-assembling nanoparticle arrays can form a highly ordered thin film over macroscopic distances in one minute.

Posted in: Electronics & Computers, Electronic Components, Photonics, Optics, Manufacturing & Prototyping, Materials, Coatings & Adhesives, Composites, Nanotechnology, News

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New Way To Make Sheets Of Graphene Discovered

Graphene's promise as a material for new kinds of electronic devices, among other uses, has led researchers around the world to study the material in search of new applications. But one of the biggest limitations to wider use of the strong, lightweight, highly conductive material has been the hurdle of fabrication on an industrial scale.

Posted in: Electronics & Computers, Electronic Components, Materials, Coatings & Adhesives, Solar Power, Energy, Semiconductors & ICs, News

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