The Future is Here: Morphable Skins

https://i1.wp.com/www.m25audi.co.uk/images/audi/technology/aerodynamics.jpgTomorrow’s cars could have a feature that will reduce wind drag and allow them to go faster: smart, morphing skins that form dimples or go smooth on command. It is all part of a growing field of mechanics that seeks to make surfaces “smart”, and it is being considered for everything from increasing aerodynamics to reducing the damage caused by hurricanes and high winds.

The research comes from MIT, where engineers have developed a smart curved surface that can morph at will to reduce drag. Known as a “smorph” (short for smart morphable surface), they were able to get their creation to wrinkle into a dimpled pattern similar to a golf ball’s, with similar aerodynamic properties. In short, when the smorph wrinkles, it is able to travel faster than if it were smooth.

smorphScientists and golfers alike have long known that the dimples on the surface of a golf ball allow it to drastically reduce drag and travel much farther than would otherwise be possible. This happens because the small dents hold the airflow near the surface of ball for a longer time. This reduces the size of the wake, or zone of turbulence, as the ball takes off. However, the mechanics employed here are a bit more complex.

In recent years, in-depth aerodynamic studies have shown that the dimples reduce drag only at lower speeds. As you move toward faster speeds, the advantage of irregularities disappears and a smooth surface becomes the best way to minimize the wake. Now, researchers at MIT have married the best of both worlds by developing a surface that can it’s smoothness on the fly to maximize aerodynamic efficiency at all speeds.

Smorph_0The smorph manages to change its shape by changing the balance between its materials. Basically, an empty core is surrounded by two different polymers. One is thick and squishy, while the outermost layer is stiff skin. As the volume of  a the inner layer is reduced by sucking air out of its hollow core, the core shrinks. The squishy layer is soft enough to contract smoothly, but the skin is forced to wrinkle. The trick is controlling exactly how a smorph wrinkles.

Because the dimples look so much like those on a golf ball’s surface, the researchers were inspired to test their creation in a wind tunnel. Sure enough, when the researchers tested the smorph in a wind tunnel, they found that it was about twice as aerodynamically efficient when dimpled. But the sheath of vortices only form at relatively low speeds, and then convert back to a smooth surface at higher speeds in order to maintain aerodynamic velocity.

smorph_1This is where smorphs could offer a huge advantage. By being able to morph to control drag, they could be especially useful in building structures that won’t collapse or incur significant damage when facing very high winds – one example being the so-called radomes, the spherical, weatherproof domes that enclose radar antennas. The researchers also say that the materials could also be used to minimize drag in cars in order to maximize fuel efficiency.

Earlier this year, Reis won an NSF grant to keep developing smorphs, which he hopes to someday scale up to use on cars, aircraft, and even buildings. There are some issues to overcome before this happens though, such as the fact that hexagonal dimples are unstable on flat surfaces. So far smorphs have only been used on a round, ball shape, but Reis and his co-authors believe they can figure out how to reproduce the pattern on slightly curved surfaces.

Alongside such concepts as morphing wings and self-adjusting and reconfigurable robots, the creation of surfaces that can change shape in order to better accommodate airflow, or be optimal for different tasks, is part of the manufacturing revolution that seeks to replace rigid structures and products with something that can adapt, flow and transform depending on what is being asked of it.

And be sure to check out this video from MIT of the smorph in action:


Sources:
wired.com, gizmag.com

The Future of Flight: Morphing Wings

morphing-wingsSince the Wright Brothers developed the world’s first airplane, scientists and aerospace engineers have understood how important airflaps and wing design are to ensuring that a plane is able to achieve lift and land safely. During and after World War II, additional lessons were learned, where the sweep of a wing was found to be central to a plane achieving higher service ceilings and air speed velocities.

Since that time, many notable improvements have been made, but some strictures have remained the same. For example, conventional wings suffer from the problem of being fixed in a single position, which makes some aspects of performance possible but other things extremely difficult. In addition, flaps have remained virtually unchanged over the years, relying on hinged joints that are limited and vulnerable.

flexfoilIn both cases, the answer may lie in flexible and seamless materials, leading to wings that can change shape as needed. Such technology could not only enable better performance, but remove the need for hinges and gears. Towards this end, Michigan-based FlexSys has developed a way to optimize wing aerodynamics with FlexFoil, a seamless variable geometry airfoil system.

In development since 2001, FlexFoil is made from what is described only as “aerospace materials,” and is seamlessly integrated into the trailing edge of the wing. Based on a technology known as “distributed compliance,” the morphing structure integrates actuators and sensors that, according to Flexsys, results in “large deformations in shape morphing with very small strains.”

flexfoil1According to a 2006 paper co-written by mechanical engineer Dr. Sridhar Kota (the FlexFoil’s inventor), the foils are:

optimized to resist deflection under significant external aerodynamic loading and are just as stiff and strong as a conventional flap.

What this translates to in real terms is a tolerance of over 4500 kg (10,000 lbs) in air loads and the ability to distribute pressure more evenly throughout the wing, resulting in less strain in any one area. It is also said to reduce wind noise by up to 40 percent on landing, and to lessen build-up of both ice and debris. But the biggest benefit comes in terms of fuel economy.

flexfoil2When retrofitted onto a wing, FlexFoil can reduce fuel consumption by a claimed 4 to 8 percent, with that number climbing to 12 percent for those wings that are built are the system. What’s more, the technology could be applied to anything that moves relative to a fluid medium, including things like helicopter rotor blades, wind turbine blades, boat rudders, or pump impellers.

FlexFoil was officially introduced to the public this week at the AIAA (American Institute of Aeronautics and Astronautics) SciTech exposition in Washington, DC. Plans call for flight tests to be performed this July at NASA’s Dryden Flight Research Center, where the flaps of a Gulfstream business jet will be replaced with the foils.

Check out this video of the airwing design and what it does here:

morphing-wings1To be fair, this is not the only case of flexible, morphing aircraft in development right now. In fact, NASA has been looking to create a morphing aircraft concept ever since 2001. So far, this has included collaborating with Boeing and the U.S. Air Force to create the Active Aeroelastic Wing (AAW) which was fitted to the F/A-18 Hornet, a multirole combat jet in use with the USAF.

But looking long-term, NASA hopes to create a design for a morphing airplane (pictured above). Known as the 21st Century Aerospace Vehicle, and sometimes nicknamed the Morphing Airplane, the concept includes a variety of smart technologies that could enable inflight configuration changes for optimum flight characteristics, and is an example of biomimetic technology.

morphing-wings2In this case, the biological design being mimicked is that of a bird. Through the use of smart materials that are flexible and can change their shape on command, the 21st Century Aerospace Vehicle is able to shape its wings by extending the tips out and slightly upward to give it optimal lift capability. In this configuration, the inspiration for the aircraft’s wings is most clear (pictured above).

But once airborne, the aircraft needs a wing that is capable of producing less wind resistance while still maintaining lift. This is why the wings, upon reaching and service ceilings in excess of 3000 meters (10,000 feet), the wings then contract inward and sweep back to minimize drag and increase airspeed velocity.
Though this program has yet to bear fruit, it is an exciting proposal, and provides a glimpse of the future.

Be sure to check out NASA’s video of the CAV too, and keep your eyes on the skies. Chances are, jets that utilize smart, morphing surfaces are going to be there soon!


Sources:
gizmag.com
, flexsys.com, nasa.gov