Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Artificial muscle as shock absorber

01.06.2012
Engineers are working on intelligent materials that can diminish vibrations and extract power from the environment. These electro-active elastomers could dampen annoying vibrations in a car, for example, or supply wireless power to sensors in otherwise inaccessible places.

It is not very fun to ride a bicycle on a street plastered with cobblestones. At least the bike has a saddle seat filled with silicone. That lessens the shocks and bumps, and counteracts some of the annoying vibrations.


This image shows the lattice-shaped electrode in the foreground, and the elastomer in the background. © Ursula Raapke

In a professional‘s eyes, the material in the saddle is an “elastomer” – a material that is yielding and malleable, like a rubber band. Engineers at the Fraunhofer Institute for Structural Durability and System Reliability LBF in Darmstadt are now working on the next generation: They are designing components made of elastomers that actively respond to unwanted vibrations, and dampen them more effectively than ever before.

Elastomers have been used in engineering for decades, such as shock absorbers in mechanical engineering or in the bearings for vehicle engines. Until now, they have had a purely passive effect on vibrations or impact collisions. It would be more effective if the elastomers were to respond proactively and counteract vibrations.

In the same way a tennis player slows down the ball on a drop shot by pulling back on her racket, an active elastomer draws out the energy from the vibration in a targeted manner by swinging in precise push-pull mode. Theoretically, this would make the vibration dissipate completely.

Elastomers vibrate under alternating current

There are already materials that are good for this purpose. “They are called ‘electroactive elastomers’,” explains LBF scientist William Kaal. “They are elastic substances that change their form when exposed to an electrical field.” The trick: apply an alternating current, and the material starts to vibrate. If there are smart electronics controlling the elastomers, making them vibrate precisely in push-pull mode, then unwanted vibrations in equipment or an engine will dissipate for the most part. To demonstrate that the principle works, the Darmstadt-based researchers created a model. Smaller than a pack of cigarettes, it is comprised of 40 thin elastomer electrode layers.

The experts call it a “stack actuator.” “The challenge was the design of the electrodes with which we apply the electric field to the elastomer layers,” as Kaal‘s colleague Jan Hansmann clarifies. Usually, electrodes are made out of metal. However, metals are relatively rigid, which impedes the deformation of the elastomer. Fraunhofer experts deliver an elegant solution to the problem: “We put microscopic-sized holes in the electrodes,” says Hansmann.

“If an electric voltage deforms the elastomer, then the elastomer can disperse into these holes.” The result is an actuator that can rise or fall a few tenths of a centimeter upon command – several times a second, in fact. To demonstrate these capabilities, William Kaal attaches a small mechanical oscillator to the device. When he turns it on, the oscillator begins shaking powerfully – the actuator has hit its resonance frequency perfectly. On the other hand, the instrument can actively absorb vibrations: If the oscillator is tapped by hand, it quickly settles down when the actuator vibrates in push-pull mode.

The LBF engineers believe one potential application for their stack actuator can be found in vehicle construction. “An engine‘s vibrations can be really disruptive,” says William Kaal. “The vibrations are channeled through the chassis into the car‘s interior, where the passengers start to feel them.” Of course, engines are installed meticulously, and yet: “Active elastomers may help further reduce vibrations in the car,” Kaal asserts.

When vibrations turn into power

The function of the stack actuator can also be reversed: rather than produce vibrations, the device can also absorb vibrations from its surroundings to produce energy. The principle works, and researchers have proven it. As they placed an electromagnetic oscillator on their stack actuator, it converted the vibrations into power. “That would be of interest, for example, if you wanted to monitor inaccessible sites where there are vibrations but no power connections,” Jan Hansmann believes – as he cites an example: the temperature and vibration sensors that monitor bridges for their condition.

The stack actuator technology has been largely perfected: “The manufacturing process can be readily automated. That is important for industrial mass production,” thinks Kaal. Nevertheless, endurance tests still have to show what the long-term viability of the intelligent actuators is like. Ultimately, they must be able to withstand harsh environments of the kind found in the engine compartment of a car.

William Kaal | Fraunhofer Research News
Further information:
http://www.fraunhofer.de/en/press/research-news/2012/june/artificial-muscle-as-shock-absorber.html

More articles from Materials Sciences:

nachricht Barely scratching the surface: A new way to make robust membranes
13.12.2018 | DOE/Argonne National Laboratory

nachricht Topological material switched off and on for the first time
11.12.2018 | ARC Centre of Excellence in Future Low-Energy Electronics Technologies

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Data use draining your battery? Tiny device to speed up memory while also saving power

14.12.2018 | Power and Electrical Engineering

Tangled magnetic fields power cosmic particle accelerators

14.12.2018 | Physics and Astronomy

In search of missing worlds, Hubble finds a fast evaporating exoplanet

14.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>