Nav: Home

Acoustic energy harnessed to soften shear-thickening fluids

September 17, 2019

ITHACA, N.Y. - Researchers are using ultrasonic waves to manipulate the viscosity of shear-thickening materials, turning solids to slush - and back again.

The study, "Using Acoustic Perturbations to Dynamically Tune Shear Thickening in Colloidal Suspensions," was published Sept. 17 in Physical Review Letters.

Shear-thickening fluids are a class of materials that flow like liquid but solidify when squeezed or sheared quickly, such as quicksand and Oobleck, the children's play slime. Technical applications for the material range from soft body armor and astronaut suits to 3D printing metals and ceramics.

But the shear-thickening process can be uncooperative: The more you manipulate the material, the more it solidifies, which in the case of 3D printing and the manufacture of concrete can lead to gunked-up nozzles and jammed hoppers.

Itai Cohen, professor of and the paper's co-senior author, previously found a way to manipulate - or "tune" - the material by breaking apart the rigid structures or force chains formed by the particles in these suspensions through perpendicular oscillation. But that method proved to be impractical. It isn't easy, after all, to shake and twist a factory pipe.

Cohen and Ph.D. student Meera Ramaswamy partnered with Brian Kirby, professor of engineering, and Ph.D. student Prateek Sehgal, who have been using acoustic transducers to manipulate micro- and nanoscale particles in Kirby's lab.

Sehgal developed a simple but effective device that consists of a bottom plate with an acoustic transducer - called a piezo - that generates ultrasonic waves.

"When you excite that piezo at a specific frequency and a specific voltage, it emanates the acoustic waves through the bottom plate to the suspension. These acoustic disturbances break the force chains responsible for shear-thickening," said Sehgal, co-lead author of the paper with Ramaswamy.

"The disturbances you're inducing are actually really, really tiny, so it doesn't take much to break the contact forces between the micro-particles," Cohen said. "This is the key insight that allowed us to think about applying these kinds of perturbations and getting it to work. Basically, any geometry where you have a flow that's thickened, you can now just slap a piezo on and de-thicken that region. This strategy just opens up the applicability to a much broader range of applications."

The researchers developed the approach by manipulating particles in substances up to 1.3 mm thick, but because ultrasound waves can propagate long distances in material, Kirby anticipates it being used on pipes as wide as a foot. Potential applications include food processing, particularly for materials that have particulate suspensions like pastes, the manufacture of concrete, as well as the 3D printing of ceramics and metals.

The use of acoustic energy is also a valuable scientific tool for researchers who are studying a material's thickening behavior and system dynamics. Typically, to study thickening, one needs to start with a relaxed suspension and ramp up the flows. This process, however, can take a long time.
The research was supported by the National Science Foundation.

For more information, see this Cornell Chronicle story.

Cornell University has dedicated television and audio studios available for media interviews supporting full HD, ISDN and web-based platforms.

Cornell University

Related Concrete Articles:

Concrete solutions that lower both emissions and air pollution
Some common strategies to reduce the greenhouse gas emissions of concrete production could have unintended consequences for local air pollution and related health damages, according to a study from the University of California, Davis.
'Wood' you like to recycle concrete?
Scientists at The University of Tokyo studied a method for recycling unused concrete with wood fibers.
Bacteria and sand engineered into living concrete
Cement and concrete haven't changed much as technology in over a hundred years, but researchers in Colorado are revolutionizing building materials by literally bringing them to life.
'Self-cleaning' concrete could keep buildings looking new (video)
Building materials that clean themselves could save immense time and labor in homes and businesses, as well as reduce disease risk in settings such as hospitals.
Finding out the factors that most influence the steel corrosion in reinforced concrete
This process causes structures to deteriorate internally and can even cause buildings to collapse.
Concrete with improved impact endurance for defense structures developed at FEFU
Engineers from the Military Studies Center at Far Eastern Federal University (MSC FEFU) developed a brand-new concrete with improved impact endurance and up to 40% made of waste: rice husk cinder, limestone crushing waste, and siliceous sand.
Ashes to concrete
Drexel University researchers have developed a process for turning the solid waste products of coal power plants into a useful ingredient that could improve properties of concrete.
Corrosion resistance of steel bars in concrete when mixed with aerobic microorganisms
Dissolved oxygen in pore solution is often a controlling factor determining the rate of the corrosion process of steel bars in concrete.
FEFU scientists developed brand-new rapid strength eco-concrete
Engineers of Far Eastern Federal University (FEFU) with colleagues from Kazan State University of Architecture and Engineering (KSUAE) have developed a brand-new rapid strength concrete, applying which there is possible to accelerate the tempo of engineering structures manufacturing by three to four times.
Brain processes concrete and abstract words differently
A new review explores the different areas of the brain that process the meaning of concrete and abstract concepts.
More Concrete News and Concrete Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

One of the most consistent questions we get at the show is from parents who want to know which episodes are kid-friendly and which aren't. So today, we're releasing a separate feed, Radiolab for Kids. To kick it off, we're rerunning an all-time favorite episode: Space. In the 60's, space exploration was an American obsession. This hour, we chart the path from romance to increasing cynicism. We begin with Ann Druyan, widow of Carl Sagan, with a story about the Voyager expedition, true love, and a golden record that travels through space. And astrophysicist Neil de Grasse Tyson explains the Coepernican Principle, and just how insignificant we are. Support Radiolab today at