Adhesion disturbed by noise

Dec 17, 2012
Adhesion disturbed by noise

Imagine a solid ball rolling down a slightly inclined ramp. What could be perceived as child's play is the focus of serious theoretical research by Manoj Chaudhury and Partho Goohpattader, two physicists from Lehigh University, Bethlehem, Pensylvania, USA. Their study, which is about to be published in European Physical Journal E, has one thing in common with childhood behaviour. It introduces a mischievous idea, namely studying the effect of random noise, such as vibrations, on the ball. They found it could lower the energy barrier to set the ball in motion.

The authors used a ramp with a micro-textured surface. This surface is akin to that of a gecko's feet, made of so-called microfibrils capable of adhering to any surface by deforming elastically. They then studied the effect of vibration on a ball left on the top of such a textured ramp. They found that the sphere starts rolling when subjected to a computer-generated random vibration.

To set the ball in motion requires activation energy, the model shows. It has been long known that the same applies to the adhesion of molecules, on a much smaller scale, as predicted theoretically by the so-called Arrhenius kinetics. This study pinpoints a finite threshold of intensity for the vibration noise above which the ball is set in motion.

This finding could have implications for the removal of from super- such as plant leaves. Other applications could also include gecko feet-mimetic adhesives, better adhesion of rubber tires on roads, and the use of fluids, instead of electronics, to perform a digital operation. In addition, new (MEMs), based on robotic fingers capable of displacing a small object, could be assisted by noise.

Explore further: Tiny magnetic sensor deemed attractive

More information: M. K. Chaudhury and P. S. Goohpattader (2012), Noise activated dissociation of soft elastic contacts, European Physical Journal E 35: 131, DOI: 10.1140/epje/i2012-12131-9

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User comments : 4

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ValeriaT
1 / 5 (4) Dec 17, 2012
They found it could lower the energy barrier to set the ball in motion.
Everyone knows, that the vibrations reduce friction. The vibrating washing machine can slide across the whole room. How they could "find" it, after then?
Q-Star
2.5 / 5 (6) Dec 17, 2012
The vibrating washing machine can slide across the whole room. How they could "find" it, after then?


If it was still plugged in they probably followed the cord. If it had worked loose then maybe they followed the scuff marks on the floor.

Of course this is constrained by the absence of of lateral-transverse-longitudinal water standing waves in the washing machine.
Widdekind
1 / 5 (2) Dec 17, 2012
coefficients of static vs. kinetic friction?
88HUX88
not rated yet Dec 18, 2012
The Lunar Reconnaissance Orbiter circling the moon will pass over the mountain and attempt to photograph the skid marks left by the washing machine sized-spacecraft as they hit the surface at 3,800 mph.

There you go.

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