Particle manipulation with acoustic waves based on Hertz- Mindlin mechanics
Résumé
A particle on a substrate can be moved by the dry friction force excited via a surface acoustic wave. The effect is referred to as vibrational transportation or Rayleigh linear motor and is used in a number of industrial applications. A traditional theory of vibrational transportation considers a particle as a material point that cannot be strained and also cannot induce any strain in the substrate. A known result consists in the fact that such a particle, with a certain choice of system parameters, can move against the surface wave. Here we use another approach based on the Hertz-Mindlin mechanics in which a deformable axisymmetric body moves on a deformable substrate. The contact zone in this case is not a point but rather a circle that generally contains a smaller circle of stick and surrounding annulus of slip. Using a previously developed numerical tool we show that such a body can also move in the direction of the wave which allows one more elaborate particle positioning. The steady drift in one of these directions can be observed (or not) depending on a combination of two system characteristics only that incorporate excitation parameters, elastic properties and particle inertia.
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