Improving the acoustic black hole effect for vibration damping in one-dimensional structures

Jacques Cuenca , Adrien Pelat (1) , François Gautier (1) , Neil Ferguson (2)

1 LAUM - Laboratoire d'Acoustique de l'Université du Mans
2 ISVR

Flexural vibrations are highly responsible for noise radiation by thin structures. In the transport industry, the damping of such vibrations is often achieved using thick viscoelastic layers, which leads to an undesirable increase of mass. In this regard, the acoustic black hole effect has received recent attention as an efficient and lightweight method for damping flexural vibrations. An acoustic black hole consists of a thin structure presenting a smooth decrease in its wave velocity along a given direction, thus acting as a wave trap where the vibrations can be efficiently damped. Such decrease of the velocity can be achieved by a variation of the mechanical parameters, namely the thickness or the Young's modulus. The present paper discusses the practical implementation of the acoustic black hole effect in one-dimensional structures. A numerical model of the flexural wave field of a beam with arbitrarily varying properties along its length is developed as a design and prediction tool. Experiments are performed in beams subjected to a variation in thickness or to a variation in Young's modulus obtained by imposing a temperature gradient. The results show an efficient reduction of the vibration level, as well as the suppression of the resonances.

Mots clés: acoustic black hole; flexural vibrations; damping; lightweight

Domaines: Acoustique [physics.class-ph]

Jacques Cuenca, Adrien Pelat, François Gautier, Neil Ferguson. Improving the acoustic black hole effect for vibration damping in one-dimensional structures. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00811277⟩