Experimental evidence of simultaneous multi resonance noise reduction using an absorber with essential non linearity under two excitation frequencies

Renaud Côte (1) , Marc Pachebat (1) , Sergio Bellizzi (1)

1 Sons

The addition of an essentially nonlinear membrane absorber to a linear vi-broacoustic system with multiple resonances is studied experimentally, using quasiperiodic excitation. An extended experimental dataset of the system re-sponse is analyzed under steady state excitation at two frequencies. Thresh-olds between low and high damping states within the system and associated noise reduction are observed and quantified thanks to frequency conversion and RMS efficiency indicators. Following previous numerical results, it is shown that the membrane NES (Nonlinear Energy Sink) acts simultaneously and efficiently on two acoustic resonances. In all cases, the introduction of energy at a second excitation frequency appears favorable to lower the fre-quency conversion threshold and to lower the noise within the system. In particular a simultaneous control of two one-to-one resonances by the NES is observed. Exploration of energy conversion in the two excitation ampli-tudes plane advocates for a linear dependence of the frequency conversion thresholds on the two excitation amplitudes.

Mots clés: Nonlinear absorber; Nonlinear energy sink; Targeted energy transfer; Quasiperiodic excitation; Acoustic resonance; Noise reduction; Frequency conversion

Domaines: Acoustique [physics.class-ph]; Vibrations [physics.class-ph]; Physique [physics]; Mécanique [physics.med-ph]; Sciences de l'ingénieur [physics]; Science non linéaire [physics]

Renaud Côte, Marc Pachebat, Sergio Bellizzi. Experimental evidence of simultaneous multi resonance noise reduction using an absorber with essential non linearity under two excitation frequencies. Journal of Sound and Vibration, 2014, 333 (20), pp.5057-5076. ⟨10.1016/j.jsv.2014.05.020⟩. ⟨hal-01089548⟩