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Thursday, July 11 • 11:00 - 11:20
CHARACTERIZATION OF A NONLINEAR SOUND ABSORBER AT LOW FREQUENCIES AND HIGH SOUND LEVELS

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The objective of this work is to develop identification techniques to characterize nonlinear acoustic loads. These nonlinear acoustic loads are here considered as a one-port acoustic system, analyzed at low frequencies and for increasing excitation levels. A specific setup of impedance tube named "Short Kundt's Tube" was built to reach high sound levels at low frequencies. Two approaches, developed in the frequency domain, are discussed in this work. The two approaches require a single acoustic pressure measurement inside the Short Kundt's Tube, and a calibration of the Short Kundt's Tube acoustic source from a set of known (linear) acoustic loads. The first approach is defined as a linearization method and gives access to the acoustic impedance which is excitation level dependent. The second one is based on a nonlinear model able to characterize energy transfer to higher harmonics. It is defined as a scattering matrix linking the harmonic components of the input and output pressure wave amplitudes. These techniques are applied for the study of two different nonlinear vibroacoustic absorbers based on the concept of targeted energy transfer.

Moderators
LH

Lars Håkansson

professor, Linnaeus University

Authors

Thursday July 11, 2019 11:00 - 11:20 EDT
Westmount 2
  T01 Ac. meas. & instrum., RS04 Instr fr snd & vibr measur & anl