Experimental evaluation and model of a nonlinear absorber for vibration attenuation

Because of their large wavelength, the noise and the vibrations at low frequencies cannot easily be reduced in the structures by using dissipative materials contrarily to the waves at middle and high frequencies. A possible technique for obtaining an attenuation is to randomly distribute absorbers in a matrix to attenuate acoustic waves and vibrations in such a low-frequency band. If linear absorbers are used, then it is difficult to obtain an attenuation on a broad low-frequency band with a reasonable number of absorbers. On the other hand, it is known that nonlinear absorbers allow the absorption bandwidth to be increased. However, such technique requires to properly design such a nonlinear absorber and to perform its experimental validation. The objective of the paper is to present the design of such an absorber with nonlinear geometrical effects and its experimental evaluation. It is experimentally proved that this nonlinearity type induces an attenuation on a broad frequency band around its first resonance. The novelty of this work is to present the design of an inclusion that has the potentiality to be reproduced at any scale, in particular for microstructured materials. For such an inclusion, we present its mechanical model for the simulation, its design, its manufacturing that is realized with a 3D-printing system, the experiments, and the experimental identification of the model. The results show that a significant attenuation is effectively obtained over a broad low-frequency band, as intended.