Metamaterials are artificially designed materials featuring properties that usually are not common in nature. They exist over a wide range of physical domains, having special electromagnetic, optical, thermal, mechanical, or acoustic properties. Vibroacoustic metamaterials (VAMMs) are a subtype of acoustic metamaterials that influence the transmission of structure-borne sound and the radiation of airborne sound by structures by the effects of destructive interferences, negative effective stiffness or mass properties within a certain frequency range. Within this frequency range, referred to as a stop band, a strong reduction of vibration amplitudes occurs. There exist two main approaches to creating VAMM, based on the Bragg effect and local resonances. Stop bands caused by local resonances are generated by arrays of local resonators that induce negative effective material properties of the overall structure. The characteristics of the stop bands are determined by the number of resonators, their distance, and their resonant frequency. This approach provides greater design flexibility than using the Bragg effect to create stop bands, that is based on negative interference and therefor is strictly bound to the wavelength of the vibration that is to be reduced.

VAMMs provide a significantly larger vibration amplitude reduction than common measures for vibration and noise reduction while being particularly suitable for lightweight designs. In recent years, VAMMs have been tested in a variety of applications and lately have been deployed to serial products. In the talk, various demonstrations of VAMMs in aerospace, automotive, machining and construction are presented (compare figure 1). Possible production processes for VAMMs are discussed, and VAMMs are compared with conventional measures in terms of vibration reduction and lightweight potential.

References
[1] D. Manushyna, M. Hülsebrock, A. Kuisl, A. De Vivo, P. Heloret, H. Atzrodt, S. Rapp: Application of vibroacoustic metamaterials for structural vibration reduction in space structures, Mechanics Research Communications, Volume 129, 10.1016/j.mechrescom.2023.104090, 2023
[2] A. Weber, S. Rieß, J. Cóndor López, H. Atzrodt, M. Hülsebrock, T. Böttcher, L. Eckstein: Application concepts and potentials of vibroacoustic metamaterials for NVH; Aachen Acoustics Colloquium 2023, Aachen