Mittwoch, 05.06.2024, 08:15-09.30 im Raum N1147

Im Rahmen des Lehrstuhlseminars wird der Doktorand Lukas Kleine-Wächter seine akutellen Forschungsergebnisse aus dem Bereich "Elastic Metamaterials for Vibration Control" vorstellen.

Der Vortrag ist hochschulöffentlich und findet in Präsenz im Raum N1147 (TUM Stammgelände) und via Zoom statt. TUM-weite Intressierte sind herzlich eingeladen, dem Vortrag und der anschließenden Diskussion zu folgen.

Um eine kurze Anmeldung der Teilnahme bei Herrn Kleine-Wächter wird gebeten.

Abstract:

New Twists of the Kelvin cell: Numerical and experimental investigations of wave propagation in Kelvin Cell-based periodic lattice architectures.

 Presenter: Lukas Kleine-Wächter, PhD-student at TU Munich & KTH Stockholm

Engineered periodic materials are a promising solution for mitigating vibrations due to their ability to modulate and inhibit elastic wave propagation in targeted frequency bands. This filtering functionality depends upon the topology and periodicity of the material microstructure and is strongly related to the acoustic dispersion in the microstructure’s constituent unit cells. Investigating the interplay between cell topology, underlying periodicity, and emerging dispersion properties is, therefore, a vital step in developing materials with customized filtering properties.

This contribution addresses the dispersion properties of periodic open-cell microstructures. A unit cell design strategy is introduced based on the Kelvin cell as a template geometry. The geometry is subsequently altered along three axis directions by imposing twists on the cell’s square faces. The geometrical changes are independently applicable in three-axis directions, which offers the potential to adjust the microstructure’s filtering characteristics based on the twist angle and choice of periodicity.

Finite element models of twisted unit cells and Bloch’s theorem for 1D periodicity are considered, and it is demonstrated that altering the template geometry by the twisting approach may enforce band gaps stemming from coupled longitudinal-torsional modes and Bragg scattering. Band gaps of the latter type can be effectively tuned by adjusting the twist angle while keeping the material parameters unchanged. While the band gap feature is directly linked to the assumption of infinitely extended periodic media, practically realizable structures are bounded by finite numbers of unit cells. Therefore, the contribution addresses the transition from infinite to finite-size periodicity through dynamic analyses of selected finite-size periodic structures. The vibration attenuation capabilities of samples manufactured from SLA printing are experimentally tested and compared to numerical results obtained from harmonically induced wave motions. Particular attention is directed to the conformity of the numerically predicted and experimentally determined attenuation region.