Examinando por Materia "Directional behavior"

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    Computational characterization of the wave propagation behavior of multi-stable periodic cellular materials
    (Elsevier Limited, 2019-01-01) Valencia, Camilo Andres; Restrepo D.; Mankame N.D.; Zavattieri P.D.; Gomez, Juan David; Mecánica Aplicada
    In this work, we present a computational analysis of the planar wave propagation behavior of a one-dimensional periodic multi-stable cellular material. Wave propagation in these materials is interesting because they combine the ability of periodic cellular materials to exhibit stop and pass bands with the ability to dissipate energy through cell-level elastic instabilities. Here, we use Bloch periodic boundary conditions to compute the dispersion curves and introduce a new approach for computing wide band directionality plots. Also, we deconstruct the wave propagation behavior of this material to identify the contributions from its various structural elements by progressively building the unit cell, structural element by element, from a simple, homogeneous, isotropic primitive. Direct integration time domain analyses of a representative volume element at a few salient frequencies in the stop and pass bands are used to confirm the existence of partial band gaps in the response of the cellular material. Insights gained from the above analyses are then used to explore modifications of the unit cell that allow the user to tune the band gaps in the response of the material. We show that this material behaves like a locally resonant material that exhibits low frequency band gaps for small amplitude planar waves. Moreover, modulating the geometry or material of the central bar in the unit cell provides a path to adjust the position of the band gaps in the material response. Also, our results show that the material exhibits highly anisotropic wave propagation behavior that stems from the anisotropy in its mechanical structure. Notably, we found that unlike other multi-stable cellular materials reported in the literature, in the system studied in this work, the configurational changes in the unit cell corresponding to its different stable phases do not significantly alter the wave propagation behavior of the material. © 2019