Andrea Colombi


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Colombi

First Name

Andrea

ORCID

0000-0003-2480-978X

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2014 - 201972020 - 202531
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Publications1 - 10 of 38
  • Shell and bio-inspired structures for elastic wave control
    Item type: Conference Poster
    Nooghabi, Aida Hejazi; Colombi, Andrea (2022)
  • A Nonlinear Metamaterial Induced by Nonlinear Damping Effect with Inertia Amplifiers
    Item type: Conference Poster
    Zhao, Bao; Van Damme, Bart; Bergamini, Andrea; et al. (2022)
  • Seismic waveform inversion for core–mantle boundary topography
    Item type: Journal Article
    Colombi, Andrea; Nissen-Meyer, Tarje; Boschi, Lapo; et al. (2014)
    Geophysical Journal International
  • Numerical Investigation of Structured Materials for Vibration Control
    Item type: Conference Poster
    Aguzzi, Giulia; Colombi, Andrea; Chatzi, Eleni (2020)
    Papers und Präsentationen der COMSOL Conference 2020
  • Geometric and material attenuation of surface acoustic modes in granular media
    Item type: Journal Article
    Zaccherini, Rachele; Palermo, Antonio; Marzani, Alessandro; et al. (2022)
    Geophysical Journal International
    Granular materials can be used in laboratory-scale physical models to simulate and study seismic wave propagation in various unconsolidated, porous heterogeneous media. This is due to the diverse available grain configurations, in terms of their shape, size and mechanical parameters, which enable the physical and geological modelling of various complex substrates. In this work, an unconsolidated granular medium, made of silica microbeads, featuring a gravity-induced power-law stiffness profile is experimentally tested in a laboratory setting. The objective is to investigate the attenuation mechanisms of vertically polarized seismic waves traveling at the surface of unconsolidated substrates that are characterized by power-law rigidity profiles. Both geometric spreading and material damping due to skeletal dissipation are considered. The understanding of these two attenuation mechanisms is crucial in seismology for properly determining the seismic site response. An electromagnetic shaker is employed to excite the granular medium between 300 and 550 Hz, generating linear modes that are localized near the surface. A densely sampled section is recorded at the surface using a laser vibrometer. The explicit solution of the geometric attenuation law of Rayleigh-like waves in layered media is employed to calculate the geometric spreading function of the vertically polarized surface modes within the granular material. In accordance with recent studies, the dynamics of these small-amplitude multimodal linear waves can be analysed by considering the granular medium as perfectly continuous and elastic. By performing a nonlinear regression analysis on particle displacements, extracted from experimental velocity data, we determine the frequency-dependent attenuation coefficients, which account for the material damping. The findings of this work show that laboratory-scale physical models can be used to study the geometric spreading of vertically polarized seismic waves induced by the soil inhomogeneity and characterize the material damping of the medium.
  • Metamaterials for groundborne vibration absorption in pillars
    Item type: Conference Paper
    Aguzzi, Giulia; Colombi, Andrea; Dertimanis, Vasilis K.; et al. (2020)
    Proceedings of ISMA2020 including USD2020
  • Locally Resonant Metasurfaces for Shear Waves in Granular Media
    Item type: Journal Article
    Zaccherini, Rachele; Colombi, Andrea; Palermo, Antonio; et al. (2020)
    Physical Review Applied
    In this paper, the physics of horizontally polarized shear waves traveling across a locally resonant metasurface in an unconsolidated granular medium is experimentally and numerically explored. The metasurface is comprised of an arrangement of subwavelength horizontal mechanical resonators embedded in a granular layer made of silica microbeads. The metasurface supports a frequency-tailorable attenuation zone induced by the translational mode of the resonators. The experimental and numerical findings reveal that the metasurface not only backscatters part of the energy but also redirects the wave front underneath the resonators, leading to a considerable amplitude attenuation at the surface level, when all the resonators have similar resonant frequency. A more complex picture emerges when using resonators arranged in a so-called graded design, e.g., with a resonant frequency increasing or decreasing throughout the metasurface. Unlike the mechanism observed in a bilayered medium, shear waves localized at the surface of the granular material are not converted into bulk waves. Although a detachment from the surface occurs, the depth-dependent velocity profile of the granular medium prevents the mode conversion and the horizontally polarized shear wave front returns to the surface. The outcomes of our experimental and numerical studies allow for understanding the dynamics of wave propagation in resonant metamaterials embedded in vertically inhomogeneous soils and, therefore, may be valuable for improving the design of engineered devices for ground-vibration and seismic wave containment.
  • Metamaterials and seismic waves in 4 square metres
    Item type: Other Conference Item
    Colombi, Andrea; Zaccherini, Rachele; Ntertimanis, Vasileios; et al. (2019)
    Abstract Book. 2019 International Congress on Ultrasonics, Bruges, Belgium, 3-6 September 2019
  • Evidence of metamaterial physics at the geophysics scale: the METAFORET experiment
    Item type: Journal Article
    Lott, Martin; Roux, Philippe; Garambois, Stéphane; et al. (2020)
    Geophysical Journal International
    The METAFORET experiment was designed to demonstrate that complex wave physics phenomena classically observed at the meso- and microscales in acoustics and in optics also apply at the geophysics scale. In particular, the experiment shows that a dense forest of trees can behave as a locally resonant metamaterial for seismic surface waves. The dense arrangement of trees anchored into the ground creates anomalous dispersion curves for surface waves, which highlight a large frequency band-gap around one resonant frequency of the trees, at ∼45 Hz. This demonstration is carried out through the deployment of a dense seismic array of ∼1000 autonomous geophones providing seismic recordings under vibrating source excitation at the transition between an open field and a forest. Additional geophysical equipment was deployed (e.g. ground-penetrating radar, velocimeters on trees) to provide essential complementary measurements. Insights and interpretations on the observed seismic wavefield, including the attenuation length, the intensity ratio between the field and the forest and the surface wave polarization, are validated with 2-D numerical simulations of trees over a layered half-space.
  • Lattice metastructures for elastic wave control
    Item type: Conference Poster
    Aguzzi, Giulia; Zaccherini, Rachele; Colombi, Andrea; et al. (2021)
    Symposium Booklet
Publications1 - 10 of 38