Emanuele Riva

Emanuele Riva
Politecnico di Milano | Polimi · Department of Mechanical Engineering

PhD

About

41
Publications
4,946
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398
Citations
Citations since 2016
41 Research Items
395 Citations
2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150

Publications

Publications (41)
Article
Rainbow trapping is a phenomenon that enables vibration confinement due to the gradual variation of the wave velocity in space, which is typically achieved by means of locally resonant unit cells. In the context of electromechanical metastructures for energy harvesting, this strategy is employed to improve mechanical-to-electrical energy conversion...
Article
This work proposes a graded metamaterial-based energy harvester integrating the piezoelectric energy harvesting function targeting low-frequency ambient vibrations (<100 Hz). The harvester combines a graded metamaterial with beam-like resonators, piezoelectric patches, and a self-powered interface circuit for broadband and high-capability energy ha...
Preprint
Full-text available
We provide a theoretical framework to mold time-modulated lattices with frequency conversion and wave-steering capabilities. We initially focus on 1D lattices, whereby a sufficiently slow time-modulation of the stiffness is employed to convert the frequency content of impinging waves. Based on the adiabatic theorem, we demonstrate that undesired re...
Article
Phononic Crystal (PnC) Gradient Index (GRIN) lenses have been intensively investigated in recent years for their promising applications in energy harvesting. Here we propose and verify, both numerically and experimentally, three designs of PnC GRIN lenses with amplification factors at the focal points of 4.33x, 7.35x and 7.49x. A design procedure b...
Article
The recent progress in the context of elastic metamaterials and modulated waveguides with digitally controllable properties has opened new pathways to overcome the limitations dictated by Hermitian Hamiltonians in mechanics. Among the possible implementations, non-Hermitian, PT-symmetric systems with balanced gain and loss have emerged as an elegan...
Preprint
Full-text available
This work studies a broadband graded metamaterial, which integrates the piezoelectric energy harvesting function targeting low-frequency structural vibrations, lying below 100 Hz. The device combines a graded metamaterial with beam-like resonators, piezoelectric patches and a self-powered piezoelectric interface circuit for energy harvesting. Based...
Preprint
Full-text available
The recent progress in the context of elastic metamaterials and modulated waveguides with digitally controllable properties has opened new pathways to overcome the limitations dictated by Hermitian Hamiltonians in mechanics. Among the possible implementations, non-Hermitian, $\mathcal{PT}$-symmetric systems with balanced gain and loss have emerged...
Article
We experimentally achieve selective wave filtering and polarization control in a three-dimensional elastic frame embedding local resonators. By connecting multi-resonating elements to a frame structure, a complete low-frequency, subwavelength bandgap with strong selective filtering properties is obtained. Theory and experiments demonstrate the meta...
Preprint
Full-text available
We experimentally achieve selective wave filtering and polarization control in a three-dimensional elastic frame embedding local resonators. By connecting multi-resonating elements to a frame structure, a complete low-frequency, subwavelength bandgap with strong selective filtering properties is obtained. Theory and experiments demonstrate the meta...
Article
Full-text available
We show efficient elastic energy transfer and wave confinement through a graded array of resonators attached to an elastic beam. Experiments demonstrate that flexural resonators of increasing lengths allow to reduce wave scattering and to achieve the rainbow effect with local wavefield amplifications. We show that the definition of a monotonically...
Article
We experimentally achieve wave-mode conversion and rainbow trapping in an elastic waveguide loaded with an array of resonators. Rainbow trapping is a phenomenon that induces wave confinement as a result of a spatial variation of the wave velocity, here promoted by gently varying the length of consecutive resonators. By breaking the geometrical symm...
Article
Full-text available
The temporal modulation of a relevant parameter can be employed to induce modal transformations in Hermitian elastic lattices. When this is combined with a proper excitation mechanism, it allows to drive the energy transfer across the lattice with tunable propagation rates. Such a modal transformation, however, is limited by the adiabaticity of the...
Preprint
Full-text available
The temporal modulation of a relevant parameter can be employed to induce modal transformations in Hermitian elastic lattices. When this is combined with a proper excitation mechanism, it allows to drive the energy transfer across the lattice with tunable propagation rates. Such a modal transformation, however, is limited by the adiabaticity of the...
Preprint
Full-text available
We experimentally achieve wave mode conversion and rainbow trapping in an elastic waveguide loaded with an array of resonators. Rainbow trapping is a phenomenon that induces wave confinement as a result of a spatial variation of the wave velocity, here promoted by gently varying the length of consecutive resonators. By breaking the geometrical symm...
Article
We experimentally demonstrate temporal pumping of elastic waves in an electromechanical waveguide. Temporal pumping exploits a virtual dimension mapped to time, enabling the generation and control of edge states, typical of two-dimensional systems, in a one-dimensional waveguide. We show experimentally that the temporal modulation of the stiffness...
Article
Full-text available
We experimentally demonstrate that a rainbow-based metamaterial, created by a graded array of resonant rods attached to an elastic beam, operates as a mechanical delay-line by slowing down surface elastic waves to take advantage of wave interaction with resonance. Experiments demonstrate that the rainbow effect reduces the amplitude of the propagat...
Article
Full-text available
In this paper we report on nonreciprocal wave propagation in a 2D radial sonic crystal with space–time varying properties. We show that a modulation traveling along the radial direction reflects in omni-directional and isotropic nonreciprocal wave propagation between inner and outer shells. The nonreciprocal behavior is verified both analytically a...
Article
In this paper we report on adiabatic pumping in quasiperiodic stiffness-modulated beams. We show that distinct topological states populating nontrivial gaps can nucleate avoided crossings characterized by edge-to-edge transitions. Such states are inherently coupled when a smooth variation of the modulation phase is induced along a synthetic dimensi...
Preprint
Full-text available
We experimentally demonstrate temporal pumping of elastic waves in an electromechanical waveguide. An aluminum beam covered by an array of piezoelectric patches connected to shunt circuits with controllable resistances enables the spatial and temporal control of the beam's stiffness. The spatial modulation produces non-trivial edge states, while a...
Preprint
Full-text available
We demonstrate that a rainbow-based metasurface, created by a graded array of resonant rods attached to an elastic beam, operates as a mechanical delay-line by slowing down surface elastic waves to take advantage of wave interaction with resonance. Experiments demonstrate that the rainbow effect reduces the amplitude of the propagating wave in the...
Article
We investigate non-reciprocal wave propagation in spatiotemporal phononic plates. Specifically, the first aim of this manuscript is to propose a general formulation of the Plane Wave Expansion Method (PWEM) that, in contrast with previous works, is applicable to any class of 2D spatiotemporal unit cells whose properties can be expanded in travelin...
Article
In this work, we experimentally achieve 1-kHz-wide directional band gaps for elastic waves spanning a frequency range from approximately 8 to 11 kHz. One-way propagation is induced by way of a periodic waveguide consisting of an aluminum beam partially covered by a tightly packed array of piezoelectric patches. The patches are connected to shunt ci...
Preprint
Full-text available
In this manuscript we report on adiabatic pumping in quasiperiodic stiffness modulated beams. We show that distinct topological states populating nontrivial gaps can nucleate avoided crossings characterized by edge-to-edge transitions. Such states are inherently coupled when a smooth variation of the modulation phase is induced along a synthetic di...
Article
We demonstrate that modulations of the stiffness properties of an elastic plate along a spatial dimension induce edge states spanning nontrivial gaps characterized by integer-valued Chern numbers. We also show that topological pumping is induced by smooth variations of the phase of the modulation profile along one spatial dimension, which results i...
Article
In this manuscript we experimentally study a modular metamaterial that is able to provide mechanical insulation for elastic wave propagation. Specifically, the structural design is based on the modes separation principle, that entails the presence of ultra-wide bandgap at low frequencies, also in presence of few lattice elements. In this paper, we...
Preprint
Full-text available
We demonstrate that modulations of the stiffness properties of an elastic plate along a spatial dimension induce edge states spanning non-trivial gaps characterized by integer valued Chern numbers. We also show that topological pumping is induced by smooth variations of the phase of the modulation profile along one spatial dimension, which results...
Preprint
Full-text available
In this work we experimentally achieve 1 kHz-wide directional band-gaps for elastic waves spanning a frequency range from approximately 8 to 11 kHz. One-way propagation is induced by way of a periodic waveguide consisting in an aluminum beam partially covered by a tightly packed array of piezoelectric patches. The latter are connected to shunt circ...
Preprint
We investigate non-reciprocal wave propagation in spatiotemporal phononic plates. In particular, the first goal of this manuscript is to present a general formulation of the Plane Wave Expansion Method (PWEM) that, in contrast with previous works, is applicable to any class of 2D spatiotemporal unit cells whose properties can be expanded in travel...
Preprint
We investigate non-reciprocal wave propagation in spatiotemporal phononic plates. In particular, the first goal of this manuscript is to present a general formulation of the Plane Wave Expansion Method (PWEM) that, in contrast with previous works, is applicable to any class of 2D spatiotemporal unit cells whose properties can be expanded in traveli...
Article
In this manuscript we investigate one-way wave propagation in spatio-temporal phononic wave-guides in which the modulation of material properties is provided piecewise in space and time. Non-reciprocal dispersion diagram is computed using a generalized plane wave expansion method, whose formulation, provided in the paper, is able to describe how a...
Article
In this paper we propose a modeling strategy for Cable Driven Parallel Robots (CDPRs) that - given their complexity - are typically addressed using simplified analysis, therefore neglecting relevant dynamics. Specifically, the finite element method is used for cables modeling, in order to account for their mass and stress-dependent stiffness. Geome...
Article
In this paper, we report the evidence of topologically protected edge waves (TPEWs) in continuum Kagome lattice. According to the bulk edge correspondence principle, such edge states are inherently linked with the topological characteristics of the material band structure and can, therefore, be predicted evaluating the associated topological invari...
Conference Paper
Spatiotemporal periodic structures are systems whose properties are periodically modulated both in space and time, able to support waves only in one direction, so breaking the so called reciprocity principle. Studies till now focused mainly on continuous systems, where properties are modulated in a continuous manner both in space and time. However,...
Conference Paper
Periodic structures are the repetition of unit cells in space, that provide a filtering behavior for wave propagation. In particular, it is possible to tailor the geometrical, physical and elastic properties of the unit cells, in order to attenuate certain frequency bands, called band-gaps or stop-bands. Having each element characterized with the s...
Conference Paper
Periodic structures provide filtering behavior for vibrations, as a result of the repetition in space of unit blocks, or unit cells. In general, they are characterized by an internal mechanical impedance mismatch, so that waves are reflected and transmitted every time a discontinuity is present. The global behavior given by waves superposition is t...

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