Elastic waveguides with time-modulated stiffness feature a frequency-periodic dispersion spectrum, where branches merge at multiple integers of half the modulation frequency and over finite wave number range. In this range, becomes complex, its real part remaining constant. The vanishing group velocity associated these flat bands leads to frequency-selective reflection an interface between nonmodulated medium one, which converts broadband input into narrow-band output centered frequency....

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 periodic waveguide consisting in an aluminum beam partially covered tightly packed array piezoelectric patches. The latter are connected shunt circuits and switches which allow modulation time the cell properties. A traveling stiffness profile obtained opportunely phasing temporal each active element,...

Abstract We report the concept and demonstration of a double-negative, resonant metamaterial characterized by both dynamic negative mass stiffness for refraction flexural wave modes means lens designed using this concept. The equivalent material properties are obtained in subwavelength regime concurrently exploiting effect mechanical resonators (negative mass) piezoelectric patches with inductive shunts stiffness), leading to double-negative behavior. Following theoretical foundations based...

Abstract We present a structural topology optimization method to tailor the hardening/softening dynamic response of nonlinear mechanical systems. The coefficient that controls this behavior is computed analytically using third-order normal-form parametrization Lyapunov subcenter manifold, which eliminates need for expensive full-order simulations and numerical continuation approximate so-called backbone curve system. further leverages adjoint efficiently computing sensitivities objective...

We present an enhanced version of the parametric nonlinear reduced order model for shape imperfections in structural dynamics we studied a previous work [1]. The is computed intrusively and with no training using information about nominal geometry structure some user-defined displacement fields representing defects, i.e. small deviations from parametrized by their respective amplitudes. linear superposition these artificial displacements describe defected can be embedded strain formulation...

Abstract We present a technique for the direct optimization of conservative backbone curves in nonlinear mechanical systems. The periodic orbits on are computed analytically using reduced dynamics corresponding Lyapunov subcenter manifold (LSM). In this manner, we avoid expensive full-system simulations and numerical continuation to approximate response. Our method aims at tailoring shape curve gradient-based with respect system’s parameters. To end, formulate problem by imposing constraints...

We report on the dynamics of graded metamaterials in context micro-electromechanical systems (MEMS). Graded are known to exhibit space confinement mechanical energy - or rainbow trapping response a tailored wave speed reduction. Such behavior, turn, is controlled by gradual variation resonant characteristics an array resonators dressed host structure which, as result, exhibits arbitrarily slow waves. The paper shows quantitatively that there adiabatic limit for rate change grading. Below...

Abstract The computation of the steady-stateresponse large finite element discretized systems subject to periodic excitations is unfeasible because excessive run time and memory requirements. One could in principle resort reduced order models stemming from high fidelity counterparts, which typically require a solution orders magnitude smaller. However, when many simulations are required, as case parametric studies, overall effort be still significant analysis process severely hindered. In...

In recent years, active periodic structures with in-time modulated parameters have drawn ever-increasing attention due to their peculiar (and sometimes exotic) wave propagation properties. Although many experimental works shown the efficacy of time-modulation strategies, benchmarks proposed until now been mostly proof-of-concept demonstrators, little feasibility solution for practical purposes. this work, we propose a micro electro-mechanical system (MEMS) structure electromechanical...

Spatiotemporal periodic structures are systems whose properties periodically modulated both in space and time, able to support waves only one direction, so breaking the called reciprocity principle. Studies till now focused mainly on continuous systems, where a manner time. However, this is not case of real mechanical systems: if hand it possible think temporal modulation by means an actively controlled smart material, other really hard imagine system that can be punctually space. For reason...

This paper describes how mechanical nonlinearities can be exploited to obtain a frequency-matched MEMS gyroscope. Exploiting the hardening behavior of oscillator, we show it is possible match drive and sense frequency by changing displacement amplitude. way, both resonance amplitudes axes are exploited, boosting sensitivity device. Moreover, near-flat response increases robustness bandwidth. A prototype yaw gyroscope was also manufactured test feasibility proposed approach.

Breaking reciprocity in wave propagation problems is of great interest within the research community, given opportunity to design new devices for one-way communication with unprecedent performances. In context mechanics and phonon transport, directional manipulation can be achieved exploiting space-time periodic materials. Namely, structures whose elastic or physical properties are functions space time. this work we experimentally study nonreciprocal a modulated beam based on piezoelectric...

Spectral submanifolds (SSMs) have emerged as accurate and predictive model reduction tools for dynamical systems defined either by equations or data sets. While finite-elements (FE) models belong to the equation-based class of problems, their implementations in commercial solvers do not generally provide information on nonlinearities required analytical construction SSMs. Here, we overcome this limitation developing a data-driven SSM-reduced from small number unforced FE simulations. We then...

This paper investigates the dynamics of compact localized modes in one-dimensional flat-band elastic lattices. Flat dispersion arises from destructive interference between neighboring elements, resulting a zero group velocity across all momenta. unique condition enables formation wave that are not only highly space and inherently non-propagative-protected by flatness relation-but also exceptionally sensitive to structural variations due enhanced wave-structure interaction. These features...

Periodic systems have long been known for their peculiar characteristics in wave propagation and studied many fields over the last century, going from electro-magnetics optics to elastic structures, which drew an increasing interest structural mechanical engineering vibration suppression control spanning broadband frequency ranges. Recently, on stream of other studies conducted different fields, spatiotemporal modulated structures studied, showing promising results that one-way so called...

Abstract The computation of the steady state response large finite element discretized systems subject to periodic excitations is unfeasible because excessive run time and memory requirements. One could in principle resort reduced order models stemming from high fidelity counterparts, which typically require a solution orders magnitude smaller. However, when many simulations are required, as case parametric studies, overall effort be still significant analysis process severely hindered. In...