Tunable evolutions of wave modes and bandgaps in quasi-1D cylindrical phononic crystals

Phil. Trans. R. Soc. A.

Kim

Yang

2018

Self Cite

We propose a tunable cylinder-based granular system that is functionally graded in its stiffness distribution in space. With no initial compression given to the system, it supports highly nonlinear waves propagating under an impulse excitation. We investigate analytically, numerically and experimentally the ability to accelerate and decelerate the impulse wave without a significant scattering in the space domain. Moreover, the gradient in stiffness results in the scaling of contact forces along the chain. We envision that such tunable systems can be used for manipulating highly nonlinear impulse waves for novel sensing and impact mitigation purposes.This article is part of the theme issue 'Nonlinear energy transfer in dynamical and acoustical systems'.

Section: Introductionmentioning

confidence: 99%

Demonstration of accelerating and decelerating nonlinear impulse waves in functionally graded granular chains

Phil. Trans. R. Soc. A.

Kim

Yang

2018

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“…Previous researches have shown that such cylindrical granular crystals provide an enhanced freedom in tailoring stress wave propagation in solids. 31,[33][34][35][36][37][38][39] For the current study, we can therefore vary the alignment of contact angles in a tunable fashion and introduce a gradient in contact stiffness along the chain-mimicking the effect of an externally applied electric field for BOs of electrons. This results in the tilting of band dispersion curves-an essential feature for the formation of the WSLs.…”

Section: Introductionmentioning

confidence: 99%

Elastic Wannier-Stark ladders and Bloch oscillations in 1D granular crystals

Shi

Journal of Applied Physics

et al. 2018

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We report the numerical and experimental study of elastic Wannier-Stark Ladders and Bloch Oscillations in a tunable one-dimensional granular chain consisting of cylindrical particles. The Wannier-Stark Ladders are obtained by tuning the contact angles to introduce a gradient in the contact stiffness along the granular chain.These ladders manifest as resonant modes localized in the space. When excited at the corresponding resonant frequencies, we demonstrate the existence of time-resolved Bloch Oscillations. The direct velocity measurements using Laser Doppler Vibrometry agree well with the numerical simulation results. We also show the possibility of further tailoring these Bloch Oscillations by numerical simulations. Such tunable systems could be useful for applications involving the spatial localization of elastic energy. a)

“…These have several unique features, including -but not limited to -the control of contact stiffness based on the stacking angles of cylinders (Khatri et al, 2012), and the utilization of cylinder lengths to induce local resonance effects due to bending (Kim and Yang, 2014;Kim et al, 2015a,b). Consequently, such systems can support a wide range of wave tailoring functionality, encompassing from filtering linear elastic waves by the formation of frequency band-gaps (Kim and Yang, 2014;Li et al, 2012;Meidani et al, 2015;Chaunsali et al, 2016) to manipulating highly nonlinear waves (Khatri et al, 2012;Kim et al, 2015a,b;Kore et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Extreme control of impulse transmission by cylinder-based nonlinear phononic crystals

Journal of the Mechanics and Physics of Solids

Toles

Yang

et al. 2017

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We present a novel device that can offer two extremes of elastic wave propagation -nearly complete transmission and strong attenuation under impulse excitation. The mechanism of this highly tunable device relies on intermixing effects of dispersion and nonlinearity. The device consists of identical cylinders arranged in a chain, which interact with each other as per nonlinear Hertz's contact law. For a 'dimer' configuration, i.e., two different contact angles alternating in the chain, we analytically, numerically, and experimentally show that impulse excitation can either propagate as a localized wave, or it can travel as a highly dispersive wave. Remarkably, these extremes can be achieved in this periodic arrangement simply by in-situ control of contact angles between cylinders. We close the discussion by highlighting the key characteristics of the mechanisms that facilitate strong attenuation of incident impulse. These include low frequency to high frequency (LF-HF) scattering, and turbulence-like cascading in a periodic system. We thus envision that these adaptive, cylinder-based nonlinear phononic crystals, in conjunction with conventional impact mitigation mechanisms, could be used to design highly tunable and efficient impact manipulation devices.