Evolution of ultrasonic impulses in chains of spheres using resonant excitation

Hutchins, David A.; Yang, Jie; Akanji, Omololu; Thomas, Peter J.; Davies, Leanne; Freear, Steven; Harput, Sevan; Saffari, Nader; Gélat, Pierre

doi:10.1209/0295-5075/109/54002

Cited by 17 publications

(39 citation statements)

References 9 publications

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“…To demonstrate the effect of the matching layer, the response of the granular chain is calculated using the analytical model described earlier [18] Figure 3 shows the velocity of the last sphere for a six-sphere granular chain terminated with an infinite steel wall. A granular chain system placed between two immovable boundaries can accommodate periodic solitary waves for a given input force and precompression force, which is explained as in-phase nonlinear normal modes by Jayaprakash et al [28].…”

Section: Resultsmentioning

confidence: 99%

“…An analytical model created by Hutchins et al [18] and later analyzed in greater depth by Yang et al [26] is used to simulate the wave propagation through the chain. The existing model that places an infinite wall behind the last sphere is modified to implement the effect of the matching layer at the end of the chain.…”

Section: A Model With a Matching Layermentioning

confidence: 99%

“…This study, therefore, focuses on maximizing the transferred energy from a chain of spheres into biological tissue and also the harmonic content, which increases the bandwidth of the generated ultrasound waves. After Nesterenko's pioneering work in 1983 [1], a great number of models were developed to simulate wave propagation in infinite and finite chains [2,4,18]. However, predicting the resonance behavior in harmonically driven monoatomic granular chains, modeling the nonlinear and dispersive effects, and minimizing the overall structure are still big challenges [5,19].…”

Section: Introductionmentioning

confidence: 99%

“…A prototype device was developed based on this nonlinearity in a one-dimensional chain of spheres by Hutchins et al [18,[21][22][23]. The developed transducer is able to transform a narrow-band sinusoidal input force into a train of wideband impulses at ultrasonic frequencies.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, a matching layer is modeled as a flexible thin circular disk clamped from the edges and merged into an existing analytical model [18,26] to identify suitable materials for biomedical applications. Different matching materials, such as glass, aluminum, acrylic, silicon rubber, and vitreous carbon, are analyzed with this model.…”

Section: Introductionmentioning

confidence: 99%

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Generation of Ultrasound Pulses in Water Using Granular Chains with a Finite Matching Layer

et al. 2017

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Wave propagation in granular chains is subject to dispersive effects as well as nonlinear effects arising from the Hertzian contact law. This enables the formation of wideband pulses, which is a desirable feature in the context of diagnostic and therapeutic ultrasound applications. However, coupling of the ultrasonic energy from a chain of spheres into biological tissue is a big challenge. In order to improve the energy transfer efficiency into biological materials, a matching layer is required. A prototype device is designed to address this by using six aluminum spheres and a vitreous carbon matching layer. The matching layer and the precompression force are selected specifically to maximize the acoustic pressure in water and its bandwidth. The designed device generates a train of wideband ultrasonic pulses from a narrow-band input with a center frequency of 73 kHz. An analytical model is created to simulate the behavior of a matching layer as a flexible thin plate clamped from the edges. This model is then verified using free-field hydrophone measurements in water, which successfully predict the increased bandwidth by generation of harmonics. The shapes of the measured and predicted waveforms are compared by calculating the normalized cross-correlation, which shows 83% similarity between both. Since the generation of harmonics is of interest in this study, the total harmonic distortion (THD) and the −6-dB bandwidth of the signals are used to analyze signal fidelity between the hydrophone measurements and the model predictions. The acoustic signals in water have a root-mean-square THD of 73%, and the model predicts a root-mean-square THD of 78%. The −6-dB bandwidths of individual pulses measured by a hydrophone and predicted with the model are 280 and 252 kHz, respectively. At these high ultrasonic frequencies, it is an experimental demonstration of resonant chains operating in water with a matching layer.

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Section: Resultsmentioning

confidence: 99%

Section: A Model With a Matching Layermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Generation of Ultrasound Pulses in Water Using Granular Chains with a Finite Matching Layer

et al. 2017

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Shear vibration modes of granular structures: Continuous and discrete approaches

et al. 2023

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This work is dedicated to the study of shear vibration modes of one‐dimensional granular microstructured beams using a discrete Cosserat model. The dynamic response of the one‐dimensional granular beam (discrete beam) is investigated for various boundary conditions, through the analytical resolution of an exact discrete eigenvalue problem. For an infinite number of grains, the dynamic behavior of the discrete problem converges towards a Bresse–Timoshenko continuum beam model. First, the effective modeling parameters, the constitutive equations and the governing equations of motion are derived in a difference form. For simply supported granular beams, the appearance of pure shear modes of vibration is highlighted (vibration modes without deflection), a phenomenon which is already known in the free vibration of a continuous Bresse–Timoshenko beam problem. The eigenfrequencies of these pure shear modes for the discrete granular beam coincide with the critical frequencies of the discrete system. These pure shear modes may appear for granular beams composed of few grains, which give a physical support of a phenomenon well studied in the literature from a continuum beam model. The eigenfrequencies of the discrete granular beam are also calculated for various boundary conditions, including clamped, hinge and free end boundary conditions. Based on the discrete element method (DEM), several numerical simulations of dynamic tests in some representative examples have been performed. The responses of the numerical approach are accurately compared against the exact results of the analytical solutions based on the difference eigenvalue problem, which illustrates the relevance of the proposed approach.

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Decorated granular crystal as filter of low-frequency ultrasonic signals

Machado

Sen

2019

Granular Matter

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Evolution of ultrasonic impulses in chains of spheres using resonant excitation

Cited by 17 publications

References 9 publications

Generation of Ultrasound Pulses in Water Using Granular Chains with a Finite Matching Layer

Generation of Ultrasound Pulses in Water Using Granular Chains with a Finite Matching Layer

Shear vibration modes of granular structures: Continuous and discrete approaches

Decorated granular crystal as filter of low-frequency ultrasonic signals

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