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Hambric, Stephen A.; Sung, Shung H.; Nefske, Donald J.

doi:10.1002/9781118693988.ch1

Cited by 10 publications

(8 citation statements)

References 1 publication

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“…In the characterization of the Star transducer undertaken here, the SPLs all fall within a linear regime to meet such an assumption. For useful results to be obtained by the BEM approach, at least six linear element edges are required to span the space of the acoustic wavelength under consideration [47]. In the following cases, this basic rule is satisfied.…”

Section: Numerical Verification Methodsmentioning

confidence: 99%

Adaptive acoustic energy delivery to near and far fields using foldable, tessellated star transducers

Zou

Harne

2017

Smart Mater. Struct.

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Methods of guiding acoustic energy arbitrarily through space have long relied on digital controls to meet performance needs. Yet, more recent attention to adaptive structures with unique spatial configurations has motivated mechanical signal processing (MSP) concepts that may not be subjected to the same functional and performance limitations as digital acoustic beamforming counterparts. The periodicity of repeatable structural reconfiguration enabled by origami-inspired tessellated architectures turns attention to foldable platforms as frameworks for MSP development. This research harnesses principles of MSP to study a tessellated, star-shaped acoustic transducer constituent that provides on-demand control of acoustic energy guiding via folding-induced shape reconfiguration. An analytical framework is established to probe the roles of mechanical and acoustic geometry on the far field directivity and near field focusing of sound energy. Following validation by experiments and verification by simulations, parametric studies are undertaken to uncover relations between constituent topology and acoustic energy delivery to arbitrary points in the free field. The adaptations enabled by folding of the star-shaped transducer reveal capability for restricting sound energy to angular regions in the far field while also introducing means to modulate sound energy by three orders-of-magnitude to locations near to the transducer surface. In addition, the modeling philosophy devised here provides a valuable approach to solve general sound radiation problems for foldable, tessellated acoustic transducer constituents of arbitrary geometry.

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Section: Numerical Verification Methodsmentioning

confidence: 99%

Adaptive acoustic energy delivery to near and far fields using foldable, tessellated star transducers

Zou

Harne

2017

Smart Mater. Struct.

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“…For the case of acoustic waves with oblique incidence angles, the diffuse power transmission coefficient (τd) may be calculated using [46] τdfalse(θ, ωfalse)=∫0π/2 τfalse(φ, θ, ωfalse) sin⁡2φ dφ,which, for the purpose of numerical evaluation, can be evaluated using angles between 0∘ and 78∘ [13]. This definition can also be used with equation (4.28) to express the diffuse STL as STLdfalse(θ, ωfalse)=10log⁡(1τdfalse(θ, ωfalse)).…”

Section: Sound Insulation Panelsmentioning

confidence: 99%

“…With the purpose of validating the PWE formulation, analytical expressions obtained from the literature are also presented. The analytical sound power transmission coefficient (τa) for an infinite constant-thickness flat plate (and thus independent of θ) with the same fluid on both sides can be calculated using [46] τasfalse(φ, ωfalse)=false(2ρ0c0sec⁡φfalse)2false(2ρ0c0sec⁡φfalse)2+false(ωρh−false(D/ωfalse)false(k0sin⁡φfalse)4false)2,which can be used in the place of the numerically obtained τfalse(φ, θ, ωfalse) in equation (4.28) to calculate the analytical STL.…”

Section: Sound Insulation Panelsmentioning

confidence: 99%

Bioinspired periodic panels optimized for acoustic insulation

Poggetto

Pugno

Arruda

2022

Phil. Trans. R. Soc. A.

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The design of structures that can yield efficient sound insulation performance is a recurring topic in the acoustic engineering field. Special attention is given to panels, which can be designed using several approaches to achieve considerable sound attenuation. Previously, we have presented the concept of thickness-varying periodic plates with optimized profiles to inhibit flexural wave energy propagation. In this work, motivated by biological structures that present multiple locally resonant elements able to cause acoustic cloaking, we extend our shape optimization approach to design panels that achieve improved acoustic insulation performance using either thickness-varying profiles or locally resonant attachments. The optimization is performed using numerical models that combine the Kirchhoff plate theory and the plane wave expansion method. Our results indicate that panels based on locally resonant mechanisms have the advantage of being robust against variation in the incidence angle of acoustic excitation and, therefore, are preferred for single-leaf applications. This article is part of the theme issue ‘Wave generation and transmission in multi-scale complex media and structured metamaterials (part 2)’.

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“…The concept of complex modulus essentially involves another representation of material damping related to the notion of complex stiffness. It is a measure of the resistance of the material to deformation that encompasses both the elastic and viscous responses [63,64]. The complex modulus approach can also carry deeper concepts of frequency, temperature, and electric/magnetic field dependence.…”

Section: Formulationmentioning

confidence: 99%

Sound transmission control through a hybrid smart double sandwich plate structure

Hasheminejad

Jamalpoor

2020

Jnl of Sandwich Structures & Materials

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A three-dimensional analytical model is developed for control of sound transmission through an acoustically baffled simply supported hybrid smart double sandwich panel partition of rectangular planform. The hybrid structure includes spatially distributed piezoelectric (PZT) and electro-rheological fluid (ERF) actuator layers arranged in a non-collocated configuration in the incident or transmitted panels. The basic formulation utilizes the relevant classical thin plate theories, Kelvin-Voigt viscoelastic damping model, Maxwell’s equations of electrodynamics, and the linear acoustic wave equations coupled by the pertinent structure/fluid compatibility relations. The conventional multi-input multi-output sliding mode control (MIMOSMC) strategy is subsequently applied to improve the sound transmission loss (STL) through the composite partition by smart (semi-active) variation of the stiffness/damping characteristics of the ERF core layer in collaboration with the (active) uniform force PZT actuator layer according to the control commands. Extensive numerical simulations present both the uncontrolled and controlled STL performances of the composite sandwich structure for four different arrangements of the active and semi-active control elements (i.e. PZT/PZT, ERF/ERF, ERF/PZT, and PZT/ERF) as well as for the single partition (ERF, PZT) sandwich panels at selected incident angles and air cavity dimensions. Four different types of vibroacoustic resonances for the composite structure are identiﬁed and briefly discussed, namely, the mass-air-mass resonance, the sandwich panel resonances, the cavity standing-wave resonances, and the coincidence resonance. The remarkable overall advantages of all four MIMOSMC-based double panel control configurations in significant attenuation of sound transmission at very low frequencies, and in the vicinity of the coupled mass-air-mass resonances as well as at the panel resonance frequency dips, are demonstrated. In particular, the proposed hybrid smart double panel (ERF/PZT or PZT/ERF) configuration (which integrates the high performance, precision, and capability of the active PZT-based panel with simplicity, reliability, and stability robustness of the semi-active ERF-based panel) is observed to display a considerably smoother broadband sound proof ability in comparison with the conventional full active (PZT/PZT) system. More importantly, it is particularly capable of delivering up to 90% of the full active control performance, with inherently less energy and actuation demands. Limiting cases are considered and validity of the formulation is rigorously confirmed by comparison with the FEM results as well as with the available data.

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Overview

Cited by 10 publications

References 1 publication

Adaptive acoustic energy delivery to near and far fields using foldable, tessellated star transducers

Adaptive acoustic energy delivery to near and far fields using foldable, tessellated star transducers

Bioinspired periodic panels optimized for acoustic insulation

Sound transmission control through a hybrid smart double sandwich plate structure

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