Ерофеев В.И., Молодушная Н.И., Семерикова Н.П. «Нелинейное эволюционное уравнение для описания распространения поперечных волн в многослойной конструкции» Вестник научно-технического развития, № 9, с. 15-20 (2019)
Рассматривается слоистая конструкция, представляющая собой две струны, лежащие на упругих основаниях Винклера, связанные между собой системой вязких элементов. При этом одна из струн совершает поперечные колебания конечной амплитуды и описывается нелинейным уравнением, динамика второй струны описывается линейным уравнением. Для описания волновых процессов от исходной математической модели произведен переход к эволюционному уравнению, представляющему собой комбинацию нескольких классических уравнений нелинейной волновой динамики (обобщенное уравнение Бюргерса, модифицированное уравнение Кортевега–де Вриза, модифицированное уравнение Островского и др.).
Вестник научно-технического развития, № 9, с. 15-20 (2019) | Рубрика: 06.15
Introduction. Microacoustic sensors based on surface acoustic wave (SAW) devices allow the sensor integration into a wafer based microfluidic analytical platforms such as lab-on-a-chip. Currently exist various approaches of application of SAW devices for liquid properties analysis. But this sensors probe only a thin interfacial liquid layer. The motivation to develop the new SAW-based sensor is to overcome this limitation. The new sensor introduced here uses acoustic measurements, including surface acoustic waves (SAW) and acoustic methamaterial sensor approaches. The new sensor can become the starting point of a new class of microsensor. It measures volumetric properties of liquid analytes in a cavity, not interfacial properties to some artificial sensor surface as the majority of classical chemical and biochemical sensors. Objective. The purpose of the work is to find solutions to overcome SAW-based liquid sensors limitations and the developing of a new sensor that uses acoustic measurements and includes a SAW device and acoustic metamaterial. Materials and methods. A theoretical analysis of sensor structure was carried out on the basis of numerical simulation using COMSOL Multiphysics software. Lithium niobate (LiNbO3) 127.86° Y-cut with wave propagation in the X direction was chosen as a substrate material. Microfluidic structure was designed as a set of rectangular shape channels. A method for measuring volumetric properties of liquids, based on SAW based fluid sensor concept, comprising the steps of: (a) providing sensor structure with the key elements: a SAW resonator, a high-Q set of liquid-filled cavities and intermediate layer with artificial elastic properties between them; (b) measuring of resonance frequency shift, associated with the resonance in liquid-filled cavity, in the response of weakly coupled resonators of SAW resonator loaded by periodic microfluidic structure; (c) determination of volumetric properties of the fluid on the basis of a certain relationship between the speed of sound in liquid, the resonant frequency of the set of liquid-filled cavities, and the geometry design of the cavity.Results. The new sensor approach is introduced. The eigenmodes of the sensor structure with a liquid analyte are carried out. The characteristic of sensor structure is determined. The key elements of introduced microfluidic sensor are a SAW structure, an acoustic metamaterial with a periodic set of microfluidic channels. The SAW device acts as electromechanical transducer. It excites surface waves propagating in the X direction lengthwise the periodic structure and detects the acoustic load generated by the microfluidic structure resonator. The origin of the sensor signal is a small frequency change caused by small variations of acoustic properties of the analyte within the set of microfluidic channels. Conclusion. The principle of the new microacoustic sensor, which can become the basis for creating a new class of microfluidic sensors, is shown.
Известия высших учебных заведений России. Радиоэлектроника, 22, № 4, с. 75-81 (2019) | Рубрика: 06.15
Modulating band gaps (extending the bandwidths or shifting into a lower frequency range) is a challenging task in phononic crystals. In this paper, elastic metamaterial plates composed of a square array of “hard” stubs or “soft” stubs on both sides of a 2D binary locally resonant plate are proposed, and their band structures are studied. The dispersion relationships and the displacement fields of the eigenmodes are calculated using finite element methods. Numerical results show that the band gaps are shifted to lower frequencies and the bandwidths are enlarged compared to classic elastic metamaterial plates. A conceptual “analogousrigid mode” that includes an “out-of-plane analogous-rigid mode” and an “in-plane analogous-rigid mode” is developed to explain these phenomena. The “out-of-plane analogous-rigid mode” mainly adjusts the band gaps into the lower frequency range, and the “in-plane analogous-rigid mode” mainly enlarges the bandwidth. Furthermore, the band gap effects of composite “hard” stubs and “soft” stubs are investigated. The results show that the location of the band gaps can be modulated into a relatively lower frequency and the bandwidth can be extended by the use of different composite stubs. These elastic wave properties in the proposed structure can be used to optimize band gaps and possibly produce low-frequency filters and waveguides.
Акустический журнал, 63, № 5, с. pp. 508-516 (2017) | Рубрика: 06.15
Sonic crystals are the periodic arrangements of scatterers embedded in a homogeneous material. Their ability to prevent sound wave to propagate in a particular range of frequency demonstrates their use as potential noise barriers. The sonic crystal considered in this work is an array of PVC cylinders (5×5) in air bounded by acrylic sheets. This paper studies the sound transmission loss in the sonic crystal by changing the location of the sidewalls. The optimized location of sidewalls of the sonic crystal to get wide band gap and high sound transmission loss has been investigated. To increase the transmission loss, a periodic structure having bi-periodicity, i.e., periodicity in two perpendicular directions is introduced. Both computational (Finite Element simulation) and experimental work has been performed to study the sound transmission loss and the band gaps. To bridge the gap between the two results, an improved finite element model has been proposed with an aim to replicate the experimental situation more closely. Generally, in experiments, insertion loss is calculated while numerically transmission loss is computed, and the two are compared. In this paper, a comparison between insertion loss and transmission loss has also been made numerically, which is compared with the experimental results.
Акустический журнал, 64, № 6, с. pp. 665-672 (2018) | Рубрика: 06.15
An analytical inverse method to design lenses of isotropic inhomogeneous refractive index (RI) distribution is presented, where the wave ray propagation is described by the eikonal equation. We show that some particular RI distributions can be obtained by the angles of incidence and emergence when the rays pass through the surfaces of the lenses. This method is applied to design lenses that perfectly focus rays or bend them to arbitrary angles. In addition, gradient refractive index (GRIN) devices are proposed, able to generate self-bending acoustic beams and obtain illusion shadows of arbitrary objects. The ray tracing and finite elements method simulation results indicate the validity of the method. The method may have potential applications in designing acoustic and optic GRIN devices for controlling energy flux, such as medical imaging, therapeutic ultrasound, acoustic levitation, energy isolation, acoustic and optic camouflaging, etc.
Акустический журнал, 64, № 6, с. pp. 684-691 (2018) | Рубрика: 06.15
Acoustic metamaterials have become a novel and effective way to control sound waves and design acoustic devices. In this study, we design a 3D acoustic metamaterial lens (AML) to achieve point-to-point acoustic communication in air: any acoustic source (a speaker) in air enclosed by such an AML can produce an acoustic image where the acoustic wave is focused (the field intensity is at a maximum, and the listener can receive the information), while the acoustic field at other spatial positions is low enough that listeners can hear almost nothing. Unlike a conventional elliptical reflective mirror, the acoustic source can be moved around inside our proposed AML. Numerical simulations are given to verify the performance of the proposed AML.
Акустический журнал, 65, № 1, с. pp. 1-6 (2019) | Рубрика: 06.15
Laidoudi F., Boubenider F., Mebarki M., Medjili F., Bettine F. «Numerical Investigation of Quasi-Lamb Modes in c–Tilted ZnO/SiC Composite Membrane for High Performance Pressure Micro-Sensor» Акустический журнал, 65, № 3, с. pp. 253-262 (2019)
Using the finite element method, we have studied the Lamb modes characteristics propagation in c tilted ZnO/SiC thin film composite membrane. Phase velocity dispersion curves, electromechanical coupling factors and the mass loading effect on the fundamental quasi Lamb modes are theoretically investigated for different rotating angle (0], τ°, 90°), τ being the angle of rotation, and for different hZnO/λ values. To develop high performance pressure micro-sensor based on thin film piezoelectric ZnO on amorphous SiC (range 0.1 to 100 Pa) the anti-symmetric fundamental qA0 mode phase shift is studied for pressure sensing.
Акустический журнал, 65, № 3, с. pp. 253-262 (2019) | Рубрика: 06.15
Li Suobin, Dou Yihua, Chen Tianning, Wan Zhiguo, Ju Luyan, Zhang Fan, Cui Xiao Xiao «Forming Low-Frequency Complete Vibration Bandgaps in a thin Nonmetallic Elastic Metamaterial Plate» Акустический журнал, 65, № 3, с. pp. 322-333 (2019)
Low-frequency vibration-bandgaps in elastic metamaterials open new possibilities to minimize low-frequency vibration and noise. Unfortunately, fabricating a complete vibration bandgap for low frequencies still represents a challenging engineering task. In this paper, a new type of a low-frequency complete vibration bandgap in a thin non-metal elastic metamaterial plate is introduced and investigated numerically. The proposed elastic metamaterial plate consists of decoupling-resonators, which are deposited on a 2D, locally resonant phononic-crystal plate, made of an array of rubber fillers, which are embedded in a nonmetallic plate. The dispersion relationship, the power-transmission spectrum, and the displacement fields for the eigenmode are calculated using the finite element method. It is shown that coupling between the local resonance mode of the decoupling-resonators and the Lamb-wave mode of the epoxy plate, consistent with the modal superposition principle, is responsible for the formation of vibration bandgaps. Moreover, the equivalent spring-mass system for the coupling-resonators can be decoupled by introducing a rubber filler. In addition, both longitudinal and the transverse elastic wave bandgaps can be tuned to the same low-frequency range. As a result, a novel kind of low-frequency complete vibration bandgap, which can damp a low-frequency elastic wave, is produced. Furthermore, the effects of the decoupling-resonators on the vibration bandgap are investigated. It is now possible that an elastic metamaterial plate can be dampen with complete low-frequency vibration bandgaps, which can potentially be used for commercial noise and vibration reduction.
Акустический журнал, 65, № 3, с. pp. 322-333 (2019) | Рубрика: 06.15