Nonlinear Acoustic Effects Research Articles

Sound Field Visualization of Specified Frequency by Combining Scanning System with Lock-in Amplifier

Abstract Sound field visualization of specified frequency is an essential method for acoustic studies, especially in nonlinear acoustics. In this paper, we designed a sound field visualization system of specified frequency (SVSF). By combining the traditional sound field scanning system with the lock-in amplifier (LIA), the SVSF can visualize the amplitude distribution of multiple arbitrary specified frequencies with only one-time sound field scanning. Further, depending on the SVSF, we analysed the nonlinear acoustic effects around the focus of a spherical coronal ultrasonic transducer array. The excitation signal is a sinusoidal signal at 40 kHz. The results show that the acoustic waves at the focus contain fundamental frequencies at 40 kHz and harmonic frequencies at 80 kHz, 120 kHz, and 160 kHz. Comparing the amplitude distribution of those frequencies, we found that higher harmonics own smaller focus areas as well as lower amplitude, which conforms to the nonlinear acoustic theory. The system is convenient for those similar studies involving the multi-frequency amplitude field comparison.

Strongly enhanced nonlinear acoustic valley Hall effect in tilted Dirac materials

Strongly enhanced nonlinear acoustic valley Hall effect in tilted Dirac materials

Studying the nonlinearity effects in ultrasound-assisted water purification and treatment systems

In light of industrial sectors' rapid and exponential growth, the deleterious specter of water pollution looms ominously over our environment. One of the significant challenges is obtaining a sustainable and energy-efficient water purification/treatment system. Since the 1990s, several research studies have been proposed to demonstrate the usefulness of ultrasound as a water purification tool. As a result, newly designed devices such as ultrasound-assisted electrochemical treatment and ultrasound-assisted heat exchanging devices are becoming more common. However, such devices' high voltage ultrasonic emission is a significant problem because the nonlinear acoustic effects are not well understood and are, therefore, not adequately integrated into the design of the devices. Furthermore, the presence of biofilms in these devices creates more complexity due to the interaction of high-amplitude ultrasonic waves with the biofilm network. To better overcome the inefficient functioning of such devices and adverse operational issues, the current study aims to investigate and explain the nonlinear ultrasonic effects in ultrasonic-assisted purification devices, with and without biofilm deposits. The obtained insight will help develop an effective design strategy for high efficiency.

Transmit beam design for tissue harmonic volume imaging of muscular tissues with a row-column array

Row-Column-addressed Arrays (RCAs), which have recently become commercially available, transmit along the rows and receive along columns of a 2D array in order to produce 3D volume images with low channel count. Imaging of the inherently three-dimensional, layered, and fibrous structure of muscular tissues in 3D using an RCA can improve evaluations of muscle function and disease compared to conventional 2D cross-sectional imaging, but volume images obtained using an RCA suffer from low lateral spatial resolution, low contrast, and grating lobe artifacts. Tissue harmonic imaging (THI) employs nonlinear acoustic effects to image at twice the transmit frequency, and can yield increased spatial resolution, increased contrast, and decreased artifacts from grating lobes. Here we investigate transmission considerations for THI in muscular tissues using a commercially available RCA (Vermon RC6gV). The parameter space is explored efficiently with frequency domain simulations of the 3D Westervelt equation. Pulse inversion imaging is applied experimentally using both steered plane wave and focused transmits to evaluate THI with an RCA in tissue phantoms and in muscular tissue. Pulse inversion volume images are compared to conventional images in terms of signal-to-noise, contrast, and ability to identify layers and fibrous structures in muscle in 3D. [Work supported by NIH HEAL Initiative R61AT012282.]

Dynamics and frequency response analysis of encapsulated microbubble under nonlinear ultrasound

Bubble dynamic behavior and frequency response of encapsulated microbubbles in nonlinear acoustic field is significant in applications such as tumor therapy, thrombolysis, tissue destruction, and ultrasonic lithotripsy. The acoustic cavitation effect includes stable cavitation and transient cavitation. The transformation from stable cavitation to transient cavitation requires a certain threshold, which is also called the transient cavitation threshold. Phospholipid-coated microbubbles are commonly used to enhance acoustic cavitation. However, the acoustic effects of different coating materials are not very clear, especially when considering the nonlinear effects caused by diffraction, scattering, and reflection during ultrasonic propagation. In this paper, the bubble dynamic behaviors and frequency responses of microbubbles under different frequencies, acoustic pressures, and viscoelastic properties of different shell materials are analyzed by coupling the Gilmore-Akulichev-Zener model with the nonlinear model of a lipid envelope and using the KZK equation to simulate the nonlinear acoustic field. At the same time, the influence of the coated material and nonlinear acoustic effects are considered. The bubble dynamic behavior and frequency response under the actually measured sound field are compared with those simulated by the KZK equation. The results show that the nonlinearity will lead the velocity of the microbubble wall to decrease, and when the pressure of ultrasound increases, the main frequency component of the microbubble oscillation increases, making the radial motion of the microbubble more violent. When the frequency changes, the closer the oscillation frequency of the microbubble is to the resonant frequency, the stronger the radial motion of the microbubble is. The coating material can change the harmonic component in the oscillation frequency. When the harmonic is close to the resonance frequency, the radial motion of the microbubble is enhanced. The elasticity of the coated material has almost no effect on the microbubble's frequency response, and the initial viscosity and surface tension of encapsulated microbubble will change the oscillation frequency distribution of encapsulated microbubble. When the initial viscosity of the coated microbubble is smaller, the subharmonic component of the microbubble oscillation increases. When the frequency of the subharmonic is closer to the resonance frequency than the main frequency, the acoustic cavitation effect is significantly enhanced. On the other hand, when the initial surface tension of the encapsulated microbubble increases, the main frequency and subharmonic component of the microbubble oscillation are enhanced, so that the acoustic cavitation effect is also enhanced. Therefore, this study can further elucidate the bubble dynamics of encapsulated microbubbles, stimulated by nonlinear ultrasound, benefiting the frequency response analysis of coated microbubbles under nonlinear acoustic fields.

Research Progress in Nonlinear Ultrasonic Testing for Early Damage in Metal Materials

There are some limitations when conventional ultrasonic testing methods are used for testing early damage in metal parts. With the continuous development of acoustics and materials science, nonlinear ultrasonic nondestructive testing technology has been used for testing of early damage in metal materials. In order to better understand the basic theory and research progress of the nonlinear ultrasonic testing technology, the classical nonlinear ultrasonic theoretical models, including the dislocation monopole model, dislocation dipole model, precipitate-dislocation pinning model, and contact nonlinear ultrasonic theory-microcrack model, are analyzed in depth. This paper introduces the application and research progress of nonlinear ultrasonic detection technology, which is derived from different acoustic nonlinear effects, such as higher harmonic, wave mixing and modulation, sub-harmonic, resonance frequency spectrum analysis, and non-linear ultrasonic phased array imaging. The key technologies and problems are summarized to provide a reference for the further development and promotion of nonlinear ultrasonic non-destructive testing technology.

Willis Coupling-Induced Acoustic Radiation Force and Torque Reversal.

Acoustic meta-atoms serve as the building blocks of metamaterials, with linear properties designed to achieve functions such as beam steering, cloaking, and focusing. They have also been used to shape the characteristics of incident acoustic fields, which led to the manipulation of acoustic radiation force and torque for development of acoustic tweezers with improved spatial resolution. However, acoustic radiation force and torque also depend on the shape of the object, which strongly affects its scattering properties. We show that by designing linear properties of an object using metamaterial concepts, the nonlinear acoustic effects of radiation force and torque can be controlled. Trapped objects are typically small compared with the wavelength, and are described as particles, inducing monopole and dipole scattering. We extend such models to a polarizability tensor including Willis coupling terms, as a measure of asymmetry, capturing the significance of geometrical features. We apply our model to a three-dimensional, subwavelength meta-atom with maximal Willis coupling, demonstrating that the force and the torque can be reversed relative to an equivalent symmetrical particle. By considering shape asymmetry in the acoustic radiation force and torque, Gorkov's fundamental theory of acoustophoresis is thereby extended. Asymmetrical shapes influence the acoustic fields by shifting the stable trapping location, highlighting a potential for tunable, shape-dependent particle sorting.

Linear and nonlinear modelling of far-field propagation of broadband shock-associated noise

A triple-scale computational model is implemented to simulate noise generated by a supersonic under-expanded screeching jet corresponding to the LTRAC (Laboratory for Turbulence Research in Aerospace and Combustion) experiment at different distances from the source. The investigation is focused on the broadband-associated noise, which is a prominent feature of the acoustic field of the LTRAC jet. In the jet near-field, the compressible Navier–Stokes equations are solved using the high-resolution CABARET Large Eddy Simulation (LES) method accelerated on Graphics Processing Units. The LES solution is substituted in the Ffowcs Williams–Hawkings (FW–H) model to obtain the noise solution in the acoustic mid field at 20 initial jet diameters from the jet nozzle exit. The mid-field acoustic solution is used as the input for the spherical generalised Burgers’ equation. The general form of Burgers’ equation is solved numerically in the frequency domain for a wide range of observer distances up to 18 million initial jet diameters, where viscous dissipation fully dominates for most frequencies. To answer the question if the nonlinear acoustic wave propagation effects for the LTRAC jet are important, the nonlinear and linear solutions of Burgers’ equation are compared.

Vortex beam interactions for the measurement of nonlinear acoustic behaviour

Spatially shaped optical fields have been widely implemented for remote sensing, enhanced imaging and communications. Many of these principles can be readily translated into acoustics, where acoustic fields that carry orbital angular momentum (OAM) have gained considerable interest in recent years. These spatially shaped fields can provide unique acoustic interactions with materials and gasses as they propagate that can be leveraged to create novel sensor technologies. We will present a technique to amplify the visibility of nonlinear acoustic effects in gasses, via the controlled interference of acoustic pulses that carry OAM. This amplification allows accurate determination of the nonlinear parameter with acoustic pressures that are 66dB lower than a direct measurement of pulse chirping. In controlled conditions, non-linear parameters can be directly measured; however, variations in environmental parameters can lead to ambiguity, which can be addressed through the use of a trained Support Vector Machine machine learning approach. This will allow measurements in variation in the nonlinear parameter 0.01 with over 99.5% accuracy and 0.001 with over 75% accuracy based on single measurements, where repeated measurements can further reduce the power requirements and increase accuracy. This approach can be used for monitoring changes in air quality and if extended to other frequencies could be used for monitoring fatiguing in metals.

Nonlinear acoustic effects in polycrystalline solids with saturation of amplitude-dependent internal friction

Theoretical and numerical studies of nonlinear acoustic effects arising from the propagation of initially harmonic waves in polycrystalline solids with saturation of amplitude-dependent internal friction have been carried out. Two main types of hysteresis are considered: elastic and inelastic. A comparative analysis of the regularities of nonlinear effects is carried out and the characteristics of nonlinear quasi-harmonic waves in such media are determined: amplitude-dependent losses and changes in propagation velocity, as well as amplitudes of higher harmonics. A method for determining the type of polycrystal hysteresis based on the analysis of theoretical and experimentally established amplitude dependences of nonlinear effects is proposed. Keywords: elastic waves, amplitude-dependent internal friction.

The Change of Non-linear Ultrasonic Characterizations in Ti-Al Alloy during Creep

We investigated the evolutions of two nonlinear acoustic characterizations: resonant frequency shift and high harmonic components, with electromagnetic acoustic resonance (EMAR) throughout the creep life in the advanced heat-resistant Ti-Al alloy, Ti-43Al-5V-4Nb. EMAR is a contactless resonant method with an electromagnetic acoustic transducer (EMAT). This method enables not only to measure exact ultrasonic attenuation of measured sample but also to eliminate nonlinear acoustic effect between the sample and transducer. We used the axial SH wave EMAT, which transmits and receives axially polarized shear wave along a cylindrical surface of a circular rod for non-ferromagnetic materials. Two nonlinear ultrasonic properties and attenuation coefficients increases significantly at the beginning of creep life and then gradually decreases to rupture.

Нелинейные акустические эффекты в поликристаллических твердых телах с насыщением амплитудно-зависимого внутреннего трения

Theoretical and numerical studies of nonlinear acoustic effects arising from the propagation of initially harmonic waves in polycrystalline solids with saturation of amplitude-dependent internal friction have been carried out. Two main types of hysteresis are considered: elastic and inelastic. A comparative analysis of the regularities of nonlinear effects is carried out and the characteristics of nonlinear quasi-harmonic waves in such media are determined: amplitude-dependent losses and changes in propagation velocity, as well as amplitudes of higher harmonics. A method for determining the type of polycrystal hysteresis based on the analysis of theoretical and experimentally established amplitude dependences of nonlinear effects is proposed.

A review on nondestructive testing of bonding interface using nonlinear ultrasonic technique

<p indent="0mm">As an important complement to traditional mechanical connections, bonded structures are widely used in industry. Under the combined effect of external loads and environmental factors, the performance of the bonding interface will deteriorate, which seriously affects the safe use of bonding structures. Therefore, the performance evaluation of bonding interfaces has always been a hot and difficult issue in the field of non-destructive testing. Traditional linear ultrasonic technology can effectively detect damage such as delamination and debonding in the bonding interface, but it is difficult to detect and quantitatively evaluate the early degradation of the bonding interface (such as closed defects and weak bonding). However, the nonlinear ultrasonic technology can overcome the low sensitivity of the traditional linear ultrasonic technology and is expected to be an effective means for nondestructive testing of early deterioration of bonding interface performance. In this paper, we review the recent development of nonlinear ultrasonic technology for bonding interface detection from theoretical models and testing experiments. From the perspectives of contact nonlinearity of the interface and material nonlinearity of the interlayer, we introduce relevant theoretical models for nonlinear ultrasonic inspection of bonded interfaces, such as nonlinear spring model, interface contact model and contact model considering the thickness of the interlayer. These models can be used for the description of various acoustic nonlinear effects (such as second harmonic generation, wave mixing and nonlinear resonance) generated by ultrasonic waves at weak bonding interfaces, but the ability of different models to characterize the nonlinear propagation behavior of ultrasonic waves at weak bonding interfaces needs to be further investigated. Meanwhile, we review the progress of three nonlinear techniques of nonlinear ultrasonic resonance, wave mixing and second harmonic generation in the experimental testing of bonding interface properties. The nondestructive testing of bonding interface using nonlinear ultrasonic resonance technique remains relatively limited. Mixing technology is of great interest because of its flexibility and selectability of excitation frequency, mode and area of action, and its ability to effectively avoid the effects of system nonlinearity. Among the nonlinear ultrasonic methods, harmonic techniques are the most widely used, and have been used for damage detection and performance evaluation of bonding interfaces, such as bonding thickness measurement, debonding detection, bond strength and fatigue life evaluation. The harmonic technique is considered as a possible solution for the quantitative detection of the interface properties of multilayer bonded structures. However, how to distinguish the harmonics generated by weakly bonded interfaces from those generated by detection systems has been a challenge for its application. Finally, we provide an outlook for the development of nonlinear ultrasonic detection technology for early degradation of bonding interfaces.

Nonlinear Acoustic Effects in Polycrystalline Solids with Frequency-Dependent Saturation of Hysteresis Losses

Nonlinear Acoustic Effects in Polycrystalline Solids with Frequency-Dependent Saturation of Hysteresis Losses

Sub-array equalization technique for the parametric array loudspeaker to reduce nonlinear distortion

The parametric array loudspeaker (PAL) is a directional loudspeaker which uses the nonlinear acoustic effect, namely the parametric array, to produce an audio beam from narrow ultrasonic beams. The PAL can efficiently deliver audible information, without generating noise to the surroundings. One significant drawback of the PAL is the nonlinear distortion. Therefore, many sophisticated methods have been proposed to preprocess the input signal of the PAL. However, those methods usually request a flat frequency response of the ultrasonic transducer array (UTA). In the past, equalization has been tried out for the whole UTA, but the performance was sometimes not satisfactory due to the inconsistent productions of ultrasonic transducers. This paper proposes to group the ultrasonic transducers by their impedances. Several sub-arrays are thereafter formed and equalized individually. The comparison results demonstrate that the propose sub-array equalization technique can suppress the nonlinear distortion of the PAL more effectively than the previous method.

Nonlinear Acoustic Effects in Polycrystalline Solids With Frequency-Dependent Saturation of Hysteresis Losses

Nonlinear Acoustic Effects in Polycrystalline Solids With Frequency-Dependent Saturation of Hysteresis Losses

About the nonlinear acoustic parameter during deformation of AMG61 alloy

Various acoustic effects are used in the study of deformation processes. Acoustic emission is most often mentioned in such studies, and the effects due to nonlinear properties of a deformable metal are the subject of the present work. These properties of real solids lead to nonlinear acoustic effects of the interaction elastic waves forbidden by the theory of elasticity of a homogeneous isotropic body. The work solves the problem of using the principles of nonlinear acoustics in studying the deformation of AMg61 alloy samples. A surface elastic wave is used to control the alloy condition. The process of the elastic wave propagation in the deformed AMg61 alloy due to nonlinear effects is accompanied by generating the double frequency, both of the longitudinal component of the wave and the shear one, the latter is forbidden by equations of the classical elasticity theory. Excitation and reception in the samples was carried out by piezoelectric converters (PES). A wedge converter with a resonance frequency of 1MHz was used to excite the surfactant. The passing surfactant was recorded by a wedge converter with a resonance frequency of 2 MHz. We justified the control technique of the nonlinear acoustic parameter with respect to amplitudes of the first and second harmonics measured during the whole deformation process. An experimental device has been developed to control the nonlinear acoustic parameter in the process of changing the structural state of the sample metal. The pilot study results of the nonlinear acoustic parameter under Amg61 alloy deformation are given. It is shown that the nonlinear acoustic parameter, as well as the acoustic emission activity, is sensitive to changing mechanisms of the defective structure evolution. The non-linearity jump formation during deformation of alloy AMg61 is recorded, which may indicate adjustment of the metal structure. The presented data demonstrate the increase of acoustic nonlinearity in metal at various deformation stages, both at early stages of elastoplastic deformation and at pre-destruction stage, which can be used as the prognostic criterion.

Nonlinear Acoustic Effects in Polycrystalline Solids with Dislocations

The equation of state for polycrystalline solids with dislocation dissipative and reactive nonlinearities is derived based on the modification of linear part of the Granato–Lucke dislocation theory of absorption. Nonlinear effects associated with the influence of a static load and a high-power standing acoustic wave in a rod resonator on the propagation of a small-amplitude (probe) wave, as well as the effects of self-action of a high-intensity running wave and its third harmonic generation, are studied theoretically.

Inversion method of bubble size distribution based on acoustic nonlinear coefficient measurement**Project supported by the National Natural Science Foundation of China (Grant Nos. 11674074 and 61701133).

Measurements of bubble size distribution require the understanding of the acoustic characteristics of the medium. The bubbles show highly nonlinear properties under finite amplitude acoustic excitation, so the acoustic fields from bubble population are easily observed at the second harmonics as well as at the fundamental frequency, which shows that the nonlinear coefficient increases obviously. The inversion method of bubble size distribution based on nonlinear acoustic effects can peel off the influence of complex environment and obtain the size distribution coefficient information of bubbles more accurately. The previous nonlinear inversion methods of bubble size distribution are mostly based on the nonlinear scattering cross-section characteristics of bubbles. However, the stability of inversion is not high enough. In this paper, we introduce a new acoustic inversion method for bubble size distribution, which is based on the nonlinear coefficients of bubble medium. Compared with other inversion methods based on linear or nonlinear scattering cross section, the inversion method based on nonlinear coefficients of bubble medium proposed in this paper shows good robustness in both simulation and experiment.

Experimental study on eliminating fire smokes using acoustic agglomeration technology

Acoustic agglomeration is a process in which an intense sound field is applied to promote relative motion and rapid agglomeration among aerosol particles. This technology is able to improve significantly and rapidly the visibility of the smoke in a fire situation, and therefore assists the quick evacuation of evacuees. In this paper, the elimination effect of polystyrene smoke using acoustic agglomeration technology is experimentally investigated. The results show that the smoke transmittance will be increased to 0.75 from the initial value of 0.24 in only 0.5 min, in a 1.5 kHz acoustic field at a sound pressure level of 141 dB. The agglomeration rate is sensitive to acoustic frequency and there is an optimal operation frequency, which indicates that the predominant mechanism is orthokinetic interaction. Under the conditions of our experiments, the optimal frequency for eliminating soot particles is determined to be 1.5 kHz. As an energy consuming process, the agglomeration efficiency increases proportionally with the acoustic power until the corresponding nonlinear acoustic effects become significant. Moreover, it is found that the agglomeration rate of thicker smoke is much higher than thin ones at the early stage of the process, but the discrepancy tends to vanish at the later stage.