Acoustical Physics最新文献

To optimize the sound absorption performance of aluminum foam, a dual-porosity aluminum foam consisting of different perforation configurations is proposed. A theoretical model of the structure is established using the transfer matrix method, and a simulation model is constructed with COMSOL software. The accuracy of the results is verified through sound absorption experiments. By analyzing the sound absorption mechanism and exploring the influence of structural parameters on sound absorption performance, the results indicate that front-perforation induces a pressure diffusion effect, effectively enhancing acoustic energy dissipation and improving sound absorption. By adjusting the radius of front-perforation, a balance between the pressure diffusion effect and acoustic energy dissipation in the matrix material can be achieved, thereby maximizing sound absorption performance. When the perforation radius exceeds 7.5 mm, the sound absorption performance of aluminum foam with side perforations is significantly superior to that with front perforation. The perforation diameter on the incident surface significantly influences sound absorption, resulting in similar performance between the inverted gradient perforation dual-porosity aluminum foam (IG-DPAF) and the “I-shaped gradient” perforation dual-porosity aluminum foam, both demonstrating excellent broadband sound absorption properties with absorption coefficients exceeding 0.8 across the frequency range of 1000–6300 Hz. Conversely, the sound absorption behavior of the positively gradient perforated dual-porosity aluminum foam (PG-DPAF) resembles that of the “+shaped gradient” perforation dual-porosity aluminum foam in terms of sound absorption behavior. This study provides novel insights for the structural design and performance optimization of aluminum foam-based sound-absorbing materials.

The aim of this paper is to find a method for tracking the resonance point of an ultrasonic transducer driven by a phase-shift PWM inverter operating in a “phase-shift + operating frequency control” scheme, as well as to overcome the drawback of IZL (Integration Zero Loop) where optimal frequency tracking is impossible when the phase-shift PWM inverter outputs the maximum power. The minimum admittance tracking system (MATS) proposed in this paper consists of a matching circuit with parameters determined by MATLAB simulation and performs experiments with the desired power to determine the L_F so that the phase-shift PWM inverter operates in a stable operating state where shock currents are not generated by a small increase in the parameter L_F of the L–C matching circuit. The MATS, which is the optimal frequency tracking method we proposed, overcame the drawback of IZL, where the optimal frequency tracking was not possible when the phase-shift PWM inverter outputs the maximum power. Moreover, it prevents the generation of shock currents that occurred on the right-branch of the inverter even when power control is performed at the resonant frequency of the load and allows the inverter to operate in a steady state.

Fundamental limitations in low-frequency bandwidth and impedance matching continue to constrain the sound insulation performance of acoustic metamaterials. In this work, a three-layer membrane-type acoustic metamaterial (MAM) is introduced as a potential solution. Through orthogonal experiments, remarkable sound insulation capabilities are demonstrated within the frequency range of 100–1200 Hz. By analyzing the eigenmodes and sound transmission loss (STL) at resonance and anti-resonance frequencies, the underlying sound insulation mechanism of the three-layer MAM is clarified. In addition, an orthogonal experiment is utilized to identify the key factors affecting sound insulation performance. Using relative bandwidth as the classification criterion, the optimal combination of influencing factors is identified, leading to improved STL performance of the multi-layer MAM and broadening the sound insulation bandwidth. This work advances low-frequency insulation performance and bandwidth, simultaneously establishing a novel and practical framework for the design of sound insulation material.

This work investigates Love-type wave transmission in a multilayered piezomagnetic (PM) and heterogeneous half-space (HHS) structure with a viscous liquid layer (VL) on top. Wave transmission behavior is investigated in both magnetically open (MO) and magnetically closed (MS) circuit boundary circumstances. The primary study focuses on the scattering behavior of phase velocity in a Love-type wave as influenced by the combination of VL, PM, and HHS. The dispersion relation for Love-type waves was calculated analytically, and phase velocity graphs were displayed and evaluated using Mathematica software. A detailed investigation was undertaken to determine the influence of important variables on phase velocity, such as material heterogeneity, piezomagnetic coupling, and viscous liquid layer thickness. The research results demonstrate the influence of VL, PM, and HHS materials on phase velocity in MO and MS conditions. Graphical comparisons reveal that piezomagnetic coupling causes significant changes in phase velocity, highlighting its role in wave propagation. The open and short circuit conditions exhibited approximately similar phase velocities, suggesting that boundary constraints had a negligible effect on wave propagation. The model only considers linear wave transmission and excludes nonlinear effects. Furthermore, the technique is predicated on idealized material properties that account for heterogeneity. The findings can be used to design and develop energy harvesters, sensors, and wave manipulation instruments using PM with viscous liquid coatings. Understanding the behaviour of surface waves, including phase velocity, is essential for efficient application in these frameworks.

A field of radiation forces in a small hemispherical drop placed on a solid horizontal substrate has been calculated. The forces are induced by capillary oscillations on the free surface of a fluid. The acoustic flow excited by radiation forces has been calculated and visualized.

The results of an analytical study of the propagation of axisymmetric normal waves in a solid circular waveguide made of a waterlike medium are presented. A waterlike medium is a medium in which the velocity of shear waves is significantly lower than the velocity of longitudinal waves. It is shown that the propagation velocities of normal waves are approximately equal to the propagation velocities in a liquid cylinder. This result is radically different from the common statement in the literature that the propagation velocities of normal waves at high frequencies are approximately equal to the velocity of a Rayleigh wave at a flat boundary. The correction to the waterlike approximation is calculated, and the contributions of the longitudinal and shear components of the fields for normal waves are obtained. An experimental illustration is provided confirming the results obtained.