Membrane-type acoustic metamaterials are thin films or plates composed of periodic units with small additional mass. A large number of studies have shown that these metamaterials exhibit tunable anti-resonance, and their transmission loss values are much higher than the corresponding quality laws. At present, most researches on membrane-type acoustic metamaterials focus on the unit cell, and the sound insulation frequency band can only be adjusted by adjusting the structural parameters and material parameters. In this paper, two kinds of acoustic metamaterials with different structures are designed, which are the center placement of the mass and the eccentric placement of the mass.The two structures have different sound insulation characteristics. By designing different array combinations of acoustic metamaterials, the sound insulation peaks of different frequency bands are obtained. This paper studies the corresponding combination law, and effectively realizes the adjustable sound insulation frequency band.

As traditional automobiles develop towards new energy vehicles, the noise, vibration and harshness (NVH) performance of automobiles is facing new challenges. Without the cover of the traditional engine noise and inlet and exhaust noise, the high-speed wind noise becomes more prominent. Thus, research on the calculation method of vehicle interior noise in high-speed driving condition is needed. However, vehicle body structure is complex, and the external excitation components are complicated. In order to analyze the method of predicting the vehicle interior noise at high speed, an idealized side mirror model is taken as the research object in this paper and the radiated noise of a panel under the fluctuating surface pressure (FSP) due to the idealized side mirror is studied. The FSP of the panel is first studied by the numerical simulations of incompressible and compressible flow field. For the incompressible flow field, the Corcos turbulent boundary layer (TBL) model is established to simulate the convective component and the boundary element method (BEM) is used to extract the acoustic component. Subsequently, the Corcos model coupling BEM method, the random modal force coupling BEM method and the deterministic modal force coupling BEM method are used separately to calculate the noise of the panel under the FSP. For the compressible flow field, the convective and acoustic component in the fluctuating pressure are separated by the wavenumber-frequency spectrum (WFS) method. The radiated noise of the panel under the FSP is calculated again by using the WFS, the method of random modal force and the method of deterministic modal force, respectively. Then, the computational time of the six methods of incompressible and compressible calculation is compared. Finally, a fast and accurate method of calculating the panel radiated noise under FSP is obtained by comparing the computational accuracy with the experimental results and combining the computational time: the method of incompressible random modal force. This method can be used to quickly and accurately analyze the vehicle interior noise at high speed, and to optimize the exterior protrusions and the vehicle sound package for improving the vehicle NVH performance at high speed.Appl. Sci. 2020, 10, 994 2 of 22 component of the outflow field in [2][3][4]. In order to analyze the effect of the acoustic component on the interior noise SPL of the vehicle, the characteristics of the acoustic component were studied. The researches show: both the convective and acoustic component are equally important contributors for the noise transmission to the vehicle cabin although the TBL pressure is 25 to 35 dB higher in level than that of the corresponding acoustic component [1].There are many kinds methods for calculating the response under the TBL excitation. One of the models for the TBL is presented by Corcos [5]. Then, Chase and Efimstov built models derived from Corcos expression, which can improve the predictions for the low-frequency range [4,6]. Birgersson et al. [7] used ...

The door sealing strip plays an important role in the sound insulation of the car, and its sound insulation performance has a great influence on the sound quality and comfort of the vehicle. The sound insulation performance of the seal can be analyzed by Finite Element-Statistic Energy Analysismodel. There are great differences in the cross-section of the door sealing strip system at different positions, which leads to the difference of sound insulation. Therefore, it is very important to study the sound insulation performance of the sealing strip by studying the parameters of different sections. This paper explores the influence of the structure of automobile sealing rib on the sound insulation performance. Taking the sound power of the receiving end of the sealing strip as the index, the orthogonal optimization test is carried out for the simplified section shape of the door seal strip: the wall thickness of the sealing strip, the height of the sealing strip and the rib length. The optimal combination of a set of sealing strip sections is established, and the sound insulation performance of the sealing strip is improved.

The target energy transfer (TET) between a membrane nonlinear energy sink (NES) and the acoustic medium inside a rectangular cavity is studied. The acoustic medium is interacted with a plate and multi-order modes coupling of the 2 structure is considered. Based on the modal expansion approach, with Green's function, Helmholtz equation and the boundary conditions of the acoustic medium and the plate, the coupling coefficient matrix of the mode of 2 structures is derived. The equations of the membrane NES, multi-order modes of the acoustic medium and multi-order modes of the plate are established, and numerical analysis is used to investigate the TET phenomenon. The results show that in condition of a single-point excitation to the plate, under a certain range of excitation levels, the membrane can be seen as a kind of NES, and the energy in the acoustic medium can be unidirectionally transmitted to the membrane NES and attenuated, reducing the sound pressure level in the cavity. At the same time, it is found that the NES can suppress multi-order sound pressure of the acoustic medium at the same time, and realize the control of cascaded resonance noise.