scholarly journals Airborne noise calculation for single-layer partitions with the concentrated parameters method

2021 ◽  
Vol 2131 (2) ◽  
pp. 022075
Author(s):  
A V Zakharov ◽  
I P Saltykov
Keyword(s):  
Sound Propagation ◽  
Single Layer ◽  
Sound Insulation ◽  
Systems Of Equations ◽  
Flexural Waves ◽  
Frequency Range ◽  
Standard Frequency ◽  
Sound Fields ◽  
Standard Spectrum ◽  
Airborne Noise

Abstract The article considers an approach to the calculation of sound insulation for building partitions with the method of concentrated parameters at the standard frequency range, which is specified in regulatory documents. The concepts of “reduced” and “concentrated” masses are introduced for objects that are sound conductors. It is noted that the physical model of sound insulation in the three conditionally allocated frequency ranges of the standard spectrum has differences. The calculated equations of sound insulation for three frequency ranges are given. Systems of equations for obtaining the calculation formulas at the first and the second frequency ranges are used. The systems consist of equations for the conservation of the amount of motion and the conservation of kinetic energy. The influence of the damping effect of air and resonant phenomena in the plate on the final value of sound insulation is described. The nature of sound propagation in the third frequency range is considered, in which, unlike the first two sections of the frequency spectrum, where the propagation of flexural waves is mainly recorded in the plate, shear and dilatational vibrations have a predominant influence on the sound insulation level. Examples of graphs for massive partitions obtained by the considered method are given. The accuracy of the proposed method is evaluated in comparison with the normative code’s method and the method based on the theory of self-matching of sound fields. A general algorithm for calculating sound insulation in the entire standard frequency range is presented.

Characterizing the Sound Insulation of a Specially Orthotropic Multi-Layered Medium

2007 ◽  
Vol 23 (1) ◽  
pp. 63-68 ◽  
Author(s):  
H.-J. Lin ◽  
C.-N. Wang ◽  
Y.-M. Kuo
Keyword(s):  
Boundary Conditions ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Single Layer ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics ◽  
Sound Transmission Class

AbstractThis work explores the sound transmission loss provided by the orthotropic multi-layers to elucidate the sound insulation of FRP (Fiber Reinforced Plastics). Mat is the major material considered in the numerical works. The transfer matrices of a single layer of the orthotropic laminate and the fluid are determined. Further, the boundary conditions on the various interface planes are arranged into matrix form. Combining the transfer matrixes and the boundary conditions and applying the transfer matrix method (TMM) yields the surface impedance and the sound transmission loss. The sound-propagation characteristics are studied. Additionally, the STC (Sound Transmission Class) of FRP and steel are compared and discussed.

scholarly journals SETTING UP A PROBLEM OF AIR-BORNE SOUND IN-SULATION CALCULATION FOR DOUBLE LAYER MASSIVE ENCLOSURES ON THE BASE OF THE MODELS WITH THE CONCENTRATED PARAMETERS

2020 ◽  
Vol 16 (4) ◽  
pp. 111-120
Author(s):  
Arkadiy Zakharov ◽  
Ivan Saltikov
Keyword(s):  
Double Layer ◽  
Sound Propagation ◽  
Graph Drawing ◽  
Practical Interest ◽  
Single Layer ◽  
Mass Action ◽  
Sound Insulation ◽  
Mass Action Law ◽  
The One ◽  
Oscillation Movement

The calculation methods on the base of the concentrated parameters models, which were formed in the XX century, allowed to get simple and theoretically consistent solutions for the problems of one-layered building partitions sound insulation finding. The sound insulation estimation for the double-layered massive building partitions also is of scientific and practical interest, as double layer partitions are the particular case of the single layer enclosure's application. The concept of concentrated parameters includes the concentrated and the reduced masses, as well as the concentrated elasticity. The criteria for the object application as a specified kind of the concentrated parameters in the acoustical problems is the presence or the absence of the oscillation movement in it. The three calculation models with the application of the concentrated (discreet) parameters that to define the sound insulation of the massive double layer enclosures are given. The equations for sound insulation computation for one layer partition are represented. They were derived on the base of momentum law and energy conservation formulas under the continuity of energy flow conditions at the interface of different media. The three main paths of sound propagation from the room with the air-borne noise to the isolated room are shown. The two frequency range are separated on the way of the direct sound propagation: at the first, the surface density of the one of two layers and the air elasticity in the inter-layer gap influence on isolation; at the second one, the predominant role belongs to the summarized insulation by the "Mass Action Law" of the two layers. The indirect way's insulation is taken in account through the additional sound insulation graph drawing. The compound insulation curve is defined by the ways, where the sound energy transmittance is maximal at the standard frequency spectrum. The method of sound insulation calculation for the double layer partitions on the base of the concentrated parameters model application is revealed. As an example, the calculation of a prefabricated double layer inter-flat wall in the panel building was performed.

scholarly journals Non-Wovens as Sound Reducers

2018 ◽  
Vol 55 (2) ◽  
pp. 64-76
Author(s):  
D. Belakova ◽  
A. Seile ◽  
S. Kukle ◽  
T. Plamus
Keyword(s):  
Absorption Coefficient ◽  
Surface Density ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Material Structure ◽  
Sound Transmission Loss ◽  
Sound Waves ◽  
Frequency Range

Abstract Within the present study, the effect of hemp (40 wt%) and polyactide (60 wt%), non-woven surface density, thickness and number of fibre web layers on the sound absorption coefficient and the sound transmission loss in the frequency range from 50 to 5000 Hz is analysed. The sound insulation properties of the experimental samples have been determined, compared to the ones in practical use, and the possible use of material has been defined. Non-woven materials are ideally suited for use in acoustic insulation products because the arrangement of fibres produces a porous material structure, which leads to a greater interaction between sound waves and fibre structure. Of all the tested samples (A, B and D), the non-woven variant B exceeded the surface density of sample A by 1.22 times and 1.15 times that of sample D. By placing non-wovens one above the other in 2 layers, it is possible to increase the absorption coefficient of the material, which depending on the frequency corresponds to C, D, and E sound absorption classes. Sample A demonstrates the best sound absorption of all the three samples in the frequency range from 250 to 2000 Hz. In the test frequency range from 50 to 5000 Hz, the sound transmission loss varies from 0.76 (Sample D at 63 Hz) to 3.90 (Sample B at 5000 Hz).

Design and simulation of Helmholtz resonator assembly used to attenuate tire acoustic cavity resonance noise

2021 ◽  
Vol 263 (6) ◽  
pp. 942-953
Author(s):  
Wei Zhao ◽  
Xiandong Liu ◽  
Yingchun Shan ◽  
Tian He
Keyword(s):  
Natural Frequencies ◽  
Helmholtz Resonator ◽  
Operating Conditions ◽  
Cavity Resonance ◽  
Frequency Range ◽  
Sound Fields ◽  
Acoustic Cavity ◽  
The Poor ◽  
Alloy Wheel ◽  
Reduction Effect

Tire acoustic cavity resonance noise (TACRN) is a typical annoying lower-frequency interior noise of a passenger car. The widely used attenuating method of attaching the porous sound absorption material in tire cavity can reduce TACRN effectively, but causes the increase of tire-wheel assembly weight and cost, also the poor durability. Additionally, the Helmholtz resonator (HR) is also used in the wheel of some cars although having only narrow effective band. The existing investigation shows that the frequency of TACRN varies with the car speed and load and also has the split characteristics. The change of TACRN frequency causes a certain difficulty to suppress TACRN effectively. Aiming at this problem, in this paper, TACRN frequency range of a specific tire cavity under different operating conditions is first calculated and analyzed. Then, for a specific aluminum alloy wheel, a HR assembly including several HRs is designed to make the natural frequencies of HR assembly cover the TACRN frequencies. Finally, the reduction effect of TACRN is simulated and evaluated by comparing the sound fields in tire cavity with/without HR assembly under same volume velocity sound source. This work is helpful for attenuating TACRN effectively under the changing operating conditions.

A Multiple-Bands Metamaterial Absorber Based in X, Ku and K-Band

2021 ◽  
Author(s):  
Muhammad Fahim Zafar ◽  
Usman Masud
Keyword(s):  
Single Layer ◽  
Wide Band ◽  
Metamaterial Absorber ◽  
Basic Unit ◽  
Frequency Range ◽  
Structure Form ◽  
Perfect Absorption ◽  
Polarization Insensitive ◽  
Band Absorption ◽  
K Band

Abstract Developing a highly efficient and multiple-bands metamaterial absorber is a hot issue in recent era. In this paper, A multiple-bands metamaterial absorber has been presented which is based in X, Ku and K-band. Firstly, we have designed two single layer basic unit cell of X-shape and cross-shape, then they are arranged in the multi-layers structure form for the purpose of obtaining multiple- bands and wide band absorption. The proposed absorber is able to work in multiple bands because it has six peaks in the frequency range of 8–24 GHz with having near perfect absorption. Moreover, the sixth peak has a wideband absorption which is 2.93 GHz. Furthermore, the proposed absorber is also tested for polarization insensitivity and also for oblique incidence. Absorption was found polarization insensitive with almost perfect absorption.

SOUND PROPAGATION THROUGH STRUCTURAL COMPONENTS UNDER CONDITIONS OF NON-RIGID CONTACT AT THE BOUNDARIES BETWEEN THEM

Akustika ◽  
2021 ◽  
Author(s):  
Konstantin Abbakumov ◽  
Anton Vagin ◽  
Alena Vjuginova
Keyword(s):  
Boundary Conditions ◽  
Inhomogeneous Medium ◽  
Dispersion Equation ◽  
Numerical Solutions ◽  
Sound Propagation ◽  
Structural Components ◽  
Frequency Range ◽  
Problem Statement ◽  
Ultrasonic Measurements ◽  
Rigid Contact

The report considers the problem statement, derivation and solution of the dispersion equation for sound propagation in a layered inhomogeneous medium with oriented fracturing, simulated by the presence of boundary conditions in the "linear slip" approximation. Numerical solutions are obtained and analyzed for the frequency range and values of the parameters of contact breaking, which is relevant in the problems of ultrasonic measurements

scholarly journals Reducing the harmful effects of noise on the human environment. Sound insulation of industrial skeleton enclosures in the 10–40 kHz frequency range

2020 ◽  
Vol 18 (2) ◽  
pp. 1451-1463
Author(s):  
Witold Mikulski
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sheet Steel ◽  
Pressure Level ◽  
Sound Insulation ◽  
Frequency Range ◽  
Noise Sources ◽  
Human Environment ◽  
Absorbing Material ◽  
Acoustic Enclosures

Abstract Purpose The purpose of the research is to work out a method for determining the sound insulation of acoustic enclosures for industrial sources emitting noise in the frequency range of 10–40 kHz and apply the method to measure the sound insulation of acoustic enclosures build of different materials. Methods The method is developed by appropriate adaptation of techniques applicable currently for sound frequencies of up to 10 kHz. The sound insulation of example enclosures is determined with the use of this newly developed method. Results The research results indicate that enclosures (made of polycarbonate, plexiglass, sheet aluminium, sheet steel, plywood, and composite materials) enable reducing the sound pressure level in the environment for the frequency of 10 kHz by 19–25 dB with the reduction increasing to 40–48 dB for the frequency of 40 Hz. The sound insulation of acoustic enclosures with a sound-absorbing material inside reaches about 38 dB for the frequency of 10 kHz and about 63 dB for the frequency of 40 kHz. Conclusion Some pieces of equipment installed in the work environment are sources of noise emitted in the 10–40 kHz frequency range with the intensity which can be high enough to be harmful to humans. The most effective technical reduction of the associated risks are acoustic enclosures for such noise sources. The sound pressure level reduction obtained after provision of an enclosure depends on its design (shape, size, material, and thickness of walls) and the noise source frequency spectrum. Realistically available noise reduction values may exceed 60 dB.

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