Calculation for the Acoustic Absorption Coefficient of Multilayered Materials by an Improved Extended Transfer Matrix Method

2010 ◽  
Vol 160-162 ◽  
pp. 1257-1263
Author(s):  
Xue Yang ◽  
Wei Xiong Yu ◽  
Shen Lin Yang ◽  
Lin He ◽  
Jin Li Sun
Keyword(s):  
Absorption Coefficient ◽  
Transfer Matrix ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Acoustic Absorption ◽  
Viscoelastic Materials ◽  
Multilayered Structures ◽  
Incidence Plane ◽  
Acoustic Absorption Coefficient ◽  
Good Agreement

This paper describes an improved extended transfer matrix method to evaluate the acoustic absorption coefficient of multi-layered structure with viscoelactic materials for perpendicular incidence plane acoustic. Here, the dynamic behavior of viscoelastic materials is taken into account. By comparing the calculated and measured results, it is shown that the results calculated by the improved extended transfer matrix method are in good agreement with the results measured. This improved extended transfer matrix method can accurately estimate the sound properties of multilayered structures with viscoelastic materials.

Computation of the Alpha Cabin Sound Absorption Coefficient by Using the Finite Transfer Matrix Method (FTMM): Inter-Laboratory Test on Porous Media

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Andrea Santoni ◽  
Paolo Bonfiglio ◽  
Patrizio Fausti ◽  
Francesco Pompoli
Keyword(s):  
Absorption Coefficient ◽  
Transfer Matrix ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Sound Absorption ◽  
Finite Size ◽  
Sound Absorption Coefficient ◽  
Radiation Impedance ◽  
Simulation Based ◽  
Private Research

Abstract The transfer matrix method (TMM) has become an established and widely used approach to compute the sound absorption coefficient of a multilayer structure. Due to the assumption made by this method of laterally infinite media, it is necessary to introduce in the computation the finite-size radiation impedance of the investigated system, in order to obtain an accurate prediction of the sound absorption coefficient within the entire frequency range of interest; this is generally referred to as finite transfer matrix method (FTMM). However, it has not been extensively investigated the possibility of using the FTMM to accurately approximate the sound absorption of flat porous samples experimentally determined in an Alpha Cabin, a small reverberation room employed in the automotive industry. To this purpose, a simulation-based round robin test was organized involving academic and private research groups. Four different systems constituted by five porous materials, whose properties were experimentally characterized, were considered. Each participant, provided with all the mechanical and physical properties of each medium, was requested to simulate the sound absorption coefficient with an arbitrary chosen code, based on the FTMM. The results indicated a good accuracy of the different formulations to determine the finite-size radiation impedance. However, its implementation in the computation of the sound absorption coefficient as well as the upper limit of the range of incidence angles within which the acoustic field is simulated, and the model adopted to describe each material, significantly influenced the results.

scholarly journals Analysis of Torsional Vibration Systems by the Extended Transfer Matrix Method

1999 ◽  
Vol 121 (2) ◽  
pp. 250-255 ◽  
Author(s):  
Yuan Mao Huang ◽  
C. D. Horng
Keyword(s):  
Transfer Matrix ◽  
Torsional Vibration ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Angular Displacement ◽  
Newton Raphson ◽  
Damped Systems ◽  
The Right ◽  
Derivatives Of ◽  
Good Agreement

This study applies the extended transfer matrix method and Newton-Raphson technique with complex numbers for torsional vibration analysis of damped systems. The relationships of the vibratory amplitude, the vibratory torque, the derivatives of the vibratory angular displacement and the vibratory torque between components at the left end and the right end of the torsional vibration system are derived. The derivatives of the vibratory angular displacement and the vibratory torque are used directly in the Newton-Raphson technique to determine the eigensolutions of systems that are compared and show good agreement with the available data.

Low-frequency sound absorption of a tunable multilayer composite structure

2021 ◽  
pp. 107754632110082
Author(s):  
Hanbo Shao ◽  
Jincheng He ◽  
Jiang Zhu ◽  
Guoping Chen ◽  
Huan He
Keyword(s):  
Porous Material ◽  
Absorption Coefficient ◽  
Composite Structure ◽  
Low Frequency ◽  
Acoustic Absorption ◽  
Multilayer Composite ◽  
Absorption Frequency ◽  
Acoustic Absorption Coefficient ◽  
Simulation And Experiment ◽  
Single Material

Our work investigates a tunable multilayer composite structure for applications in the area of low-frequency absorption. This acoustic device is comprised of three layers, Helmholtz cavity layer, microperforated panel layer, and the porous material layer. For the simulation and experiment in our research, the absorber can fulfill a twofold requirement: the acoustic absorption coefficient can reach near 0.8 in very low frequency (400 Hz) and the range of frequency is very wide (400–3000 Hz). In all its absorption frequency, the average of the acoustic absorption coefficient is over 0.9. Besides, the absorption coefficient can be tunable by the scalable cavity. The multilayer composite structure in our article solved the disadvantages in single material. For example, small absorption coefficient in low frequency in traditional material such as microperforated panel and porous material and narrow reduction frequency range in acoustic metamaterial such as Helmholtz cavity. The design of the composite structure in our article can have more wide application than single material. It can also give us a novel idea to produce new acoustic devices.

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