Low-frequency broadband sound absorption material based on asymmetric film-type sub-wavelength structure

Abstract

The invention provides a low-frequency broadband sound absorption material based on an asymmetric film-type sub-wavelength structure. The material comprises several sound absorption units. Each sound absorption unit comprises a framework, a flexible film and eight mass blocks with different weights. The framework is arranged in a window style. The flexible film is fixed to the framework in a tensioning mode so as to form four equivalent noise elimination units. Each two blocks of the eight mass blocks form one group and the groups of the blocks are fixed to films of the noise elimination units in a one-to-one correspondence mode respectively. The several sound absorption units are expanded towards peripheries in a framework plane and are spliced to form the low-frequency broadband sound absorption material based on the asymmetric film-type sub-wavelength structure. A whole structure is a quadrilateral sound absorption unit material mainly formed by the flexible film and a mass block system. Because of asymmetric distribution of the mass blocks, a dynamic characteristic shows that a plurality of frequency points with zero equivalent mass density are possessed, which means that a plurality of peak values of sound absorption coefficients are possessed. Under an influence of an asymmetric mode, total elastic strain energy of the structure is higher than strain energy of a symmetric mode in a full frequency range.

Description

technical field [0001] The invention relates to a sound-absorbing material for low-frequency vibration and noise reduction, in particular to a low-frequency broadband sound-absorbing material based on an asymmetric film-like sub-wavelength structure. Background technique [0002] Noise is ubiquitous in modern society, including traffic noise from highways and high-speed railways, construction noise from construction sites, industrial noise from large factories and mines, and life noise in daily life. People have come up with various ways to reduce vibration and noise, reduce or eliminate the adverse effects of noise. Noise is not only useless, but more importantly, it has a very serious negative impact on human body and machinery. Among them, the harm of low-frequency noise is more serious, and its control has long been a very challenging topic. Because ordinary materials have relatively low dissipation rates near low frequencies, low-frequency noise has strong penetrating ...

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Problems solved by technology

[0004] However, when dealing with low-frequency problems, although membrane-based acoustic metamaterials have good low-frequency characteristics, the reduction of resonance frequency is at the expense of resonance bandwidth. Absorbing membrane-type acoustic metamaterials proposed by many scholars have a Broadband sound absorption, but only a narrower bandwidth in the low frequency band

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