Abstract
The various types of metamaterials only have a sound transmission loss (STL) peak at the resonant frequency but are still constrained by the law of mass sound insulation at other frequencies. In this paper, a low-frequency and wideband resonant metamaterial plate with a front radial membrane was designed in order to improve the noise reduction band. Bandgap and STL were calculated by using the finite element method. Studies have shown that in the range of 1 Hz–100 Hz for new metamaterials, the frequency band with STL greater than 30 dB accounts for 75%, and the noise reduction starting frequency is 11 Hz. The mechanisms were investigated by a comprehensive analysis of mode shapes and sound intensity streamlines and then verified by the negative effective density and equivalent mass–spring model. The mechanism analysis shows that there is a wide bridge coupling bandgap between the respective bandgaps of the plate and the membrane. This novel metamaterial not only guarantees the low-frequency and wideband acoustic performance but also alleviates the problem of instability of the noise reduction performance of the membrane material after long-term use, providing a potential application in low-frequency and wideband noise control.
Highlights
In recent years, because of economic and social development and progress, people have paid more and more attention to the environment in which they live, and environmental pollution has received increasing attention
The resonance modal B1 contained in this order band shows the (0, 1) modal of the membrane at 20.849 Hz. Because it differs very little from the frequency of the (1, 0) modal of 20.988 Hz in modal B2, it is not drawn separately in Fig. 4 and represented by the letter B
The effective dynamic density of the system consisting of four radial membranes can be defined as ρeff
Summary
Because of economic and social development and progress, people have paid more and more attention to the environment in which they live, and environmental pollution has received increasing attention. Noise pollution has become one of the main environmental pollutions in cities.. Epidemiological studies have shown that noise exposure can cause hearing damage (acute or chronic ear diseases) and cardiovascular disease. These effects may seriously affect the health and quality of life. Low-frequency noise has the characteristics of long wavelength and long propagation, and it is more harmful to the human body.. The control of low-frequency noise urgently needs better methods and materials Low-frequency noise has the characteristics of long wavelength and long propagation, and it is more harmful to the human body. the control of low-frequency noise urgently needs better methods and materials
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