Active acoustic metamaterial based on local resonance

Abstract

The invention relates to an active acoustic metamaterial based on local resonance. According to the metamaterial, a hard sheet metal material is used as a substrate plate; a plurality of magnetic massblock units are embedded in the substrate plate; each magnetic mass block unit is composed of a magnetic mass block and a circular thin film fixed to the magnetic mass block, the magnetic mass blockunits are periodically arranged on the substrate plate in a lattice form, an electromagnet with adjustable current magnitude and positive and negative currents is further arranged above each magneticmass block unit, the vertical distance between each electromagnet and the corresponding magnetic mass block is 2-3 cm, and the electromagnets are used for applying adjustable reverse restoring force to the magnetic mass block units. According to the acoustic metamaterial provided by the invention, the electromagnets with adjustable current are introduced, and the intrinsic frequency of the thin film type acoustic metamaterial unit is actively adjusted, so that the sound insulation peak frequency is adjusted, the metamaterial has negative mass density, the sound insulation quantity far higher than the mass law can be realized, and the low-frequency line spectrum sound insulation is realized.

Description

technical field [0001] The invention belongs to the technical field of acoustic stealth materials, in particular to an active acoustic metamaterial based on local resonance. Background technique [0002] The comfort of the cabin in a long-term combat environment is an important factor to ensure the combat effectiveness of the ship. The high air noise in the cabin not only affects the communication of naval officers and soldiers, but also interferes with their daily life. As my country's ships perform long-distance voyage missions more and more frequently, cabin air noise has received more and more attention. [0003] At present, the commonly used method is to arrange light-weight, small-size, low-frequency, and strong-attenuation sound-absorbing and sound-insulating materials in the sound source cabin and sound-receiving cabin, and use conventional sound-absorbing materials such as parallel perforated plates and multi-layer perforated plates Acoustic structure, layered poro...

AI Technical Summary

Problems solved by technology

However, it is difficult to adjust the thin film and mass block once they are manufactured. Since the eigenfrequency of the thin film acoustic metamaterial is fixed, the frequency corresponding to the related sound insulation peak is also determined, and only a very narrow frequency band around it is determined. Good internal sound insulation

Therefore, for some cabins with variable sound fields, this acoustic metamaterial cannot automatically adjust the sound insulation peak frequency according to the spectral characteristics of different sound sources, and it is difficult to perform targeted sound insulation for different incident sound waves.

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