A review of the types of metamaterials and their application in reducing unwanted noise and vibrations

Today, in order to reduce noise and vibrations, meta-materials are used as a barrier, attenuator or absorber of vibration and sound in various fields such as aerospace, automotive and pollutant control. Meta-materials are synthetic materials made from single cells with dimensions smaller than the desired wavelength of sound waves, repeated alternately in a larger scale, which can effectively reduce the amplitude of sound waves in the desired frequency range. In this review article, research conducted in the field of various metamaterials, especially acoustic and elastic metamaterials, and their applications and results in reducing noise and unwanted vibrations of the environment have been studied. In most researches, numerical calculations have been performed using the Bloch-Floquet theorem to calculate the Bloch cell phase of a single metamaterial cell. The results of this research show that by using acoustic and elastic meta-materials, the vibrations and low frequency noise of a system can be reduced to a desirable level. It becomes a means of increasing the energy band gap. Increasing the degree of release of local resonators is another way to increase energy gap and further reduce vibration.