Measurement And Application Of Composite Acoustic Metamaterials

A quieter sound environment is a requirement for daily life.It is of practical importance to design and build composite acoustic materials to achieve better control of acoustic waves.The design of acoustic metamaterials needs a precise measurement of the effective mass density and effective bulk modulus of the material.The development of accurate measurement of acoustics metamaterials for the effective parameters of the structure of acoustic materials for the design,acoustic metamaterials development is essential.In this thesis,In order to precisely obtain the effective parameters of acoustic metamaterials,the impedance tube measurement tool is used and we use NI LabVIEW software to compile a measurement system.A new algorithm is developed considering multi-reflection in the impedance tube system.Finally,based on the effective acoustic parameters of the acoustic metamaterials,we explored how to achieve coherent perfect absorption using the acoustic metamaterials.The arrangement for this thesis is as follows:In the first chapter,the background of metamaterial research has been introduced,including both the research progress of electromagnetic and acoustic metamaterials.In the second chapter,we introduce the measuring system we developed,including the impedance tube,the transfer matrix method and the LabVIEW measurement program compiled.In the third chapter,the formula of acoustic parameters under multiple reflections has been deduced using the transfer matrix method.We show by simulations and experiments that our new algorithm shall be applicable to various researches where precise effective parameters are needed.We explored the realization of the acoustic coherent perfect absorption in Chapter 4.The acoustic parameters of acoustics metamaterials have been deduced,and the measurement system is developed by a modified impedance tube system.The corresponding measuring LabVIEW software is developed...