The purpose of the research is to assess the sound absorption performance(SAP)of acoustic metamaterials made of double-layer Nomex honeycomb structures in which a micro-orifice corresponds to a honeycomb unit.For this...The purpose of the research is to assess the sound absorption performance(SAP)of acoustic metamaterials made of double-layer Nomex honeycomb structures in which a micro-orifice corresponds to a honeycomb unit.For this purpose,the influences of structural parameters on the SAP of acoustic metamaterials were investigated by using experimental testing and a validated theoretical model.In addition,the sandwich structure was optimized by the genetic algorithm.The research shows that the panel thickness and micro-orifice diameter mainly affect the second resonant frequency and second peak sound absorption coefficient(SAC)of the structure.The unit cell size is found to influence the first and second resonant frequencies and two peaks of the SAC.An extremely low side-length of the honeycomb core decreases the SAP of the structure for low-frequency noise signals.Additionally,the sandwich structure presents a better SAP when the diameter of micro-orifices on the front micro-perforated panel(MPP)exceeds that of the back MPP.The sandwich structure shows better noise reduction performance after the optimization aiming at the noise frequency outside trains.展开更多
基金Project(51775558)supported by the National Natural Science Foundation of ChinaProject(2019 JJ 30034)supported by the Natural Science Foundation for Excellent Youth Scholars of Hunan Province,ChinaProject(20181053303 gg)supported by the Training Objects of Young-Middle-Aged Backbone Teacher in Ordinary Universities of Hunan Province,China。
文摘The purpose of the research is to assess the sound absorption performance(SAP)of acoustic metamaterials made of double-layer Nomex honeycomb structures in which a micro-orifice corresponds to a honeycomb unit.For this purpose,the influences of structural parameters on the SAP of acoustic metamaterials were investigated by using experimental testing and a validated theoretical model.In addition,the sandwich structure was optimized by the genetic algorithm.The research shows that the panel thickness and micro-orifice diameter mainly affect the second resonant frequency and second peak sound absorption coefficient(SAC)of the structure.The unit cell size is found to influence the first and second resonant frequencies and two peaks of the SAC.An extremely low side-length of the honeycomb core decreases the SAP of the structure for low-frequency noise signals.Additionally,the sandwich structure presents a better SAP when the diameter of micro-orifices on the front micro-perforated panel(MPP)exceeds that of the back MPP.The sandwich structure shows better noise reduction performance after the optimization aiming at the noise frequency outside trains.
