金属片镶嵌微缝薄膜结构的吸声特性分析

Sound absorption property about microslit membrane decorated with relatively rigid platelets

为了使声波在低声压级、低频带达到理想的吸收效果,本文提出了金属片镶嵌微缝薄膜结构理论模型,并分析了该模型的吸声机理。首先将该结构的力学模型看作多自由度系统,构建振动微分方程,得到了金属片镶嵌薄膜的分布位置与每段薄膜弹性系数之间的关系。并在此基础上分析了激励频率与固有频率之间的关系,得出基频对该结构吸声效果的影响。然后利用有限元软件对该结构的模态振型和声阻抗进行了分析,得到了镶嵌在微缝薄膜上的金属片与声波的耦合形式。最后通过试验对该结构的吸声特性进行了验证,结果表明:吸收峰值受镶嵌位置影响较小,平均吸声系数变化不大,一阶固有频率会受镶嵌位置的改变而改变。

To realize the ideal absorption effect about low-decibel and low frequency band, the theory modelabout microslit membrane decorated with relatively rigid platelets is established, and the sound absorptionmechanism of the model is analyzed. First of all, the force model of the structure regards as the system ofmulti degree-of-freedom, and the vibration differential equation is established, the relationship between thedistribution of membrane decorated with relatively rigid platelets and the each part of membrane elasticitycoefficient is obtained. The relationship between exciting frequency and natural frequency is analyzed, theinfluence of the structure absorption effect due to fundamental frequency is obtained. And then the modalshapes and acoustic impedance of the structure are analyzed by finite element method(FEM), the interactionrelationship between microslit membrane decorated with relatively rigid platelets and sound wave is obtained.Finally, the sound absorption property of the structure is tested by experiment The results show that theabsorption peak is hardly affected by the distribution of membrane decorated with the metal strips, the averageabsorption coefficient is stable, the first order frequency is mostly affected by the distribution of membranedecorated with the metal strips.