金属片镶嵌微缝薄膜结构的吸声特性分析*

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。

Sound absorption property about the metal strip of distribution in microslit membrane

To realize the ideal absorption effect about low-decibel and low frequency band, the theory model about the metal strip of distribution in microslit membrane structure is established, the sound absorption mechanism of the model is analyzed. The force model of the structure regards as the system of multi degree-of-freedom, and the vibration differential equation is established, the relationship between the distribution location of the metal strip membrane and the part of membrane elasticity coefficient is obtained. The relationship between exciting frequency and natural frequency is analyzed, the influence of the structure absorption effect due to fundamental frequency is obtained. The modal shapes and acoustic impedance of the structure are analyzed by finite element method(FEM), the interaction relationship between the metal strip of distribution in microslit membrane and sound wave is obtained. The sound absorption property of the structure are tested by experiment.