局域共振单元与薄膜复合声子晶体板结构的低频降噪

Reduction of Low-frequency Noise in Phononic Crystal Plates with Composite Locally Resonant Structures and Thin Membrane

提出了一种局域共振单元复合声子晶体板结构,并结合有限元对晶体板结构的带隙特性、隔声性能进行了分析.结果表明,共振带隙的产生是由共振单元与板中传播的弹性波相互耦合造成的,耦合强度直接影响共振频率和带隙宽度,隔声效果与薄膜的厚度直接相关.通过改变薄膜的厚度可以将隔声效果调节到满足机舱飞行员正常驾驶的要求.该结构在200dB以下具有良好的隔振效果,最大隔声量达到150dB.该研究为获得良好的隔声效果提供了理论支持,在航空发动机减振降噪方面具有潜在的应用前景.

A kind of locally resonant phononic crystal plate with composite unite was introduced, and the band gap characteristics and sound transmission loss of the proposed structure were investigated with the finite element methods. It is found that the interaction between the local resonances and the traveling wave modes in the plate results the locally resonant band gap, whose bandwidth and sound insulation effect depend on the interaction strength and the thickness of thin membrane by changing structure parameters. By changing the thickness of the thin membrane, the proposed phononic crystal structure is demonstrated to meet the normal flight. The results show that the structures possess sound insulation effect below 200 dB and highest sound transmission loss up to 150 dB. The study provides a theoretical basis to obtain good sound insulation effect, and has a potential application value in the reducing of noise and vibration in the aero-engine.