背衬对多层材料吸声覆盖层的影响

根据波导有限元-传递矩阵法建立了背衬条件下的多层材料吸声覆盖层的理论模型并与仿真软件COMSOL建立的有限元模型对比证明模型有效。在COMSOL模型的基础上讨论了单层壳体背衬和双层壳体背衬条件下的覆盖层的吸声性能并比较了在双层壳体背衬条件下不同空腔结构的吸声性能。结果表明：单层壳体背衬条件下，随着钢背衬厚度增大，吸声波峰向低频移动但峰值变小；两层壳体的水层厚度增大，波峰向低频移动，波峰渐渐增多，峰值减小；在非耐压壳体厚度增大时，三种厚度情况下的吸声系数曲线大致相同说明外壳厚度对于吸声系数的影响很小；圆柱型空腔在低频表现稍好一些，而椭球型空腔在整体表现均好于其余两种情况。

Effect of backing on sound absorption behavior of multi-layered material anechoic coating

Based on the waveguide finite element-transfer matrix method,a backing of multi-layered material anechoic coating theoretical model is established,which is compared with the model of finite element built by COMSOL.The result shows the finite model is valid.Based on COMSOL finite element model,the absorption property of anechoic coating is discussed under single-shell backing and double-shell backing ,the absorption property of different cavities under double-shell backing is compared.The result shows that the absorption peak moves to lower frequency and absorption peak value drops as the more thickness of the steel shell plate under single-shell backing.In additon,the water layer between the shells thickens,absorption peak value moves to low frequency,the number of peak increases and the peak value drops.The curves of absorption coefficient between different thicknesses shells are almost same ,which illustrate that the effect of absorption coefficient between different thicknesses shell is little.The absorption property of anechoic coating embedding cylinder cavity at low frequency and ellipsoid cavity at middle and high frequency is better.