一种含柱形空腔结构橡胶层的吸声机理及优化*

摘要

The finite element method is introduced to investigate the absorption of a rubber slab (20 mm thick) with one layer of cylindrical cavities. It has a lower frequency absorption peak than that with spherical cavity in the same size, which is determined by the monopole resonance of cavities. Analysis of partial wave scattering verifies that the absorption peak is induced by the monopole resonance. Power dissipation density and displacement pattern of one unit cell is used to clarify intuitively the absorption mechanism of the cavity. Then the effect of damping of transverse modulus on the absorption is investigated under the condition of a steel backing. Both the physical and structural parameters of the rubber slab are optimized by a genetic algorithm for favorable absorption from 1.5 to 10 kHz.%采用有限元法，分析了含单层柱形空腔橡胶层(厚度20 mm)的吸声性能，表明其吸声峰频率比相同尺寸的球形空腔低，这与单个柱形和球形空腔的单极共振频率相对应，通过谐波散射分析证实了空腔单极共振引起的能量耗散增强了声波的吸收。采用能量耗散功率及位移场分布，对柱形空腔结构的吸声机理进行了深入分析.其次，在钢背衬条件下分析了横波损耗因子对橡胶层吸声特性的影响，并采用遗传算法对含不同尺寸柱形空腔橡胶层在1.5-10 kHz 频段上的吸声特性进行了优化，获得了较好的宽频吸声效果.