Effects of snowflake swing arm parameters on sound insulation performance of thin film acoustic metamaterials

A snowflake swing-arm thin film acoustic metamaterial (MAM) structure design is proposed to solve the problem that common acoustic insulation materials cannot achieve both lightweight and effective attenuation of low frequency noise.The metamaterial structure is framed in stainless steel, and eight rectangular aluminum blocks and one cruciform aluminum block (four swing arms) are pasted on the surface of a 0.025 mm thick polyimide (PI) film to form a resonant part. The influence factors of the additional circular mass block MAM are simulated and analyzed, and the influence rules of the mass block radius and the prestress, thickness and radius of the film on the sound insulation are revealed. The sound insulation performance of MAM with different swing arms distribution is calculated, and the results show that the MAM with 4 swing arms has the best sound insulation effect. On this basis, a snowflake symmetrical swing arm MAM is proposed, and the results show that its sound insulation performance is further improved. The sound insulation performance of the MAM sample with additional mass block and the snowflake symmetrical swing arm was tested by the impedance tube system. The experimental results were compared with the simulation results, and the accuracy of the simulation calculation and the sound insulation effect of the snowflake symmetrical swing arm were verified. The snowflake symmetrical swing arm MAM has multiple peak sound insulation value, and the sound insulation value can reach 55.4 dB at 250 Hz, which provides a new idea for low frequency sound insulation and has potential engineering application prospect.