Research On Sound Insulation Properties Of Semi-active Control Membrane-type Acoustic Metamaterial

With the expansion of the city,the number and capacity of the distribution transformers in the residential area have increased,and the resulting low frequency noise pollution is more serious.The noise generated by the substation is basically mainly medium and low frequency noise,low frequency noise due to low frequency,slow attenuation,and difficult to control.The sound absorption of low frequency noise has always been one of the difficulties in the acoustic field.Since the acoustic metamaterial has a negative equivalent mass density and negative equivalent volume modulus having a special engineering application value in the low frequency noise reduction.In this paper,a semi-active control membrane-type acoustic metamaterial structure is designed,which is a membrane-type metamaterial such as an aluminum frame,a rubber membrane-type,and a spiral tube such as a central mass.The material produces a stabilized magnetic field by a fluid solenoid to control the force of the center Nd Fe iron magnet mass,which in turn controls the membrane-type tension,and finally controls the inherent frequency of the membrane-type acoustic metamaterial.Through theoretical calculations,simulation simulation,and experimental exploration have made detailed analysis and research on their sound absorbing characteristics,sound insulating mechanism,and structural parameters.The main research contents are as follows:A semi-active control membrane-type acoustic metamaterial model was established,designed and prepared a sample tube matched with the impedance tube test system,and built an experimental test platform.Through the simulation calculation and impedance test method,a semi-active control membrane-type acoustic metamaterial structure for the 50 Hz noise characteristics of the substation is selected,and the impact of the material on different structural parameters is explored;the current intensity is also explored.In the influence of the accepted peak frequency,finally analyzed by simulation simulation results of the additional mass membrane-type membrane-type,and the sound streamline and the like,the insider mechanism of the membrane-type acoustic metamaterial is revealed.The results show that the material has excellent low frequency sound insonso characteristics near 50 Hz,and has broadband characteristics.Through the exploration of the sound insulation mechanism,it was found that the membrane-type in the membrane-type occurred at50 Hz,which losted the energy of the sound waves,so it can be accepted.In addition,when the mass of the center mass increases,the material has a fixed frequency to the low frequency offset;the material inherent frequency is offset when the membrane-type tension is increased.Finally,the power of the energization solenoid is increased,and the sound peak is offset to the high frequency,and the regulation of the inherent frequency of the material can be realized.