Simplified Microstructural Unit Model for the Study of Sound Absorption Behavior of Microporous Foam Materials

Aiming at the difficulty of quantitatively predicting the sound absorption coefficient of a microstructural foam material through its microstructure size, an SEM method is proposed to establish a simplified unit model of the microstructural aluminum foam. Using this model to simulate the topology of the microstructural aluminum foam, the relationship between the unit's topological characteristics and the key non-acoustic parameters, including static flow resistance, viscous characteristic length, thermal characteristic length, and tortuosity coefficient, can be established. On the basis of the simplified unit model, the open porosity is introduced to clarify the relationship between the porosity and tortuosity of the microstructural foam material. So the accuracy for predicting the sound absorption coefficient of the microstructural aluminum foam is improved. The BK impedance tube is used to measure the sound absorption coefficient of the microstructural aluminum foam specimen, and the experimental measurement results are consistent with the theoretical prediction results. The specimens with a thickness less than 30 mm prepared in this research achieve broad-band and high-efficiency sound absorption, with an average sound absorption coefficient of 0.8 in the 1 100-6 500 Hz frequency band. This research may provide a basis for the design, optimization and preparation of microstructural foam materials with better sound absorption behavior. © 2021, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.