A novel semi-analytical methodology for predicting sound absorption of anechoic coatings with arbitrary rotary cavities dependent on temperature and frequency

In response to the shortcomings of existing studies on the sound-absorbing characteristics of an anechoic coating, which most ignore the frequency factor and are expensive for temperature-tunable hydroacoustic experiments, a novel semi-analytical methodology that considers both frequency and temperature is proposed in this paper. Based on the dynamic mechanical thermal analysis technique and time-temperature superposition principle, the temperature and frequency spectra of two rubber materials are tested and expanded in turn. Meanwhile, a complete acoustic prediction model is developed employing the non-uniform waveguide theory for an overburden containing arbitrary rotary cavities. Furthermore, taking a lining embedded with ramped cavities as the research structure, the theoretical model is firstly validated by an absorptive measurement conducted with the hydroacoustic impedance tube test-system, and then the acoustic influences of the material properties and geometric parameters of each sublayer, as well as the temperature factor, are investigated in-depth to reveal the multiple energy dissipation mechanisms. These results show that the present semi-analytical method can accurately and effectively predict the dynamic sound absorptions of a covering in the wide temperature-frequency range of T-g similar to T-g + 50 degrees C and 10 Hz similar to 10(6) Hz.

Automated summary

In this paper, a novel semi-analytical methodology is proposed to predict the dynamic sound absorptions of a covering accurately and effectively in a wide temperature-frequency range. The theoretical model is validated experimentally and reveals multiple energy dissipation mechanisms.