Vibro-acoustic coupled analysis method for sandwich structures

A kind of modal expansion method based on acoustic waveguide modes was presented to investigate the vibro-acoustic coupled performance of sandwich structures and its weak coupling form was also developed. The waveguide boundary included two forms of pressure released boundary and rigid boundary. In comparison with the structural modal expansion method and the acoustic modal expansion method of a sound cavity, the influence of orders of acoustic modes and acoustic waveguide modes on the calculation accuracy of the sound transmission loss was analyzed and the vibro-acoustic coupled performance and sound pressure distribution of sandwich structures under different boundary conditions were studied. It was shown that the needed orders of acoustic waveguide modes and acoustic modes of the sound cavity are determined with the highest frequency of the calculated frequency range; the bigger the highest frequency, the more the orders of the acoustic waveguide modes and acoustic modes of the sound cavity; the comprehensive effect of structural vibration modes and acoustic modes of sandwich structures leads to their vibro-acoustic coupled characteristics; the 'beam-air-beam' resonance, standing-wave resonance and structural resonance reduce the sound insulation performance of a structure; the sandwich boundary affects vibro-acoustic coupled features of sandwich structures obviously; the sandwich sound field distributions are not exact same for the same physical phenomenon with the above three different methods, the sound field distribution characteristics can reflect the mechanism of occuring physical phenomena. © 2016, Editorial Office of Journal of Vibration and Shock. All right reserved.