An investigation of the structure-borne sound transmission in a T-joint equipped with a dynamic vibration absorber based on fluid-structure interaction dynamics

A novel analytical method is presented in this paper for evaluating the propagation characteristics of structure-borne sound in a T-joint, the web plate of which is in contact with heavy fluid. Firstly, based on the dynamics of fluid-structure interaction, a mathematical model that considers the effect of fluid is established for the T-joint, which is equipped with a dynamic vibration absorber. The waves in the T-joint structure are described by the dynamical equation of thin plates, while the motion of fluid is described by the Helmholtz equation in the ideal acoustic medium. For the convenience of mathematics, the semi-infinite fluid domain is extended virtually into the infinite space. The Fourier transform method is utilized to obtain analytical solutions with high precision. Several examples are given to analyse the characteristics of the coupled transmission of bending and longitudinal waves in the T-joint. Comparisons are made with the results for the no-fluid case. The effects of the mass and frequency parameters of the dynamic vibration absorber on the inhibition of longitudinal wave transmission are also investigated. It is found that the existence of the heavy fluid has a significant influence on the propagation of bending waves in the T-joint. The dynamic absorber can inhibit the longitudinal waves in the web plate of the T-joint, while it has no effect on the bending waves.