A Piece-wise Calculation Scheme for the Mid-to-high Frequency Vibro-acoustic Simulations

Mid-to-high frequency modelling is computationally costly and technically challenging owing to the complex wavelength compositions involved in typical vibroacoustic systems, which lead to a large amount of degrees of freedoms. In the present paper, the Condensed Transfer Function (CTF) approach is revisited to tackle this problem. It is demonstrated that the modelling efficiency of the CTF method can be greatly increased through a proper selection of the Condensation Functions (CFs) and the contribution from different CF terms highly depend on their spatial matching with the physical wavelengths of the system. For each targeted frequency range, complex exponential functions are shown to be able to describe the dynamic behavior of the coupling surface, which separates the adjacent subsystems, with only a few dominated terms. Numerical results show a piece-wise convergence behavior of the CTF method when these dominated terms are carefully extracted from the entire CF series. Based on these observations, a CF series selection criterion is proposed, applicable to the mid-to-high frequency region in a system involving either acoustic-structure coupling or acoustic-acoustic coupling among subsystems. The proposed calculation scheme allows the system response to be calculated within each frequency band, one at a time in a progressive and piece-wise manner, resulting in a great increase in the computational efficiency.