New approximations of external acousticstructural interactions: Derivation and evaluation
New approximate models for external acoustics interacting with flexible structures are developed. The basic form of the present models is obtained by a combination of the Laplace-transformed retarded and advanced potentials with the weighting parameter as part of the model equation. It is shown that the maximum attainable time-derivative of convergent approximate models is two, hence any attempt to include higher orders will lead to non-convergent models. The present external acoustic model is implemented and interfaced with a finite element structural analyzer for the transient response analysis of submerged spherical and cylindrical shells subjected to a series of incident waves. Comparisons of the present results with the classical analytical solutions and the Doubly Asymptotic Approximations (DAAs) show that proposed model offers improved accuracy especially for early-time responses, exhibits computational robustness, and maintains the impulse response consistency that are desirable for inverse problems. The present model is applied for a shock response correlation of an experimental complex ring cylinder, which demonstrates the applicability of the proposed approximate model to practical engineering problems.
external acoustics structureacoustic interactions retarded and advanced acoustic potential