Abstract
A cavity viscoelastic structure has a good sound absorption performance and is often used as a reflective baffle or sound absorption cover in underwater acoustic structures. The acoustic performance field has become a key research direction worldwide. Because of the time-consuming shortcomings of the traditional numerical analysis method and the high cost of the experimental method for measuring the reflection coefficient to evaluate the acoustic performance of coatings, this innovative study predicted the reflection coefficient of a viscoelastic coating containing a cylindrical cavity based on an artificial neural network (ANN). First, the mapping relationship between the input characteristics and reflection coefficient was analysed. When the elastic modulus and loss factor value were smaller, the characteristics of the reflection coefficient curve were more complicated. These key parameters affected the acoustic performance of the viscoelastic coating. Second, a dataset of the acoustic performance of the viscoelastic coating containing a cylindrical cavity was generated based on the finite element method (FEM), which avoided a large number of repeated experiments. The minmax normalization method was used to preprocess the input characteristics of the viscoelastic coating, and the reflection coefficient was used as the dataset label. The grid search method was used to fine-tune the ANN parameters, and the prediction error was studied based on a 10-fold cross-validation. Finally, the error distributions were analysed. The average root means square error (RMSE) and the mean absolute percentage error (MAPE) predicted by the improved ANN model were 0.298% and 1.711%, respectively, and the Pearson correlation coefficient (PCC) was 0.995, indicating that the improved ANN model accurately predicted the acoustic performance of the viscoelastic coating containing a cylindrical cavity. In practical engineering applications, by expanding the database of the material range, cavity size and backing of the coating, the reflection coefficient of more sound-absorbing layers was evaluated, which is useful for efficiently predicting the acoustic performance of coatings in a specific frequency range and has great application value.
Highlights
The technical method of laying periodically arranged cavity structures on the surface of a material to improve the acoustic performance has been widely adopted [1–5], especially in stealth submarines, which are often used as reflective baffles or sound-absorbing covers
In terms of the acoustic prediction of the laying of acoustic coatings, Tang [8] proposed a method for calculating the sound scattering of nonrigid surfaces by using physical acoustics, which laid the foundation for the calculation of the echo characteristics of submarine laying anechoic tiles
Scholars have carried out research regarding the optimization of the design of the acoustic performance of viscoelastic acoustic coatings with cavities [15–19]
Summary
The technical method of laying periodically arranged cavity structures on the surface of a material to improve the acoustic performance has been widely adopted [1–5], especially in stealth submarines, which are often used as reflective baffles or sound-absorbing covers. After years of development, based on the physical characteristics of the viscoelastic cavity sound-absorbing layer’s material and structure, the use of theoretical analysis and numerical calculations to carry out acoustic research has achieved rich results. Ivansson et al [12,13] replaced the calculation methods of electron scattering and the optical band gap to analyse the viscoelastic sound-absorbing cover layer and calculated the acoustic performance of various periodically distributed spherical and elliptical cavities. Meng et al [14] used the harmonic analysis module of the finite element analysis software ANSYS to calculate and analyse the acoustic performance of a sound-absorbing cover when a plane wave was incident perpendicularly and further analysed the influence of the selection of the outer boundary shape of the acoustic coating unit on the calculation results. The above research shows that the acoustic performance of viscoelastic acoustic coatings that contain a cavity has become a key research direction worldwide, and the main research methods have concentrated on traditional basic theoretical research, numerical analysis and experimental verification
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