Simulation Analysis And Control Of The Acoustic Scattering Of Cylinder And Shell Structure

As the only physical field that can be transmitted over long distances in water,sound waves have special significance for the detection of underwater targets,and the acoustic scattering of underwater targets is the information source of active sonar.Therefore,the study of underwater target acoustic scattering and how to reduce the target acoustic scattering becomes very meaningful.At present,the research on the acoustic scattering of underwater complex targets is mainly based on the finite element method,and the finite element method can be divided into frequency domain and time domain.This paper first obtains the Rayleigh solution of solid spheres and spherical shells through theoretical derivation,and then compares the results with the finite element frequency domain and time domain solutions to illustrate the accuracy of the finite element method.The calculation results of the dimensional axisymmetric model are compared with the calculation results of the finite element three-dimensional model,which illustrates the accuracy of the calculation using the two-dimensional axisymmetric model under the excitation of non-axisymmetric loads for the axisymmetric structure,and then the research on acoustic scattering and acoustic scattering control is carried out based on these finite element solution methods.The specific work is as follows:In the study of acoustic scattering from cylindrical shell structures,the form function of the infinitely long cylinder is firstly derived through theoretical deduction,and the acoustic target strength of the finite-length rigid and elastic cylinder is calculated through the finite element two-dimensional axisymmetric model,which explains the role of the rigid term and elastic term in the scattering field,and then the theoretical calculation method of calculating the acoustic target strength of the finite-length cylindrical through the form function of the infinite-length cylinder is introduced,and the acoustic target strength of the finite-length cylinder obtained by the theoretical calculation method is compared with the finite element solution,which illustrates the applicability and accuracy of the theoretical calculation method.The acoustic scattering of a finite-length cylindrical shell is studied following the same idea,and then the applicability and accuracy of the theoretical method to calculate the acoustic scattering of a finite-length cylindrical shell are evaluated.Considering that the actual finite-length cylindrical shell structure is very complicated inside,the same idea is used to study the finite-length cylindrical shell structure with diaphragm structure.The acoustic target strength under two incident conditions is discussed,and the applicability and accuracy of such structures caculated using the theoretical method is demonstrated.Finally,the acoustic target strength of finite and infinite quadrangular prismatic shells is calculated and compared with those of cylindrical shells.In the study of acoustic scattering control,the form function of the solid sphere for the laying acoustic coating is obtained through theoretical deduction,and then the influence of the thickness of the laying acoustic coating and the loss factor on reducing the acoustic target strength is studied by the finite element frequency domain method,and then the finite element method is used to study the influence of the thickness of the acoustic coating and the loss factor on reducing the acoustic target strength.The effect of laying acoustic coating is verified through the finite element time domain method.The finite element frequency domain method is used to determine the effect of acoustic scattering reduction in air and water after laying two elastic thin layers.Subsequently,it is determined that this laying method used to reduce the acoustic target strength on a finite-length rigid cylinder,and by changing the length of the cylinder,the influence of the length change on the acoustic scattering reduction effect is obtained.