The Characteristic Researches On The Shell Scattering With Dissimilar Thickness

Scattering is one of the fundamental problems of underwater acoustic, In which the characteristics of the target has been studied. Restricted by the practical conditions, most of the researches about the sound scattering of complex and big-scale shell-structure are carried on models, In this case, How to get the characteristics of the prototype through the experiments on the models becomes the key problem.Based on the principle of similarity, When the material of prototype and the fluid around it are same as ones of its scaled-down model, and the similar condition of geometrical sacle are exactly satisfied, meanwhile, the similar ratio of frequency between the prototype and its scaled-down model is inversely proportional to the similar ratio of their geometric properties, the sound scattering of the prototype and model are the completely the same, the directivity of sound pressure in far field and the response function of points for the prototype are equal to ones of its scaled-down model respectively. This paper tried to use the finite element and boundary element method to settle the acoustic scattering from elastic complex shell submerged in an unbounded fluid field.Because of great scale-down, the similar conditions of the thickness between prototype and model can not be satisfied, it is called the thickness dissimilarity. Distorted model leads to distortion of acoustic field. Making a lot of imitations on the computer, The paper analysed the relationship between dissimilar value of thickness and distorted acoustic field, it also made a graph of the characteristics of the point pressure dissimilarity contacted by the dissimilar value of thickness from different frequencies, and discussed the approximate compensation by different material when the value of dissimilar thickness was three.