frequency response function of a submarine hull

in this research, simplified physical model of the submarine hull has been considered as a cylindrical shell containing ring stiffeners. it identification is done in low frequency, so, the goal is to determine frequency response function is in frequencies of low than 100 hz. for determination of it, mass matrix, stiffness matrix and damping matrix of model should be extracted. the structure is modeled in ansys11 software, and is meshed with triangular element. displacement domain of each node is considered in radial and axial direction, number of structural elements and coordinates of nodes are theoretically analyzed by matlab software based on finite element rotating shell. three matrixes above are extracted, then the natural frequency is obtained and then diagram of function is drawn in the low frequency range. the achievements of using this method are determination of response of propeller−shafting system of hull, coupling propeller−shafting system to hull, the optimization of resonance changer in low frequencies due to reduction of transmission noise of propeller to submarine hull with technique of genetic algorithm, description of the acoustic signature of submarine due to submarine propeller excitation which is being investigated by the department of mechanics and this method can be considered as one of the maritime technologies and implemented as plan applicable in marine industries.