Accession Number : AD0271460

Title :   THEORETICAL DEVELOPMENTS IN THE VIBRATIONS AND ACOUSTIC ANALYSIS OF HULLS

Corporate Author : J G ENGINEERING RESEARCH ASSOCIATES BALTIMORE MD

Personal Author(s) : GREENSPON,JOSHUA E.

Report Date : DEC 1961

Pagination or Media Count : 1

Abstract : Efforts are being made to develop a general shell type method that can be applied to the vibration and acoustic analysis of ship and submarine hulls; one in which the displacements, frequencies and sound field can be obtained by use of digital computer calculations. The method that was developed to obtain the hull stiffness char-ACTERISTICS DOES NOT MAKE ANY ASSUMPTION REGARDING THE SHAPE OF THE STRUCTURE BUT DIVIDES THE STRUCTURE INTO RECTANGULAR STIFFENED PLATE ELEMENTS, BAR ELEMENTS AND ADDED MASS ELEMENTS. The external forces on the shell include the forces due to machinery, propeller, etc. plus the pressure due to vibration of the hull in the water. The resulting set of equations that the computer must solve for the amplitudes of each of the elements is a coupled set which involves the mass and elastic properties of the shell, the elastic characteristics of the mountings for the rigid masses, the mass and moment of inertia of the rigid masses and the forces induced on the hull. The computer will determine the amplitudes of vibration of the elements and masses under the given force system. The pressure on the outside of the hull can then be computed directly, knowing the amplitude and the mutual impedances of the hull elements. (Author)

Descriptors :   *ACOUSTIC IMPEDANCE, *HYDRODYNAMICS, *SHIP HULLS, *SUBMARINE HULLS, ACOUSTICS, CYLINDRICAL BODIES, FUNCTIONS(MATHEMATICS), INTEGRAL EQUATIONS, PRESSURE, SHIP MODELS, STRESSES, SHELLS(STRUCTURAL FORMS), THEORY, TRIGONOMETRY, VIBRATION

Distribution Statement : APPROVED FOR PUBLIC RELEASE