FREE-VIBRATION OF PARTIALLY FILLED, HORIZONTAL CYLINDRICAL-SHELLS

The exact solution to the free vibration problem of circular cylindric al shells half-filled with liquid and with the shell axis orthogonal t o the gravitational field is analytically obtained and approximate mod els are proposed to estimate natural frequencies and mode shapes of pa rtially filled shells. In the problem considered, the free surface of the liquid is parallel to the shell axis with lack of the axisymmetry of the liquid-shell system. The shell is considered to be simply suppo rted at both ends. The kinetic energy of the system is analytically ev aluated for an inviscid and incompressible liquid. Natural frequencies and mode shapes are found by using a Galerkin equation obtained by mi nimizing the Rayleigh quotient. The study is based on the development of the radial displacement in a Fourier series and it is independent o f the shell theory. Numerical data are presented for both eigenvalues and eigenvectors. The curves of natural frequencies as functions of th e water level in the shell are shown. The theoretical study is validat ed through comparison with results of experimental modal analyses perf ormed on a AISI 304 stainless steel pipe supported by two thin diaphra gms and filled with water to different levels. (C) 1996 Academic Press Limited