3-DIMENSIONAL EFFECTS ON THE NATURAL VIBRATIONS OF CRACKED TIMOSHENKO BEAMS IN WATER

An efficient and quick numerical method for the computation of the vertical natural vibrations of a Timoshenko beam in water is given. The method is based on one-dimensional Timoshenko beam finite elements for the structural part and on fluid boundary elements for the fluid part, in both coupled and uncoupled versions. Various boundary conditions, including the free-free case, can be taken into account. The longitudinal correction factor J (for three-dimensional and end-effects) is computed and compared with other published values. It is found that the J values remain almost the same for Euler-Bernoulli and Timoshenko beams of the same geometry, material and boundary conditions. The J values were also computed for a Timoshenko beam with a transverse crack and compared with those found for the uncracked beam. The results obtained were almost identical.