Long-term structural analysis of 3-D ship structures using a new stiffenedplate element

The paper presents the development of a technique for long-term 3-D structu ral analysis of the complete ship using a new stiffened plate element. The 3-D analysis involves the 3-D finite element modeling of the vessel and eva luation of hydrodynamic pressures using the 3-D linear diffraction theory. The elegance of the present stiffened plate element is that it call accommo date arty number of arbitrarily oriented stiffeners within the plate elemen t. Thus, the formulation obviates the use of mesh fines strictly along the longitudinals and transverses of the ship, which minimizes the required num ber of degrees of freedom of the finite element model of the complete vesse l and reduces the computational effort considerably. The long-term predicti on for the worst hydrodynamic pressures in the lifetime of the ship is carr ied our using the ISSC spectrum and scatter tables of Indian coastal waters . As an example problem, long-term structural analysis of a mini-bulk carri er in Indian coastal waters is presented in the paper. The long-term pressu res are estimated with a probability of exceedence of 10(-4) and principal stresses ale calculated. It is shown that the present method provides a new elegant, and economic technique Sor long-term 3-D structural analysis of t he complete ship.