Long-Term Structural Analysis of 3-D Ship Structures Using a New Stiffened Plate Element

Abstract

The paper presents the development of a technique for long-term 3-D structural 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 evaluation of hydrodynamic pressures using the 3-D linear diffraction theory. The elegance of the present stiffened plate element is that it can accommodate any number of arbitrarily oriented stiffeners within the plate element. Thus, the formulation obviates the use of mesh lines strictly along the longitudinals and transverses of the ship, which minimizes the required number of degrees of freedom of the finite element model of the complete vessel and reduces the computational effort considerably. The long-term prediction for the worst hydrodynamic pressures in the lifetime of the ship is carried out using the ISSC spectrum and scatter tables of Indian coastal waters. As an example problem, long-term structural analysis of a mini-bulk carrier in Indian coastal waters is presented in the paper. The long-term pressures are estimated with a probability of exceedence of 10−4 and principal stresses are calculated. It is shown that the present method provides a new, elegant, and economic technique for long-term 3-D structural analysis of the complete ship.