This paper explores a practical application of shape optimization in combination with finite element analysis in ship structural design. For an improved structural design of ships, different optimization techniques are outlined. A basic problem of linear strength analysis is solved to validate the proposed optimization strategy. Parametric models are used to accommodate changing dimensions during the optimization process. As a practical example, a floor of a doublebottom structure is optimized with respect to weight.
Typically, ship structural design is largely based on experience. If optimization is performed, it is often done on a manual basis by the interpretation of results of finite element analysis (FEA) by structural experts. While this is a very valid approach for basic structural design, further improvements could be expected by the use of integrated optimization algorithms. Structural optimization deals with methods and applications of mathematical optimization to the computer aided optimum design of structures. The task of the mathematical optimization process is to find the optimum point, from any starting point, and to do so with as little computation as possible (Hughes, 1983). A certain number of design variables (e.g. thickness, shape or cross section area of a structure) has to be determined in a way that the objective function (e.g. minimal weight of a construction) is best fulfilled in compliance with the state variables (e.g. strength, stiffness or production). Depending on the design variables, structural optimization can be classified as follows (Sekulski, 2009):
Choice of material
Scantling optimization For scantling optimization (dimensioning), the design variables are restricted to parameters that are used for direct determination of the structural element stiffness.
However, Rahman (1996, 1998) illustrates the applicability of scantling optimization to marine structures.