Automatic size optimization of FPSO turret area with application of point set based outer shell FE modeling

This paper presents an automatic size optimization framework for the typical internal turret of FPSO. For optimization preparation, a point set based modeling method is proposed to offer finite element (FE) models of outer shell for hydrodynamic load calculation. The FE model of outer shell is built rapidly by establishing mesh through point set, which are extracted by intersecting three-dimension (3D) geometric surface of hull with orthogonal plane groups. For size optimization, an integrated optimization platform on Isight coupled with FE analysis based on MSC.PATRAN&NASTRAN is established. The Radial Basis Function (RBF) models are applied to approximate the yield stresses of the structure without computationally expensive FE analysis during the optimization process. A typical turret area of FPSO has been taken as an example to show the whole process of size optimization including the application of point set based FE modeling method on hydrodynamic load calculation and the process of searching optimal thickness distribution of the turret that minimizes the weight under actual engineering constraints. The optimization result shows the feasibility and rapidity of point set based FE modeling method and the efficiency of the optimization framework.