Ship Structure Optimization Using CAD-FEM Integration

Amirouche Amrane, JD Caprace, Philippe Rigo (University of Liege)

CHALLENGE - In ship structural design optimization methodologies, are not yet widely implemented in industrial applications. In this paper two different studies are presented: the optimization of a double bottom structure and the optimization of the duct structure. In both cases the challenge was to create an automatic procedure integrating CAD generation, CAD transformations and FEM analysis.

SOLUTION - modeFRONTIER has been used to drive the geometry creation and the ANSYS simulation. Both numerical and unordered variables have been used at the same time. In fact, stiffeners dimensions are taken from a catalogue available. In the both optimization studies, the SIMPLEX algorithm has been used because considering only weight optimization with structural constraints on maximum stresses.The optimization process uses a 3D CAD model transferred from the CAD software AVEVA Marine to the idealization module. This module generates a simplified geometry based on FEM needs in ANSYS and then the idealized CAD model is transferred to the FEM tool to create a meshed and loaded structural model. The results (stress, displacement, volume etc.) are then transferred to the optimizer modeFRONTIER which evaluates values of the objective function and the constraints.












BENEFITS - The implemented modeFRONTIER workflow using the SIMPLEX algorithm is able to finding a good solution in a limited number of iterations regardless the highly constrained problem. It enables to reduce the weight of a double bottom ship structure: the volume decreased (-38%) and the Von Mises stress at the optimum iteration is 221.68 MPa (-12% than the limit).  Regarding the ship deck structure optimization, the optimum is reached on the 278th iteration in which the weight value decreased by 13.6% and the Von Mises stress is 225.4 MPa (-34% than the initial geometry).