Multi-Fidelity Fluid-Structure Interaction Optimization for Weight Reduction of High-Speed Small Craft

With the aim of improving standard and often too conservative approaches in ship design, this paper presents a framework for the multi-fidelity (MF), multi-objective, and multidisciplinary optimization of a high-speed small craft in realistic environmental and operating conditions. This activity is performed in collaboration with the Naval Surface Warfare Center Carderock Division. The optimization addresses the weight reduction and the structural safety (expressed by the factor of safety, FS) increase of the generic prismatic planing hull (GPPH). The hull model is realized with a parametric CAD model using 32 design variables, defining plate and beam sizing. A realistic load distribution and structural weight are considered. A design space dimensionality reduction method is used, namely the parameter model embedding (PME) and its extension goal-oriented PME (GO-PME). A MF surrogate model is built using additive correction of high- (HF) and low-fidelity (LF) solutions and iteratively refined by an active learning method. The performance are assessed by fluid-structure interaction (FSI) simulations, performed with two levels of fidelity varying the loading condition. Hydrodynamic loads are evaluated by computational fluid-dynamics simulations performed with CFDShip-Iowa V4.5 and computational structural dynamics is performed with COMSOL Multiphysics. Design space dimensionality reduction methods achieve up to 60% design space reduction while representing up to 95% original variability. A Pareto set is identified that entirely dominates the original solution, two significant solutions are investigated providing 32% and 22% weight reduction and FS reduced but still feasible and increased, respectively.