A Study On Multi-objective Optimization Of Whole-ship Structure Under Static And Dynamic Condition

By far, ship structural optimization problem is mainly limited to the localstructures, and is always solved as single-objective optimization problem ofminimizing the structural weight with static strength constraint or frequencyconstraint, with less consideration of dynamic response characteristics. Taking aself-propelled cutter suction dredger as the study object, we studied some keytechnologies about finite element analysis, sensitivity analysis and multi-objectiveoptimization. The main research works are as follows:(1) The3D finite element model of a whole-ship structure was built and analyzed.We discussed some key technologies about finite element calculation and performedthe strength assessment, real eigenvalue analysis and dynamic response analysis of aself-propelled cutter suction dredger.(2) The sensitivity analysis of whole-ship structure was done. The choices ofdesign variables for multi-objective optimization and multi-objective hierarchicaloptimization based on the stiffness distribution of whole-ship structure was discussedand the sensitivity of mass, stress, displacement, natural frequency and accelerationwere calculated.(3) A comparative study on multi-objective optimization methods wasperformed. The mathematic model and simulation design flow suited formulti-objective optimization of whole-ship structure under static and dynamiccondition were built and we solved the multi-objective optimization model using theNSGA-II, NCGA belong to the direct method and the ideal point, fully layered belongto the indirect method, and compared the optimizing effect of each optimizingmethod.(4) A study on multi-objective hierarchical optimization based on the stiffnessdistribution was done. Adopted a whole-ship structural hierarchical optimization method to perform fivelevel multi-objective optimization.