The Optimal Design Of The Keelbox Of Racing Yacht

Keelbox is the unique structure of racing yacht whose function is to keep the retractable keel lifting up and down straightly.The keelbox is easily broken for playing the mainly part of bearing carrier of racing yacht,how to improve the strength of keelbox is a question need to be solved urgently for the shipyards and owners.In this paper a broken keelbox is taking into account as specific cases.The main content of the paper comprises:1)To capture the stress and deformation of the keelbox,the finite element analysis method have been performed.A finite element model of racing yacht is established with the technical drawing.Calculating the hydrodynamic pressure and response amplitude operators of RAOs in several waves condition of racing yacht by frequency domain analyzing method.Based on the simulation results,it is concluded the wave angle which cause the most motion amplitude of racing yacht.Take the hydrodynamic pressure and acceleration of center of gravity as inputting load,The findings from this study shows that the maximum stress of keelbox is 48.78 MPa,the stress distribution shows good agreement with realistic one.Establishing optimization model with the structure response.2)The optimum structural design of keelbox based on response surface method.Multistage optimization is used in shape and size optimization of the top hat section of the broken area of keelbox.The top plate,pectoral plate,thickness of composite plies were chosen as design parameters.Stress and deformation were selected as constraint condition.Strain energy density was used as objective functions.The Design of Experiment method,DOE approach was constructed to screening of design variables and fitting the response surface.Optimum results showed that proposed optimization methodology reduce 75.92% strain energy,23.6% maximum stress.The method presents in this section can solve the strength promotion process.3)Stacking-sequence optimization of fiber reinforced plastic based on genetic algorithm.The stacking sequence was chosen as design parameters.Taking Tsai-Wu strength criterion as objective functions.An experimental data was used for comparison and validation of the numerical simulations.Meanwhile.Experimental and numerical values showed good agreement.The study improve 29.40% layer intensity ratio of the keelbox,The method present in this paper could be used as the strength promotion process of keelbox.