Reinforcement Design Of Old Ship Based On Stochastic Sensitivity

Considerating the operating cost, China’s shipping owners tend to buy second-handboats in the middle-age because of the economy. So ship extended service problems willbe naturally appeared. Due to the corrosive effects of the marine environment, theeffective thickness of the steel structure of service ships will inevitably declined, whichalso leds to the loss of structural strength. In this case, strengthening the structuralstrength to ensure the ships in extended service and cost less becomes a problem. If thisissue is handled well, enormous social and economic benefits will be bringed about.Sensitivity analysis for important mechanical structure of the ship, can be helpful forjudging the design parameters which contribute more for strength preformance. Andprovide theoretical support for strengthening the ship’s structure.Firstly, ANSYS was used as a computing platform to study the techniques ofstochastic sampling for sensitivity calculation. The thickness of steel sturcure of a cabinsegment model was used as the design variables, and the evaluation index of mechanicalproperties was used as output variables. Comparing different parameters of stochasticsampling in sensitivity calculation to get the optimal sampling parameters combination.Using this cambination, computing time can been reduced greatly.Secondly, using the finite element method, the fine model of the beam knee of aship in service (Shengli151) has been made. The stochastic sensitivity factors havebeen calculated using the thickness of steel shell of the beam knee under corrosion asthe design variables, the evaluation index of mechanical properties and geometricdimension of model as output variables. The main parameters affecting the structureperformance has been filtered out. As these effects parameters used as design variables,three different types of parameter optimization of the typical structure of the beam kneehave be taken. The strengthening scheme has been provided to enhance the performanceof the beam knee.Finally, stochastic sensitivity analysis has been applied to a cabin segment modeland the floating crane(SL151). The thickness of steel sturcure of a cabin segment modelwas used for the design variables, and the evaluation index of mechanical propertieswere used for output variables. Considering finite element analysis results, the structuralweaknesses area has be strengthened in three ways guided by the result of stochasticsensitivity analysis. Strengthen the ship in these ways can get better results with lesscost, achieving to improve economic efficiency.