Study On The Influence Factors And Optimization Analysis Of Double-hull Structure Crashworthiness

The increasing emphasis on the marine resources has made the shipping industry develop rapidly. The route density increases, combined with the weather and artificial factors lead to the frequency increasing of ship collision accidents. Ship as a complex and huge maritime mobile building, once the collision accidents happened, the consequence is very serious. It may lead to personnel casualties, hull structure damage or serious environmental pollution. So it’s very important to study on ship collision problems and look for the ways to enhance its crashworthiness.Because of the strong nonlinearity of the impact problem, the difficulty of its solution is increased. In this paper, the ANSYS/LS-DYNA explicit dynamic analysis software is used for the numerical simulation analysis. The analysis approach is verified through the stiffened plate frame structure collision analysis. At the same time, the mechanics model is simplified according to the structure deformation in the collision, and the simplified analytic formula of collision force is derived by using plastic mechanics knowledge. This formula can be used to estimate the crashworthiness of stiffened plate structures preliminarily.According to the determined numerical simulation method, a 30 million ton VLCC ship is taken as the research object to establish the double-hull structure collision model. The deformation of each component in the process of collision is analyzed in this paper. At the same time the differences of the structure crashworthiness under different conditions is analyzed to discuss the influence of the external factors changing.By summarizing the method of enhancing the structure crashworthiness, the method that changing the component size is simplified into the geometrical parameters changing, the two using crashworthiness material methods that filling crashworthiness material in double hull structure and installing the fender device outside the double hull are simplified into the equivalent material parameters of the side structure changing. At the same time, by considering the different impact resistance of the different components and the different crashworthiness material laying positions, a discussion is made about the influence on the overall structure crashworthiness when the geometrical and material parameters of different components changing.According to the crashworthiness changes caused by the different parameters, the specific energy absorption is taken as the optimization objective, and the elastic modulus, yield stress and geometrical parameters of each component are taken as the optimization variables respectively. The response surface optimization method combined with the appropriate experimental design methods is used for the double hull structure crashworthiness optimized design. The optimization schemes are put forward.