Fractal Characteristic Of Warship Impulsive Environment

The impulsive environmental is an important indicator of the vitality of warship, and it also reflects the anti-shock capability of warship. To accurately calculate and analyze the impulsive environment of warship, which is under the attack of underwater explosion, is the precondition to evaluate the warship's vitality. However, the structure response of the warship under the attack of typical shock load is very complex. The distribution of the shock response spectrum on the warship structure seems to have no rule. In practical engineering applications, the impact of spectrum can only describe the impulsive environment of the specific point of ship structure. It can't make the description from the view of the region or whole ship. To cope with this problem, based on the research of shock response spectrum theory, this article uses the fractal theory to do the research and analysis on the distribution rule of the shock response of the warship which is impacted by the shock load of underwater explosion. The research work is summarized as follows:Firstly, from the perspective of impulsive load and warship shock response, the basic of the impulsive environment of the warship under the attack by underwater explosion is researched. Through the view of impulsive load, the basic phenomena of underwater explosion and impulsive factor are studied and summarized. The character and normal description methods, through the view of shock response of warship, are discussed. At last, the method to make the impact spectrum is offered.Secondly, the numeric characteristic of impulsive environment of warship, as the base of the follow-up deep research, is studied. It is mainly divided into two parts, the numerical simulation of underwater explosion and the character of the distribution of shock response spectrum. Numerical simulation of underwater explosion mainly focuses on the practice process and the problems which need for attention. And the method of setting shock condition is introduced. The character of the distribution of the warship's shock response is studied, by the use of the shock spectrum, in the last part of the chapter. Thirdly, based on the numeric analysis, the feasibility of using the fractal theory to research the warship impulsive environment is proved. The essential introduction of fractal theory is put in the first instance. And the sand-box method to calculate the fractal dimension is imported. To ultimately prove the feasibility, the research work is processed respectively from the view of three factors (impulsive factor, grid-scale and the warship's own structure) which can affect the distribution of the warship's shock response. What's more, the result that fractal dimension can reflect the acuteness grade of the warship's shock response is proved ultimately.Finally, based on multi-fractal theory, the method of evaluating the warship impulsive environment is imported. The essential theory of multi-fractal method and the calculation of multi-fractal spectrum are discussed. Then the multi-fractal spectrum of the distribution of the warship shock response is got by the use of statistical method. And the conclusion that the distribution accords the multi-fractal character is proved. It's also proved that the parameters of multi-fractal spectrum are very sensitive to warship's transmutation. The formulas that can predict the structure damage information of warship is got, based on the theory of multi-fractal theory.