Research On Frequency Domain And Time Domain Characteristics Of Shock Environment Of Ships

Ships will inevitably been attacked by all kinds of weapons during their lifetime. The vitality of ships and the safety of the crew are determined by the shock resistance. There are three aspects to study involves shock resistance. First, how to calculate shock environment. Second, how to improve shock resistance of the equipments. Third, how to surge guard better. The first aspect must be solved first, for we can not ensure the validity of research on shock resistance of the equipments unless we know exactly the shock environment. Therefore, the research on shock environment is meaningful.In this paper, the frequency domain and time domain characteristics of shock environment have been researched based on two typical finite element models of ships. The probability distribution of shock environment, the revised time domain simulation method and the prediction method of shock environment have been obtained in order to be used in shock resistance design.Based on the results of numerical calculation, numerous data of shock environment have been accessed using the PSO neural networks, which applied Monte-Carlo method for random sampling. On this basis, the relationships between the parameters of attacks and the equipments location and shock environment have been discussed through canonical correlation analysis. Then, the principal component analysis and factor analysis have been done for ship zoning using dynamic clustering method. Lastly, the parameters of the probability distribution of all the region have been gained, which can help to define the shock environment under the conditions of random attacks.The shock resistance of main shipborne equipments can largely determine the vitality of ships. In this paper, the time domain simulation method of BV043/85, which has usually been used, has been discussed. After the introduction of empirical mode decomposition method, which is suitable for the analysis of strongly non-linear and non-stationary signals, the interaction of shipborne equipments and shock environment has been researched. Based on this, the time domain simulation method of BV043/85 has been validated, and the amendments have been proposed to provide reference for anti-shock calculations.There are many factors which affect the shock environment, so it is very complex to calculate it. It is significant to estimate the shock environment in the absence of experimental data. In this paper, the BP neural network and improved orthogonal experimental design method have been used to predict the impact of the environment. Then, after summing up the law of numerous data of shock environment, the forecasting formula has been obtained using regression analysis. Its prediction effect has been verified in order to be applied to forecast the shock environment in preliminary engineering.