Reliability Analysis Of Ship Dynamic Random Stiffened Plate Explosion Loading

In modern sea warfare, it usually takes torpedo, underwater mine etc as underwater weapons. Tremendous high temperature and high pressure energy could happen instantly when non-contact water explodes. All these energy spread outward immediately, with water compressed around shot point and shock wave, at the mean time with bubble. Bubble pulsation may cause the phenomenon of sagging and hogging of the ship, which may cause the ship break from the middle. Compared to ship broken with contacting explosion and cabin broken, non-contact explosion damage is more serious. The probability of noncontact explosion is far lower than that of noncontact explosion. Therefore, the research on the noncontact underwater explosion is more worthy of our attention.This paper is mainly to study the structural response and dynamic reliability of stiffened plate under the action of random blast loading. Based on the theory of explosion shock wave, comparative analysis of numerical simulation and empirical formula of underwater explosion shock wave,on the basis of the numerical simulation, the influence of grid size on the calculation results is studied. We choose the optimal grid size of numerical simulation to study the propagation process of underwater explosion. Research on the statistical law of explosion load,analysis of the dynamic response of stiffened plates under random blast loading. At last, the dynamic reliability of stiffened panels are discussed, the main research contents are as follows:(1)LS-DYNA is used to analyze the propagation characteristics of underwater explosion. Comparison of peak pressure and empirical formula,they are in good agreement.On this basis, the effect of mesh size on the peak pressure of shock wave is studied by the finite element model;(2)select the density of explosives, water density as random variables, Monte Carlo method combined with finite element method, get the probability density of the peak pressure of the shock wave at different time, and to test whether they obey normal distribution, the probability density function is fitted by the maximum entropy method,study on the statistics of explosive load at different time;(3) in order to study the reliability of stiffened plates under random blast loading,the vibration equation and the dynamic response of the thin plate structure under the action of explosion load are derived by analytical method. Vibration equation and structural response of a single degree of freedom model are derived. And the equivalent stiffness method is usedto solve the vibration equation of stiffened plate under blast loading. Taking the 100 kg charge as an example, the reliability of the thin plate and stiffened plate structure was studied by using the first order two moment way.(4) Numerical simulation and analysis of stiffened plate with LS-DYNA software in the far field underwater explosion, the dynamic response of stiffened plate under blast loading is obtained. And the analytical results are compared with the analytical results,the elastic modulus, tangent modulus, yield strength, Poisson's ratio and water density were selected as random variables. We use Monte Carlo method and maximum entropy method to get the probability distribution of the response, a preliminary study on the dynamic reliability of structure.