Research On Modeling Methods For Damage Assessment Of Ships Under Explosive Attack

With the wide application of explosive weapons in modern warfare,the navy,with surface ships as its main fighting force,is inevitably threatened by anti-ship weapons.With the impact of explosives,the damage effect assessment is of great significance to evaluating the condition of system damage,vitality,floating navigation,performance,remaining operational capability,and maintaining the overall fleet combat effectiveness.It also react on anti-ship weapons and related protection technology research and optimization.However,the cost of parameter extraction by real ship test is too high and unrepeatable,so the establishment of mathematical and physical models and their simulation have become a better method to study the damage effect of ships.In this paper,the modeling method of ship damage assessment under explosive attack is studied and analyzed.Aiming at the evaluation process of damage status,this paper uses the longitudinal hierarchical structure,since it involves multi-module,multi-system and multi-level analysis.The following research methods are adopted in this paper: firstly,the physical model and mathematical model of explosive are described in basic aspects.In local aspects,due to the characteristics of the explosives themselves,relevant numerical simulation and model analysis of the detonation process are carried out.Then,the physical damage concrete model of ship structure such as deck structure and pipeline system which is caused by the implosion fragmentation is simulated and solved.According to the damage condition of the physical layer,the probability algorithm of damage probability of the whole ship system is analyzed step by step by using the methods of probability theory and mathematical statistics.Based on the large data throughput of the damage evaluation system,the architecture and optimization methods in software development are proposed.In this paper,according to the time axis and the order from bottom to top,several important modules of ship damage evaluation modeling and analysis are studied in terms of model establishment and method,and the analysis process of relevant typical working conditions is also carried out.At the beginning,we describe the mathematical and physical models of explosives.This chapter describes the modeling process mainly carried out by the finite element method,including the theoretical basis of explosion impact phenomenon and fragment penetration phenomenon,Lagrange and Euler dynamic equations,and relevant constitutive models.Then,the relevant simulation of the internal detonation of the explosive is carried out,and the specific model is built and the results are extracted according to the typical working conditions.Then the charge comparison of three different high explosives was conducted to evaluate the damage effectiveness of each.The shock wave produced by the detonation of high-energy explosives will have a great impact on the ship structure.In this chapter,the mathematical model of shock wave is established and the smooth particle method is introduced to analyze its advantages over the traditional finite element method.The simulation analysis of the initiation process is completed by using this method,and the relevant characteristics of shock wave damage are obtained.And then,fragment produced by explosion is one of the most important elements which cause physical damage.This chapter is related to mathematical modeling method of the penetration process,including the Lagrange method and penalty function method,the determining process of penetrating the structure,etc..Then,typical impact process example model of fragment for cabin structure and piping structure are conducted,according to the different initial conditions for the penetration process parameters are analyzed.Finally,the overall damage degree of a ship is closely related to the location of the gunshot and shipboard equipment.In this chapter,based on the first-level physical warfare damage model above,Bayesian probability network is introduced to abstract the ship cabin and the system attached to it into the nodes of the probability graph model.Finally,the probability assessment algorithm of damage probability for the whole ship system is derived.On the basis of its large throughput,this paper designs the parallel and distributed architecture in the development process of the practical simulation program,the setting method of the distributed parallel computing cluster,the concrete application of entity-connection model in the program architecture and the database optimization method.