A Rapid Assessment Program On Warship Structures Damaged Subjected To Underwater Explosion

Modern torpedoes,mines and anti-ship missiles pose a great threat to the vitality and combat effectiveness of warships.The assessment of damage degree of large warships has become a hot issue in this field.In practical applications,it’s particularly important to quickly assess the residual strength of ships damaged by underwater explosions,which is an important basis and support for the survival of ships in wartime.Based on the damage process of underwater explosion to the ship,this paper will carry out three parts: the calculation of the underwater explosion load,the analysis of the longitudinal strength and calculation of residual strength of the ship subjected to underwater explosion.According to the corresponding theoretical model and empirical formula,combined with rules and regulations and simplified methods proposed,the ship structure damage assessment program subjected to underwater explosion was compiled,so that quickly evaluate damage state of the ship in the process of underwater explosion.Finally,the reliability of the assessment program in this paper is verified by finite element simulation of numerical model.It is verified that the program can assess the damage of ship structures subjected to underwater explosion,which has good application value and broad prospects in engineering.The underwater explosion load calculation program module mainly predicts the underwater explosion pressure of different explosive quantities,different source point positions,and different gauge point positions.The semi-empirical and semi-analytical formulas are used to describe the pressure at each stage of the underwater explosion.By compared with the experimental data and the analysis results of ABAQUS finite element program,it can verify the accuracy of the pressure results of the empirical formula.Finally,the calculation process of the formula is formed into a program for rapid prediction of underwater explosion load pressure.The program module of longitudinal strength assessment of ships subjected to underwater explosion is designed to evaluate the total underwater explosion strength of the ship.According to the explosion and environmental parameters,the calculation method of the load can be given when the ship is subjected to underwater explosion,and combined with the scale parameters of the ship target,the information of the hazard profile can be gotten.Finally,whether the ship has sufficiently total longitudinal strength can be checked according to the corresponding regulations.A rapid estimation method of the bubble bending moment in underwater explosion is proposed,and it is formed into a program to quickly check the total longitudinal strength of ships subjected to underwater explosion.The main function of the residual strength assessment program module is to realize the residual strength evaluation after ship damage caused by underwater explosion.Based on the research of ships damaged by underwater explosions,all the loads suffered by the ship and the dangerous profile information contained crevasses are recalculated.Taking the corresponding rules as reference,the ship’s residual strength after underwater explosion is given.The problem of component reduction of the dangerous section when the ship structure is broken after underwater explosion is discussed,and a method for calculating the dangerous section’s parameters of the based on the idea of component grouping is proposed,which forms the residual strength check procedure of the ship after underwater explosion.Through the finite element numerical simulation,the rapid estimation method of the bubble bending moment in the longitudinal strength evaluation program module and the method of calculating the section parameters by grouping reduction of components in the residual strength evaluation program module of the ship subjected to underwater explosion are verified.The simple hull girder model is used to carry out the numerical calculation of underwater explosion,and the residual ultimate strength of the damaged model is analyzed.Finally,the underwater explosion moment results from numerical calculation and bubble moment result from the rapid estimation method,the ultimate moment obtained from the simulation analysis of residual ultimate strength and the calculation results of the component group reduction method are compared respectively.The rationality and reliability of the two methods used in the program assessment module are verified,and the value range of the dynamic correction coefficient of the underwater explosion bubble bending moment is given.