Research On The Coupling Damage Of Surface Warship Structures To Underwater Explosions

The research on the damage of the ship structure under underwater explosion is an important part of the ship’s survivability design.Many modern warship damage cases and liveing fire test practices show that explosion distance of underwater weapons is the most critical attack parameter to warship’s damage.The underwater far field explosion usually only produces the impact safety of the ship equipment and the total strength and local strength of the structure,while underwater contact explosion often causes local breach and waterflooding.The development of modern underwater weapons is very fast and the attack distance and azimuth can be accurately controlled.In the near field underwater explosion range,both shock wave and bubble loads can damage warship structure and cause total damage and local damage.At the same time,the strong interaction and coupling between total damage and local damage can result in the aggravation of damage.However,the damage coupling involves such as fluid-structure interaction,damage modes interaction,structures damage failure,etc.strong nonliner problems under strong underwater explosive shock.There is still a lack of deeply theoretical and experimental research and scientific prediction and analysis methods in this field which seriously constraints the efficient design and evaluation of the damage power of weapons in water and the survivability enhanced design and assessment of ship structure.The calculation method of local damage and total damage of underwater explosion of surface ship structure established in this paper which is based on theoretical,experimental and numerical methods.Based on that,the interaction between two types of damage is analyzed,and the local and global coupling damage characteristics of surface ship structures caused by underwater explosion is also presented.Firstly,the existing research results of underwater explosion load are reviewed and load calculation method or semi empirical formula suitable for the study of local damage of ship structure is selected.Based on the DAA2 method and ABAQUS FEM software,fluid-structure interaction method for underwater near field explosion is proposed.Theoretical and experimental research on bubble dynamics and jet load characteristics of underwater explosion is also carried out,the empirical formula and measured data of water jet load are obtained.All of them are used as an input load calculation tool for the study of hull structural damage.Secondly,the plastic deformation calculation method and the breakage criterion of rectangular plate,plate frame and cabin structure have been formed in the theoretical and experimental study of the local damage of the hull structure caused by shock wave.It also gives the local damage characteristics of typical ship structure subjected to underwater explosion.Then,explosion experiment on cabin model is carried out for research,which finally shows that the method in this paper can be used as an effective means to calculate,design and evaluate the local damage of the ship structure.Moreover,comprehensive and meticulous research on the overall response of the whip and damage of the hull girder under UNDEX are carried out.The correlation coefficient of ship hull strength and the conversion law of model test are verified by different scale shrinkage model tests.A damping model which considers the hull structure,internal and external fluid factors is proposed.After the hull girder model test,it can improve the calculation precision of the hull girder method of high amplitude whipping response by thirty percent.The overall safety radius and damage radius of the surface ship are proposed,and the overall damage characteristics of the typical surface ship structure are analyzed.This method can be used as an effective means to calculate,design and evaluate the overall damage of the ship structure.Finally,based on the above work,the interaction between local and overall damage of underwater warship structure is discussed and analyzed.A coupling damage factor is proposed,and the local and overall coupling damage characteristics of surface ship structure underwater explosion are given.This method can be used as an effective means to calculate,design and evaluate the damage of surface ship structure under underwater explosion.