| With the use of precision-guided weapons such as torpedoes in various navies,ship structural strength is under great threat.Underwater non-contact explosion produces a large impact dynamic bending moment,which may seriously threaten the longitudinal strength of ship.The research on the longitudinal strength of ship structure under underwater explosion is paid more and more attention.In this paper,the sound-solid coupling method is used to study the total strength of ship structure under the action of underwater explosion load,which can provide guidance for the design of ship anti-explosion structure.At present,due to carry out the testing result anti explosion shock test the limits of use of the similarity theory to carry out the related is more realistic than the model test method,this paper,by using the similarity theory of underwater explosion,for condensation method.finally than similar problems on the model test of the research,to the development of ship model experiment of underwater explosion to provide certain reference value.The main research contents of this paper are as follows :(1)Firstly,the numerical calculation method of acoustic structure coupling is introduced.Based on the data of hull beam model test,the effectiveness of numerical method in calculating the response of underwater explosion structure is verified.(2)The finite element modeling of a ship is carried out,and the accuracy of the finite element model is verified from the perspective of the modal characteristics of the hull structure.On this basis,the overall response characteristics of ship profile,such as average stress,whip motion amplitude and equivalent plastic strain,are calculated by using the acoustic-solid coupling numerical method under various working conditions,and the influence of temporal and spatial distribution of explosion point on the overall response of ship is summarized.At the same time,considering the bubble pulsation load,the impact environment distribution of the ship is studied,which provides reference for the anti-impact design of the ship.(3)Combined with the existing theoretical model of whip motion of hull beam under underwater explosion,a simplified finite element model of hull beam is proposed.The results show that the calculation error of the simplified finite element model is less than 20% when the impact factor is small or the plastic strain of the structure is very small,which meets the requirement of engineering accuracy.The total longitudinal strength of underwater non-contact explosion of a ship is checked with the impact dynamic bending moment.(4)The similarity of dynamic response of warship prototype and scale model test under underwater explosion is studied.The similarity criterion of response of elastic-plastic structure under shock wave load is deduced by using similarity theory dimensional analysis method,and the correctness of similarity criterion is proved by the stiffened plate model based on complete geometric similarity.At the same time,the similarity criterion of hull beam under bubble pulsation load is derived,and the correctness of similarity criterion is proved by hull beam model based on complete geometric similarity.(5)The limitation of underwater explosion test for the complete geometric scale model of the whole ship,that is,when all components are scaled according to the scale size,some plate thickness and profile size will be too small.In order to solve the above practical problems,a certain degree of distortion of plate thickness and profile is carried out based on the complete geometric similarity model,and the conversion relationship between the response of distortion model and the response of reference model is obtained by using the finite element prediction coefficient method,so as to predict the dynamic response of prototype with distortion model.(6)According to the similarity rule of structural response under bubble pulsation load,when the complete geometric scale model and the prototype response are similar,the static water pressure at the explosion source should be equal.The complete geometric similarity model with the explosion source static water pressure equal to the prototype is defined as the reference model.Considering the distortion of the hydrostatic pressure,the finite element prediction coefficient method is used.The conversion relationship between the response of the hydrostatic distortion model and the response of the reference model is obtained and the dynamic response of the prototype can be predicted by the distortion model. |
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