Study On Dynamic Response Characteristics Of Hull Structures Subjected To Combination Of Underwater Explosion And Wave Load

In the actual naval battle scenarios,the ships would experience the combined load of the underwater explosion impact and the wave load.The structural response superposition and amplification effects caused by the combination of different loads would cause the sudden dynamic collapse of the hull girder,which seriously threatens the vitality of the warships.In this paper,theoretical analysis,numerical simulation and experimental test were carried out.On the one hand,the dynamic response process of the whole hull girder under the combination of underwater explosion and wave load was analyzed in detailed.On the other hand,the influence of in-plane initial compressive pressure caused by the wave load on the impact load induced dynamic buckling bearing capacity of the typical loacal deck grillage,and the dynamic response characteristics of hull girder subjected to the combined action of underwater explosion and wave load were further investigated.The main research work of this paper is as follows:（1）A simplified theoretical model of the hull girder was established,and the differential equations of motion of the hull girder under the action of simplified wave load and impact load of underwater explosion bubbles were derived,respectively.The influence of wave periods on the motion response was discussed,the conditions of different ship lengths and explosion distances were compared and analyzed.The differential equations of motion of hull girder under the combined action of underwater explosion and simplified wave load were further established and solved,from which the dynamic response characteristics of hull girder subjected to combined load were explained and discussed theoretically.（2）The test results of a model strucutre subjected to underwater explosion in the literature were analyzed.In addition,numerical simulations of experimental tests were performed by employing the acoustic-solid coupling method in ABAQUS.The numerical results were compared with the test data to verify the reliability of the numerical calculation method in solving the dynamic response of the hull girder under the underwater explosion load.Furthermore,a numerical method for the predicting the dyamcic response of structure under combined action of underwater explosion and wave load based on ABAQUS multi-step analysis was proposed,by incorporating the wave load calculation and analysis program.The influence of wave with different intense and initial strcuture states（deflection）on the response of the combined loaded structure was discussed.（3）A quasi-static ultimate bearing capacity test and numerical calculation of a typical deck grillage under in-plane compsreeive load were carried out.In addition,the analysis of the dynamic buckling of deck grillage under in-plane impact loads was further analyzed.The differences and relations between quasi-static ultimate strength and dynamic buckling were compared and analyzed.The underlying mechanism of dynamic buckling collapse of the structure was discussed in depth from the aspects of load amplitude,frequency of impact load and energy conversion.Finally,the wave load was equivalent to the initial quasi-static in-plane compression load of the deck grillage,and the dynamic response of the deck frame under initial compression was further investigated.