Research On Ship Stiffened Plates Under The Synergistic Effects Of Fragments And Shock Wave

Ship stiffened plates is a component unit of surface warship.In order to assess the vitality of surface warship under the attack of anti-ship missile or artillery,the dynamic damage characteristics of ship stiffened plates under the explosive loadings of anti-ship missile or artillery must be confirmed first.High-speed fragments and shock wave were produced with the explosive of anti-ship missile or artillery.Damage characteristics of ship stiffened plates under the synergistic effects of fragments and shock wave were investigated mainly by experimental and numerical methods in this paper.Mainly researches and results were accomplished as below.The explosive loadings characteristics of warhead were revealed.The expansion and rupture of the nonstandard cylindrical warhead case was simulated based on SPH method,and the speed distribution law of the nonstandard cylindrical warhead fragments was investigated.The nonstandard cylindrical warhead explosive experiment was carried out,and three typical modes of warhead fragments were proposed.After that,the accuracy of modified Fisher formula calculating equivalent bare charge was verified.Damage experiments of ship stiffened plates with two kinds of nonstandard cylindrical warheads were implemented,and the main damage modes(mode I-petals bending failure and mode II-tensile rupture)of ship stiffened plates were proposed.The effect law of synergistic damage modes varying with different scaled distances was investigated,and the critical scaled distance between different damage modes aimed at experimental model was given.Besides,the main formation reason of large petals hole was analyzed,and the damage results under the coupling loadings between naked and stiffened plates were compared.The coupling damage process of ship stiffened plates under the synergistic effects of fragments and shock wave was simulated using SPH-FEM method,and the generation and action mechanism of synergistic damage effects was revealed.Based on the numerical results,mode II can be subdivided into two damage modes,mode IIa-the boundary of plates appears plastic deformation,center appears tensile rupture,mode IIb-the boundary and center of plates appears tensile rupture.Dimensionless impulse~*i was imported into synergistic damage issue and the critical value of~*i between different synergistic damage modes was given.A decoupling method which was used in predicting the response of target plates under the synergistic effects of fragments and shock wave was proposed.Deformation experiment of perforated plates under the impulsive loading of blast wave was implemented.Then the numerical method was verified.The deformation process of three types perforated plates under the impulsive loading of blast wave was simulated,and the effect law of central deflection of plates varying with different shapes or areas of perforated hole was obtained.Besides,based on the deflection formula of non-hole thin plate,a deflection gain coefficient was proposed,and a central deflection formula of three types perforated plates was established by fitting numerical results.