| Warheads' armor piercing and delayed explosion in cabins are main attacking ways.Warships which serve as important weapon platforms are damaged or even destroyed by explosive loads at sea.Hence,in order to protect important cabins and extend life of warships,it's meaningful to study the ways of reinforcing cabin structures under blast loads.The key point of this study is to analysis the response of cabin plates under inner blast loads.The response of cabin plates under inner blast loads include production and propagation of air blast loads and its key parameters.In addition,deflection,energy absorbing and damage modes of the cabin plates are also one part of the research.Acceleration and displacements research of cabin plates containing vents are also studied below.FEM program ANSYS/LS-DYNA is used to do numerical simulation,and simulation results are used to make comparison with experimental and theoretical methods.Details of research contents and conclusions can be seen as follows.(1)Propagation of air blast wave and experienced equations of important parameters are studied.With the using of ALE algorithm and its basic controlled equations in ANSYS/LS-DYNA,explosion in air is conducted and results can be used to make comparison with test results and experienced equations.Additionally,numerical simulation method are used to do the research on peak over-pressure of air influenced by non-reflect boundary.From the research above,some conclusions can be made.Blast wave is one kind of special air wave with rarefaction wave.Henrych experienced formulas can calculate peak overpressure and Sadovskyi experienced formulas can calculate specific impulse.Ranges of non-reflect boundary will increase with increasing of air regions.Ratio of modeling size and testing size will get larger with great peak over-pressure and when modeling size is getting some extents,the non-reflect boundary will be impaired.(2)Energy method is used to calculate plates' displacements under air blast load.As the use of numerical simulation method,response of different forms of stiffened plates are simulated and effects of stiffeners to plate-air's coupled surface are concerned mostly.According to the analysis above,stiffeners effect peak overpressure and displacements of testing points.The stiffening ways of facing to blast loads get lower overpressure compared with backing to blast loads.What's more,when testing points are closed to explosive center,stiffeners have no effect to overpressure in testing points,and they are unable to influence blast wave reflection regions.(3)Propagation of blast wave in cabin is studied and normal incidence,oblique incidence and convergence of blast wave are cared mostly.The modes of cabin structures which are damaged and destroyed ways by blast loads are discussed.Numerical simulation methods are used to simulate response of cabin structure under inner blast loads and effects of venting holes' size,locations and numbers on the response.According to results above,stiffened plates' stress concentration are mainly in boundaries and stiffeners.The size of venting holes is negative correlation with cabin structure response.As with the same size of venting holes,smaller number of venting holes can get better results.For a certain mass of explosive and a definite relative distance between explosive and holes,there will be a critical size of vents.When area is smaller than this size,venting holes' effects are not obvious;when area is bigger than this size,venting holes can reduces cabin structure response conspicuously.What's more,the critical size is positive correlation with relative distance between explosive and holes.For a definite mass of explosive,smaller number of venting holes are beneficial to reduce structure response with shorter relative distance between explosive and holes.With longer relative distance,number of venting holes is almost useless to structure response. |
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