Research On Damage Assessment Method Of Mulit-Cabin Structure Under Internal Explosive Load

With the rapid development of anti-ship weapons,their damage and hit ratio have been improved greatly,and the threat to the safety of ship has attracted more and more attention.However,the semi-piercing anti-ship weapon can effectively act on the ship structure by blasting inside the ship,which puts forward higher requirements for the anti-blast and anti-impact performance of the ship structure.Especially the anti-ship missile,its damage to the hull is very serious.Scope of damage includes the multi-layer structure of the hull,even the whole cabin.Therefore,it is practically significant to study the assessment method of damage effect of ship structure under explosive load.Under internal blast,the damage law of multi-cabin structure and the distribution law of implosion load in the cabin were studied in this paper.And then the assessment method of structural damage effect was put.In this paper,the damage effect of typical multi-cabin structures was studied when naked spherical TNT explodes in the structural center,and the main research contents and conclusions are as follows:Firstly,basing on the typical single-cabin experiment of internal blast,the reliability of the numerical calculation method was studied,by the multi-material fluid-solid coupling algorithm in the AUTODYN that is a dynamic nonlinear explicit finite element calculation software.And the paper discussed the influence of the mesh size of different discrete finite element models about the calculation results.The method of reasonable selection of grid size was given for calculating the cabin internal blast in AUTODYN with the multi-material fluid-solid coupling algorithm.The multi-cabin structure was divided into:explosion cabin,coplanar cabin,common boundary cabin and common point cabin.Based on a large number of numerical simulation results,the structural damage rules of multi-cabin structure under internal blast of different masses of TNT were discussed.The bulkheads were classified according to the damage rules,and the damage grade was proposed.The influence law of damage effect of typical multi-cabin structure under internal blast with different TNT masses was discussed,and it was found that the ratio of deflection to thickness(?/H)has clear linear relationship with the ratio of the quality to the volume of the cabin(m/V),and so is the ratio of length to thickness of tearing(l/H).Based on the failure criteria of bulkhead and the damage rule of multi-cabin structure under internal explosive load,the dimensionless number B_c was obtained through dimensional analysis and derivation,and the number can reflect the characteristics of internal explosive load,material properties and structure,and so on.Based on the dimensionless number B_c,the prediction curve and corresponding formula of damage grade of typical multi-cabin structure under internal explosive load were given.Furthermore,a rapid prediction assessment method was proposed.The damage effect of typical multi-cabin structures under internal explosive load is simulated with three structural sizes.Through the analysis of the load distribution law of the bulkhead and the influence characteristics of the structure sizes,the following characteristics were found:for typical cabin structures,most areas of the smallest bulkhead subjected to approximately uniformly distributed load in the explosion cabin;the center of longest boundary subjected the highest pressure load.In the coplanar cabin,the peak pressure at the boundary of bulkhead is lower than that at the surface,and the pressure peak at the corner is lower than that at the center of boundary.The conclusion of this paper can provide valuable reference for a large structure based on the typical multi-cabin structure,the paper can provide a basis for damage assessment technology of the structure under internal explosive load.