Study On Anti-explosion Performance Of Ship Door With Arrow-shaped Negative Poisson’s Ratio Structure

In recent years,China attaches great importance to the research and development of ship protective structures,which has significantly improved the protective capabilities and levels of important cabin structures.However,as an outfitted cabin door,a conventional steel door or a watertight door is still used.Under the action of anti-ship weapon shock waves,its protection ability is much lower than that of the cabin structure,and it is prone to damage first.This causes shock waves,smoke,etc.to enter the cabin,threatening the safety of personnel and equipment in important cabins.At present,there are few domestic researches on the anti-explosion performance of cabin doors.At the same time,due to the limited weight of the cabin doors,the largescale reinforced concrete door structure used in underground engineering cannot be adopted.This dissertation proposes to apply the arrow-shaped negative Poisson’s ratio structure to the cabin door to improve the explosion resistance of the door.The main research contents and conclusions are as follows:(1)The relationship between the equivalent Poisson’s ratio,the equivalent elastic modulus,and the cell parameters of the arrow-shaped negative Poisson’s ratio structure was studied using a theoretical analysis method.Then the influence of geometric nonlinearity on the equivalent parameters is studied,and it is found that as the vertical strain increases,the Poisson’s ratio decreases first and then increases,which is because the displacement direction of the end points on both sides of the cell gradually changes from lower right to upper right,resulting in a process in which the lateral compression rate increases first and then decreases.Through the comparison of stress-strain curves,it is found that the arrow-shaped negative Poisson’s ratio structure has the characteristics of yield lag,stiffness strengthening and strength strengthening.In addition,a numerical calculation method was adopted to modify the equivalent Poisson’s ratio analytical formula by introducing a correction factor m.(2)The dynamic mechanical properties of the arrow-shaped negative Poisson’s ratio structure were studied using numerical calculation methods.Studies have shown that under impact loads,both sides of the arrow-shaped honeycomb structure shrink laterally toward the middle,which has a significant negative Poisson’s ratio effect.In quasi-static compression or medium strain rate compression,the negative Poisson’s ratio effect is obvious,resulting in the "platform stress" gradually increasing,so the dynamic response of the structure only shows two stages of elasticity and gradual compaction.During high strain rate compression,it manifests itself in three phases:elasticity,platform and compactness.When loading at ultra-high strain rate,it shows two stages of impact end elasticity and sudden climbing.With the increase of strain rate,the platform stress of arrow-shaped negative Poisson’s ratio structure increases nonlinearly,and the specific energy-strain curve shows a linear increase.And accelerated climbing,which has a very good energy absorption effect and strain rate strengthening effect.(3)The arrow-shaped negative Poisson’s ratio structure was applied to the door of the cabin,and the influence of honeycomb parameters(load,cell angle,cell layer)on the anti-explosion performance of the door was studied.The research shows that the increase of the peak load will gradually make the deformation mode of the structure tend to local deformation at the impact end.Increasing the duration of the load makes it easier to deform the structure to the compact stage,so that the energy absorption performance of the structure is brought into full play.Secondly,the anti-knock performance of the door body is similar to the cell angles a and b.The smaller the cell angle,the more negative the Poisson’s ratio effect,and the smaller the backplate deformation.The anti-knock performance optimization in this dissertation can reach56%.In addition,when the overall thickness is controlled,the energy absorption effect of the honeycomb layer will be gradually exerted only when the number of cell layers reaches three layers.With the increase of the number of cell layers,the absorption energy is transferred from the back plate to the honeycomb layer.When it reaches 6layers,the anti-knock performance tends to be flat.Finally,a simple multi-parameter optimization was performed on the arrow-shaped structure gate body according to the previous law,and a better structure was obtained,which also verified the rationality of the conclusion.(4)The control mass is consistent with the explosion load,and the finite element models of the optimized door structure,foam aluminum sandwich door and ordinary ship door optimized from the previous chapter are established.Through comparative analysis of simulation calculations,it is found that the compression energy absorption and anti-explosion mechanism of aluminum foam are different.The arrow-shaped negative Poisson’s ratio structure is carried by two methods of compression energy absorption and local strengthening of weak locations.In addition,the displacement of the back panel of the arrow-shaped honeycomb structure door is the smallest,which is23.8% lower than that of the ordinary cabin door structure,and the displacement of the back panel of the foam aluminum door body is the second,which is 17.4% lower than the ordinary door structure.It can be seen that the arrow-shaped negative Poisson’s ratio door has good anti-explosive performance under the same mass,and is suitable for ship protection.