Analysis Of Underwater Explosion Resistance Of Gradient Corrugated Sandwich Structure

The lightweight sandwich structure characterized by greater specific rigidity and specific strength has excellent cushioning and energy absorption capabilities under the impact of underwater explosions.The protection ability of the warship under the underwater explosion can be effectively improved when the key part of the warship was fabricated by the lightweight sandwich structure.The underwater explosion resistance of the sandwich structure would be better when a gradient design scheme was adopted in the multi-layer core because the deformation coupling effect between the various layers of the sandwich structure is used to improve the structural energy absorption ability.In this paper,a multi-layer density gradient corrugated sandwich structure was designed,and the protective capability of the multilayer gradient corrugated sandwich structure under the underwater explosion impact was investigated by an underwater explosion experiment followed by the systematical numerical simulations.First,the steel specimens of multi-layer homogeneous corrugated sandwich structure and density gradient corrugated sandwich structure were prepared by the method of bending-vacuum brazing.The underwater explosion test was carried out by setting up an underwater explosion experimental tank.The impact wave was generated by the near-water surface explosion of 200 g of TNT explosive.The stress of the bars supporting the sandwich structure was tested by a dynamic testing device.The transmitted loads and the deformation modes of multi-layer homogeneous corrugated sandwich structure and multi-layer density gradient corrugated sandwich structure were,comparatively,analyzed under underwater explosion impact.Second,the dynamic finite element analyzing software LS-DYNA was used to simulate the underwater explosion experiment of the multi-layer corrugated sandwich structure.The transmitted load obtained in numerical simulation was compared with the experimental results.The energy absorption and the core deformation performance of the multilayer sandwich structure were systematically studied.The effect of the configuration on the underwater explosion resistance was discussed.The underwater explosion resistances of the double-corrugated sandwich structure and the single-corrugated sandwich structure were,comparatively,analyzed.The results show that the double-corrugated sandwich structure can reduce the transfer impulse and the transfer load of the back plate,which has better anti-explosion performance than the single-corrugated sandwich structure.Finally,LS-DYNA software was used to numerically analyze the underwater explosion resistance of the clamped double-corrugated sandwich structure.The non-reflective boundary conditions were used to simulate the underwater explosion impact in infinite water field.The peak deflection of the back face-sheet,the supporting force at the edge of the structure and the energy absorption were taken as the evaluation indexes of the anti-explosive performance.The effect of the density gradient ratio of the gradient double corrugated sandwich structure,the thickness ratio of the front/back face-sheet and the stand-off distance on the underwater explosion resistance of the structure was discussed.The result analysis shows that the density increasing gradient configuration can effectively reduce the impulse transmission of the structure and improve the specific energy absorption of the structure,and its anti-explosion performance is better than that of homogeneous configuration,which has reference value for marine equipment protection.