Shock Resistance And Experimental Study Of The Coatings On Warship Subjected To Underwater Explosion

The fighting capacity and vitality of a warship depend on its underwater explosion shock resistance. In order to meet the developments of modern warship, strengthen the blast resistance technology, protect the hull, and improve the overall shock environment, a research on the shock resistance and experimental study of the coatings on the hull wet surface subjected to underwater explosion was carried out in this paper. The results explain the dynamic characteristics, shock resistance, and mechanism of different coatings subjected to underwater explosion, and give a resolution to new coating and further optimization, and lay a good theoretical foundation for practical application. Main researches completed are as follows:(1) Parametric analysis of coatings’compression behavior and mechanical performance:According to rubber test data, an appropriate hyperelastic constitutive model was selected to define the model parameters; The dynamic compressive behavior and characteristic of different periodic coatings, including hexachiral honeycomb, re-entrant honeycomb and circular honeycomb, were analyzed; The effects of compression speed, cellular topology, height, and relative density on compression performance were explored; The mechanisms of deformation, energy absorption, and buffering of the coatings of the same material and weight were studied to find the reasonable structure with the best crush performance.(2) The interaction mechanism of underwater blast shock loading and coatings:The wave transmission law through an air bounded system or a water bounded system subjected to shock pressure wave, under non-contact underwater explosion, fluid-structure interaction (FSI) effect, coating’s dynamic response, and the dissipation of shock wave energy were studied; The shock resistance between solid rubber and honeycomb coatings of the same weight was compared; The isolation and dissipation mechanisms of shock energy based on the impedance mismatch and deformation and energy absorption were explored from the protective effects of cell topology, height, relative density, and panel materials.(3) The optimization design of layered circular gradient coatings:On the background of fluid-structure interaction (FSI) effect and graded energy absorption of functionally graded materials, the intrinsic relationship between compression performance and shock protective effect of layered circular coatings was discussed under different underwater shock wave pressure amplitudes; By comparing the shock response spectrum of metal plates with these coatings under air and underwater explosions, the influence of the coatings on the transient responses can be revealed.(4) Performance on the deformation and energy absorption of the coating on submarine’s wet surface:In order to solve the existing contradiction between high hydrostatic pressure and shock resistance, a hexagonal honeycomb coating was improved that two steels were placed in the honeycomb, referring to the thought of " high static stiffness and low dynamic stiffness"; The characteristics on deformation and energy absorption of the coating subjected to high hydrostatic pressure and shock were studied; The influences of steel sheet thickness and eccentricity on compression performance and shock resistance were discussed.(5) Experimental research:Two kinds of live UNDEX tests were carried out, including the response characteristics of the air-backed structures and circular plates with various coatings; Actual effects of the coatings and simulation results were assessed through the comparison of free field pressure, wall pressure, acceleration, and strain. Combined with the image data about the cavitations near the coupling surface and the jet formation and collapse, the shock resistance mechanism of the coatings were studied, which is very helpful in understanding the process of shock wave and bubble acting on the flexible coatings.