Research On Damage Characteristic Of Ship Multi-layer Structure Subjected To Underwater Near-by Explosion

With the extensive use of precision-guided weapons, the probability that ships and otherwater structure are directly attacked has been increased. Compared to the far-field underwaterexplosion, researches concerning the underwater near-by explosion are not investigatedthoroughly and systematically due to many reasons. First, theoretical analysis aboutunderwater near-by explosion is limited to simple structures; it is not possible for the complexstructures to get the theoretical solution. In addition, the current underwater explosion testsare mainly far-field explosion oriented and trials about stiffened plates and scale model arenot a true reflection of the entire ship’s anti-explosion capabilities. Therefore, this paper isderived by numerical calculation and theoretical means to study damage characteristic aboutsingle layer plate, double bottom tanks, and the broadside defense cabin subjected tounderwater near-by explosion loading, the main research content includes the following threeaspects:Firstly, the validity of numerical algorithm was verified through shock wave empiricalformula and the contact explosion tests, the simplified model of clamped square plate andstiffened plate were established, the propagation property of underwater contact explosionshock wave, the deformation characteristic of structure and the pressure property of flow fieldwere achieved. The influence of ship bottom grillage’ relative stiffness to its failure mode wasinvestigated; the typical failure patterns of ship bottom grillage were summarized.Secondly, considering the influence of inner stiffened structure of double bottom tanks,the underwater shock wave’s transmission property of outside plate in double-shell structurewas analyzed based on plane wave theory. The loading characteristic of internal plate ofdouble bottom tanks during different loading condition subject to underwater near-byexplosion was researched, and the influence of explosive distance and loading condition toloading characteristic of internal plate was discussed.Finally, the finite element model of broadside defense cabin was established, thepropagation characteristic of shock wave in broadside defense cabin and the dynamicresponse of broadside defense cabin was theoretically and numerically calculated, failuremechanism of shipboard fluid cabin subject to high-speed shrapnel and the high-speed shrapnel decay process of absorption tank are simulated, the influence of space allocation ofeach cabin to the anti-explosion capabilities was investigated.