PREDICTION OF STRUCTURAL DAMAGES AND ARMAMENT ACCELERATIONS OF A SURFACE NAVAL SHIP DUE TO UNDERWATER EXPLOSIONS

초록

Underwater explosion (UNDEX) caused by torpedoes yields the largest subsurface load that can be applied to a naval surface ship. The purpose of this paper is to estimate the extent of structural damages and accelerations acting on major armament systems by UNDEX for a large naval surface ship. The hull of the naval surface ship was modeled using Abaqus, a commercial finite element analysis code. By applying the Geers and Hunter UNDEX model provided by Abaqus, the primary shock wave and the secondary bubble wave based on doubly asymptotic approximation were implemented. The DSSE-HC model (Hosford-Coulomb combined with a localized necking model) enhanced for strain-rate effect was applied to estimate the extent of structural damages caused by UNDEX. Since the DSSE-HC model is not supported by Abaqus, the material subroutine was independently developed. The range of structural damages predicted by the DSSE- HC model was compared with that predicted by the constant failure strain model, which is widely used for UNDEX problems, to identify a difference in the structural damage. As a result, it was confirmed that there is a large difference in resulting damage. That is, the constant failure strain model predicted overestimated the extent of damage depending on the assumed failure strains. In addition, the accelerations acting on the various armament systems also showed significant differences. To predict the structural damage and acceleration of the armament system due to a UNDEX in the future, it was found that it is necessary to apply a fracture model with an advanced mechanical background rather than a simple fracture model.

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