Effects of fracture models on structural damage and acceleration in naval ships due to underwater explosions

초록

This study examined the structural damage quantitively due to a near-field underwater explosion (UNDEX) using a more reasonable fracture model. Technical backgrounds of the Geers-Hunter UNDEX model and combined HC-LN fracture model based on Hosford-Coulomb (HC) and localized necking (LN) were reviewed. A finite element analysis (FEA) model for which the UNDEX experiment was performed was generated. Two fracture models were applied to the FEA model: constant strain and HC-LN fracture models. A user subroutine was developed to implement the HC-LN fracture model. The material constants for the aluminum alloy that was the model ship material were calculated using tensile tests and their FEAs. The HC-LN fracture model predicted a similar extent of damage to that in the experiment. The constant strain fracture model predicted an unrealistic fracture in the bottom shells that reduced the hull girder bending capacity and thus the increased acceleration history. A damage extent can be estimated accurately only by UNDEX FEAs with a more reasonable fracture model.

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