Modelling of Close-Proximity Underwater Explosion Loads and Structural Response – Phase 1

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Authors
  1. Dunbar, T.E.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN);MARTEC Ltd, Halifax NS (CAN)
Abstract
To assess the ability of existing simulation tools to capture the physics of close proximity underwater explosion (UNDEX) experiments, three simulations are carried out: one using a rigid plate target and two using deforming plate targets. For the first simulation only the fluid domain is modelled since the structure is assumed to be perfectly reflecting. The charge is a RP-83 detonator at a standoff distance of 0.8Rb above the center of the circular rigid plate, where Rb is the maximum free-field bubble radius. Results indicate that the proximity of the explosive to the plate increases the bubble period by approximately 17% over the free-field case. Both the shock and the collapse of the gas bubble result in strong impulsive loads on the target plate. For the other two cases, the simulations involve coupling of the structural response and fluid loading. A previously-developed approach is used where the fluid solver (Chinook) and the structural solver (LS-DYNA) communicate dynamically for simulations involving responding targets. For these simulations the charge is 20g of C4 at standoff distances of 0.25Rb and 0.85Rb above the center of a square steel plate of thickness 1.21 mm. Deformation and failure behaviour are calculated with and without strain-rate effects and for two different failure strains. Extensive plastic deformation of the target plate occurs in all cases. It is also shown that strain-rate sensitivity of the material

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Keywords
LS-DYNA;Underwater explosions (UNDEX);Simulations
Report Number
DRDC-ATLANTIC-CR-2008-272;MARTEC-TR-09-14 — Contractor Report
Date of publication
01 Sep 2009
Number of Pages
84
DSTKIM No
CA033716
CANDIS No
533095
Format(s):
Electronic Document(PDF)

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