Shock and bubble collapse loading for close proximity underwater explosions with rigid and deformable targets

Shock and bubble collapse loading for close proximity underwater explosions with rigid and deformable targets

Riley, M.
Smith, M.
Alin, N.
van Aanhold, J.E.
Lee, J.
TNO Bouw en Ondergrond

2010

The study describes recent simulation results for underwater explosions in close-proximity to rigid and responding targets. Simulations are performed using Chinook, an Eulerian computational fluid dynamics (CFD) code, in standalone mode and coupled with the Lagrangian solver LS-DYNA. Predicted fluid pressures and target deformations are compared with measurements taken from two series of experiments. One series involved 40g and 200g C4 charges detonated at standoff distances of 0.6, 1, and 1.5 times the free-field bubble radius from a rigid surface. The other test series involved 1.1g charges detonated at various standoff distances from responding target plates of varying thickness and material. The two-dimensional and three-dimensional simulations of the rigid target tests primarily focused on the modelling of gas bubble collapse and water jetting behaviour. It was found that the two dimensional analyses produced bubble periods and impulse loading that compared well with experimental data. The results for the numerical simulations, especially the arrival times of the bubble collapse, were found to be very mesh dependent and refining the mesh did not always produce better results. In general, two dimensional modelling provides a good initial understanding of the physics for an acceptable computational effort. The three dimensional simulations were found to produce improved impulse predictions for the rigid targets compared to the two-dimensional simulations. For the responding target plate simulations, the shock loading, cavitation, cavitation closure, bubble collapse and water jetting, all contribute to the response of the target. The final displacements of the target plates were found to be acceptable compared to experiments; however, the displacements resulting from each of the loading mechanisms were found to vary significantly

Building Engineering & Civil Engineering
CMMC - Centre for Mechanical & Mar. Con.
TS - Technical Sciences
Mechanics

http://resolver.tudelft.nl/uuid:a8df7ded-394d-42c7-b564-5b9482acf63c

427693

80th Shock and Vibration Symposium, 1-16

conference paper