Assessment of LS-DYNA and Underwater Shock Analysis (USA) Tools for Modeling Far-Field Underwater Explosion Effects on Ships

This thesis investigates the use of the numerical modeling tools LS-DYNA and USA in modeling general far-field underwater explosions (UNDEX) by modeling a three-dimensional box barge that is subjected to a far-field underwater explosion. Past UNDEX models using these tools have not been validated by experiment and most are limited to very specific problems because of the simplifying assumptions they make. USA is a boundary element code that requires only the structural model of the box barge. LS-DYNA is a dynamic finite element code and requires both the structural model and the surrounding fluid model, which is modeled with acoustic pressure elements. Analysis of the box barge problem results finds that the program USA is a valid tool for modeling the initial shock response of surface ships when cavitation effects are not considered. LS-DYNA models are found to be very dependent on the accuracy of the fluid mesh. The accuracy of the fluid mesh is determined by the ability of the mesh to adequately capture the peak pressure and discontinuity of the shock wave. The peak pressure captured by the model also determines the accuracy of the cavitation region captured in the fluid model. Assumptions made in the formulation of the fluid model causes potential inaccurate fluid-structure interaction and boundary condition problems cause further inaccuracies in the box barge model. These findings provide a base of knowledge for the current capabilities of UNDEX modeling in USA and LS-DYNA from which they can be improved in future work.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Aerospace and Ocean Engineering

Department dc:contributor.department

Aerospace and Ocean Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2006

Author dc:creator

• Klenow, Bradley A.

Chair dc:contributor.committeechair

• Brown, Alan J.

Committee members dc:contributor.committeemember

• Hughes, Owen F.
• Kapania, Rakesh K.

• USA
• shock capture
• non-reflecting boundaries
• LS-DYNA
• Underwater explosion

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-05242006-113217

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/42786