UNCLASSIFED: DISTRIBUTION A. APPROVED FOR PUBLIC RELEASE UNCLASSIFED: DISTRIBUTION A. APPROVED FOR PUBLIC RELEASE A Conformal, Fully-Conservative Approach for Predicting Blast Effects on Ground Vehicles

A new blast code, Loci/BLAST, has been coupled with the commercial structural dynamics package LS-DYNA to provide a fully-coupled simulation strategy for predicting the effects of blast on a ground vehicle. Loci/BLAST is a fully-conservative, computational fluid dynamics code with the capability to model soil and blast using a multispecies formulation with advanced equations of state. The two-way coupling between Loci/BLAST and LS-DYNA provides a robust mechanism for predicting the blast-induced deformation of structural elements with no topology changes. The efficacy of the resulting software is demonstrated by comparisons of predicted deformations for a constrained plate with experimental data. Results are also presented for a notional hull subjected to the effects of detonation of a buried IED. 1.0 INTRODUCTION Predicting the effects of a blast on a vehicle and its occupants due to the detonation of an improvised explosive device (IED) is a challenging task. In addition to the effects of the blast, the effects of soil, which could have a high water content, must also be included. An attractive strategy, which is much less costly than experimental approaches, is to employ numerical simulations to predict these complex interactions. The fidelity of the numerical simulations can vary from empirical models to hydrocode simulations to decoupled Computational Fluid Dynamics (CFD) and Computational Structural Dynamics (CSD) simulations to fully-coupled fluidstructure interaction (FSI) simulations. There are two widely used, candidate methodologies for blast simulations: 1) Lagrangian methods or 2) Eulerian methods. Lagrangian methods simulate material deformations directly by coupling the deformation of the material with movement of the discrete mesh. These methods are usually based on a finite-element formulation and have proven to be both robust and efficient. For highly plastic or fluid flow problems, they are subject to mesh tangling that can lead to issues with both accuracy and robustness. In the case of soil in close proximity to an explosive event, the soil undergoes severe deformations that can present challenges for a Lagrangian method. In addition, material and energy leakage are problems associated with Lagrangian simulation methodologies. Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE 09 FEB 2014 2. REPORT TYPE Journal Article 3. DATES COVERED 13-03-2013 to 20-01-2014 4. TITLE AND SUBTITLE A Conformal, Fully-Conservative Approach for Predicting Blast Effects on Ground Vehicles 5a. CONTRACT NUMBER W56HZV-08-C-0236