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United States Navy ships (including surface ships and submarines) must be designed for surviv -ability following engagement by threat weapon attack. While it would be impossible to create ships that are impervious to attack, ships are designed to achieve a level of survivability that provides post-attack mission capability for some engagements, and graceful degradation for more severe attacks. In addition, ships are required by law to demonstrate their response survivabil -ity due to threat attack by performing a live re test and evaluation program. e attack on the USS Cole in 2000 served as an important example of the need for survivabil -ity requirements. To achieve this level of survivability, ship structure, as well as vital ship equipment/systems, must be designed and validated for the required level of ?hard -ness? to meet these requirements. While modeling and simulation (M&S) has been a key element of the design process for many years, validating ship hardness tradition -ally has been accomplished primarily by physical testing. e use of M&S for survivability design of navy ships started in the 1960s with the development of the dynamic design analysis method, used for equipment and foun -dation design, to ensure shock hardness. As computer technology evolved along with the development of more robust and comprehensive M&S software (primarily nite element applications), the use of M&S expanded to more detailed and sophisticated equipment modeling. It also grew to include transient analysis of structural and equip -ment response using empirical loading, as well as post-hit mission capability assessment using fault tree-based logic models for ship system operability. These M&S approaches complimented the navy?s rigorous testing programs, which include vital equip -ment shock qualication testing, full-scale shock trials (FSST), total ship survivability trials (TSST), and surro -gate ship testing (engagement of decommissioned ships with threat weapon attacks). Most of the M&S work to date has been performed using commercial nite element soft -ware (such as NASTRAN, ABAQUS, and ANSYS). While these tools are robust and reliable, they don?t provide the features necessary to realistically model the response of full-ship representations (including ship systems) to threat engagement. Additionally, current commercial tools don?t eciently use the massively parallel architecture of today?s high-performance computers (HPC). Developing realistic modeling Starting in the 1990s, the navy (in cooperation with aca -demia, industry, and the DOE national laboratories) engaged in research to develop M&S software that could BY E. THOMAS MOYER Operability, Post-Hit Assessing ship survivability using modeling and simulation en-USJuly 2012 en-US en-USwww.sname.org/sname/mt A full-scale shock trial against the Winston S. Churchill.