Dr. Tom Moyer, NSWC/Carderock Full Ship Shock Test Modeling Dr. Tom Moyer, NSWC/Carderock 15 April, 2008 Highlight all text in each block and type in new info.

M&S For Ship UNDEX Response Modeling & Simulation (M&S) Is Used By The Navy To Predict Ship Structure & Systems Response To Underwater Explosion Threats Design & Qualification Of Ship Systems Pre-Test Prediction Of Full Ship Shock Trial Response M&S Being Evaluated For More Extensive Use For Design & Qualification Of Ship Systems Major Component In FSST Alternative(s)

Summary of Underwater Explosion Phenomena Bulk Cavitation Region Ocean Bottom Bottom Reflected Wave (Traveling partially through bottom material) (Traveling entirely through water) Water Surface Surface Reflected Wave Spray Dome Air Plume SZ Direct Shock Waves Burst Bubble at first Minimum First Bubble Pulse

DYnamic System Mechanics Advanced Simulation DYSMAS DYnamic System Mechanics Advanced Simulation A fully-coupled hydrocode for simulating underwater explosion phenomena and their effects on naval structures

DYSMAS DYnamic System Mechanics Advanced Simulation . GEMINI Euler solver Shock and Fluid Dynamics DYNA-N & PARADYN Lagrange solvers Structural Response DFBEM BEM solver Bubble & Fluid Dynamics Standard Coupler Interface Fully Coupled Fluid-Structure Interaction HYDROCODE FOR SIMULATION OF UNDERWATER EXPLOSION EFFECTS

DYSMAS V & V Approach Verification Procedure Documentation of the DYSMAS code and its capabilities Documentation of configuration management & model verification calculations Documentation of laboratory and small-scale validation calculations Comprehensive report applicable to UNDEX applications Validation Procedure (Phase I - General Validation) Acquire validation-quality UNDEX loading and hull response data for platform design and weapon lethality applications using surrogate ship Pre- and post-test comparisons of DYSMAS simulations vs test data Code validation against full-scale, realistic ship structure Validation Procedure (Phase II - Application-specific Validation) Design & acquire validation-quality UNDEX loading and response data for specific (local) platform structures Code validation against design-specific concepts

TYPICAL DATA ANALYSIS Full Record 1/e * Pmax Shock Wave Shock Wave (extended) 1st Bubble Pulse

EFSP

Lagrangian Model 16,165 Nodes 21,053 Elements

Results – Innerbottom, Vertical Velocity Below FWD STBD Mount 8976 FWD

Eulerian Simulation T: 5.0 msec T: 5.4 msec T: 5.9 msec T: 6.8 msec

Lagrangian Simulation T: 6.2 msec T: 10.0 msec T: 13.2 msec T: 50.0 msec

Innerbottom Vertical Acceleration DYSMAS vs EFSP Test FWD 60 lbs HBX, 20 ft Hrz Stdf

DYSMAS/SUMMARY DYSMAS Is Widely Used In Navy Community For UNDEX Simulations 2007 JASON Review Concluded Good Agreement With Liquid Response Good Agreement With Short-time Structural Response Structural Response [After Initial Impulse] Can Be Improved A validated M&S could evaluate/improve component-testing methodology

Beyond DYSMAS => CREATE DYNA_N/PARADYN Lack Many Of The FEM Features Needed For Improved UNDEX Simulations DYNA_N/PARADYN Employ Antiquated Software Constructs Maintenance Difficult/Time Consuming Adapting To Evolving Computer Hardware Challenging Gemini Is Sufficiently Validated & Employs Modern Software Engineering Constructs Standard Coupler Interface Limits Calculation Scaling On Parallel Platforms SOLUTION: Develop Gemini/Lagrange Solver With Parallel Coupling

CREATE Objectives For UNDEX Develop Robust Computational Capability To Predict Response Of Surface Ships & Submarines To UNDEX Loading System/Component Environments Structural Response & Damage Scenarios Stand-Off UNDEX Close-In UNDEX SURFEX Interface w/ Ship State Modeling ASAP/ARM FASST 16

CREATE USE CASE I Standoff UNDEX Response Objective: Quantify ship response to standoff UNDEX shot geometries Problem Characteristics: Linear-elastic hull structure (no appreciable damage) Point-to-point non-linear elements (e.g., shock mounts) Linear-elastic equipment & system response End-User Products Quantify equipment location shock environments Specifications for isolation systems (mounts & rafts) Develop more-representative equipment qualification environments for component-level testing

CREATE USE CASE I Standoff UNDEX Response Capabilities from CREATE program: Integrated modal analysis capability Integrated (implicit) static pre-calculation capability Hydrostatic pre-stress, static bending moment Optimized explicit code solution procedure for pure linear-elastic problems Bulk of design cases Improved modal characteristics of equipment & systems Enables smoother, more accurate incorporation of vendor sub-models Results Synthesis => Design Requirements, Performance Assessments, Design Modifications Fully Integrated With Ship Design Tools Includes Integration w/ ASAP/ARM Development of “REPLAY” strategies Meets All Requirements For FSST Replacement Calculations Doesn’t linear elastic focus make implicit mechanics critical?

CREATE USE CASE II Severe UNDEX Response Objective: Quantify equipment response and damage to more severe shot geometries Problem Characteristics: Non-linear hull structure response Point-to-point non-linear elements (including shock mount bottoming) Non-linear equipment and system response End-User Products Equipment and system damage and operability assessments Hull structural performance LFT&E Assessments (w/ limitations)

CREATE USE CASE II Severe UNDEX Response Capabilities from CREATE program: Includes list from Use Case I Multi-length scale modeling strategies All-up simulation capability Telescoping analysis strategies Applications using “REPLAY” functions Fragility assessment capability Enables design margins to be assessed Enhanced Mission Effectiveness Assessment Enhanced Results Synthesis Methodology Quantification Of Margin & Uncertainty

CREATE USE CASE III LFT&E Assessments Objective: Quantify ship structural damage due to LFT&E UNDEX scenarios Problem Characteristics: Extremely Non-linear hull structure response Large hull deformations w/ Significant Contact & Significant Material Failure Time Evolutionary Structural Degradation End-User Products Primary structural damage Cascading structural damage effects Equipment and system damage and operability assessments

CREATE USE CASE III LFT&E Assessments Capabilities from CREATE program: Improved failure models & failure criteria Damaged based failure models More-accurate damage progression Energy conserving damage propagation More-accurate damage patterns Fracture based damage models (perhaps) Particle methods (perhaps) More-accurate contact algorithms No miss contact detection Energy/Momentum conserving forces

Technical Approach Integrate Gemini Into Evolving SIERRA Architecture From SNL Leverage Existing Substantial DOE Commitment Evolve SIERRA To Address More Efficient Parallel Workload Distribution General, Scale-able Euler/Lagrange Coupling Enhance Lagrange Capabilities In SIERRA For UNDEX Requirements Robust Structural Element Library Multi-Length Scale Modeling Modal Sub-Structuring (CMS) …

CREATE/UNDEX Development Team Organization CREATE UNDEX Navy Lead CREATE UNDEX M&S Development NSWC/CD Lead Leveraged Related Programs ONR NAVSEA OSD Board Of Advisors Navy Technical Authority PEO Ships PEO Carriers PEO Submarines Subject Matter Experts Software Design Working Group SNL Lead Langrange Element Working Group Euler Element Working Group NSWC/IH Lead Results Synthesis Working Group

CREATE/UNDEX Schedule

Summary DYSMAS Provides Navy UNDEX Response M&S Capability Sufficient For FSST Alternative Limited System Design/Qualification Support Limited Structural Damage Prediction Capability CREATE/UNDEX Capability Will Expand Application For System Design/Qualification Enhance LFT&E Assessments Support Design Of Cheaper & Safer Ships