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Full Ship Shock Test Modeling

Dr. Tom Moyer, NSWC/Carderock

15 April, 2008

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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)

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WaterBulk Cavitation Region

Ocean Bottom

Bottom Reflected Wave(Traveling partially throughbottom material)

Bottom Reflected Wave(Traveling entirelythrough water)

Water Surface

Surface ReflectedWave

Spray DomeAir

Plume

SZ

Direct ShockWavesBurst

Bubble at firstMinimum

First BubblePulse

Summary of Underwater Explosion Phenomena

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DYSMAS

DYnamic System Mechanics Advanced Simulation

A fully-coupled hydrocode for simulating underwater explosion phenomena and their

effects on naval structures

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DYSMASDYnamic System Mechanics Advanced Simulation

.

GEMINI

Euler solver

Shock and Fluid Dynamics

DYNA-N &PARADYNLagrange solvers

Structural Response

Standard Coupler Interface

Fully Coupled Fluid-Structure Interaction

DFBEM

BEM solver

Bubble & Fluid Dynamics

HYDROCODE FOR SIMULATION OF UNDERWATER EXPLOSION EFFECTS

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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

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TYPICAL DATA ANALYSIS

Full Record

Shock Wave

Shock Wave (extended)

1st Bubble Pulse

1/e * Pmax

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EFSP

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Lagrangian Model

• 16,165 Nodes• 21,053 Elements

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Results – Innerbottom, Vertical Velocity Below FWD STBD Mount

8976

FWD

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Eulerian Simulation

T: 5.0 msec

T: 6.8 msec

T: 5.4 msec

T: 8.3 msec

T: 5.9 msec

T: 11.8 msec

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Lagrangian Simulation

T: 6.2 msec

T: 10.0 msec

T: 13.2 msec

T: 50.0 msec

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D Y S M A S A S S IS T

T im e (m sec )

Ac

ce

lera

tio

n (

g's

)

-2 0 0

-1 0 0

0

1 0 0

2 0 0

3 0 0

0 1 0 2 0 3 0 4 0 5 0

D Y S M A S A S S IS T

T im e (m sec )

Ac

ce

lera

tio

n (

g's

)

-2 0 0

-1 0 0

0

1 0 0

2 0 0

3 0 0

0 1 0 2 0 3 0 4 0 5 0

D Y S M A S A S S IS T

T im e (m sec )

Ac

ce

lera

tio

n (

g's

)

-2 0 0

-1 0 0

0

1 0 0

2 0 0

3 0 0

0 1 0 2 0 3 0 4 0 5 0

D Y S M A S A S S IS T

T im e (m sec )

Ac

ce

lera

tio

n (

g's

)

-3 0 0

-2 0 0

-1 0 0

0

1 0 0

2 0 0

3 0 0

4 0 0

0 1 0 2 0 3 0 4 0 5 0

Innerbottom Vertical Acceleration

DYSMAS vs EFSP Test

FWD

60 lbs HBX, 20 ft Hrz Stdf

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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

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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

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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

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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

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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 ToolsIncludes Integration w/ ASAP/ARM

– Development of “REPLAY” strategiesMeets All Requirements For FSST Replacement Calculations

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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)

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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 capabilityEnables design margins to be assessed

Enhanced Mission Effectiveness Assessment

Enhanced Results Synthesis Methodology

Quantification Of Margin & Uncertainty

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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

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CREATE USE CASE III

LFT&E Assessments

• Capabilities from CREATE program:– Improved failure models & failure criteria

Damaged based failure models

– More-accurate damage progressionEnergy conserving damage propagation

– More-accurate damage patternsFracture based damage models (perhaps)

Particle methods (perhaps)

– More-accurate contact algorithmsNo miss contact detection

Energy/Momentum conserving forces

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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)– …

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CREATE UNDEX Navy Lead

CREATE UNDEX M&S DevelopmentNSWC/CD Lead

Leveraged Related Programs•ONR•NAVSEA•OSD

Board Of Advisors•Navy Technical Authority•PEO Ships•PEO Carriers•PEO Submarines•OSD•Subject Matter Experts

Software Design Working GroupSNL Lead

Langrange Element Working GroupNSWC/CD Lead

Euler Element Working GroupNSWC/IH Lead

Results Synthesis Working GroupNSWC/CD Lead

CREATE/UNDEX Development Team Organization

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CREATE/UNDEX Schedule

FY-08 FY-09 FY-10 FY-11 FY-12 FY-13INITIAL DEVELOPMENTUC-1 BETA RELEASEV 1.0 (UC-1 & BETA UC-2)V 2.0 (UC-1,2 & BETA UC-3)V 3.0 (UC-1=>3)

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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