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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Summary of Underwater
Explosion Phenomena
Surface Reflected
Wave
Plume
SZ
Air
Spray Dome
Water Surface
Water
Bubble at first
Minimum
Bulk Cavitation Region
First Bubble
Pulse
Burst
Direct Shock
Waves
Bottom Reflected Wave
(Traveling entirely
through water)
Bottom Reflected Wave
(Traveling partially through
bottom material)
Ocean Bottom
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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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DYSMAS
DYnamic System Mechanics Advanced Simulation
.
GEMINI
DYNA-N &
PARADYN
Euler solver
Lagrange solvers
Shock and Fluid
Dynamics
Structural Response
DFBEM
BEM solver
Bubble & Fluid
Dynamics
Standard Coupler
Interface
Fully Coupled FluidStructure Interaction
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 - Applicationspecific Validation)
• Design & acquire validation-quality UNDEX loading and response data for specific (local)
platform structures
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 Code validation against design-specific concepts
TYPICAL DATA ANALYSIS
Full Record
1/e * Pmax
Shock Wave
Shock Wave (extended)
1st Bubble Pulse
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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: 5.4 msec
T: 5.9 msec
T: 6.8 msec
T: 8.3 msec
T: 11.8 msec
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Lagrangian Simulation
T: 6.2
msec
T: 10.0
msec
T: 13.2
T: 50.0
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Innerbottom Vertical Acceleration
DYSMAS vs EFSP Test
300
400
100
0
-100
FWD
Acceleration (g's)
Acceleration (g's)
300
200
-200
200
100
0
-100
-200
-300
0
10
20
30
40
50
0
10
Time (msec)
ASSIST
DYSMAS
300
300
200
200
100
60 lbs HBX, 20 ft Hrz Stdf
0
-100
-200
Acceleration (g's)
Acceleration (g's)
DYSMAS
20
30
40
50
40
50
Time (msec)
ASSIST
100
0
-100
-200
0
10
20
30
Time (msec)
DYSMAS
ASSIST
40
50
0
10
20
30
Time (msec)
DYSMAS
ASSIST
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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 componenttesting 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 Tools
Includes Integration w/ ASAP/ARM
– Development of “REPLAY” strategies
Meets All Requirements For FSST Replacement Calculations 18
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 capability
Enables 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 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
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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 Development Team
Organization
CREATE UNDEX Navy Lead
Leveraged Related Programs
•ONR
•NAVSEA
•OSD
CREATE UNDEX M&S Development
NSWC/CD Lead
Software Design Working Group
SNL Lead
Board Of Advisors
•Navy Technical Authority
•PEO Ships
•PEO Carriers
•PEO Submarines
•OSD
•Subject Matter Experts
Langrange Element Working Group
NSWC/CD Lead
Euler Element Working Group
NSWC/IH Lead
Results Synthesis Working Group
NSWC/CD Lead
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CREATE/UNDEX Schedule
FY-08
FY-09
FY-10
FY-11
FY-12
FY-13
INITIAL DEVELOPMENT
UC-1 BETA RELEASE
V 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
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