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Computational Simulation Computational Simulation of Blast Effects on of Blast Effects on Structural ComponentsStructural Components

Daniel G. LinzellDaniel G. LinzellAssociate ProfessorAssociate ProfessorCivil and Environmental EngineeringCivil and Environmental Engineering

Lyle N. LongLyle N. LongDistinguished ProfessorDistinguished ProfessorAerospace EngineeringAerospace Engineering

Abner ChenAbner ChenPh.D. CandidatePh.D. CandidateCivil and Environmental EngineeringCivil and Environmental Engineering

EmreEmre AlpmanAlpmanPostdoctoral ResearcherPostdoctoral ResearcherAerospace EngineeringAerospace Engineering

Acknowledgements

Office of Naval Research

Penn State University Applied Research Lab

APCI

Objectives

Detailed coupled gas/chemistry simulations of detonations Large scale simulations of pressure loadings using time-accurate CFDFluid/structure simulations under blast/impact loadingsCoating materials to help make structures blast/impact resistant – polyurea

Background – Blast resistant materials (polyurea)

PolyureaIntroduced by Texaco in 1989Known Advantages vs. Polyurethanes (traditional coatings)Applications

DoD – Civil InfrastructureDoD – other apps

Army/Navy – Spray on armor (Humvees)Navy – Ship hulls (U.S.S. Cole)

Other – Civil InfrastructureRail carsWater storage tanksChemical plant infrastructure

Sources: PCI: http://www.pcimag.com/CDA/Archives/779f754db76a7010VgnVCM100000f932a8c0DefenseReview.com: http://www.defensereview.com/article502.html, Polymer Materials for Structural Retrofit, Knox et al., AFRL

DoDapplications –Polyurea

AFRLERDC-WESArmyNavyPentagon

RetrofitPublic domain?

Source: Polymer Materials for Structural Retrofit, Knox et al., AFRL; Army Times

Untreated stud wall

Coated with polyurea

Background – Blast resistant materials (polyurea)

Blast Simulation CFD Method

Unstructured-grid, time-accurate Euler codeFinite volume, Runge-Kutta time marchingCode is called PUMA2Has been in use at Penn State for many years, thoroughly validated on a wide range of problems

Blast CFD - Assumptions

75 lbs. of TNTExplosive is spherical in geometryUniform explosion

Blast CFD - Initial Pressure Profile

Initial Pressure Profile

0

20000

40000

60000

80000

100000

120000

140000

160000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

r/R

p/p

0

Blast CFD - Pressure HistoryPressure Histories at Different Locations

1

10

100

1000

10000

0 0.00005 0.0001 0.00015 0.0002 0.00025 0.0003 0.00035 0.0004 0.00045 0.0005

t (sec)

P (a

tm) r = 1m

r = 0.5mr = 0.2m

Blast CFD – PUMA2 Comparisons to ConWep

Blast CFD - Simulations Including Steel Plate

Plate Dimensions (60in by 60in) 75 lbs. of TNTPlate located approx 3 ft away from the explosive

Blast CFD - Loading History at Plate Center

Loading History at the Center of the Plate

0.01

0.1

1

10

100

1000

0 0.001 0.002 0.003 0.004 0.005 0.006

t (sec)

P (a

tm)

Commercial codesCommercial codesInteractionInteraction

Loosely coupledLoosely coupled

Mechanisms behind protection?Mechanisms behind protection?Parameters to control performance?Parameters to control performance?

Background –Fluid/structure simulations

3-D

Focus Areas –fluid/structure interaction

Numerical fluid/structure programMaterial modelsComparison of ABAQUS and LS-DYNAComparison of PUMA2 and ConWepEffect of polyurea on steel plate under blast loading

Experimental fluid/structure programMaterial propertiesValidation testing

Fluid/structure interaction

Numerical fluid/structure programMaterial models – via literatureComparison of ABAQUS and LS-DYNAComparison of PUMA2 and ConWepEffect of polyurea on steel plate under blast loading

Experimental fluid/structure programMaterial propertiesValidation testing

Material model - SteelSteel (AISI 4340)

Johnson-Cook material model (Kurtaran and Eskandarian, 2003)A=66.7, B=100.4, n=0.26, C=0.014, and m=1.03

( )[ ] ( )[ ][ ]m**npl T1εCln1εBAσ −++= &

plε : equivalent plastic strain

*ε& : normalized plastic strain rate

roommelt

room

TTTT

T−−

=*

Material model - PolyureaPolyurea (APCI)

Mie-Gruneisen equation of state (Fuentes 2006)A hydrodynamic material modelA function of density and internal energy

)( HmH EEPP −Γ=− ρ

ρρ0

0Γ=Γ 0Γ 0ρ

02ρηH

HPE =

ρρ

η 01−=

2

200

)1( ηηρ

sC

PH −= C0 and s are material constants

: material constant : reference density

Numerical programAbaqus - ExplicitLS-DynaPUMA2

Fluid/structure interaction

Numerical fluid/structure programMaterial modelsComparison of ABAQUS and LS-DYNAComparison of PUMA2 and ConWepEffect of polyurea on steel plate under blast loading

Experimental fluid/structure programMaterial propertiesValidation testing

Numerical analysis-ABAQUS and LS-DYNA

Pressure time-history of the impact load

0 0.002 0.004 0.006 0.008 0.01 0.012Time (sec)

0.0E+000

1.0E+004

2.0E+004

3.0E+004

4.0E+004

5.0E+004

6.0E+004

Pre

ssur

e (p

si)

Displacement

0 0.002 0.004 0.006 0.008 0.01 0.012Time (sec)

-2

-1.5

-1

-0.5

0

0.5D

ispl

acem

ent (

in)

ABAQUSLS-DYNA

Von Mises Stress

0 0.002 0.004 0.006 0.008 0.01 0.012Time (sec)

0.0x100

2.0x104

4.0x104

6.0x104

8.0x104

1.0x105

1.2x105

1.4x105V

on M

ises

Stre

ss (p

si)

ABAQUSLS-DYNA

Internal energy

0 0.002 0.004 0.006 0.008 0.01 0.012Time (sec)

0E+000

2E+004

4E+004

6E+004

8E+004

1E+005

Inte

rnal

Ene

rgy

(lb-in

)Comparison of internal energy for mesh size 1"x1"x1"

LS-DYNAABAQUS

Fluid/structure interaction

Numerical fluid/structure programMaterial modelsComparison of ABAQUS and LS-DYNAComparison of PUMA2 and ConWepEffect of polyurea on steel plate under blast loading

Experimental fluid/structure programMaterial propertiesValidation testing

Numerical program –Comparison of PUMA2 & ConWep

FEM program: LS-DYNASteel plate: 60”x60”x0.25”Steel (AISI 4340)

Johnson-Cook material model – literature, no failure criterion

Load PUMA2 CFD code (complex spatial and temporal loading)ConWep (Blast function provided in LS-DYNA)

Background

CFD code, PUMA2Solve Euler equationsNeglect viscous effect

Blast function (ConWep)U.S. Army Waterways Experiment StationEmpirical model

Configuration of the model

Comparison of displacements

0 0.002 0.004 0.006 0.008Time (s)

-12

-10

-8

-6

-4

-2

0z-

disp

lace

men

t (in

)

PUMA2ConWep

Comparison of von Misesstress

0 0.002 0.004 0.006 0.008Time (s)

0

20000

40000

60000

80000

100000

120000

140000

160000

180000V

-M s

tress

(psi

)

PUMA2ConWep

Fluid/structure interaction

Numerical fluid/structure programMaterial modelsComparison of ABAQUS and LS-DYNAComparison of PUMA2 and ConWepEffect of polyurea on steel plate under blast loading

Experimental fluid/structure programMaterial propertiesValidation testing

Numerical program –Effect of polyurea on steel plate under blast loading

Steel plate: 60”x60”x0.25”Thickness of coating: 0”, 0.25”, 0.5”Steel (AISI 4340)

Johnson-Cook material model

Polyurea (Air Products)Mie-Gruneisen Equation of State

Load: PUMA2 CFD code (complex spatial and temporal loading)

Numerical program – Steel plate without polyurea

Numerical program – Steel plate with 0.25” thick polyurea

Numerical program – Steel plate with 0.5” thick polyurea

Deflection at the center

0.02.04.06.08.0

10.012.014.016.018.020.0

0.000 0.001 0.002 0.003 0.004 0.005

Time (s)

Disp

lace

men

t (in

)

No coating0.25" polyurea0.5" polyurea

Kinetic energy

0.E+001.E+062.E+063.E+064.E+065.E+066.E+067.E+068.E+069.E+06

0.000 0.001 0.002 0.003 0.004 0.005

Time (s)

Kine

tic e

nerg

y (lb

f-in)

No coating0.25" polyurea0.5" polyurea

Current focus areas –numerical program

Sensitivity analysesModel constructionConstitutive model selection – Polyurea (e.g. viscous or crushable foam vs. M-G)

Numerical failure mode predictionCoated platePressure, temperature, impactRelevant loading regimes

Failure criteria predictionMembrane action - polyureaInterface failure - polyurea and steel

Fluid/structure interaction

Numerical fluid/structure programMaterial modelsComparison of ABAQUS and LS-DYNAComparison of PUMA2 and ConWepEffect of polyurea on steel plate under blast loading

Experimental fluid/structure programMaterial propertiesValidation testing

Experimental program

Material propertiesCharacterization – steel and polyurea

Validation TestingImpact and/or Blast

Coated and uncoatedVarying coating thickness

LocationsPSU CITELOthers

Coupon testing - Steel

•ASTM E8•Extensometer - displacement

Results – stress vs. strain

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16True strain (in/in)

0

20000

40000

60000

80000

100000

120000Tr

ue s

tress

(psi

)

Material constants for JC model

Using a least squares fitting methodMaterial constant A = 66.7 (ksi)Material constant B = 100.4 (ksi)

( )[ ] ( )[ ][ ]m**npl T1εCln1εBAσ −++= &

Current focus areas –experimental program

Coupon testing –Polyurea (APCI)Validation testing specimen prepValidation testing determination and matrix development

Summary

Questions?

Contact Info

LinzellDLinzell@engr.psu.edu

Longlnl@psu.edu