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