linzell - computational simulation of blast effects on structural components

7/27/2019 Linzell - Computational Simulation of Blast Effects on Structural Components

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Computational SimulationComputational Simulation

of Blast Effects onof Blast Effects on

Structural ComponentsStructural Components

Daniel G. LinzellDaniel G. LinzellAssociate ProfessorAssociate Professor

Civil and Environmental EngineeringCivil and Environmental Engineering

Lyle N. LongLyle N. LongDistinguished ProfessorDistinguished Professor

Aerospace EngineeringAerospace Engineering

Abner ChenAbner ChenPh.D. CandidatePh.D. Candidate

Civil and Environmental EngineeringCivil and Environmental Engineering

EmreEmreAlpmanAlpmanPostdoctoral ResearcherPostdoctoral Researcher

Aerospace EngineeringAerospace Engineering


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Acknowledgements

z Office of Naval Research

z Penn State University Applied Research Lab

z APCI


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Objectives

z Detailed coupled gas/chemistry simulationsof detonations

z Large scale simulations of pressure loadings

using time-accurate CFDz Fluid/structure simulations under blast/impact

loadings

z Coating materials to help make structuresblast/impact resistant polyurea


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Background Blast resistant

materials (polyurea)

z Polyureaz Introduced by Texaco in 1989z Known Advantages vs. Polyurethanes (traditional coatings)z Applications

z DoD Civil Infrastructurez DoD other apps

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

z Other Civil Infrastructure Rail cars Water storage tanks Chemical 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


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z DoD

applications Polyureaz AFRL

z ERDC-WES

z Army

z Navy

z Pentagon

z Retrofitz Public domain?

Source: Polymer Materials for StructuralRetrofit, Knox et al., AFRL; Army

Times

Untreated stud wall

Coated with polyurea

Background Blast resistant

materials (polyurea)


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Blast Simulation CFD Method

z Unstructured-grid, time-accurate Euler code

z Finite volume, Runge-Kutta time marching

z Code is called PUMA2

z Has been in use at Penn State for manyyears, thoroughly validated on a wide rangeof problems


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Blast CFD - Assumptions

z 75 lbs. of TNT

z Explosive is spherical in geometry

z Uniform explosion


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Blast CFD - Initial Pressure

Profile

Initial Pressur e Profi le

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/p0


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Blast CFD - Pressure History

Pressure His to r ies a t D i f fe ren t L oca t ions

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(atm) r = 1m

r = 0.5m

r = 0.2m


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Blast CFD PUMA2

Comparisons to ConWep


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Blast CFD - Simulations

Including Steel Plate

z Plate Dimensions (60in by 60in)

z 75 lbs. of TNT

z Plate located approx 3 ft away from the

explosive


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zz Commercial codesCommercial codes

zz InteractionInteractionzz Loosely coupledLoosely coupled

zz Mechanisms behind protection?Mechanisms behind protection?

zz Parameters to control performance?Parameters to control performance?

Background

Fluid/structure simulations

3-D


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Focus Areas

fluid/structure interaction

z Numerical fluid/structure program

z Material models

z Comparison of ABAQUS and LS-DYNA

z

Comparison of PUMA2 and ConWepz Effect of polyurea on steel plate under blast

loading

z Experimental fluid/structure programz Material properties

z Validation testing


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Fluid/structure interaction


z Material models via literature


z

Comparison of PUMA2 and ConWepz Effect of polyurea on steel plate under blast

loading




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Material model - Steel

z Steel (AISI 4340)

z J ohnson-Cook material model (Kurtaran andEskandarian, 2003)

z A=66.7, B=100.4, n=0.26, C=0.014, and m=1.03

( ) ( )[ ]m

**npl T1Cln1BA ++= &pl

: equivalent plastic strain

*& : normalized plastic strain rate

roommelt

room

TT

TTT

=

*


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Material model - Polyurea

z Polyurea (APCI)

z Mie-Gruneisen equation of state (Fuentes 2006) A hydrodynamic material model

A function of density and internal energy

)( HmH EEPP =

00= 0 0

02H

HPE =

01=

2

2

00

)1(

s

C

PH = C0 and s are material constants

: material constant : reference density


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Numerical program

z Abaqus - Explicit

z LS-Dyna

z PUMA2


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z Material models


z

Comparison of PUMA2 and ConWepz Effect of polyurea on steel plate under

blast loading




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Numerical analysis-

ABAQUS and LS-DYNA


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Pressure time-history of the

impact load

0 0.002 0.004 0.006 0.008 0.01 0.012

Time (sec)

0.0E+000

1.0E+004

2.0E+004

3.0E+004

4.0E+004

5.0E+004

6.0E+004

Pressure(psi)


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Displacement

0 0.002 0.004 0.006 0.008 0.01 0.012Time (sec)

-2

-1.5

-1

-0.5

0

0.5

Displaceme

nt(in)

ABAQUS

LS-DYNA


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Von Mises Stress

0 0.002 0.004 0.006 0.008 0.01 0.012

Time (sec)

0.0x100

2.0x104

4.0x104

6.0x104

8.0x10

4

1.0x105

1.2x105

1.4x105

VonMisesStess(psi)

ABAQUSLS-DYNA


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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

IntenalEnegy(lb-in

)

Comparison of internal energy for mesh size 1"x1"x1"LS-DYNA

ABAQUS


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z Material models


z


blast loading




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Numerical program Comparison of PUMA2 & ConWep

z FEM program: LS-DYNA

z Steel plate: 60x60x0.25z Steel (AISI 4340)

z Johnson-Cook material model literature, no

failure criterion

z Loadz PUMA2 CFD code (complex spatial and

temporal loading)z ConWep (Blast function provided in LS-DYNA)


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Background

z CFD code, PUMA2

z Solve Euler equations

z Neglect viscous effect

z Blast function (ConWep)

z U.S. Army Waterways Experiment Station

z Empirical model


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Configuration of the model


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Comparison of displacements

0 0.002 0.004 0.006 0.008Time (s)

-12

-10

-8

-6

-4

-2

0

z-d

isplacement(in)

PUMA2

ConWep


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Comparison of von Mises

stress

0 0.002 0.004 0.006 0.008Time (s)

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

V-Mstess(psi)

PUMA2

ConWep


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z Material models


z


blast loading



N i l


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Numerical program

Effect of polyurea on steel plateunder blast loading

z Steel plate: 60x60x0.25

z Thickness of coating: 0,0.25, 0.5

z Steel (AISI 4340)

z J ohnson-Cook material

model

z Polyurea (Air Products)

z Mie-Gruneisen Equation

of Statez Load: PUMA2 CFD code

(complex spatial andtemporal loading)


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Numerical program Steel plate

without polyurea


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with 0.25 thick polyurea


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with 0.5 thick polyurea


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Deflection at the center

0.02.0

4.0

6.0

8.010.0

12.0

14.0

16.0

18.0

20.0

0.000 0.001 0.002 0.003 0.004 0.005

Time (s)

Displacem

ent(in)

No coating

0.25" polyurea

0.5" polyurea


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Kinetic energy

0.E+00

1.E+06

2.E+06

3.E+06

4.E+06

5.E+06

6.E+06

7.E+06

8.E+06

9.E+06

0.000 0.001 0.002 0.003 0.004 0.005

Tim e (s)

Kinetic

ene

rgy

(lbf-in) No coating

0.25" polyurea

0.5" polyurea


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Current focus areas

numerical program

z Sensitivity analyses

z Model constructionz Constitutive model selection Polyurea (e.g. viscous or

crushable foam vs. M-G)

z Numerical failure mode predictionz Coated platez Pressure, temperature, impact

z Relevant loading regimes

z

Failure criteria predictionz Membrane action - polyurea

z Interface failure - polyurea and steel


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z Material models


z Comparison of PUMA2 and ConWep

z Effect of polyurea on steel plate underblast loading




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Experimental program

z Material properties

z Characterization steel andpolyurea

z Validation Testing

z

Impact and/or Blastz Coated and uncoated

z Varying coating thickness

z Locations

z PSU CITEL

z Others


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Coupon testing - Steel

ASTM E8Extensometer - displacement


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Results stress vs. strain

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

True s train (in/in)

0

20000

40000

60000

80000

100000

120000

True

stres

s

(psi)

M t i l t t f JC


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Material constants for JC

model

z Using a least squares fitting method

z Material constant A = 66.7 (ksi)z Material constant B = 100.4 (ksi)

( ) ( )[ ] m**npl T1Cln1BA ++= &

C t f


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Current focus areas

experimental program

z Coupon testing Polyurea (APCI)

z Validation testing specimen prepz Validation testing determination and matrix

development


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Summary


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Questions?

Contact Info

z Linzell [email protected]

z Long [email protected]

linzell - computational simulation of blast effects on structural components

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