hershey lodge preconference symposium 17 march 2008 state-of-the-art technological developments in...

Hershey LodgeHershey Lodge

Preconference SymposiumPreconference Symposium17 March 200817 March 2008

State-of-the-Art TechnologicalState-of-the-Art Technological Developments in Concrete – Developments in Concrete –

Computational Modeling, Computational Modeling, Emphasis on Blast EffectsEmphasis on Blast Effects

Daniel G. LinzellDaniel G. LinzellAssociate ProfessorAssociate Professor

Department of Civil and Environmental EngineeringDepartment of Civil and Environmental EngineeringPenn State University Penn State University



Acknowledgements PSU

Faculty - James Anderson, Lyle Long, Barry Scheetz, Andrea Schokker

Grad Students – Emre Alpman, Abner Chen, Andrew Coughlin, Eric Musselman, Richard Myers, Thara Viswanath

Sponsors PSU Applied Research Lab Office of Naval Research AFRL APCI Ogden Tech. Kontek Industries



Objectives - COMPUTATIONAL Background – Finite Element Analysis Background – Innovative Materials (Polyurea) Background – CFD Simulations Examination of innovative concretes under

simulated blast loads – long fiber concrete Coating materials to help make structures

blast/impact resistant - polyurea



Background – Finite Element Analysis (FEA) What is FEA?

Computer-based numerical technique (1940s/50s)

Calculating strength and behavior of engineering structuresDeflection, stress, vibration, buckling, many other

itemsSmall or large deflection effectsElastic, inelastic, plastic material response



FEA Structure is broken down into many small

simple blocks or elements Behavior of individual element described with

relatively simple equations Element behavior equations combined

Large set of simultaneous equations describing behavior of whole structure (EASY FOR PCs)

After solving equations, extracts behavior of individual elementsUsed to get stress, deflection, etc. anywhere



Tip Of Cover Plate

BeamColumn

Cover Plates

Vertical Roller

Horizontal Roller

Blast Pressures

0.00E+00

5.00E-02

1.00E-01

1.50E-01

2.00E-01

2.50E-01

3.00E-01

3.50E-01

4.00E-01

0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.00

Time (sec)

Dis

pla

cem

ent

(in

)

Peak Difference = 9.89%

Experimental

Numerical



FEA Why useful?

Can evaluate behavior of complex structures using systematic, proven approachFewer assumptions built into analysis?

Relatively efficient – allows for parametric/optimization studies relatively efficiently

Able to be performed using basic PC platformsEconomical? Depends.



FEA Types of Analyses?

Discussed earlierDeformations – large vs. smallMaterial response – elastic vs. inelastic vs. plastic

ResponseStatic, dynamic, blast, impact, contact, buckling,

transient, etc. Able to be performed using rather basic PC

platforms



FEA Possible pitfalls?

Model creation and discretization (element #)“Always make it look like the picture”

LoadsCorrectly calculated? Applied? All included?

Boundary conditions (“supports”)Correctly accounted for? Applied? All included?

Material behaviorCorrectly represented throughout its anticipated

load range



FEA How become proficient?

Practice, practice, practice Understand theory behind FEA method and

how computer forms and solves the problem Attend workshops and conferences organized

by software vendors, professional groups



Background – Innovative Materials Drs. Scheetz and Schokker

Concrete Me

Polyurea



Background – Polyurea Polyurea – innovative protective coating system

Introduced by Texaco in 1989 Known Advantages vs. Polyurethanes (traditional

coatings) Applications

DoD – Civil Infrastructure DoD – other apps

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

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



DoD applications – Polyurea AFRL ERDC-WES Army Navy Pentagon

Retrofit Public domain?

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

Untreated stud wall

Coated with polyurea

Background – Polyurea



Blast Simulation CFD Method (Long, PSU) Unstructured-grid, time-accurate Euler code Finite volume, Runge-Kutta time marching Code is called PUMA2 Has been in use at Penn State for many

years, thoroughly validated on a wide range of problems



Blast CFD - Assumptions

75 lbs. of TNT Explosive is spherical in geometry Uniform 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 (

atm

)

r = 1m

r = 0.5m

r = 0.2m



Blast CFD – PUMA2 vs. ConWep



Blast CFD - Simulations w/ Plate

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

explosive



Blast CFD - Loading History @ 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 (

atm

)



Structure - commercial codesStructure - commercial codes InteractionInteraction

Loosely coupledLoosely coupled

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

Background – Fluid/structure simulations w/ CFD



Focus Areas – Innovative Concretes Numerical fluid/structure program

Material models Component representation Response of various components under impact and blast

loading



Long Fiber Concrete – Material Model Create and validate material model Accurately describes behavior of long carbon

fiber reinforced concrete Dynamic loads – Impact 1st LS-Dyna



Long Fiber Concrete – Material Model Selected Model – Cowper-Symonds (Tension and

Compression)

0.5

1

1.5

2

2.5

1.00E-08 1.00E-06 1.00E-04 1.00E-02 1.00E+00 1.00E+02 1.00E+04

Strain Rate

DIF

Cowper and SymondsExperimental Data

1

10

1.E-09 1.E-07 1.E-05 1.E-03 1.E-01 1.E+01 1.E+03Strain Rate

DIF

Cowper and Symonds

Experimental Data



Focus Areas – Innovative Concretes Numerical fluid/structure program

Material models Component representation Response of various components under impact and blast

loading



Long Fiber Concrete – Impact Model Instrumented Impact

Element selection and discretization (element #) How represent fibers? Boundary conditions



Model Instrumented Impact How represent fibers? Discrete. Concrete - solids, reinforcement - truss (perfect bond) Rate effects important

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0 5 10 15 20 25 30

Time (ms)

Dis

pla

cem

en

t (in

)

Actualc=1c=1.5c=1.6c=2

Long Fiber Concrete – Impact



Model Instrumented Impact How represent fibers? Smeared. Rate effects again important

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0 5 10 15 20 25 30

Time (sec)

Dis

plac

emen

t (in

)

Actual48"48-2.048-2.6




Model Instrumented Impact How represent fibers? Strain erosion with nonlinear

springs.




Model Instrumented Impact – Work for Blast? Controlled by post failure response – 2 selected models NG




Long Fiber Concrete – Blast Model Blast

How represent fibers? Tension. Available material models in LS-Dyna First static, then dynamic




Normally reinforced




Normally reinforced

Crack Pattern




With long fibers

LS-Dyna Mat’l Model 179 H0

L0

H15

L15




Application – barrier systems



Focus Areas – Innovative Coatings Numerical fluid/structure program

Material models Comparison of ABAQUS and LS-DYNA Effect of polyurea on plate under blast loading



Material model - Polyurea Mie-Gruneisen equation of state (Fuentes

2006) Hydrodynamic material model, F(density, internal

energy)

)( HmH EEPP

0

00 0

02H

H

PE

01 2

200

)1(

s

CPH

C0 and s : material constants

: material constant : reference density



Numerical program Abaqus - Explicit LS-Dyna PUMA2



Numerical analysis-ABAQUS and LS-DYNA

99 in

1 in

5 in

Fixed end Fixed end

Area of the uniform distributed pressure load



Pressure time-history

0 0.002 0.004 0.006 0.008 0.01 0.012Tim e (se c)

0.0E+000

1.0E+004

2.0E+004

3.0E+004

4.0E+004

5.0E+004

6.0E+004P

ress

ure

(p

si)



Displacement

0 0.002 0.004 0.006 0.008 0.01 0.012Tim e (se c)

-2

-1.5

-1

-0.5

0

0.5

Dis

pla

cem

en

t (in

)

ABAQ US

LS-D YN A



Von Mises Stress

0 0.002 0.004 0.006 0.008 0.01 0.012Tim e (se c)

0.0x10 0

2.0x10 4

4.0x10 4

6.0x10 4

8.0x10 4

1.0x10 5

1.2x10 5

1.4x10 5V

on

Mis

es

Str

ess

(p

si)

ABAQ US

LS-D YN A



Internal energy

0 0.002 0.004 0.006 0.008 0.01 0.012Tim e (se c)

0E+000

2E+004

4E+004

6E+004

8E+004

1E+005

Inte

rna

l En

erg

y (l

b-i

n)

C o m p a riso n o f in te rn a l e n e rg y fo r m esh s ize 1 "x1 "x1 "LS-D YN A

ABAQ U S



Configuration of the model

3.2 ft

75 lb of TNT



Comparison of displacements

0 0.002 0.004 0.006 0.008Tim e (s)

-12

-10

-8

-6

-4

-2

0z-

dis

pla

cem

en

t (in

)

PU M A2

ConW ep



Effect of polyurea on plate under blast loading

Thickness of coating: 0”, 0.25”, 0.5”

Polyurea (Air Products) Mie-Gruneisen Equation

of State Load: PUMA2 CFD code



t = 0”



t = 0.25”



t = 0.5”



Deflection at the center

0.02.0

4.06.08.0

10.0

12.014.016.0

18.020.0

0.000 0.001 0.002 0.003 0.004 0.005

Time (s)

Dis

pla

cem

ent

(in

)

No coating

0.25" polyurea

0.5" polyurea



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

Time (s)

Kin

etic

en

erg

y (l

bf-

in)

No coating

0.25" polyurea

0.5" polyurea



Summary



Questions?

Contact Info

Daniel Linzell [email protected]

hershey lodge preconference symposium 17 march 2008 state-of-the-art technological developments in...

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