ERNEST 2017 report

Concrete modelling for impact simulations

Alexis Fedoroff

Introduction

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Why accurate material modelling in impactsimulations?

Concrete is a difficult material to model (heterogeneous,anisotropic, porous, multi-phase, multi-scale, brittle, …)

Behavior under impact is poorly known (strain rate effect, inertiaeffect, capillary effect, high speed crack propagation, …)

Effect of concrete material model parameters predominant inlarge scale structural impact simulations.

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Continuum concrete modelling

Concrete modelling

Phenomenological(macroscale)

Continuumplasticity

Continuumdamage

Physically based(multi-scale)

Microplane(LFM in RVE)

strain

stre

ss

strain

stre

ss

yield

damageinitiation

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Impact simulation

rate dependence(compression)

Inertia effects

Quasi-staticconfinementdependence

Free watercovection

Crackpropagationinertia

Phenomenological Physical (micro-scale)

rate dependence(tension)

Voidcompaction

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Literature survey of continuum concrete models

Plasticity Damage NL-elasticity Fracture Impact effects

Ottosen (1977) -> Winfrith x

Mazars (1986) -> PRM (2010) x strain rate

Krieg (1978) -> KST (1983) x x confinement

Bazant (1996) ”Microplane” x

Lubliner & al. (1989)”Barcelona”

x x

Lee & Fenves (1998) x x

User defined Abaqus CDP x x strain rate +confinement

X.D. Vu (2013) (PRM + KST) x x x strain rate +confinement

Goals

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use state-of-the-art materialmodels in impact simulations

write Abaqus usermaterials

get deeper knowledgein continuummechanics

customize Abaqusmaterials (CDP)

investigate alternativemethods (DEM,meshless Lagrangian,peridynamics, …)

What has been done so far…

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What has been done so far… in a nutshell

Literature survey of concrete modellingThermodynamic damage-plasticity continuum approachThe ”Barcelona” concrete model (J Lubliner, et Al. A plastic-damage model for concrete.Int.J. of Solids and Structure, 1989.)

The ”Lee-Fenves” concrete model (J.H. Lee and G. Fenves. Plastic-damage model forcyclic loading of concrete structures. Journal of Engineering mechanics, 1998.)

Enhancement of the Abaqus CDP modelA confinement stress dependent concrete model (T. Gabet. Thèse:Comportement triaxial du béton sous fortes contraintes: influence du trajet de chargement. Université JosephFourier, Grenoble, 2006.)

Study of element deletion as a way of materializing cracks inimpact simulations

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Material parameter sensitivity study: shape ofthe yield surface

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Study of triaxiality of concrete: dependence onconfinement stress

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Investigation of mesh size regularizationaccording to Hillerborg’s method

Future plans

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Plans for 2017

SMiRT-24: ”A physically motivated element deletion criteria forthe concrete damage plasticity model”

Enhance CDP with strain rate sensitivity in tension

Write a VBA-Excel routine for material input data generation

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Plans for 2017: material data generator

0,00E0

1,00E7

2,00E7

3,00E7

4,00E7

5,00E7

6,00E7

0,0E0 1,0E-1 2,0E-1 3,0E-1 4,0E-1

cohe

sion

stre

ss(P

a)

inelastic strain

Cohesion stress evolution incompression

conf. (Pa) = 0.00E+00

conf. (Pa) = 5.93E+06

conf. (Pa) = 1.19E+07

conf. (Pa) = 1.78E+07

conf. (Pa) = 2.37E+07

conf. (Pa) = 2.96E+07

conf. (Pa) = 3.56E+07

conf. (Pa) = 4.15E+07

0,00E0

5,00E6

1,00E7

1,50E7

2,00E7

2,50E7

3,00E7

0,0E0 1,0E-4 2,0E-4 3,0E-4 4,0E-4 5,0E-4

cohe

sion

stre

ss(P

a)

inelastic displacement (m)

Cohesion stress evolution in tensionrate (m/s) = 1.00E-06

rate (m/s) = 1.00E+00

rate (m/s) = 1.52E+00

rate (m/s) = 2.31E+00

rate (m/s) = 3.51E+00

rate (m/s) = 5.34E+00

rate (m/s) = 8.11E+00

rate (m/s) = 1.23E+01

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Plans for 2018 and later

Aquire the know-how to write Abaqus user materials

Apply to the Ragueneau-Gatuingt-Cremona crack frictionaldissipation model to include hysteresis

Build a comprehensive material library to be used in concretestructure simulations.

to conclude …

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base camp

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