Homogeneous Materials Using

baconossifiedMechanics

Oct 29, 2013 (4 years and 10 days ago)

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10/30/2013

1

Wave Propagation Prediction in
Homogeneous Materials Using
Hybrid Lattice Particle Modeling

Investigators: Ge Wang, Ahmed. Al
-
Ostaz,
Alexander H.
-
D. Cheng and P. Raju Mantena

Civil Engineering Department

University of Mississippi

Research Background


Dynamic

deformation

often

involves

wave

propagation,

i
.
e
.
,

stress

has

to

travel

through

the

material

body
.




Dynamic

fracture

and

fragmentation

under

high

strain

rate

loads

(impact,

blasting,

crush,

collapse,

high

speed

puncture/penetration,

comminution,

.
etc
.
)

has

broad

civilian/military

applications
.

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2

Hopkinson Bar Test

(by M.A. Kaiser, 1998)

Shock on a sharp
-
nosed

supersonic body

Spallation as a result of impact without

penetration of the impacting object

(
http://en.wikipedia.org/wiki
)

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3

Outline



Brief

review

of

major

macroscopic

dynamic

fracture

approaches


Hybrid

lattice

particle

modeling

(HLPM)



HLPM

of

wave

propagation

and

applications


Conclusions

10/30/2013

4

Outline



Brief

review

of

major

dynamic

fracture

approaches


Hybrid

lattice

particle

modeling

(HLPM)



HLPM

of

wave

propagation

and

applications


Conclusions

1. Brief review of major dynamic
fracture approaches


Continuum

Mechanics

Based

Approaches

(CMBA)
:



FEM



Discrete

Element

Based

Approaches

(DEBA)
:


PFC,

SPH,

PM,

etc
.


Combinations

of

CMBA
-
DEBA
:


PFEM,

MPM

(material

point

method),

etc
.

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5

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6

Simulations with meshing techniques

Meshless (SPH)

Lagrange

Euler

ALE

(Arbitrary Lagrange Euler)

FEM

(AUTODYN course materials)

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7

Outline



Brief

review

of

major

dynamic

fracture

approaches


Hybrid

lattice

particle

modeling

(HLPM)



HLPM

of

wave

propagation

and

applications


Conclusions


10/30/2013

8

Hybrid Lattice Particle Modeling (HLPM) of Dynamic Fragmentation of Solids


Ge Wang, Ahmed Al
-
Ostaz, Alexander H.
-
D. Cheng and P. Raju Mantena

Department of Civil Engineering, the University of Mississippi, MS 38655, http://www.olemiss.edu/~gewang














Motivations

Mechanical

behavior

of

a

solid

material

is

controlled

by

its

microstructure
.

Complex

macroscopic

behaviors,

such

as

fracture

and

failure,

arise

from

microstructure

interactions
.

Thus,

if

the

microstructure

and

the

microstructural

interactions

within

a

numerical

model

could

be

correctly

and

accurately

replicated,

then

that

model

should

precisely

reproduce

the

macroscopic

behaviors
.

However,

current

computing

power

limits

the

size

of

the

atomic

ensemble

to

numbers

of

atoms

that

are

too

small

to

be

useful

for

most

engineering
-
scale

systems
.

Hybrid

Lattice

Particle

Modeling

(HLPM)

is

developed

to

directly

mi mic

microstructural

features

and

can

be

executed

in

reasonable

times

on

standard

computers
.

Model Introduction

H
LPM

is

a

dynamic

simulation

that

uses

small

discrete

solid

physical

particle

(or

quasi
-
molecular

particles)

as

a

representation

of

a

given

fluid

or

solid
.

Different

particle

interaction

schemes

and

mesh

structures

can

be

adopted
.

It

combines

the

knowledge

of

both

lattice

modeling

and

particle

modeling
.

Interactions of HLPM

Linear:

Non
-
linear:

(a) Polynomial


(b) Lennard

Jones

Validations of HLPM

(a) Epoxy in tension (b) Indentation of polymeric materials

Meshing structures

Applications of HLPM

High strain rate loading:

Thermally induced fracture:

(a) Temperature

(b) Fracture

Mixture

of

calcite

and

pyrite

subject

to

a

microwave

Blasting:

Crack propagation:

Spallation of plate impact:

Wave propagation:

3
-
D puncture/penetration:

Numerical discretization scheme in PFC (particle
flow code), PFEM (particle finite element method)
and HLPM


PFC








HLPM








PFEM







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9

critical time increment:

k

: the stiffness

m
: a point mass

x
:

displacement

critical time increment:

k

: the stiffness

m
: a point mass

u
:

displacement

critical time increment:

k

: the stiffness

m
: a point mass

r
:

displacement

10/30/2013

10

Outline



Brief

review

of

major

dynamic

fracture

approaches


Hybrid

lattice

particle

modeling

(HLPM)



HLPM

of

wave

propagation

and

applications


Conclusions

HLPM simulations of Wave Propagation
Prediction in Homogeneous Materials


Problem descriptions:


Material properties:


Theoretical wave propagation speeds:


1
-
D:




2
-
D:







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11

1
-
D: L=12.7
cm

2
-
D: A=12.7x1.21

(cont.)

Using dynamic BC



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12


Dynamics BC:

. Duration=

Wave propagation speed: (i)
1D
: 2000.0 m/s; (ii)
2D
: 2133.0 m/s

Horizontal amplitude

(cont.)

Using dynamic BC

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Vertical amplitude

(cont.)

Using Kinematic BC

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Kinematic BC:

constantly

Wave propagation speed: 2133.0 m/s

Horizontal amplitude

(cont.)

Using Kinematic BC

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Vertical amplitude

Applications

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16

(a) HLPM simulations

(b) MD simulations

(A. M. Krivtsov, 2004)

Spall Crack Formation

(cont.)

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17

HLPM simulations

(a) weak interface interaction

(b) strong interface interaction

(cont.)

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18

Cavity Blasting

HLPM simulations

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19

Outline



Brief

review

of

major

dynamic

fracture

approaches


Hybrid

lattice

particle

modeling

(HLPM)



HLPM

of

wave

propagation

and

applications


Conclusions

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20

Conclusions


Hybrid

lattice

particle

modeling

(HLPM)

can

be

an

alternative

tool

to

explore

wave

propagation

in

materials
.



HLPM

is

being

developed

ultimately

for

investigating

shock

wave

related

problems
.



Validations

are

required

in

the

coming

stage
.

October 30, 2013

21

Grant Acknowledgement

Department of Homeland Security
-
through Southeast Region Research

Initiative (SERRI), USA.

ONR, Office of Naval Research, Solid Mechanics Program, USA.