acoustic emission analysis for failure identification … emission analysis for failure...

1 09/11/2014

1. Motivation

2. Methods of AE analysis

3. Validation of classification procedure

4. Applications

5. Summary

Acoustic emission analysis for failure identification in composite

materials

Markus G. R. Sause Experimental Physics II

Institute of Physics

University of Augsburg

2 09/11/2014

y

x

DV

1. Motivation

failure of materials

t

x

After

Before

Freund et al. J. Appl. Mech-T. ASME 39 601-602 (1972)

Scruby J. Phys. E: Sci. Instrum. 20 946-955 (1987)

Sause et al. J. Nondest. Eval. 29:2 123-142 (2010)

all microscopic failure mechanisms in composites generate acoustic emission

3 09/11/2014

1. Motivation

failure of fiber reinforced composites

acoustic emission for material research

in te r-p ly d e la m in a tio n

f ib e r b re a k a g e

16

.2 m

m

0 °

S p e c im e n 1

S p e c im e n 2

cross-ply stacking

Challenges:

• complex modes of failure

• scatter of material properties

Possibilities:

• improved failure theories

• improved testing methods

4 09/11/2014

1. Motivation

failure of fiber reinforced composites

• monitoring of structure in the field

• detection of abnormal behaviour

• indication of imminent failure

acoustic emission for monitoring of structural integrity

CFRP structural part Space Shuttle Discovery Manhattan Bridge

5 09/11/2014

Signal

prediction

Material

analysis


of damage

Amount Position Type

Counting Localization Classification

AE signal

200 300 400 500

-0.1

0.0

0.1

Ampli

tude [

V]

Zeit [µs]

6 09/11/2014


AE source localization

Dt-based localization:

• uses sensor array attached to specimen

• calculation of arrival time differences

• inverse calculation of source position

• visualization as function of load

Source density:

low medium high

A E -s o u rc e

t1

t2

d iffe re n c e in p ro p a g a tio n

le n g th

r1

rS o u rc e

(0 ,0 ,0 )

r2

t0

grip region

specimen

force

7 09/11/2014


Identification of failure mechanisms

Definition of

features

Feature based pattern recognition and numerical validation:

feature 2

feature 1

Feature

Extraction

0 500 10000.00

0.05

0.10

Inte

nsitä

t

Frequenz [kHz]

0 500 10000.00

0.05

0.10

Inte

nsitä

t

Frequenz [kHz]

0 500 10000.00

0.05

0.10

Inte

nsitä

t

Frequenz [kHz]

feature 1 feature 2

Frequency [kHz]

Frequency [kHz]

Frequency [kHz]

Inte

nsity

Inte

nsity

Inte

nsity


Sause et al. Comp. Sci. Technol. 72 167-174 (2012)

Sause et al. Pat. Rec.Letters 33:1 17-23 (2012)

8 09/11/2014

feature 2

feature 1

feature 1 feature 2

0 500 10000.00

0.05

0.10

Inte

nsitä

t

Frequenz [kHz]

0 500 10000.00

0.05

0.10

Inte

nsitä

t

Frequenz [kHz]

0 500 10000.00

0.05

0.10

Inte

nsitä

t

Frequenz [kHz]

Definition of

features


Feature

Extraction

Frequency [kHz]

Frequency [kHz]

Frequency [kHz]

Inte

nsity

Inte

nsity

Inte

nsity

Application of

pattern recognition

algorithm






9 09/11/2014

feature 2

feature 1

feature 1 feature 2

0 500 10000.00

0.05

0.10

Inte

nsitä

t

Frequenz [kHz]

0 500 10000.00

0.05

0.10

Inte

nsitä

t

Frequenz [kHz]

0 500 10000.00

0.05

0.10

Inte

nsitä

t

Frequenz [kHz]

Definition of

features


Feature

Extraction

Frequency [kHz]

Frequency [kHz]

Frequency [kHz]

Inte

nsity

Inte

nsity

Inte

nsity

Application of

pattern recognition

algorithm

Numerical

validation






10 09/11/2014

in-situ methods

Thermography Digital Image Correlation

in-situ CT electromagnetic

emission

online microscopy

model predictions

analytical calculations

numerical modeling

single source experiments

micromechanical experiments

model composites


Which secondary knowledge can link AE signals

and their source?

in-situ CT

11 09/11/2014


FEM modeling of acoustic emission

AE source modeling (simple example):

• explicit modeling of crack growth in material by cohesive zone type approach

• simultaneous modeling of acoustic signal propagation

von Mises stress

2 mm

coordinate system

origin

2D-plane

x

z

y x

y

crack growth

a

force F

fixed constraint

5.2 mm

signal detection point

12 09/11/2014

AE source modeling (simple example):



crack growth

radiation

radiation

accumulated stress velocity field

(near field)

velocity field

(far field)

13 09/11/2014

AE source modeling (composite):



AE sensors

AE source:

Fiber-PML

Composite-PML

RVE

crack model

Details of FEM modeling procedure:

Sause et al. 19th ICCM, Montreal (2013)


Sause et al. J. Acoustic Emission 28 109-121 (2010)

Sause et al. Composites Part B 53 249-257 (2013)

Sause J. Acoustic Emission 29 (2012)

Sause J. Acoustic Emission 31:1 (2013)

Sause et al. Sens. Act. A 184 64-71 (2012)

Sause et al. 29th EWGAE, Vienna (2010)

source modeling signal propagation signal detection

Matrix cracking t < 5x10-5s

Fiber breakage t < 5x10-5s

14 09/11/2014

0 200 400 600 800 1000 12000

20

40

60

Matrix crack, all angles (IFF)

Out-of-plane delamination (DEF)

Fiber-Matrix debonding (DEF)

Fiber bundle breakage (FF)

Single Fiber breakage (FF)

Simulation

Pa

rtia

l P

ow

er

2 [

%]

Weighted Peak-Frequency [kHz]

source-sensor distance

Matrixcrack (IFF)

Interfacial failure (DEF)

Fiber breakage (FF)

0 200 400 600 800 1000 12000

20

40

60

Pa

rtia

l P

ow

er

2 [

%]

Weighted Peak-Frequency [kHz]

Experiment


Result of forward modeling procedure

Comparison between simulation and experiment:

• similar cluster structures observed for experiment and simulation

• possibility to correlate experimental signal clusters to respective source mechanisms

Model based validation of cluster origins

15 09/11/2014

1

WD sensor specimen

force

4. Applications

short beam shear test

Acoustic emission:

• detection using one WD sensor

• 40dB preamplification

• 10 MSPs acquisition rate

• 20 kHz – 1 MHz bandpass filter

Mechanical parameters:

• velocity1 mm/min

• loading till first load drop

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

0

200

400

600

800

1000

1200

1400

1600

Kra

ft [

N]

Traversenweg [mm]

50

100

150

200

250

300

350

400

450

500

Akku

mu

liert

e A

nza

hl A

E-S

ign

ale

AEonset

FAE

Fvisible

cross-head displacement [mm]

forc

e [N

]

n

um

be

r of sig

na

ls

16 09/11/2014

4. Applications

tensile testing

Specimens:

• Sigratex CE 1250-230-39

prepreg

• Cross-ply stacking with

additional reinforcements

in non-tapered regions

Acoustic emission:

• detection using two WD sensors

• 40dB preamplification

• 10 MSPs acquisition rate

• 20 kHz – 1 MHz bandpass filter

4.2

mm

2 .0 m m

0 °

9 0 °

9 0 °

0 °

0 °

2.2

mm

0 °

4 5 °

0 °

0 °

9 0 °

0 °

9 0 °

1 3 5 °

0 °

0 °

[0 /9 0 /9 0 /9 0 /0 ] s y m

[0 /0 /9 0 /9 0 /0 ] s y m

[0 /0 /9 0 /0 /0 ] s y m

W D -S e n s o r

S p a n n -

b e re ic h

18

0 m

m

1 6 m m

2

74

mm

1

K ra ft

M a rk e r fü r D e h n u n g s m e s s u n g

Mechanical parameters:

• velocity1 mm/min

• loading till load drop to 40% Fmax

• non-contact optical strain measurement

gripping

region markers for strain measurement

17 09/11/2014

4. Applications

acoustic emission recorded during tensile test

0.0 0.2 0.4 0.6 0.8 1.0 1.20

200

400

600

800

1000

1200

1400

1600

Laminate [0/0/90/0/0]sym

Matrix Cracking

Interfacial failure

Fiber breakage

str

ess [

MP

a]

strain [%]

Stress-strain curve

0 400 800 1200 1600 2000 2400

0

20

40

60

80

100

120

140

160

180

200

220

accu

mu

late

d n

um

be

r o

f sig

na

ls

time [s]

Evolution of failure mechanisms:

matrix cracks in off-axis plies

onset of delamination

onset of single filament failure

18 09/11/2014

4. Applications

comparison to Puck‘s failure criteria

0

200

400

600

800

1000

1200

1400

[0/0/90/0/0]

sym [0/0/90/90/0]

sym [0/90/90/90/0]

sym

Calculated

First ply failure

Last ply failure

Measured

Onset Matrix cracking

Onset Interfacial failure

Onset Fiber breakage

Maximum stress

Str

ess [

MP

a]

Calculated

First ply failure

Last ply failure

Measured

Onset Matrix cracking

Onset Interfacial failure

Onset Fiber breakage

Maximum strain

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

[0/0/90/0/0]

sym [0/0/90/90/0]

sym [0/90/90/90/0]

sym

Str

ain

[%

]

Comparison to acoustic emission results:

• onset of first ply failure in good coincidence with onset of matrix cracking and interfacial failure

• onset of first filament failure preceeds last ply failure systematically

19 09/11/2014

Source density:

• unequal density of acoustic emission sources during experiment

• indicates changes in crack growth

microscopic origin?

2 5 0 m m

C F K -P ro b e

W D -S e n s o re n

x

1 2

R is s s p itz e

3

H ilfs s e n s o r

3-4

mm

crack progress vs. time pseudo-3D view

x 60 mm

100 s

t

4. Applications

DCB – Double Cantilever Beam

20 09/11/2014

0 10 20 30 40 50 60 70 80 900

500

1000

1500

2000

2500

SE-Ersteinsatz

Matrixrisse

Interfaceversagen

Faserbruch

Kraft-Weg Kurve

Akkum

ulie

rte A

nzahl der

SE

-Sig

nale

[#]

Zeit [s]

0 2 4 6 8 10 12 14

0

10

20

30

40

50

60

70

Kra

ft [

N]

Traversenweg [mm]

• systematic relationship between

contributions of different failure

mechanisms and the resulting

fracture toughness values

• confirmed by microscopy

investigations of fracture surface

4. Applications

DCB – Double Cantilever Beam

forc

e [N

]

n

um

ber

of sig

na

ls

cross-head displacement [mm]

time [s]

0 50 100 150 200 250 300 350 400 450 500 550

0

10

20

30

40

50

60

70

80

90

100

Rela

tive a

kkum

ulie

rte S

ignala

mplit

ude [%

]

GIc - Wert [J/m²]

Hexcel R

TM

6=

168 [J

/m²]

HexP

ly914=

103[J

/m²]

Matrixriss

Lineare Regression

Interfaceversagen

Lineare Regression

Faserbruch

rela

tive

accu

mu

late

d s

ign

al a

mp

litu

des [%

]

GIc-value [J/m²]

matrix cracking

interfacial failure

fiber breakage

force-disp. curve

matrix cracking

linear regression

interfacial failure

linear regression

fiber breakage

AE onset

21 09/11/2014

5. Summary

acoustic emission allows for

1. localization of active damage in composite materials

2. distinction of different failure types in composite materials

acoustic emission allows for a variety of possibilities to diagnose and

understand damage progression in fiber reinforced composites and

hybrids

other applications adressed in the past comprise bondings, ENF, NOL-

rings, CT-specimens, SENB-specimens, DENT-specimens, TDCB-

specimens, peel-tests, fiber fragmentation, single filament testing,

coating integrity, sandwich structures, burst pressure tests, windmill

blades, …

Summary:

22 09/11/2014

Dr. G. Obermeier

Dr.-Ing. A.-M. Zelenyak

M. Sc. T. Guglhör

M. Sc. S. Kalafat

M. Sc. A. Monden

M. Sc. S. Richler

M. Sc. E. Laukmanis

Dipl. Phys. S. Gade

B. Sc. F. Staab

B. Sc. U. Buchner

B. Sc. N. Anderle

B. Sc. N. Schorer

S. Bessel

Dipl.Ing. (FH) S. Schmitt

Acknowledgments:

Thank you for your attention!

acoustic emission analysis for failure identification … emission analysis for failure...

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