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UNIVERSITY OF THE BASQUE COUNTRY DETERMINATION OF TRANSVERSE COMPRESSIVE STRENGTH OF LONG FIBER COMPOSITES BY THREE-POINT BENDING OF [90m/0n] LAMINATED STRIPS N.Carbajal, A. Arrese, G. Vargas, F. Mujika 5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011 Determination of transverse compressive strength of long fiber composites by three- point bending of [90m/0n] laminated strips 1

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5th International Conference on Composites Testing and Model Simulation EPFL, Lausanne, 2011. UNIVERSITY OF THE BASQUE COUNTRY. DETERMINATION OF TRANSVERSE COMPRESSIVE STRENGTH OF LONG FIBER COMPOSITES BY THREE-POINT BENDING OF [90m/0n] LAMINATED STRIPS. - PowerPoint PPT Presentation

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Page 1: UNIVERSITY OF THE BASQUE  COUNTRY

1

UNIVERSITY OF THE BASQUE COUNTRY

DETERMINATION OF TRANSVERSE COMPRESSIVE STRENGTH OF LONG FIBER COMPOSITES BY THREE-POINT

BENDING OF [90m/0n] LAMINATED STRIPS

N.Carbajal, A. Arrese, G. Vargas, F. Mujika

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

Page 2: UNIVERSITY OF THE BASQUE  COUNTRY

2

OUTLINE

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

1. INTRODUCTION2. ANALYTICAL APPROACH3. OPTIMAL CONFIGURATION4. EXPERIMENTAL5. RESULTS AND DISCUSSION6. CONCLUSSIONS

Page 3: UNIVERSITY OF THE BASQUE  COUNTRY

3Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

1. INTRODUCTION

• Three-point bending tests of cross-ply laminate strips are proposed for determining transverse compressive strength.

• Stress state has been obtained based on the hypothesis of the Classical Beam Theory (CBT)

• An adequate configuration has been obtained by imposing the condition of maximum ratio between compressive stresses at 90º layer and tensile stresses at 0º layers.

• Three-point bending tests with different thicknesses and spans have been carried out.

Page 4: UNIVERSITY OF THE BASQUE  COUNTRY

4Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

MAIN HIPOTHESES

• Longitudinal strain on x axis ex is a linear function of z, where the reference of z coordinate is at the midplane.• The only non vanishing stress components in each ply are sx and ts.• Each ply is linearly elastic.

2. ANALYTICAL APPROACH

Page 5: UNIVERSITY OF THE BASQUE  COUNTRY

5Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

STRESS-STRAIN RELATIONS AT A LAYER

000

0

0 Tz

qq k

x

s

x

s

x

kss

xx

ks

x

e

ts

LTxykss

kss

xkxx

kxx

GGS

q

ES

q

1

1

zdzm

zdzm

dzn

dznh

h ss

h

h xxh

h ss

h

h xx

2/

2/

2/

2/2/

2/

2/

2/

t

s

t

s

FORCES AND MOMENTS PER UNIT LENGTH

Page 6: UNIVERSITY OF THE BASQUE  COUNTRY

6Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

STRAINS AND CURVATURES OF MIDPLANE

s

x

s

x

ss

xxxx

ss

xxxx

Txx

Tx

ddb

aba

mm

n

e

0

0

0000000000

0

0

n

kkk

kijij

n

kkk

kijij

n

kkk

kijij

zzqd

zzqb

zzqa

1

31

3

1

21

2

11

3121

Tzzqm

Tzzqn

n

kkk

kx

kxx

Tx

n

kkk

kx

kxx

Tx

1

21

2

11

21

000 ss

xxxxxx

Txxx

TxxxT

x

xxxxxx

xxxMx

dabndmb

dabmb

20

20

e

e

xxxxxx

Txxx

TxxxT

x

xxxxxx

xxxMx

dabnbma

dabma

2

2

Page 7: UNIVERSITY OF THE BASQUE  COUNTRY

7Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

STRESS RATIO

1211)1( 2

0

90

TT

TM

x

Mx

rrr

ss

1

1Tr

L

T

EE

hhr T

T

OPTIMAL THICKNESS RATIO

MAXIMUM STRESS RATIO

ss

2

0

90

Mx

Mx

Page 8: UNIVERSITY OF THE BASQUE  COUNTRY

8Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

STRESS RATIO, THICKNESS RATIO AND MODULUS RATIO

=0.03

=0.07=0.11

=0.23

=0.41

=0.58

=0.92

=1

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

rT

Page 9: UNIVERSITY OF THE BASQUE  COUNTRY

9Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

CONDITIONS IMPOSED FOR OPTIMAL CONFIGURATION

• Neutral axis has to be located as close as possible to the bottom part of 90º layer in order to avoid tensile stresses at 90º layer. • Maximum thermal stresses must be lower than transverse strength in

order to avoid premature failures in 90º layer. • Maximum tensile stresses at 0º layer must be lower than tensile strength.

3. OPTIMAL CONFIGURATION

Page 10: UNIVERSITY OF THE BASQUE  COUNTRY

10Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

OPTIMAL CONFIGURATION FOR T6T-F593 -> [904n/0n]

90º

hT

hL

h = 5·hL

b

z

y

z0=-h/2

z2= h/2

z1=3h/10

Page 11: UNIVERSITY OF THE BASQUE  COUNTRY

11Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

MAXIMUM TRANSVERSE COMPRESSIVE STRESS

2

2

3

90

2563681400225

ss

p

Mx

236hmx

p s

TRANSVERSE COMPRESSIVE STRENGTH FOR T6T-F593

pM

x 390 64.0 ss

Page 12: UNIVERSITY OF THE BASQUE  COUNTRY

12Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

T6T-F593 CARBON/EPOXY

Sample h (mm) hT (mm) hL (mm)[909/03]-30[9016/04]-30[9020/05]-40

2.072.973.90

1.552.383.12

0.520.590.78

SAMPLES

THREE-POINT BENDING

%10L 1min01.0

dtd xeMTS electromechanical machine

Roller radius = 2.5 mm

4. EXPERIMENTAL

ET (GPa) EL (GPa) Yt (MPa) Xt (MPa) GLT (GPa) LT L (ºC-1) T (ºC-1) (ºC) 8 108 134 1564 4 0.3 -2.81·10-7 3.61·10-5 -155

Page 13: UNIVERSITY OF THE BASQUE  COUNTRY

13Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

-400

-16

-208

1456

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

sxM (MPa)

-418

25-371

1552

-2.00

-1.00

0.00

1.00

2.00

sx (MPa)-56542

-3381

14339

zNA= 0.62

ex·106

-19

41

-162

96

sxT (MPa)

5. RESULTS AND DISCUSSION

STRESS PROFILES [909/03]- 30

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14Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

-421

9 123

1524

-2.00

-1.00

0.00

1.00

2.00

sxM (MPa)

-443

52

-22

1587

-2.00

-1.00

0.00

1.00

2.00

sx (MPa)-59473

-164

14663

zNA= 0.92

ex·106

-22

42

-14563

sxT (MPa)

STRESS PROFILES [9016/04]- 30

Page 15: UNIVERSITY OF THE BASQUE  COUNTRY

15Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

-404

9 118

1463

-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

sxM (MPa)

-426

51

-271526

-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

sx (MPa)-57449

-209

14100

zNA= 1.18

ex·106

-22

42

-14563

sxT (MPa)

STRESS PROFILES [9020/05]- 40

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16Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

PHOTOS OF FAILURE

Page 17: UNIVERSITY OF THE BASQUE  COUNTRY

17Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

0

500

1000

1500

2000

0 0,5 1 1,5 2 2,5

P (N)

d (mm)

[9020/05]-40

"P4"

"P3"

"P2"

"P1"

LOAD UNLOAD CYCLES PRIOR TO FAILURE

Page 18: UNIVERSITY OF THE BASQUE  COUNTRY

18Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

• Optimal cross-ply configuration for determining transverse compressive strength by three-point bending only depends on the relation between transverse and longitudinal modulus.• For optimal configuration of a given material the ratio between maximum stresses at 90º and 0º layers are maximum and only depends on the relation between transverse and longitudinal modulus.• Transverse compressive strength values are very similar between them.• The appearance of damage agrees well with the transverse compressive failure related to end-loaded compression tests. • No tensile failure has been found prior to final failure.

6. CONCLUSIONS

Page 19: UNIVERSITY OF THE BASQUE  COUNTRY

19

THANK YOU FOR YOUR ATTENTION

5th International Conference on Composites Testing and Model SimulationEPFL, Lausanne, 2011

Determination of transverse compressive strength of long fiber composites by three-point bending of [90m/0n] laminated strips