D amage initiation and development in textile composites: A - - PowerPoint PPT Presentation

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D amage initiation and development in textile composites: A gallery

Stepan V. LOMOV, Dmitry S. Ivanov, Vitaly KOISSIN, Jan KUSTERMANS, Katleen VALLONS, Jian XU, Ignaas VERPOEST Department MTM, Katholieke Universiteit Leuven, Belgium Valter CARVELLI, Vanni Neri TOMASELLI Politecnico di Milano, Italy Björn VAN DEN BROUCKE EADS Innovation Works, Munich, Germany Volker WITZEL IFB - Institut für Flugzeugbau, Universität Stuttgart, Germany

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A gallery

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C

• ntents

1. Introduction: Experimental and modelling methods for studying progressive damage 2. Woven composite 3. Non-crimp fabric composite 4. Structurally stitched composite 5. Conclusions

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1. Introduction: Experimental and modelling methods for studying progressive damage 2. Woven composite 3. Non-crimp fabric composite 4. Structurally stitched composite 5. Conclusions

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Test method: quasi static tension

2D-24

100 200 300 400 500 0.5 1 1.5 2 2.5 3 3.5 strain, % stress, MPa 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08 1.E+09 1.E+10 AE stress-strain AE events AE cumulative

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08 1.E+09 0.2 0.4 0.6 0.8 1 strain, % AE energy

cumulative energy energy of events 0.E+00 5.E+03 1.E+04 0.2 0.4 0.6 0.8 1 strain, % AE energy 0.E+00 5.E+07 1.E+08 0.2 0.4 0.6 0.8 1 strain, % AE energy

1 2 a b c min 1 2

Displacement-controlled tension (Instron) Acoustic emission (Vallen) Strain-mapping (LIMESS)

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Test methods: tension-tension fatigue

Load-controlled (MTS, Schenk) R = 0.1 f = 6…10 Hz

time stress max min

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meso-F E : R

• ad map

Geometric modeller Geometry corrector Meshing Assign material properties Boundary conditions FE solver, postprocessor Homogenisation Damage analysis

N+1 N N+2

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D amage model in F E A

Damage initiation: Hoffmann

2 9 2 8 2 7 6 5 4 2 3 2 2 2 1

) ( ) ( ) (

LT ZL TZ Z T L T L L Z Z T

C C C C C C C C C F

• 2

9 2 8 2 7 6 5 4 3 2 1

1 , 1 , 1 1 1 , 1 1 , 1 1 1 1 1 2 1 1 1 1 2 1 1 1 1 2 1

s LT s ZL s TZ c Z t Z c T t T c L t L c Z t Z c T t T c L t L c T t T c L t L c Z t Z c L t L c Z t Z c T t T

F C F C F C F F C F F C F F C F F F F F F C F F F F F F C F F F F F F C

Definition of the damage mode

L T Z

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1. Introduction: Experimental and modelling methods for studying progressive damage 2. Woven composite

• Static tension
• Finite element analysis

3. Non-crimp fabric composite 4. Structurally stitched composite 5. Conclusions

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Woven carbon/epoxy composite

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Tension

0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.005 0.01 0.015 average strain local strain

point #1

0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.005 0.01 0.015 average strain local strain

eps_X at applied strain 1% point #5

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F E modelling: Material properties and mesh

fine mesh: 26,639 elements coarse mesh: 5375 elements

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F E modelling: results

200 400 0.0 0.5 1.0 strain, % stress, MPa experiment fine mesh rough mesh rough mesh stiffening fine mesh stiffening

eps_T, strain 0.29% damaged elements 0.29%

• 0. 52%

0.29 0.24 0.05 _1, % 0.07 0.08 0.03

• 43.6

42.9 3.8 E, GPa FEA, fine mesh Experiment

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1. Introduction: Experimental and modelling methods for studying progressive damage 2. Woven composite 3. Non-crimp fabric composite

• Tension
• Tension-tension fatigue
• Finite element analysis

4. Structurally stitched composite 5. Conclusions

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N

• n-crimp fabric carbon/epoxy composite

loading direction

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N C F , T ension

(+45/-45, +45/-45)s Loading in fibre direction Damage initiation at strain 0.3% Saturation of the system of transversal cracks

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N C F , tension-tension fatigue

200 400 600 800 1000 1,E+00 1,E+01 1,E+02 1,E+03 1,E+04 1,E+05 1,E+06 1,E+07 1,E+08 Number of cycles to failure Max stress (MPa) BD+ BD-

Damage initiation stress level in static tests in BD+ Damage initiation stress level in static tests in BD-

MD BD+ BD - CD

1 1 _ult Fatigue limit is HIGHER than the damage initiation threshold

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D amage development in fatigue, load 250 MP a

500,000 1,000,000 5,000,000

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D amage saturation in fatigue

Load: 250 MPa (damage initiation level)

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N C F , finite element analysis

mesh in the plies fibre orientations near an opening change of Young module Puck’s stress intensity factor at the damage initiation level

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1. Introduction: Experimental and modelling methods for studying progressive damage 2. Woven composite 3. Non-crimp fabric composite 4. Structurally stitched composite

• Tension
• Tension-tension fatigue

5. Conclusions

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S tructurally stitched N C F carbon/epoxy composite

540 45° /-45° 556 0° /90° areal density, g/sq. m 5 mm 63 VF, % 3.2 plate thickness, mm 15 twist, 1/m 67 linear density, tex carbon 1K stitching

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Tension: stitched VS non-stitched

Change after stitching stitched non-stitched AE energy

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Tension: damage patterns

non- stitched stitched strain 0.3% strain map (eps_X) on the surface of the tufted composite structural stitching PES stitching on NCF

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Tension-tension fatigue

100 200 300 400 500 1.E+ 00 1.E+ 01 1.E+ 02 1.E+ 03 1.E+ 04 1.E+ 05 1.E+ 06 1.E+ 07 Failure Cycles Stress [ MPa] Unstitched 0º Unstitched 90º

1

100 200 300 400 500 1.E+ 00 1.E+ 01 1.E+ 02 1.E+ 03 1.E+ 04 1.E+ 05 1.E+ 06 1.E+ 07 Failure Cycles Stress [MPa]

Stitched 0º Stitched 90º

1 non-stitched stitched Fatigue limit is HIGHER than the damage initiation threshold

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1. Introduction: Experimental and modelling methods for studying progressive damage 2. Woven composite 3. Non-crimp fabric composite 4. Structurally stitched composite 5. Conclusions

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C

• nclusions

1. The methodology of studying damage processes in textile composites, has been successfully applied to different materials in conjunction with fatigue testing and FE modelling. 2. Clear relation is identified between the damage initiation limit in static tests and fatigue life limit, as well as analogy between the progressive damage patterns for static tests (increasing strain) and fatigue (loading cycles). 3. Meso-FE modelling proved to be able to produce adequate description of damage processes in textile composites.