C orrelations between damage initiation thresholds in textile - - PowerPoint PPT Presentation

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C orrelations between damage initiation thresholds in textile - - PowerPoint PPT Presentation

Feb 25, 2024 409 likes •635 views

C orrelations between damage initiation thresholds in textile composites and fatigue life limits Stepan V. Lomov, Valter Carvelli, Ignaas Verpoest Department MTM Katholieke Universiteit Leuven Department of Structural Engineering

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TexComp 10 - 25 October 2010 1 1

C

  • rrelations between damage initiation

thresholds in textile composites and fatigue life limits

Stepan V. Lomov, Valter Carvelli, Ignaas Verpoest Department MTM – Katholieke Universiteit Leuven Department of Structural Engineering – Politecnico di Milano

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TexComp 10 - 25 October 2010 2 2

C

  • ntents

1. Tension-tension fatigue of textile composites 2. Acoustic emission monitoring of damage in textile composites 3. Relation between the static damage thresholds and fatigue limit 4. Conclusion

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TexComp 10 - 25 October 2010 3 3

1. Tension-tension fatigue of textile composites 2. Acoustic emission monitoring of damage in textile composites 3. Relation between the static damage thresholds and fatigue limit 4. Conclusion

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TexComp 10 - 25 October 2010 4

Test methods: tension-tension fatigue

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

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S

  • N

curve

50 100 150 200 250 300 350 400 450 500 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

I II III

stress, MPa number of cycles

glass/epoxy plain weave laminate

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TexComp 10 - 25 October 2010 6

P rogressive damage

fatigue at load 140 MPa

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1. Tension-tension fatigue of textile composites 2. Acoustic emission monitoring of damage in textile composites 3. Relation between the static damage thresholds and fatigue limit 4. Conclusion

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TexComp 10 - 25 October 2010 8

Q uasi 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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TexComp 10 - 25 October 2010 9

D amage at the threshold loads

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 2

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TexComp 10 - 25 October 2010 10

A re the damage thresholds and the fatigue life connected?

50 100 150 200 250 300 350 400 450 500 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

stress, MPa number of cycles

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1. Tension-tension fatigue of textile composites 2. Acoustic emission monitoring of damage in textile composites 3. Relation between the static damage thresholds and fatigue limit 4. Conclusion

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G lass/epoxy composites

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P lain weave glass/epoxy

Fatigue life limit corresponds to the initiation of the AE events [Lomov, Bogdanovich et al, Comp A, 2009] [Carvelli, Lomov, Bogdanovich et al, CSTE, 2010]

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TexComp 10 - 25 October 2010 14

3D woven glass/epoxy

Fatigue life limit corresponds to the initiation of the AE events [Lomov, Bogdanovich et al, Comp A, 2009] [Carvelli, Lomov, Bogdanovich et al, CSTE, 2010]

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C arbon/epoxy composites

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3D woven carbon/epoxy

100 200 300 400 500 600 700 800 900 1000 1.E+00 1.E+02 1.E+04 1.E+06 1.E+08 fatigue cycles maximum fatigue stress, MPa

Fatigue life limit corresponds to the onset of strong AE events [Karahan, Lomov, Bogdanovich et al, Comp A, 2009]

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N C F carbon/epoxy

Fatigue life limit is well above the onset of strong AE events [Vallons, Lomov et al, Comp A, 2009]

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N C F carbon/epoxy, structurally stitched

Fatigue life limit is well above the onset of strong AE events [Carvelli, Lomov et al, CSTE, 2010]

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3D carbon/epoxy braid

200 400 600 800 1000 1200 1400 0.002 0.004 0.006 0.008 0.01 0.012 strain stress, MPa 1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04 1.00E+05 1.00E+06 1.00E+07 1.00E+08

Fatigue life limit is well above the onset of strong AE events [Carvelli, Lomov, Bogdanovich et al]

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TexComp 10 - 25 October 2010 20 20

1. Tension-tension fatigue of textile composites 2. Acoustic emission monitoring of damage in textile composites 3. Relation between the static damage thresholds and fatigue limit 4. Conclusion

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S ummary: fatigue limit vsdamage initiation threshold

_min: first AE event _1: damage initiation _2: initiation

  • f high energy

damage events _ULT: failure

NCF carbon/epoxy, stitched NCF carbon/epoxy NCF carbon/epoxy, unstitched plain weave glass/epoxy 3D glass/epoxy carbon/epoxy braid 3D carbon/epoxy