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Multiscale Damage Detection inConductive CompositesRaj C Thiagarajan, PhDATOA Scientific Technologies Pvt Ltd             ...
ATOAST• We Provide Multiphysics  Engineering Design Solutions• Driven by Material Unity Vision• We are the first COMSOL  C...
Multiscale Damage Detection inConductive Composites• Multiscale nature of damage• Damage Modes in composites• Damage detec...
Multiscaledamage mechanism Structure    Part      Laminate             Fiber             Matrix                   Mo...
Why                                                                                 Potential Safety Risk                 ...
Damage Mechanisms• Fiber   – Fiber breaks                             (a)• Matrix  – Matrix crack             (b)• Interfa...
Structural Health monitoringExisting Techniques• ultrasonic, acoustic emission, X-ray and eddy current Piezo   sensors wit...
Numerical investigation•   The electrical conduction    mechanism and the    effect of damage in CFRP    composites were  ...
Results : Fiber breaks• UD composites• Electrode on edge• Resistance change vs  fiber breaks• Parallel resistance  model b...
Results: Matrix Cracks• Matrix crack  density vs  change in  resistance• Can detect  matrix cracks  also      ATOA Scienti...
Results : Delamination• Delamination  length vs  resistance  change.• Delamination  growth  between  fibres     ATOA Scien...
Conclusions• The COMSOL model results show that the electrical  resistance change is sensitive to fiber breaks and  delami...
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Multiscale Damage Detection in Conductive Compositesosites_p1

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Conductive Composites such as carbon fiber reinforced composites are increasingly used in safety critical aerospace applications. The catastrophic macro structural failure of composite structures initiates from a micro level failure event such as fiber breaks. The ability to detect damage early on can improve the safety level and reliability of composite structures. A multilevel self-sensing damage detection techniques ability to detect damage at various length scales are numerically explored using COMSOL multiphysics software. The simulation methodology and results are reported highlighting the multilevel damage detection capability. The electrode configuration and detection sensitivity is also reported.

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Multiscale Damage Detection in Conductive Compositesosites_p1

  1. 1. Multiscale Damage Detection inConductive CompositesRaj C Thiagarajan, PhDATOA Scientific Technologies Pvt Ltd ATOA Scientific Technologies Engineering Simulation For Innovation
  2. 2. ATOAST• We Provide Multiphysics Engineering Design Solutions• Driven by Material Unity Vision• We are the first COMSOL Certified Consultant from India• ATOAST JOTHI foundation• www.atoastech.com ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 2
  3. 3. Multiscale Damage Detection inConductive Composites• Multiscale nature of damage• Damage Modes in composites• Damage detection techniques• Self sensing Carbon fiber Composites• Numerical model – Implementation – Results and discussion ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 3
  4. 4. Multiscaledamage mechanism Structure  Part Laminate Fiber Matrix Molecular c 0.142 nm 0.3345 nm 0.669 nm a b  ATOMIC bond breakage ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 4
  5. 5. Why Potential Safety Risk without diagnostics (SAFETY)• Increase use of composites in safety critical application. Design life Severe usage• Increase reliability and Designed usage safety levels Service Mild Limit usage• Reduce cost and cycle Time in Operation time Additional use may be gained through• Focus on carbon fiber diagnostics (COST) composites ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 5
  6. 6. Damage Mechanisms• Fiber – Fiber breaks (a)• Matrix – Matrix crack (b)• Interface (c) – Delamination – Longitudinal (d) cracks ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 6
  7. 7. Structural Health monitoringExisting Techniques• ultrasonic, acoustic emission, X-ray and eddy current Piezo sensors with ultrasonic tomography, Embedded Optical fibers (FBGs)Limitations• Based on external or embedded sensors.• Embedded sensors/electrodes/FBGs lead to initiation of damage in composites.Self sensing of Carbon fiber composites ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 7
  8. 8. Numerical investigation• The electrical conduction mechanism and the effect of damage in CFRP composites were simulated in COMSOL using AC/DC Electric Currents Interface.• Homogeneous composite model with effective properties• Micromechanical model with constituent properties ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 8
  9. 9. Results : Fiber breaks• UD composites• Electrode on edge• Resistance change vs fiber breaks• Parallel resistance model behavior• Very sensitive to fiber breaks. ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 9
  10. 10. Results: Matrix Cracks• Matrix crack density vs change in resistance• Can detect matrix cracks also ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 10
  11. 11. Results : Delamination• Delamination length vs resistance change.• Delamination growth between fibres ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 11
  12. 12. Conclusions• The COMSOL model results show that the electrical resistance change is sensitive to fiber breaks and delamination.• The homogenized and micromechanical model demonstrated the changes in resistance as function of damage.• The methodology developed can be used to improve the damage detection capability and reliability of composite structures by Virtual optimisation. ATOA Scientific Technologies Pvt Ltd | www.atoastech.com | COMSOL Conference 2011 | SM Composites 12

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