1. ESTIMATION OF THE REMAINING LIFETIME ON COMPOSITE MATERIALS BY MODELING THE ACOUSTIC EMISSION APPEARANCE RATE M. Darwiche (LAUM - ESEO), G. Bousaleh (Libanese University), D. Schang (ESEO), R. El Guerjouma (LAUM) mohamad.darwiche@hotmail.com

2. Overview Motivations Test Method Results Conclusion and Perspectives 2 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

3. Motivations 3 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

4. Motivations 4 Type of material Lifetime prediction Type of damage  “The use of composite materials is becoming of greater interest in different industrial fields, especially aircraft, aerospace, naval industry, etc… ”.  Some studies are needed to guaranty the proper functioning of the materials: M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

5. Motivations 5  “The use of composite materials is becoming of greater interest in different industrial fields, especially aircraft, aerospace, naval industry, etc… ”.  Some studies are needed to guaranty the proper functioning of the materials: Lifetime prediction Type of damage Type of material M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

6. Motivations Lifetime prediction : creep test  Seven tensile specimens have been tested (8 plies unidirectional fiberglass reinforced with resin) with the same stress level  Seven different rupture time : (539s, 159s, 3362s, 1831s, 992s, 145s and 845s). 200 mm 20 mm 6 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

7. Test 7 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

8. 8 Creep test monitored using acoustic emission Creep test : a constant stress is applied Acoustic emission device M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

9. time Amplitude () signals N° > 70 > 35 > 20 > 9 > 4 < 4 9 Creep test monitored using acoustic emission Acoustic Emission distribution versus time M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

10. Phase 1: Dramatic increase of acoustic emission due to the macromolecular connections. Phase 2: The acoustic activity is low, the deformation varies linearly with time. It’s the most dominant phase throughout the creep test. Phase 3: is characterized by a sudden acceleration of the AE rate causing the rupture of the material. Test 10 1 2 3 time Acoustic Emission distribution versus time M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

11. Test 11 1 2 3 time  Challenge : predict the rupture time of a tensile specimen from the reference time t ref t ref trtr M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

12. Method 12 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

13. Method 13 Normalization technique AE reconstruction Reference time detection 1 2 3 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

14. Method 14 CS’ = CS / NT Є [0, 1] ; CS: cumulative number of AE, NT: total number of AE t’ = t / tr Є [0, 1]; t: time, tr: rupture time 1.Normalization technique M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

15. Method 15 All samples normalized 1.Normalization technique M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

16. Method 16 2.Polynomial reconstruction Best fitting = Minimal error M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

17. Method 17 3.Reference time detection derivation M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

18. Method 18 3.Reference time detection Reference time localization after 50% decrease the AE rate M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate " t re : reference time localized after 50% decrease the AE rate error :

19. Specimen 1 Specimen 7 Method Model creation test 19 6 tensile specimen Specimen 1 To guarantee the performance : - K-fold cross validation (K=7) - one cross validation : Specimen 7 Specimen 2 Specimen 3 Specimen 4 Specimen 5 Specimen 6 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

20. Results 20 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

21. Results 21 Looking for other reference times M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate " Reference time localization after the decrease of the AE rate by : 10%, 20%, 30%, 40%, 50%, 60%, 70% and 80%

22. Results 22 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate " m ref : mean value of t ref t re : estimated rupture time er : error Rupture time estimation from t ref10%, t ref 20%,t ref 30%, t ref 40%, t ref 50%, t ref 60%, t ref 70% and t ref 80%

23. m ref : mean value of t ref t re : estimated rupture time er : error Results 23 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate " Rupture time estimation from t ref10%, t ref 20%,t ref 30%, t ref 40%, t ref 50%, t ref 60%, t ref 70% and t ref 80%

24. Results 24 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate " Comparing results Best results

25. Conclusion 25 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "

26. Conclusion An interesting step for lifetime prediction… if we have a specimen on use, ones we can localize t ref and then estimate the remaining lifetime. 26 Perspective: looking for relation into the second phase to estimate the remaining lifetime M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate " with t ref10%, we can estimate the rupture time from 0.4% of the integral lifetime with an error about 6.36%

27. Questions Thank you… Any questions ? Any suggestions ? 27 M. Darwiche " estimation of the remaining lifetime on composite materials by modeling the acoustic emission appearance rate "