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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

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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 "

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

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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 "

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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 "

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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 "

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

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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 "

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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 "

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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 "

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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 "

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

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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 "

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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 "

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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 "

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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 "

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

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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 :

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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 "

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

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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%

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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%

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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%

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

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

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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%

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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 "

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