Th e rm o -che m ical be haviour of charring m aterials. TGA / DSC analysis for chemical kinetics and energetics modelling

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2 Outlines Research framework Th e rm o -che m ical be haviour of charring m aterials TGA / DSC analysis for chemical kinetics and energetics modelling Heat and mass transfer within charring materials Anisotropic thermal behaviour and homogenisation Multi-species pyrolysis modelling Th e rm o -mechanical behaviour and damage Mechanical properties assessment as a function of temperature Application to tension loading and delamination characterisation Fire be haviour of com posite m aterials Fire dynamics and interaction with decomposition volatiles Flame/composite coupled simulation 2

3 Research framework ONERA as an interface between academia and industry Fire behaviour of composites = multi-sca le problem X-ray µt omography, Length scale Condensed matter [mg - mm] Laser-i nduced decomposi t i on of a composit e t est coupon Material [g - cm] Structure [kg - m] Aircraft/Engine [t - m] Charred thermoplastic nodules 3 Delamination Influence of the charring nodules on t he onset of delaminat ion damage Fr am e/ Sk i n/ St r i nger hybrid junctions

4 Research framework Methodology of investigation Conventional approach and current limitations Fire behaviour Multi-physics Anisotropic thermo-mechanics Complex fire dynamics Interface interactions Experimental Standard tests Measurements Test conditions Expensive Difficult cone calorimetry, FAR25.856(b):2003, ISO2685:1998(e) limited, biased if embedded within coupons radiant panel, gas or fuel burner, free room conditions only representative of specific test conditions Numerical Model dimension Input parameters Boundary conditions Couplings mainly 1D, 2D (Therm akin), 3D (Gpyro, PATO) numerous! tensorial properties, temperature-dependent reaction-dependent constant uniform temperature or heat flux, unexposed surfaces BC? ignored! Key cha llenges: better testing environment control to investigate material response and damage mechanisms accurate material properties assessment not to rely on optimisation algorithms model formulation relevant to involved phenomena, thermal and mechanical loadings, interactions 4

5 Research framework Methodology of investigation Re qu ire m e n ts de fin ition Main idea: isolating each physics and dividing the problem into elementary bricks Preliminary properties characterisation properties not adjusted with fire test results Designing dedicated thermal decomposition experiment precise test conditions controlled heat flux distribution in space and time non-uniform heating to reveal orthotropic thermal response heat flux magnitude representative of fire tests non-intrusive measurements to analyse the material transient behaviour Post-test m icrograp hic im aging cross-section views of damaged coupons Deve loping m ode lling fram ework orthotropic heat and mass transfer within decomposing porous medium advanced homogenisation methods for properties evolution as a function of temperature and decomposition Understand the material behaviour to propose relevant damage mechanisms scenarios from complementary experimental and numerical analysis 5 Next steps: Models for post-fire structural response, delamination onset and growth, flame/structure interactions

6 Research framework Methodology of investigation Expe rim e n ta l fa cilitie s deve lope d a t ONERA BLADE facility Th e rm o -ch e m ica l behaviour IN JECT facility Th e rm o -m e ch an ical behaviour Nu m e rica l tools deve lope d a t ONERA FIRE facility Fire behaviour Numericalm u lt i-physics software for energetics and propulsion sim ula tions Material and structure a na lysis and sim ula tion software Mu lt i-species pyrolysis numerical software + ADeTheC toolbox 6

7 Thermo-chemical behaviour of charring materials TGA / DSC analysis for chemical kinetics and energetics modelling ADETHEC: a post-proce ssin g toolbox for kin e tics and energetics a n a lysis of de com posin g com posite m a te ria ls easy plot and data comparison of TGA and DSC measurements identification of Arrhenius param eters for chem ical kinetics modelling of reaction rate equation user-defined reaction mechanisms integration of DSC signals to extract the heat of reactions reconstruction of species evolution as a function of temperature Input data for pyrolysis model 7

8 Heat and mass transfer within charring materials Anisotropic thermal behaviour and homogenisation Homogenisation of the thermal properties REV VIRGIN resin CHARRING resin CHARRED m atrix char char gas* gas(es) gas(es) (* initial porosity) fib re s m Thermal properties at the virgin state m 0 Bridging functions using homogenisation theory Thermal properties at the charred state m f Pyrolysis re action T 8

9 Heat and mass transfer within charring materials Anisotropic thermal behaviour and homogenisation Onset and propagation of delamination damage Back surface IR measurements Temperature evolution on the back surface Detection of delamination damage from IR thermographic measurements: iso-contour of ϊt/ϊt=0 Good correlation with micrographic analysis on damaged test coupons 9

10 Heat and mass transfer within charring materials Multi-species pyrolysis modelling Th e rm o -ch e m ica l re spon se with in th e la m in a te du rin g la se r-induced decomposition Modèle de Dégradation Thermique des Composites Anisotropic heat and mass transfer Arrhenius reaction rate equations Multi-spe cie s form ulation Darcy s flow of de com position volatile s within the porous m e dium Mori-Tanaka homogenisation of the thermal conductivity tensor Validation against temperature measurements on the BLADE facility before the onset of delamination 10

11 Thermo-mechanical behaviour and damage Mechanical properties assessment as a function of temperature I N JECT : INternal Joule heating for thermo mechanical characte risa tion Tensile machine Use Joule heating High heating rate Neglect the decomposition effect on the mechanical properties Multi instrumentation Characterisation in temperature of classical composite coupons 11

12 Thermo-mechanical behaviour and damage Application to tension loading and delamination characterisation I N JECT : INternal Joule heating for thermo mechanical characte risa tion Tension Loading Out of plane loading Young Modulus [GPa] dt / dt [ C/ s] Time [s] Tim e [s] 100W 0W 150W 200W 100W Electrical Power : 20 W 4.3 A IR Ca m e ra Loading roller Tef lon Insert Support roller Temperat ure [ C] Temperature [ C] Teflon Insert Loading roller Teflon Insert DIC Tim e [s] Ca m e ra IR Ca m e ra 12

13 Fire behaviour of composite materials Fire dynamics and interaction with decomposition volatiles FIRE: Fla m e -wa ll Interaction Research Experiment Fire dynamics non-intrusive measurements using LDV (Laser Doppler Velocimetry) 13 Anisotropic thermal response during fire decomposition Interaction between fire and composite materials

14 Fire behaviour of composite materials Flame/composite coupled simulation De fin in g re leva n t numericalcou plin g Uncoupled simulation constant heat flux distribution High heat flux causes important decomposition Classical ae ro-th e rm al sim u lation data exchanges: [ Ф ] flame <=> [ T ] solid (Convective) heat flux decreases as the surface temperature increases In e rt (N 2 ) gas blowing surface data exchanges: [ Ф ] flame <=> [ T ; m N2 ] solid Film cooling effect because [ T gas ] solid < [ T gas ] fluid Ign itab le (C 3 H 8 ) gas blowing surface data exchanges: [ Ф ] flame <=> [ T ; m C3H8 ] solid Film cooling effect but gas ignition extends the decomposition area 14

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