Analysis of the fire reaction of fiber reinforced polymer matrix composites exposed to a flame
Creators: name:  A. COPPALLE 
name:   E. SCHUHLER 
name:   W. WANG 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: STRUCTURES
MATERIALS
POLYMER
COMPOSITE

description: In the aircrafts, composite materials are now widely used. An important issue is that they may be exposed to a flame, during a malfunction of the engines or after a crash. Under such circumstances, the composite is degraded and it loses its performances. In order to test the fire reaction of the materials, there are several standard tests specific to aeronautical applications [1], in particular some of them use propane or kerosene impinging flames [2-3]. However, they are expensive, time consuming and requires heavy equipment. They can be used only for certification, and it is hard to use it for development and optimisation of new products with improved fire reaction. Therefore, before certification, these new products have to be analysed and tested at laboratory scales. This is often achieved with a cone calorimeter that apply on the sample a radiative flux on the sample [4-5]. However, the maximum thermal stress is limited to 100kw/m2, which is well beyond the values encountered in real scenarios, and a direct flame impact is a more realistic thermal stress. Therefore, a new bench test was built in order to analyse at small scales, typically with sample size of a dozen of centimeters, the behaviour of composites under a kerosene flame. Compared to standard tests, more measurement setup can be installed allowing scrutinizing in details the behavior of the sample during tests, and analyses can be easily done on a larger number of samples. The kerosene burner of the bench test is made of a combustion chamber fed with a spray of kerosene (0.27g/s) and a flame-tube (30 cm long and 5 cm diameter), thus providing at the exit a homogeneous flux of hot gases. The combustible to air ratio is equal to 80 % of the stoichiometric value. The temperature on the flame axis is measured by thermocouples, with values equal to 1100 C. The heat flux is measured with a gardon-type gauge put in front of the flame, and providing a value equal to 118kW/m2 kw/m2 at 10 cm from the flame exit. The flexibility of the bench test is that the heat flux can be varied in the range 80kW-180kW, by changing the distance between the flame tube exit and the sample, or the air and kerosene flow rates. The temperature of the rear face has been observed using an IR camera, and the sample mass losses monitored during tests with a load cell. As an exemple, the test results for two carbon fiber reinforced polymer matrix composites, a thermosetting-based (epoxy 8552) and a thermoplastic-based (PEEK), will be shown and analyzed. The comparison of the temperature and the mass loss during the tests will highlight the main differences observed on the behavior of these composites exposed to a kerosene flame. Acknowledgement: This work is part of the RIN AEROFLAMME project, funded by the Normandy regional council. References. [1] A. P. Mouritz, A.G. Gibson. Fire Tests for Composites. In: Fire Properties of Polymer Composite Materials. Solid Mechanics and Its Applications, vol 143 (2006). Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-5356-6_11 [2] ISO2685:1998(E). Aircraft-environment test procedures for airborne equipment resistance to fire in designated fire zones. [3]. FAR25.856(b):.Title 14 code of Federal test methods to determine the burnthrough resistance of thermal/acoustic insulation materials (Appendix F, Part VII), 2003. [4] S. I.Stoliarova, S. Crowley. R. E.Lyon, G. T.Linteris. Prediction of the burning rates of non-charring polymers. Combustion and Flame, 156 (2009), 1068-1083. https://doi.org/10.1016/j.combustflame.2008.11.010 [5] N. Grange, K. Chetehouna, N. Gascoin, A. Coppalle, I. Reynaud, S. Senave. One-dimensional pyrolysis of carbon based composite materials using FireFOAM, Fire Safety Journal 97 (2018) 6675. https://doi.org/10.1016/j.firesaf.2018.03.002