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1347
Fracture Properties of Catalyst Coated Membranes

In a parallel study, a fracture mechanics model based on Paris Law theory and capable of simulating the *ex situ* crack propagation in the CCM during typical fuel cell operating conditions is developed. The model incorporates the characteristic time, temperature, and humidity dependent elastic-viscoplastic mechanical behaviour of CCMs [1] through a sub model developed using the finite element method (FEM) in *COMSOL Multiphysics ^{®}*. The stress-strain relationship of CCM simulated by the FEM sub model is validated at all combinations of 23 ºC and 70ºC temperature, 50% and 90% relative humidity; and 0.0001 s

^{-1}and 0.001 s

^{-1}strain rates. Fundamental fracture mechanics parameters,

*viz.*J-integral, stress intensity factor (K), and configuration correction factor (ccf) are obtained iteratively for incremental changes in the crack length. These parameters together with the experimental crack propagation data enable the construction of Paris Curves at various temperature and humidity conditions. Information from the Paris Curves is used to predict the time taken by a CCM crack to increase from initial crack length

*a*to final crack length

_{i}*a*under typical fuel cell conditions.

_{f}The CCM crack propagation data collected and simulation capability developed during this work are considered to be important contributions towards developing a holistic understanding of mechanical fatigue and fracture phenomenon which are active during fuel cell operation and which ultimately lead to its failure.

**Acknowledgements:**

This research is supported by Ballard Power Systems and the Natural Sciences and Engineering Research Council of Canada through an Automotive Partnership Canada (APC) grant.

**References**

[1] M.A. Goulet, R.M.H. Khorasany, C. De Torres, M. Lauritzen, E. Kjeang, G.G. Wang, et al., J.of Power Sources. 234 (2013) 38–47

[2] R.M.H. Khorasany, M.-A. Goulet, A. Sadeghi Alavijeh, E. Kjeang, G.G. Wang, R.K.N.D. Rajapakse, J. Power Sources. 252 (2014) 176–188.

[3] A. Sadeghi Alavijeh, M.-A. Goulet, R. Khorsany, J. Ghataurah, C. Lim, M. Lauritzen, et al., Fuel Cells. (2015) 204–213.

[4] A. Sadeghi Alavijeh, R.M.H. Khorasany, A. Habisch, G.G. Wang, E. Kjeang, J. Power Sources. 285 (2015) 16–28.

[5] R.M.H. Khorasany, A. Sadeghi Alavijeh, E. Kjeang, G.G. Wang, R.K.N.D. Rajapakse, J. Power Sources. 274 (2015) 1208–1216.

[6] R.M.H. Khorasany, A. Sadhegi, E. Kjeang, G.G. Wang, R.K.N.D. Rajapakse, J. Power Sources. 279 (2015) 55–63.

[7] Y. Singh, R.M.H. Khorasany, A. Alavijeh, E. Kjeang, G. Wang, R.K.N.D. Rajapakse, Fracture Properties of Fuel Cell Membranes, in: 226th Meet. Electrochem. Soc., Cancun, 2014.