TY - JOUR
T1 - Humidity and temperature cycling effects on cracks and delaminations in PEMFCs
AU - Banan, R.
AU - Zu, J.
AU - Bazylak, A.
N1 - Publisher Copyright:
Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
PY - 2015/4/1
Y1 - 2015/4/1
N2 - Temperature and relative humidity (hygrothermal) cycles during PEM fuel cell operation can lead to the introduction and exacerbation of micro-scale mechanical defects. We developed a two-dimensional finite element model based on cohesive zone theory to describe the delamination propagation at the cathodic membrane/catalyst layer interface due to temperature and hygrothermal duty cycles. Particularly, the effects of hygrothermal cycle amplitudes, relative humidity (RH) distribution profiles, and gas flow channel position were studied. It was found that doubling the hygrothermal cycle amplitude resulted in a 6-fold increase in fatigue stresses, and a defect length growth to 0,1 mm before reaching the end of the fuel cell life (40,000 cycles). A counter intuitive result was also observed, whereby a crack located within the membrane was found to grow faster than a delamination located at the catalyst layer/membrane interface. When introducing an anode/cathode channel offset, a 2-fold increase in the rate of delamination propagation was found compared to the case with the aligned anode and cathode channels.
AB - Temperature and relative humidity (hygrothermal) cycles during PEM fuel cell operation can lead to the introduction and exacerbation of micro-scale mechanical defects. We developed a two-dimensional finite element model based on cohesive zone theory to describe the delamination propagation at the cathodic membrane/catalyst layer interface due to temperature and hygrothermal duty cycles. Particularly, the effects of hygrothermal cycle amplitudes, relative humidity (RH) distribution profiles, and gas flow channel position were studied. It was found that doubling the hygrothermal cycle amplitude resulted in a 6-fold increase in fatigue stresses, and a defect length growth to 0,1 mm before reaching the end of the fuel cell life (40,000 cycles). A counter intuitive result was also observed, whereby a crack located within the membrane was found to grow faster than a delamination located at the catalyst layer/membrane interface. When introducing an anode/cathode channel offset, a 2-fold increase in the rate of delamination propagation was found compared to the case with the aligned anode and cathode channels.
KW - Cohesive Elements
KW - Delamination
KW - Fatigue
KW - Humidity and Temperature Cycles
KW - Interfaces
KW - Mechanical Degradation
KW - Polymer Electrolyte Membrane Fuel Cell
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U2 - 10.1002/fuce.201400118
DO - 10.1002/fuce.201400118
M3 - Article
AN - SCOPUS:84928371213
SN - 1615-6846
VL - 15
SP - 327
EP - 336
JO - Fuel Cells
JF - Fuel Cells
IS - 2
ER -