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Assessment of the Sealing Joints within SOFC Stacks by Numerical Simulation
Author(s) -
Müller A.,
Goswami S.,
Becker W.,
Stolten D.,
de Haart L. G. J. Bert,
Steinbrech R. W.
Publication year - 2006
Publication title -
fuel cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.485
H-Index - 69
eISSN - 1615-6854
pISSN - 1615-6846
DOI - 10.1002/fuce.200500115
Subject(s) - materials science , ceramic , stack (abstract data type) , composite material , interconnection , strain energy release rate , stress (linguistics) , fracture mechanics , joint (building) , fracture toughness , toughness , fracture (geology) , structural engineering , computer science , engineering , programming language , computer network , linguistics , philosophy
The advantage of the numerical simulation of the mechanical behaviour of a complex system, like a fuel cell stack, is that the potential initiation of failure can be detected in an early stage of development. For most planar SOFC stacks the sealing joints are the components where the highest level of demand is made, so potential crack propagation in this region has to be investigated in order to reveal weaknesses. The sealing joints are subjected to high thermal loads, caused by the manufacturing process and the service conditions, which may lead to fracture in the vicinity of the interfaces of the interconnect and the layers of the cell. This is due to the different layer‐wise thermo‐mechanical behaviour of the individual materials. The simulation of growing cracks along the different interfaces between the cell and glass ceramic (as the joining material), i.e., the interconnect and glass ceramic, shows that the numerical calculation of the energy release rates helps to find a joint design that avoids crack initiation. The criticality of the joints can be assessed by comparing the calculated energy release rate with the individual toughness of the joined materials and of the interface itself. Stress‐based crack initiation is discussed, as a further necessary criterion. Fracture occurs only if a characteristic value of the stress level, the strength, is exceeded. Together, these two criteria seem sufficient for crack initiation and propagation at bimaterial interfaces.