Long crack behavior in a thermal barrier coating upon thermal shock loading |
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Authors: | Y Liu C Persson S Melin J Wigren |
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Affiliation: | 1.Division of Materials Engineering,Lund University,Lund,Sweden;2.Division of Solid Mechanics, Department of Mechanical Engineering,Lund University,Lund,Sweden;3.Volvo Aero Corporation,Trollh?ttan,Sweden |
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Abstract: | The behavior of macroscopic long cracks in the ceramic top coat of a thermal barrier coating (TBC) system subjected to thermal
shock loading and the influence of the cracks on the coating durability were investigated experimentally and numerically.
Thermal shock testing was conducted until coating failure. Comparisons were made with coating samples without macroscopic
cracks. The experimental results revealed that the presence of macroscopic cracks reduces the life of the TBC. The finite-element
method, with a fracture mechanics approach, was applied to analyze preexisting long cracks, and the calculations correlate
well with the experimental findings. It was found that the life of the coating is reduced with crack length as well as with
maximum cycle temperature. It was also found that the stress-intensity factors for long cracks are initially high and decrease
with the number of temperature cycles, which indicates that rapid crack growth occurs during the first number of cycles. |
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Keywords: | finite-element method long cracks thermal barrier coatings thermal shock tests |
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