Combined lock-in thermography and heat flow measurements for analysing heat dissipation during fatigue crack propagation
During fatigue crack propagation experiments with constant force as well as constant stress intensity lock in thermography and heat flow measurements with a new developed peltier sensor have been performed. With lock in thermography space resolved measurements are possible and the evaluation allow...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Gruppo Italiano Frattura
2015-10-01
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| Series: | Fracture and Structural Integrity |
| Subjects: | |
| Online Access: | http://www.gruppofrattura.it/pdf/rivista/numero34/numero_34_art_51.pdf |
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| Summary: | During fatigue crack propagation experiments with constant force as well as constant stress
intensity lock in thermography and heat flow measurements with a new developed peltier sensor have been
performed. With lock in thermography space resolved measurements are possible and the evaluation allows to
distinguish between elastic and dissipated energies. The specimens have to be coated with black paint to
enhance the emissivity. The thickness of the coating influences the results and therefore quantitative
measurements are problematic. The heat flow measurements are easy to perform and provide quantitative
results but only integral in an area given by the used peltier element. To get comparable results the values
measured with thermography were summarized in an area equivalent to that of the peltier element. The
experiments with constant force show a good agreement between the thermography and the heat flow
measurements. In case of the experiments with a constant stress intensity some differences become visible.
Whereas the thermography measurements show a linear decrease of the signal with rising crack length, the heat
flow measurements show a clearly nonlinear dependency. Obviously the measured energies in thermography
and peltier based heat flow measurement are not comparable |
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| ISSN: | 1971-8993 1971-8993 |