The contribution deals with a thermographic method for a determination of fatigue limit of a cyclically loaded sample. Infrared thermography is a method for a noncontact temperature measurement. Quantitative and high accuracy thermographic measurement requires knowledge of optical properties of the measured sample surface. Thermographic paints with high emissivity are often used for these purposes. These paints also should fulfill additional requirements on mechanical loading properties if they are used for cyclic loading tests. Results of several thermographic high-emissivity paints testing are presented. Known fatigue limit testing methods were verified and improved in terms of our research. A novel 2D approach to the thermographic fatigue limit evaluation improves a visualization of the tested part violation. Experiments with different samples, using different loading frequencies and different coefficient of loading force asymmetry were performed to validate the thermographic fatigue testing method. The results of validation tests and a procedure for an automatic online evaluation of fatigue limit thermographic measurement are introduced.Keywords: Cyclic loading, infrared thermography, high emissivity paint, fatigue limit evaluation
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