Abstract
This research is to present a new method for fatigue crack length measurement using an ion sputtered film, the thickness of which is several tens nanometer, based on the principle that the electric resistance of the film increases with the growth of a crack. The relationship between the electric resistance and width of the film was investigated and expressed accurately by a presented equation. A grid pattern ion sputtered film was proposed for crack length measurement. Fatigue crack lengths in a bending test specimen are measured with a grid pattern film and a microscope. From the comparisons of the crack length measured by the film and microscope, a good agreement is verified and the availability of the presented method is confirmed. Since the film is extremely thin, it can be used for the measurement of a micro crack as well as crack initiation detection.
