The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A surface acoustic wave method for in situ monitoring of fatigue crack initiation and evolution from a pit-type surface flaw is described. The method is demonstrated for fatigue tests on Al 2024-T3 and Inconel 718 samples with different surface pit sizes. The surface acoustic wave signature is acquired continuously during the fatigue cycle without stopping the fatigue test. Crack initiation and propagation are identified clearly from the ultrasonic surface wave reflection signals. Crack initiation in the Inconel 718 sample is observed to occur at a much later stage of fatigue life than in the Al-2024-T3 sample. The ultrasonic results are supported by fractographs of fracture surfaces. Small crack sizing is performed from the ultrasonic signatures using the low frequency scattering model.