Louisiana State University and Agricultural & Mechanical College

Mehdi Amiri Darehbidi

Michael Khonsari

Mehdi Naderi Abadi

A method and apparatus are disclosed for approximating in real time the fracture fatigue entropy (FFE) of a metallic object subjected to cyclic loading. Such objects experience fatigue, which can lead to failure after a number of loading cycles. The disclosed invention allows for real time monitoring of the entropy increase in a metallic object under cyclic loading, and allows for removing the object from service before fatigue fracture occurs. Through use of the present invention, users may keep metallic objects in service for longer periods, because such objects may be safely taken closer to the fatigue fracture point. The invention therefore can effectively extend the useful life of many critical components and reduce downtime resulting from repair or premature replacement.

Fracture fatigue entropy determination

A method and apparatus are disclosed for predicting the service life of a metallic structure subjected to cyclic loading. Such structures experience fatigue, which can lead to failure after a number of loading cycles. The disclosed invention allows for an accurate prediction of the number of cycles to failure for a metallic structure by observing the slope of the rise in surface temperature of the structure after the cyclic loading has begun. The method of this invention provides early and accurate predictions of service life and does not require destructive testing. The method and apparatus of the present invention may be installed on working equipment, thus providing service life predictions for materials in real world use. The invention uses an empirically derived relationship that was confirmed using analytical relationships and material properties. The derived formula uses two constants that may be determined empirically using a disclosed process. The constants also may be estimated mathematically. The apparatus may include a wireless temperature sensor mounted on the metallic structure of interest and a data analysis unit to perform the needed calculations.

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Baton Rouge, LA, United States of America

Mehdi Amiri Darehbidi