A review was made of the result's that have been published of experi¬mental and theoretical investigations of low-cycle fatigue phenomena. Two experimental programs were conducted using 2024 aluminum alloy, one with notched sheet specimens with theoretical elastic stress concentration factors of 2.0, 2.5, and 4.0, the other with unnotched round specimens. For the notched specimens it was found that a straight line relationship existed between the range of strain measured at the edge of the notch and the number of cycles to failure when these variables were plotted on log-log scales. This straight line relation¬ship was also found to describe the unnotched specimen test data. In addition, for the unnotched specimen results an interaction diagram was constructed with range of strain as the ordinate and mean strain as the abscissa with cycles to failure as a parameter. With the aid of this diagram the fatigue behavior near ultimate load is discussed.
展开▼
