REEXAMINATION OF CUMULATIVE FATIGUE DAMAGE ANALYSIS - AN ENGINEERING PERSPECTIVE

A method which has evolved in our laboratories for the last 20 yers is re-examined with the intent of improving its accuracy and simplicity of application to engineering problems. Several modifications are introduced both to the analytical formulation of the damage curgve approach, and to the procedure for modifying this approach to achieve a double-linear damage rule formulation which immensely simplifies the calculation. Improvements are also introduced in the treatment of mean stress for determining fatigue life of the individual events that enter into a complex loading history. While the procedure is completely consistent with the results of numerous two-level tests that have been conducted on many materials, it is still necessary to verify applicability to complex loading histories.