Mean Strain Effects on the Strain Life Fatigue Curve

Aluminum 7075-T6 was tested using a Fatigue Material Test System. After creating the monotonic and cyclic stress-strain curves to verify material properties, strain life test data were replicated twenty times each to obtain the statistical description of standard strain life curve for zero mean strain. ne mean strain was then varied to create a total of four statistically described curves. Accounting for the statistical distribution, various characteristics were plotted in order to better understand the effects of mean strain. For example, strain range was plotted against the mean strain for given lives and results were compared to equations in use today that account for mean stress.