A Weibull based cumulative fatigue failure prediction method

The probabilistic fatigue method developed by Nash for least life type distributions is extended to treat intermediate stress levels for which no fatigue data is available. The Weibull distribution is utilised with parameters expressed as functions of the fatigue stress. A new procedure is presented utilising the Gatts equation for smoothing statistical life data for different stress levels. If coupled with statistical data on static properties, use of this method could significantly reduce the number of stress levels needed for statistically significant fatigue testing. The best available statistical fatigue data due to Wagner and Mischke is used. Weibull parameters are determined using several methods, with a combined Maximum Likelihood and graphical method recommended.