Plotting Average Frequency in Fatigue Analysis

Is it possible to plot the statistical average frequency used by the Steinberg method in the Mechanical Fatigue Tool? 

Not directly, but you can obtain and plot it using user defined results. The statistical average frequency is defined as: [1/(2*pi)*(velocity/displacement)]. 

You can extract the displacement as one user-defined result and the velocity as another user-defined result. You can then calculate the statistical average frequency as another user-defined result using the displacement and velocity user-defined results. 

 The displacement is the first moment of the stress term. The velocity is the second moment. Thus, for example, you can calculate the statistical average frequency for 1-sigma equivalent stress (SPSD) by extracting the displacement (first moment) as a user-defined result and the velocity (second moment) as another user-defined result. You can then create a third user-defined result using the expression: [1/(2*pi)*(velocity/displacement)] 

You can then plot the statistical average frequency user-defined result. See attached test model. 

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