Daniel Shaw
Ansys Employee

I concur with Chandra' reply.  Ansys nCode DesignLife is our best tool for directly combining the effect mean stress from a static load with PSD loading.  You just need to associate a static stress result set with a PSD loading in the DesignLife Load Mapper.  If you do not have an Ansys nCode DesignLife license and need to use the Mechanical Fatigue Tool (FT), there is a workaround that might be useful.  If the mean stress is relatively uniform in the critical region, you could extract it and assess its effect using a mean stress correction theory (probably either Goodmand or Gerber).  You could then include that mean stress effect by adjusting the material's S-N curve to create a S-N curve that includes the mean stress effect.  If the mean stress is not relatively uniform, it would require more user effect to find the mean stress at multiple locations and create multiple S-N curves.  A conservative approach is to use the maximum mean stress in the entire structure to adjust the S-N curve.