Hi Van Ha,

The frequency sweep is to take into account some uncertainties in the Caesar model such as support stiffness, etc. So it's better to use the maximum displacement at resonant mode and check the level of fatigue stress comparing it to the endurance limit of material. If I remember it right, Mr. Dave also explains other means to check the output from Caesar II other than what the program selected. Say if you have failed tee and you want to get the stress result there.

Any other opinion is greatly appreciated.

Cheers!!!