Caesar II - Duvidas sobre Harmonic.

[MecFlex]

Dear Experts,

I am conducting a fatigue analysis study on Caesar II and I have some questions regarding the input of data for a suction tube.

The suction of a pump is affected by vibrations with a frequency of 4,667 Hz (in the second 90º bend) and an amplitude of 1 mm in the horizontal direction. A pump operates at 3,600 RPM (60 Hz). From what I understand, the motivation is generated due to the turbulent flow caused by the flow velocity.

I would like to clarify the following questions:

Fatigue Analysis: To perform a fatigue analysis, I can use the static input of the program and apply the frequency to the curve. Is my understanding correct?

Harmonic Analysis in Caesar II: In harmonic analysis, how can I input this data to assess whether there is a risk of resonance?

 

[johnengkol]

The 4.667 Hz are based on measurement or modal analysis on CII ?

By using static input of the program, i am not sure when will you put the frequency of 4.667 Hz to your input. Because static input are based on Fatigue curve on BPVC Sec VIII Div-2 approach, there is no relation between actual measured frequency on this static input of the Caesar II program.

I think it is more suitable if you use dynamic approach (harmonic) to this case along with initial frequency that has resonance risk,
there is frequency input on the program. But please be careful, as Caesar user guide mentioned that "harmonic jobs the calculated stresses are assumed to be zero-to-peak calculations so that they are compared to only half of the stress value extracted from the fatigue curve"