Problem:

What is the simplest way to check system against the vane frequency of pumps in the piping system?

Example:

System has three (3) pumps producing ~ 150Hz frequency into the system. Want to excite the system only with the pump frequencies, but the input menus is asking for displacements, forces and etc,  Only interested in knowing if pumps will push the piping system into excessive vibration or resonance frequency.

Solution:

Dynamic Analysis Harmonic Load case is the best way. In order to use this feature user would need:

a. All information required by the Harmonic Load dialog:

• Damping ratio
• Point Name
• Frequency
• Phase Angle
• Harmonic Load  in Imposed:  Acc. (in/s/s), Acc. (G), Velocity (in/s), Displacement (in), or Force (lbf)

b. Accurately model the system including the restraint stiffness.

If any of the above information is missing, simply perform a Dynamic > Modal analysis and avoid the forcing frequency from the pumps. 

Or, simulate the acoustic model using Bentley PULS. Another Bentley Application that can calculate the shaking forces and export them using harmonic HMF file directly to AutoPIPE. 

Note: contact your Account Manager Sales person to discuss PULS availability and limitations. 

See Also

How can I include pulsation forces from piston type pump to piping?

Dynamic "Harmonic" Analysis

Bentley AutoPIPE