Hi,

My Client found the vibration problem on the piping system. He request me to solve this problem by using CaesarII. This system consists Choke Valve and Ball valve. Vibration is caused by the high pressure drop thru the choke valve.

I try to do dynamic analysis by using Modal Analysis to find out the natural frequency which match with the actual vibration.

My question is what is required data from measure from site to meet or use to compare with the shape of vibration at any mode of natural frequency. I guess that the displacement at vibration frequency. What else?

Thank you.

If you are sure it is a system response, using Modal Analysis you should find a frequency mode shape that matches reality, if your model is accurate and boundary conditions are correct. Don't worry initially about magnitude of displacements. Careful use of additional restraints MAY solve your problem

You may have a different problem since choke valve vibration is usually high frequency. You may have pipe wall and component vibration (causing section ovalisation or multi lobe shapes like a bell) which Caesar cannot deal with. This kind of vibration is a common failure mode. The cheapest solution is often to buy a low noise valve trim.