Vibration analysis motor base plate

[0702518]

Hi, Looking for a pointer on where to start with a problem we have on site.
It has been a long time since I last did vibration calculations. I would normally use a software package but this is not available so I need to go back to first principles, any advice would be greatly appreciated.

We have a motor on site that is above vibration alarm limits. Further investigation, phase analysis and amplitude readings across the motor feet, base plate and steelwork suggest that the base plate the motor feet are bolted on to is too thin and vibrating with the motor. I believe the solution is to increase the thickness of the base plate which will stiffen the structure and reduce the vibration. I would like to try and perform some calculations to estimate what impact this thickness change will have. Does anyone have experience with this?

Kind regards

 

[Tmoose]

What are the frequencies of interest? 1X motor rotation, belt rpm, driven equipment 1X, ???
Are there compounding factors like "critical speeds" if variable speed?

How far does your vibration survey extend beyond the motor feet? Do you eventually get to a location in the support structure the amplitude of the concerning "vibration" frequency is less than 0.01 ips peak ?

 

[desertfox]

Hi
I'm not doubting that the base plate is too thin but have you check how tight the fixing bolts are before doing anything else?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein