Hi all,
I'm fairly new to vibrations with Sim Mech.
Can anyone shed me some light regarding Frequency response and Random Vibration Analysis?
When should I use frequecy response and when should I use random vibration?
I had tried reading them in autodesk help but still can't really understand.
Thanks!
Solved! Go to Solution.
Solved by arizawilmer. Go to Solution.
Hi
is easy with examples....
Frequency response:
You have a motor that vibrate to a exact frequency, how are you structure going to response?
Random Vibration
You have the suspension of a car that has to support the vibration of the road, you put the specter of the norm and the simulation evaluate with a random sample over that specter.
So is it safe to say that, if I have only one frequency I should go for frequency response, and if I have a set of frequencies to simulate I should go for random vibration?
Thanks for clarifying these for me.
Yes, in random vibration you will use a spectrum, a band of frequencies in witch the software will generate random vibrations to test your structure. This is used in automotive industry and aeronautical industry.
Hi!
Just blending into this discussion here...
I'm also quite new to vibration analysis.
I have a skid/base frame with a motor and a pump. The motor driving the pump runs at 1769rpm (29,48 Hz), and the exchange is 1 to 1 so the pump has the same rpm. There is also an internal gear on the pump that gives an additional exitation frequency of 27 X rpm 795,96. At the test (physical test run of the produced skid) we get som unwanted vibrations that we are trying to reduce as much as possible. The motor seems to be very well balanced and its foundation is stiff enough, so we assume that the vibrations aren't coming from the motor. The pump however is mounted on a pedestal on top of the skid/steel frame, and this pedestal seems to be to weak, as the pump vibrates during test run.
What I want to do for a start is to recreate the testrun situation, see if we can simulate a similar vibration situation, and from there take measures to reduce the unwanted vibrations.
So, to my question: do I use frequency response or random vibration?
Additional questions:
Since we don't have any specific excitation forces or accelerations, is it reasonable to use a percentage of the pump weight as excitation force?
Is it correct to enter a low damping ratio to get a maximum response?
Hope you can help me!
Thanks!
HI
As you know the frequency I will start with a frequency response.
You have a excellent book example you can reproduce your problem in the software and find a solution trough Finite elements.
Maybe you can find that the frequency that you calculate is not exactly the frequency of the structure, maybe there is some damping but I will start with frequency response.