Random Response XY plot output for X-direction

[FakeCaptainGabriel]

Hello there, I have a model that is a metallic payload on a vibration fixture and running random response on it.

The PSD plot input is from 20-2000Hz. I conducted modal analysis for it and the first nat freq was 3000+Hz which is away from the maximum operating freq range. 

I dont think my results should look like this please help and see if it is probably the setup of my random response

My aim is to find the acceleration responses at certain places that i had selected using the XY plot function but got such results .....

I should be seeing some peaks at certain excitation frequencies but seems like i cant see it from my set of results

 

[John_Holtz]

Hi @FakeCaptainGabriel 

Can you clarify why you expect to see peaks in the graph, and at what frequencies (or where) you expect them?

The peaks normally occur at the natural frequencies. Since your first frequency is 3000 Hz which is above the range of 2000 Hz that you are vibrating the model, the analysis has not gotten to the first peak yet. To confirm this, you could extend the PSD input from 2000 Hz to 10,000 Hz (keep the value constant), and run the random response analysis out to 10,000 Hz excitation. Then you should start to see the behavior you are expecting.

Another way to state this is as follows: The part vibrates at a higher frequency than the PSD, so random vibration is not a problem.

John