Random Vibration Duration

[sarclee]

Hi, I would like to know if the duration is different for the same random vibration test profile, would the energy still the same?

For example, if the part break under the profile below for 60sec, would this failure occurs to be expected for the same profile for 20sec?

Are we able to capture this in the simulation as time is not the input? Is it no different in PSD?

Thank you so much!

 

[SWComposites]

the longer you run the vibration test the more likely there will be failure. any simulation would need to include time.

 

[sarclee]

Thanks for your reply @SWComposites.

Random vibration is a linear analysis. No input for the duration.

 

[IRstuff]

Isn't the reason why something might break under vibration the critical thing?

Presumably, if it's some sort of fatigue failure, duration is absolutely critical to the failure, just like bending a fork once is probably tolerable, but bending it 6 times will break it, although the amplitude of the bend is also a critical factor.

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[sarclee]

@IRstuff, there are some screws are broken.

The Grms is too high than it is designed but the duration is shorter... I was thinking how to consider the time factor....

However, I think if the Grms reached to the peak and it breaks the screws then I can consider using that Grms level into simulation to check the forces regardless the duration.

I don't think there is a risk of fatigue as the number of testing is a few times.... but then high cycle of fatigue?