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Combination of independent vibrations for fatigue analysis

Combination of independent vibrations for fatigue analysis

Combination of independent vibrations for fatigue analysis

(OP)
I am working on the fatigue analysis of a component subjected to combined transportation and machine operating vibrations.  I have time signals of fatigue stresses induced by transportation vibration and by machnie operating vibration seperately; but not both simultaneously.  Both vibrations are indepnedet to each other.  I want to know how to construct a time signal of fatigue stress under both vibrations simultaneously from the time signals I have, because it is difficult to measure it.  

Thank you very much.  Jian Chen

RE: Combination of independent vibrations for fatigue analysis

I think you'd be safe adding them together, because they are uncorrelated.

Cheers

Greg Locock

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RE: Combination of independent vibrations for fatigue analysis

(OP)
Thank youver very much.  But how to add them together?  The two vibrations can have random phase difference.  Assume that the system is linear.  Jianiion Chen

RE: Combination of independent vibrations for fatigue analysis

In the time domain you just add them.

CombinedTimeHistory(t)=transportation(t)+machine(t)

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

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