Random Vibration RMS Stress
Random Vibration RMS Stress
(OP)
Hi all,
Not sure if this is the best place for this post but here we go...
How do I account for a factor of safety with RMS stresses abtained from an random vibration FEA analysis using an acceleration Vs frequency PSD excitation input. Is it a simple case of doubling the RMS stress value for a factor of safty of 2? ,I plan to use this RMS stress to calculate fatigue life/damage using minors rule but when it comes to the 2 or 3 sigma the already doubled one sigma value is effectivly doubled and then doubled again which surely cannot be correct!?
or
is the damage life prediction adjusted, i.e if a part had a life of 1000 hours at factor of saftey of 1 it would only last 500 hours at FOS 2
Any help, comments or discussion on this topic is welcomed and appreciated,
Many thanks
Not sure if this is the best place for this post but here we go...
How do I account for a factor of safety with RMS stresses abtained from an random vibration FEA analysis using an acceleration Vs frequency PSD excitation input. Is it a simple case of doubling the RMS stress value for a factor of safty of 2? ,I plan to use this RMS stress to calculate fatigue life/damage using minors rule but when it comes to the 2 or 3 sigma the already doubled one sigma value is effectivly doubled and then doubled again which surely cannot be correct!?
or
is the damage life prediction adjusted, i.e if a part had a life of 1000 hours at factor of saftey of 1 it would only last 500 hours at FOS 2
Any help, comments or discussion on this topic is welcomed and appreciated,
Many thanks





RE: Random Vibration RMS Stress
On the other hand measured stresses vary by 30% or so for supposedly identical events, in my field, so a margin of 20% or so, for a doubling of life, may not be conservative.
Cheers
Greg Locock
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RE: Random Vibration RMS Stress
RE: Random Vibration RMS Stress
RE: Random Vibration RMS Stress