Here is a paper.
Estimating Fatigue Damage from Stress Power Spectral Density Functions: estimate_fatigue_psd.pdf
Note that the duration for the example in the paper was 600 sec.
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This following Matlab program calculates the cumulative rainflow fatigue damage for an input stress PSD using the following wideband methods:
1. Wirsching & Light
2. Ortiz & Chen
3. Lutes & Larsen, Single-Moment
4. Benasciutti & Tovo, alpha 0.75
5. Dirlik
6. Zhao & Baker
Reference:
Random Vibrations: Theory and Practice (Dover Books on Physics)
The stress PSD and the fatigue strength coefficient must have consistent stress units.
The input PSD must have two columns: freq(Hz) & stress(unit^2/Hz)
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Main scripts:
Vibrationdata Signal Analysis Package
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The following values are “For Reference Only.”
m = fatigue exponent
A = fatigue strength coefficient
Aluminum 6061-T6 with zero mean stress
m=9.25
A=9.7724e+17 (ksi^9.25)
A=5.5757e+25 (MPa^9.25)
Butt-welded Steel Joints
m=3.5
A=1.255e+11 (ksi^3.5)
A=1.080e+14 (MPa^3.5)
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See also:
Mrsnik, Janko Slavic, Boltezar, Frequency-domain methods for a vibration-fatigue-life estimation – Application to real data: mrsnik_article_vib_fatigue.pdf
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– Tom Irvine
Hi Tom,
Do you happen to have a .pdf writeup on the application of this? I don’t have access to Matlab.
Thanks,
Doug
Doug,
I will try to post one in a week or so. In the mean time, you could order the Random Vibration reference book. It is less than $20.
– Tom
Great, Thanks, Tom! I may order one, too, but it is always great to see how you decode all the theory into a usable ‘engineering’ math form! Ha ha