Number of cycles calculation at specific frequency
Dear,
I am trying to know how the Optistruct calculate the damage factor in a sine sweep vibration, but currently I was confused by the way to calculate the cycles at specific frequency by using the stress results output from the FR simulation, the way to calculate the cycles is shown in Optistruct User Guide, page 307, which is attached below. Inhere the cycles at specific frequency can be calculated by using f/v, but it's not easy for me to understand. By using this theory, if we adding more frequency points in the Freqi cards, then the total cycles in a frequency range will be increased, which will induce a higher damage factor in this end.
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Meanwhile, I did this calculation by using Excel, and attached below:
In this sheet, the first two columns are outputted from Optistruct, the 3rd is the cycles calculated by using the formula suggested in the User Guide, the 4th is the method based on my understanding....
I see the deviation of the total cycles in this frequency range is much big, can someone tell me why? Thanks a lot!
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