LIFETIME
Result extraction
Q: Can fatigue results for the Flexlok be extracted in some other way or is LIFETIME the only option? I mean, can the flexlok (max) stress ranges for the desired load step differential be extracted from some .mpf file or similar?
A: You can use BPOST to export a range of different stress results to *.mpf files, and use this as a basis for fatigue calculations. Make sure that the rate of storage to the raf file is sufficiently frequent.
Stress components in the fatigue analysis for the BOUNDARY model
Q: Can the different stress components be exported via BPOST, so that I can perform the same fatigue analysis as LIFETIME reports?
A: You can export the different stress components by use of the NOPLOT command for the relevant node ranges in the BOUNDARY model. The node numbers can be seen in XPOST. The sigma-yy, sigma-zz and sigma-yz components are obtained directly via BPOST. Note that for the axial stresses, the normal and transverse components sigma-nx and sigma-tx must be added to the sigma-xx component to arrive at the total stresses.
Data in the *.lof file
Q: The *.lof lifetime output file has a list of the Boundary and Pflex nodes and some stresses info between timesteps: DSigma-M1 - Mod.-DSigma-M1 - Mean-Sigma-M1 - DSigma-M2 - Mod.-DSigma-M2 - Mean-Sigma-M2. What are the meaning of the different stresses listed?
A: The results in the *.lof file will be according to the input from the fatigue data file (the CFATFL part of the FLEXCROSS input) If you process both longitudinal (denoted M1) and transverse (denoted M2) failure modes, the meaning of the parameters are:
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DSigma-M1: stress range mode 1
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Mod.-DSigma-M1: mean stress corrected stress range mode 1
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Mean-Sigma-M1: mean stress, mode 1
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Damage-M1: damage for current case, mode 1
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Acc.-Damage-M1: accumulated damage for cases till current case
Correspondingly for the M2/transverse mode.
The method of calculation will depend on the choice made in the fatigue data file.