In their recent paper 1 Segalman and coauthors estimate the probability distribution for the von Mises stress resulting from Gaussian random loadings of zero mean. Although they do not explain clearly what use is intended for this “important result for reliability of structures,” we anticipate that it must be somehow related either to fatigue or to the estimation of the extreme value over some return period (peak factor). The problem with the von Mises stress when it is defined in the time domain as it is in this paper is that:
• it is always positive and does not reduce itself to the applied alternating stress in the simple uniaxial case.
• its frequency content is not consistent with the frequency content of the stress components and the natural frequencies of the structure.
By Dan Segalman, Garth Reese, Richard Field, Jr., and Clay Fulcher and published in the January 2000 issue of the JOURNAL OF VIBRATION AND ACOUSTICS, Vol. 122, No. 1, pp. 42–48.
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