Q) In 8.1, why are principal stresses and stress intensity no longer available in postprocessing for PSD (random vibration) analyses?

A) In 8.0 and prior versions, derived stress quantities (SEQV, S1, S2, S3, SINT) were simply based on the components. Since the stress components from PSD analyses are 1-sigma results and have no sign, the applicability of the use of these statistical stress components in evaluating derived stress quantities is questionable.
In 8.1, the Segalman-Reese paper was used as a basis for calculating SEQV. The Segalman-Reese paper provides a method of determining the probability distribution of equivalent stress (SEQV). However, no provision for S1, S2, S3, or SINT was used in the paper, so, currently these items are zeroed out in the ANSYS output. Note that the resulting SEQV values are not Gaussian or centered about zero as the stress components are.


Q) In 8.1, why are principal stresses and stress intensity no longer available in postprocessing for PSD (random vibration) analyses?

A) In 8.0 and prior versions, derived stress quantities (SEQV, S1, S2, S3, SINT) were simply based on the components. Since the stress components from PSD analyses are 1-sigma results and have no sign, the applicability of the use of these statistical stress components in evaluating derived stress quantities is questionable.
In 8.1, the Segalman-Reese paper was used as a basis for calculating SEQV. The Segalman-Reese paper provides a method of determining the probability distribution of equivalent stress (SEQV). However, no provision for S1, S2, S3, or SINT was used in the paper, so, currently these items are zeroed out in the ANSYS output. Note that the resulting SEQV values are not Gaussian or centered about zero as the stress components are.





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