membrane plus beding and total stress 2

[farzad1]

hello friends;

i need to know is it possible that membrane plus bending in a region be higher than total stress in that region ? if so , what causes this happen ? and what should we name it ?

 

[prex]

Rewording your question as "Is it possible that membrane plus bending stress intensity in a segment be higher than maximum stress intensity in that segment?", the answer is: Yes, it is possible.
However this is not a frequent situation, and I've never met a situation where this condition was critical to stress checking.
As an example take a stress that's linear over half thickness and zero over the other half. Something not far from this condition may occur in a thermal shock situation (unsteady state), with inner wall temperature suddenly changing.

prex

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[corus]

As prex has pointed out, the cause is due to the stress linearization method used to calculate your linear bending stress through the thickness. My guess is that the stresses would be secondary, ie. either caused by thermal loads or by a geometric discontinuity.

The total stress at the surface is the membrane plus bending plus peak stress. You can name it the total stress, or surface stress if you like.

Refer to a pressure vessel design standard for descriptions of these terms.

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