I was given the Femap Stress Linearization Tool recently and it works great! I was wondering if anyone could provide some advice and/or reasoning regarding when to use Tresca stress vs. von Mises stress? In addition, any reasoning for when to use the "Full Component Bending" option?
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I think the reason is in the different criterion used in the pressure vessel analysis:
ASME Section VIII Division 2 require Von Mises stress;
EN 13445 require Tresca criterion
To really understand the difference between Von Mises and Tresca I would review Mohrs Circle and learn it that way. Visually it helps me to understand the difference between the two and why the allowable shear strength is different for each type of stress averaging. API and BPVC commonly refer to Von Mises however there are codes that are more conservative which use Tresca. Tresca is commonly used because its a "real life" measurement of surface stressing which can in return be used to non-destructively determine an estimated average internal stress. Hopefully this helps.
Regarding the Full Component Bending option, according to ASME 2007 SECTION VIII, DIVISION 2, ANNEX 5.A LINEARIZATION OF STRESS RESULTS FOR STRESS CLASSIFICATION, the answer is never. In this document, used to write the Stress Linearization tool, the bending components of stress "are calculated using only for the local hoop and meridional (normal) component stresses, and not for the local component stress parallel to the SCL, or in-plane shear stress".
The full component bending option simply shows the alternative solution if all components of the stress tensor are used.
PV Engineering hosts some great material regarding stress linearization -
including an interesting note regarding Tresca vs. von Mises -
"Note – von Mises stresses can be 85% to 100% of the reported Tresca stress for the same input data. Von Mises stress criteria of VIII-2 2007 edition is less conservative than the 2006 Tresca criteria."