Detemination of Stress types in FEA 2

[Thomasmac]

Hello,

I'm currently learning FEA analysis of pressure vessels using the ANSYS software and would like to know if there are any (free) web based resources that can help unravel the mystery behind how to classify the different stress types according to ASME.

Illistrations showing the difference between primary and secondary stresses would be realy helpfull.

Thanks in advance

Ryan

 

[zjliang]

Ryan, i've been using ANSYS for div 2 vessels and section-III vessels for many years but did not find the exact classification. However, the rule of thumb is just to follow the definition of the secondary stress in ASME and use separate loading steps in your calculation.

Generally spearking, temperature related stress is always treated as secondary stress. Some stresses around some discontinuties like nozzle due to pressure or piping loads might have some features of secondary stress, they are still evaluated by the primary bending limitation for conservative.

Hope it helps.
Thanks

 

[TGS4]

Ryan,

Welcome to the field of FEA in pressure vessels. Glad to see that you are asking such an insightful question. First off, check the engtips archives - there have been lots of discussion on this item. Second, get a copy of WRC 429 and read it thoroughly (I'll have to warn you - it's a surefire cure for insomnia). Third, find a copy of the ASME "Criteria of the Design-by-Analysis Rules in ASME Section III and Section VIII, Division 2". Then, there have been many good papers written at the ASME Pressure Vessel and Piping Conference. I belive that the ASME store have on-line access to more recent papers -

http://store.asme.org/category.asp?...%5Fname=Pressure+Vessels+and+Piping%A0&Page=1

Finally, come back here with more questions - glad to help. If you can, I would also recommend coming to the ASME PVP conference - this year's conference is in San Antonio, TX.

 

[UKCats]

Stresses are classifed (Primary, Secondary, Peak, etc) in ASME Section VIII, Div 2, Appendix 4, Table 4-120.1