Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

WRC297 vs FEA 1

Status
Not open for further replies.

Ehiman1

Civil/Environmental
Joined
Oct 17, 2014
Messages
59
Location
IT
Hello,
I was checking stress values in nozzle - shell junction with WRC297 and finite elementh method analysis, but I can't understand why there are a lot of differences between these 2 methods.
With WRC 297 I have the bigger stress value at 170% of allowable; with FEA I have the bigger stress value at 60% of allowable.
I designed nozzle and vessel with Compress.
Have you evere had a problem like this one?
I don't understand why the values are so different, because I use the same loads, materials and sizes.
 
Use hand calculation.

Regards
 
I was thinking I had seen comparisons before, with something more like 30% difference. Forget where, either the WRC 297 publication or maybe some of the vessel handbooks.
Things to check:
-whether both results also include effects of internal pressure in the vessel
-whether stresses compared are the same, IE, bending vs membrane
-whether loading is identical or not
 
The philosophy/rationale/theory of WRC 107/297 are described in the document itself. It will have different results from FEA even with identical geometries, properties and loads.
 
I did a parametric study of a few geometries some time ago and found that WRC 297 stresses are 30-100% higher than FEA when t/T > 1.0.
For thinner nozzles the difference is even greater.
WRC 297 is very conservative. This is why it is rarely used in industry.
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor

Back
Top