Thank you all for your nice explanation(Posts) about Static fatigue analysis.

What I understood from the posts and Design chapter of 31.3 is that the Static fatigue analysis can be done in two methods(correct me if i am wrong) and they are as follows,

1) Find out Stress range reduction factor(31.3) and do static analysis with Reduced Expansion stress range using normal EXP case.

2) The method given in Technical refference manual.


My question is

a) What is the difference between these two methods and their output?


one difference which i found is that if I use method number 2, i can analyse more than one case(cases with different number of operating/displacement cycles).

Please Guide.

thanks in advance.

Hi,
Very first thing you need to take care is that the calculation done in your above mentioned point numbers 1 & 2 are totally different.
By putting stress reduction factor you can check only EXP stress range for respective number of cycles.
Fatigue is something which you need to check when there are fluctuations or variations in temperature or pressure or both. For fatigue check C-II will follow ASME SEC VIII DIV II,APPENDIX V which is also expained in Tech Reference Manual. Here you need to select Fatigue curves,form the load cases for fatigue,assign process given number of cycles to fatigue load cases in load case editor. Read the technical ref manual. Procedure is available for fatigue check. This is what I came to know after reading tech ref manual but you discuss the same with other seniors before proceding.

So very first thing is get clear idea for the requirement of regular stress check & fatigue check.

Hope I answered your question.

Have a nice day & Keep Smiling

Regards,
Innovate

Dear Beginner,

I would encourage you to visit the website of Paulin Research Group for some informative articles on SIF,Fatigue , Markl's curve, factor of safety used on cycles and stress and also read the document NUREG CR3243.You will get the answer that you are looking for.The important thing is to understand what Markl did ,how he did and how the curves were generated.NUREG CR3243 will explain you the diference between approaches of B31 and the SEC VIII and SEC III approaches.

Regards