Dear All,

I am doing a vessel analysis, in which i have to do fatigue analysis. The input given to us for fatigue analysis is presuure cycles as well as temperature cycles. I am using a PVElite software, But in Pvelite i am able to enter only pressure cycles.

I am able to the "Pressure Fatigue Analysis" as per ASME, But i am not getting that how to do the "Thermal Fatigue Analysis".

The given data for "Thermal Fatigue Analysis" was minus 5 degree celcius to 60 degree celcius & the number of cycles are 100. Fatigue Life given is 25 years.
Can anyone suggest me, how can i perform this calculations. Can anyone please provide me the literature on "Thermal Fatigue anaylsis" or any link where i can find the details on thermal Fatigue.

_________________
Makrand Pandurang Sakpal,
Static Equipment Design,
makrands9@gmail.com,
Ph no:- 9967949656.

1. Is your vessel a plain tank or some more complicated contraption?
2. Are you able to determine fluid temperatures and HTC's for all internal and external surfaces of all parts?
3. Are your transient states well defined or is it just quasi-static consideration?
4. Has your customer determined acceptance criteria for low-cycle fatigue?
5. What is the material of construction and do you have relevant epsilon-N data for it?
6. Do you use or can subcontract an FEA?

_________________
Konrad Anikiel

1. Is your vessel a plain tank or some more complicated contraption?
Ans:- Its not more comlicated vessel, but consist of around 30 nozzles.

2. Are you able to determine fluid temperatures and HTC's for all internal and external surfaces of all parts?
Ans:- under normal calculations vessel thickness is 25 mm & we can consider the worst case for temperatures.

3. Are your transient states well defined or is it just quasi-static consideration?

4. Has your customer determined acceptance criteria for low-cycle fatigue?
Ans:- Yes

5. What is the material of construction and do you have relevant epsilon-N data for it?
Ans:- SA516 Gr 70

6. Do you use or can subcontract an FEA?
Ans:- We can subcontract an FEA. But still we want to design it at our own. So please if u have any literature for that, can u give it to me? Either any link from where i can get idea on thermal fatigue...

_________________
Makrand Pandurang Sakpal,
Static Equipment Design,
makrands9@gmail.com,
Ph no:- 9967949656.

Hi Makrand,
From your reply I can see that it should be perfectly doable with a quite simple FEA. Without FEA, I doubt whether you can find any general computational examples more complicated than thermal ratcheting in tubular steam generators. You might be lucky though- start looking for some good design books and articles on steam generators used in power plants, nuclear ones in this number. I can't recommend anything particular, sorry. In case you decide to try finite elements, I can give a couple of advices

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Konrad Anikiel