Primary membrane stresses(Pm), Bending stresses(Pb), Local membrane stress(Pl)

[Anonymous]

Is it possible  for nastran to calculate the primary and local membrane stresses and the bending stress?

In the stress linerization tool, i can get the Pm and Pb, but i really need to get the local membrane stress too. 

It is on a rectangular plate.

Best regards.

[sohan.kumar.thiruvakkadu]

Hi @Anonymous 

Can I know what do you exactly mean by Local membrane stress and why do you need it?

Do you have any reference image, sketch or calculation which can clarify on local membrane stress.

[Anonymous]

I need to calculate the stresses in a heat exchanger due to a “Danish standard, EN13445 Annex C”. Thise stresses had to be evaluated due to get the heat exchanger on the market and acceptable by a second Company. 

[dreierWTK29]

You can use Pm from the stresslinearisation tool. You have to check areas in which the stress is higher because of gross structural discontinuity such as nozzles or flanges. See the definition in table C  - 3 of EN 13445.

[Anonymous]

But i have to use Pm and Pl Also. NOT only pm from the stress tool

[John_Holtz]

Hi @Anonymous 

Perhaps because I am not familiar with the Danish specification, it is not clear to me what is meant by the "local membrane stress". That is why Sohan was asking for some information (an image, sketch, something to explain what it is, how it is calculated, and so on).

Unless the "local membrane stress" is just the "X-Normal", "Y-Normal", or "Z-Normal" stress in Nastran,  Nastran will not provide the answer that you want. Hopefully the specification will explain how you can calculate it. (The "X-Normal", "Y-Normal", and "Z-Normal" are the stress (tension or compression) at the nodes in the local directions.)

[dreierWTK29]

My understanding of the definition is shown in the following picture. I hope this helps.

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[Anonymous]

That helped a lot. Thank you very much!