BPVC check for plastic collapse - Elastic plastic analysis 1

[flakyman]

Hello all,
I am trying check a pressure vessel for plastic collapse and am using the elastic-plastic method. The load combinations are given in Table 5.5. The load combinations want us to add scaling factors. I am able to scale all loads without much trouble except temperature. What would e the best way to scale up the temperatures?

1) Should I scale the min and/or max temp?
2) Should I scale up the delta T?

If I do scale up the temperature should I create the material curves to the higher temp or the material resistance should be left alone?

Any insight into this is greatly appreciated.

Thank you

 

[marty007]

This load case is interested in determining the stresses caused by temperature.

It does not make sense to scale the actual temperatures, becasuse this would modify your stress/strain curves.

The question is, what causes the stress due to temperature? It is the displacement due to thermal growth.

So, my understanding is that the best way to address this load case is to scale-up the coeficient of thermal expansion for the material. This way you can use the correct stress/strain curve for your design temperature, while still inducing scaled-up stresses due to thermal effects.

Cheers,
Marty

 

[TGS4]

marty007 has retained his learning from my training course. Well done! His recommendation is exactly correct. You do not want to mess around with the actual temperatures - you will need them to be correct for other temperature-dependent properties.