Flexibility Analysis

[frd03]

Hello everyone,

Some weeks ago I started a discussion about the rules presented in ASME code to flexibility analysis, in special about the allowable stress SA ( due to thermal displacements )which were got from Markl paper.

I have studied some models (with Abaqus - FEA) with nonlinear plasticity, including thermal loads steps (cycling) involving temperatures up to 300 oC due to not get a creep range to steels and I have got some interesting results.
For example, I did not observe a meaningful reduction of thermal stresses with the pass of cycles ( already considering residual stresses and plasticity ) in agree with thermal relaxation proposed in that paper ( but I could notice this effect in creep rates ), another thing was about the SIFs, where in same cases, like the inner radiu of elbow, I got stresses above the values indicated by the classic analysis.
In a preliminary evaluation I think that this part of code could be divided in temperature ranges ( up to 350 oC and above )with differents calculus each one.
I will apreciate to receive opinions about this.

Thanks
Francisco

 

[jte]

Francisco-

I would encourage you to consider writing a paper about your research and publishing it at the 2008 ASME Pressure Vessels and Piping conference. That is a forum where you will get some good exposure and discussion of your findings. Info for the 2007 PVP is at

https://asmeconferences.org/PVP07/index.cfm.

I would expect to see the 2008 version up in late July / early August. Your topic would fall under the Design and Analysis track.

jt