carbon steel strain hardening 2

[groveri]

I'm doing an FEA of a carbon steel line composite pressure vessel with fully reversed plastic loading during the autofrettage cycle. I have the elasto-plastic stress-strain data, but I'm looking for guidance for hardening during the compressive part of the cycle following the initial tension. My FEA code can handle isotropic or kinematic hardening or something in between. My application has significant yielding during the first autofrettage load cycle. Working load cycles are elastic if isotropic hardened, but border line if kinematic. The steel is SA516 GR 70, about 0.3% carbon. I need some guidance wrt type of hardening - a reference source would be nice.

 

[salmon2]

Search "cyclic stress strain curve" in google images, you will see a bunch of stress strain curves that may help you with your question. Hope this helps.

 

[unclesyd]

The supplier of your equipment should have the data you need.
Here are two papers that discuss autofrettage of various objects. The second paper has a diagram of the stress distribution whereas the first only describes it. There is also a paper on monitoring the process.

http://harwoodeng.com/articles/