Thermal Cicling and Stress Relaxation

[frd03]

Hi all,

I started recently to work with Abaqus using thermal cicling loading and plasticity. To a first model ( a carbon steel pipe ) I used several steps increasing and decreasing the temperature values ( temp. room up to temp. max. and return to room ) and initially I think that were presented good results but looking for better modelling and results I have some doubts, like:

a) I used the step times and increment as default ( 1 ) and how I do not have time-dependent material properties ( like creep )I thought that this would not be important. Is it right ?
b) I would like to introduce "cycle hardening" with goal to get or verify ( if to happen) " mean stress relaxation" and I choosed the sub-options inside of plastic properties, the program asked me "combined" and I put to "cycle hardening" the yeld stress and plastic rate, similar to plastic datas field imput before ( because I do not have specifc material tests ). Could I work this way ? or would have a better way ?

Thanks for the help !

 

[Yoman228]

For steel pipe, you could try this value for a test run.

*MATERIAL,NAME=x52_cyc
*ELASTIC
207E9,.3
*PLASTIC,HARDENING=combined, data type=parameters
350e6, 3600e6, 29

 

[frd03]

Thanks Yoman228 ,

Please, Could you explain me what are these parameters e your units ?

Did you already do some similar modelling to verify "stress relaxation " what would have been your evaluation ?


Thanks

 

[corus]

Creep generally isn't important for steel until you get to temperatures above 400C and then the effect isn't seen for some months. Much higher temperatueres are a different kettle of fish though and you'd have to think of phase transformations of the material and the rest.

corus