Material property change 2

[corus]

After heating a material to a certain temperature chemical reactions produce a permanent material change in the properties of that material. How can this change be incorporated within a thermal transient analysis so that once reaching this temperature the material effectively changes into a different material?

corus

 

[mrgoldthorpe]

Corus,
My first thought is to use a field variable and user subroutine USDFLD, with GETVRM(...) called there to get the temperature. If the temperature ever exceeds the critical value, then the field variable can be switched from the initial value (0) to the new value (1). The material properties are specified in terms of the field variable,eg:

*ELASTIC, DEPENDENCIES=1
** E nu temp field_variable
200000.0 , 0.3 , , 0.0
200000.0 , 0.3 , , 0.999
50000.0 , 0.35 , , 1.0
50000.0 , 0.35 , , 10.0

...would give a step change in E and Poosson's ratio when the field variable is set to unity. Remember to set at the start:
*INITIAL CONDITIONS,TYPE=FIELD,VARIABLE=1
NALL, 0.0

I hope this provides good for thought.
MRG

http://www.analysis.demon.co.uk

 

[mrgoldthorpe]

Corus, did that suggestion solve your problem?

http://www.analysis.demon.co.uk

 

[corus]

Your advice was excellent and the job worked (eventually) just fine.

corus