Learning Forum

[helen.durand]

Hello,

In a transient thermal and transient structural simulation, I am using APDL command objects to change material types (using the MPCHG command). I want to display the element material assignments during the solution by creating a user defined result.

I tried to do this using the expression PNUMMAT (which displays element material numbers); however, the displayed results seem to only show the material assignments from the prep phase, and any changes to the material assignments that I am making during the solution phase are not displayed.

Is this a limitation of the PNUMMAT expression, or could this be a sign that material types are not getting changed during the solution phase?

Thank you

 

[Govindan Nagappan]

This is probably a limitation of PNUMMAT that it only shows material assignment done under /prep7

Can you use /PREP7, change the material and go back to /SOLU?

Another way to check material assignmnt is by selecting the "solution" branch, go to "Worksheet" and show "Material and Element Type information"

 

 

[Govindan Nagappan]

You can also check the "solution information" for the feedback from the MPCHG command

For example, I used these commands

cmsel,s,body1,elem
mpchg,3,all
allsel

I got the following feedback in solution information:

SELECT      COMPONENT BODY1                          

 SET MATERIAL OF SELECTED ELEMENTS TO     3

 SELECT ALL ENTITIES OF TYPE= ALL  AND BELOW

 

[helen.durand]

Thank you for the reply! 

Looking at the worksheet in my simulation, I still only see the element assignments from the prep phase.

I used the ELIST,ALL command to verify that some elements are being changed at every loadstep (I put the command at the beginning of the APDL command object that is set to run at the start of every loadstep in the solution phase).

For example,  at the start of loadstep 1, the printout is this (all elements are assigned material type 50 during the prep phase):

At the start of loadstep 2 (elements 1 and 2 were assignd material type 30):

At the start of loadstep 3 (elements 3 and 4 were assigned material type 30):

However, when I look at the worksheet I do not see any mention of materialtype 30:

The issue has been that calling ELIST,ALL at every loadstep for a reasonably large geometry makes the solution file extremely long, and it is difficut to assess whether the element numbers are being assigned correctly.

[Govindan Nagappan]

Consider using prep7 if possible

Example:

/prep7
cmsel,s,body1,elem
mpchg,3,all
allsel

/solu

 

==================================================

 

Or if the ETLIST is sufficient, select 1 element or few elements and write the output instead of writing it for full model 

=====================================

Or you can redirect the feedback from MPCHG command to a separate text file using /output

 

======================================

Material number is not a result. So the historical change in mat number is probably not saved in the rst file. 

 

 

 

[helen.durand]

Those sound like good options. Thank you for your help!