March 7, 2023 at 10:10 am
John Miller
Subscriber

 

 

 

Hello Dave,

 

thank you for your response. You are right, it’s better to stay in /solu, but the model is forcing me to do so. Without leaving the solution, it’s not difficult to achieve a material extrusion for AM Process with the aid of ekill and ealive. I simplified my model to make it more clear how it works.

The Problem with my model is that I need the current surface for radiation application. You can see it in the picture below. During material extrusion via ealive the current surface is constantly changing, which makes it difficult to use the GUI radiation dialogue. For this, you can use only the final exterior surface, but this is not the exterior surface during the material extrusion. During extrusion with ealive the inner elements/nodes become currently exterior and after a few lines interior.

Without restarting it looks like this (for the 6th time step):


With restart that’s the result (for the 6th time step):

 

The code of the two APDL snippets I use looks like this:


Command object 1 (“initial_ekill) for the element deletion of the volume to be generated:
Code:
________________________________________
nropt,full
/prep7
cmsel,s,path
ekill,all
finish
/solu
________________________________________

This kills the element of the “path”, which is the volume to be generated step by step via ealive.

Without restarting it works fine, because the /prep7 is only called one time.


Command object 2 (“AM_process”) for the element seletion of the volume to be generated:

Code:
________________________________________

tintp,,,,1.0
nropt,full
! Parameter
t=1
….
…
*do,iijj,….! Outer loop for AM phase iii =1 and cooling phase iii=2
*if,iijj,….
*do,i,… ! AM loop with ealive
/GOPR


! Force Single Frame restart
rescontrol,none


! Deleting the temperature from the previous time step
cmsel,s,path,node
cm,Tload,node
ddele,…


! Element activation for the newly extruded volume
esel,r,…
…
cm,alive,elem
ealive,alive


! Applying the thermal load (temperature) to the volume/node activated by ealive
cmsel,s,path,node
nsel,r,…
…
cm,load,node
D,load,temp,TL
! Select external nodes


/com,*****************************Currently External Nodes*****************************
cmsel,s,path,elem
esel,r,…
nsel,s,…
cmsel,u,…
cm,external,node
/com,******************************************************************************


! Constant print bed temperature
nsel,none
esel,none
cmsel,s,…
cm,bednodes,node
D,bednodes,temp,Tbed

allsel,all
outres,all

Time,i*dt
solve

! Excursion into the preprocessor for the creation of surf152 elements for convection and radiation
/prep7
/GOPR
/com,Start surf152 for convection
esel,s,….
….
….
esurf
allsel,all

/com,End surf152 generation for convection


! Restart of solution phase
/solu
trnopt,full
nropt,full
thopt,full
antype,,restart


! Application of the thermal load on surf152 elements
esel,s,ename,,152
…
allsel,all
outres,all,all
*enddo
! cooling
*elseif,iijj,…


/com,****************************Cooling Step***********************************
/GOPR

…
allsel,all
outres,all,all
*do,jjj,…
/GOPR
…
solve
*enddo
/com,******************************************************************************
*else
*endif
*enddo

 

The database must be saved in this way so that initially the body “path” is killed and during the AM process the former generated volume, because of a former step won’t be deleted.

I thought about using:

/config,noeldb,0 !

to write results into the database.

 

With best regards

John