I am trying to simulate the deposition of a single extruded path using element birth and death technique. In each load step one element is activated. The initial temperature of the activated element (in the current load step) is to be the nozzle temperature. The initial temperatures of the previously activated elements is obtained from the results (temperature field) of the previous load step. The steps adopted in the model are as follows:
I am facing the following issues:
Since I am new to ANSYS, any suggestions w.r.t these two issues and help in identifying the mistakes in my code/approach will be greatly appreciated.
The relevant screenshots from APDL as well as the code have been attached for reference.
Currently, I seem to have identified one possible issue. It seems, the Temperature DOF of the nodes of the deactivated elements need to be constrained (at a high temperature) before solving each load step. Since, fundamentally in both FDM and the welding process each activated element represents a fixed amount of material deposited at a higher temperature. So, when an element is activated, it should initially have a high temperature. This may be achieved by deleting the temperature DOF on the activated element.
I included this in the first approach (of solving all load steps in a single file) and the results (both spatial temperature distribution as well as thermal history at specific locations) seem to be proper now.
However, suggestions on whether this is a proper approach or not (w.r.t the process physics of FDM) and other alternative approaches, would be really very helpful in this regard.
Ansuman Sahu , Regarding query no. 2 in your question,
In your code, after setting the initial temperature by TUNIF, set TIME as 0. Then start a *DO loop.
The loop should run from 1st to the last load step.
Inside the *DO loop, activate (EALIVE) the required elements sequentially. To achieve this, your element numbering should follow some ordered series in the zone where they would be sequentially activated.
Then apply your boundary conditions.
Then increase time by the time step size.
TIME_NOW=TIME_NOW+0.5 !!times step size=0.5
TIME,TIME_NOW !!set TIME to the current time
DELTIM,0.5,0,0 !!! Set min and max time steps
The solve inside the loop.
/STATUS,SOLU
SOLVE
Don't use LSWRIE/LSSOLVE. It may not work EALIVE/EKILL
Delete all loads in this step
End the loop
!!! In this way, your solution of each step would become the initial condition for the next step
Thanks Sandipan Baruah ,
I have re-arranged the commands as per your suggestions and the simulation is now giving a proper temperature distribution and thermal history. As you have mentioned, the temperature distribution results of the previous step becomes the initial condition for the next, hence the LDREAD command is also no longer required.
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