Learning Forum

[rohansom]

I’m currently working on a project investigating how reheating affects the austenite percentage in L-DED (Direct Energy Deposition) of SS, and we are trying to extract accurate time–temperature curves from Ansys Additive DED. I had a doubt regarding the power mode in Ansys DED

We're encountering issues specifically with the Power Mode. The simulations often produce unrealistically high temperatures. Increasing the cluster volume has helped to generate more reasonable results for single-layer cases. However, when simulating two layers with the same parameters, the first layer exhibits very low peak temperatures during its own deposition, but then receives significantly higher temperatures during the reheating stage from the second layer—a behavior that doesn't appear physically accurate.

Could anyone suggest how to address this issue? I’ve attached images of the single- and double-layer results for reference, and I’m happy to provide more details if needed.

[John Doyle]

Perhaps you need to calibrate the dwell time to allow for a longer pause between the completion of this cluster and the beginning of the next, not including laser travel time.

[rohansom]

Hi John, thanks for getting back. 
I increased the dwell time and tried it for different dwell times. It doesn't make any difference. This was for the first layer of a two-layer print in power mode. I have chosen a single layer as a single cluster. Making it a smaller cluster will skyrocket the temperature. 

 

[John Doyle]

Could material specific heat be too low?  Also, I assume there is a bonded MPC contact between first layer and baseplate.  Perhaps switch contact formulation to Augmented Lagrange and try calibrating the TCC (Thermal Contact Conductance) to a value that produces a reasonable heat transfer without over cooking the small cluster volume.

[rohansom]

I did change to augmented formation. Tried different TCC, it didn't help. 
The first image is between the first layer and the base plate. The second image is between the first layer and second layers. The third image is the temperature profile, no change.

[rohansom]

https://youtu.be/FG1fWrU53jU
This is the animation of a two-layer print; you can see it the first layer is not reaching the high temperature as expected. 

[rohansom]

This problem doesn't exist if I try the temperature mode. But the problem is in the first layer deposition, which assumes the average temperature to be the maximum temperature.