A question about Interlayer dewll time at the start of each layer

[LPH0696]

Dear Author,
I recently encountered an issue while using AdditiveFOAM, specifically when simulating a multi-layer LPBF process. I wanted to set a dwell time at the start of each layer by setting the tParam parameter in the first line of the ScanPath file for each layer to 0.001s (as shown in the figure). However, I noticed that this setting only took effect on the first layer and did not apply to the second layer or subsequent layers. Could you please help me analyze where I might have made a mistake in my configuration?

The first layer scan path The second layer scan path

[colemanjs]

What is happening is that in the runLayers wrapper, the first scan-path timing entry is overwritten for every layer after the first one. Because of that, a dwell time placed in the first tParam entry only takes effect for layer 1, and is replaced for layer 2 and beyond.

So in your case:

• setting tParam = 0.001 s at the start of each layer works for the first layer
• for later layers, runLayers resets that first timing value to match the previous layer end time from system/controlDict:endTime
• as a result, the intended start-of-layer dwell is lost

So this is not really a mistake in your setup, but a limitation of the current multi-layer wrapper.

At the moment, there are two practical ways to handle this:

1. Use an end-of-layer dwell instead of a start-of-layer dwell
   This works better with the current wrapper, because only the first scan-path timing entry is modified. Later timing entries are left unchanged. If you include dwell time in the total layer duration, make sure the corresponding endTime in system/controlDict is long enough to cover it.

2. Modify runLayers if you want a true start-of-layer dwell for every layer
   In that case, the wrapper would need to preserve the original first tParam offset instead of overwriting it.

[LPH0696]

Thank you for your detailed response and advice.