Independent geometries affecting each other

General Questions
1

Hello all, I am trying to simulate a contact problem in which I am wearing an orthosis on a model.

Model
Model1280×641 257 KB

The armpit support (1) elevates the arm, but I believe I had to separate the orthosis while doing it (4 different geometries). You can see the results,2025_04_22_HS1188_Remake2_Multistep5.zip (1.2 MB)
In the video between the 4th and 6th seconds, the second geometry somehow affects the body even though it is not touching it? So, I would like to ask,

  1. Could you tell me why this is happening?
  2. Do I need another boundary condition? It might be overconstrained so that it gave me wrong results, but I don’t know how to understand this.
  3. I am doing this simulation with 7 steps. Is this a lot?

Thank you for reading.

2

Isn’t that because of the armpit support (part number 1) intersecting (rather incorrectly - with significant penetrations) with the body model ? Depending on how BCs change across the steps, it may also be some sort of elastic springback. It shouldn’t be caused by part number 2 unless there are some non-default settings such as small-sliding (you don’t have that enabled, do you?).