# Independent geometries affecting each other

**URL:** <https://prepomax.discourse.group/t/independent-geometries-affecting-each-other/2643>\
**Category:** General Questions\
**Created:** [April 22, 2025, 12:55pm UTC](https://prepomax.discourse.group/t/independent-geometries-affecting-each-other/2643 "2025-04-22T12:55:31Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Akilyon](https://avatars.discourse-cdn.com/v4/letter/a/3ec8ea/32.png) [@Akilyon](https://prepomax.discourse.group/u/Akilyon)\
**Post date:** [April 22, 2025, 12:55pm UTC](https://prepomax.discourse.group/t/independent-geometries-affecting-each-other/2643/1 "2025-04-22T12:55:31Z")

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

 ![Model](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/b/b8e1e3326a94fb884bc96e2d81ed1db594d3a891.png)  
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](https://prepomax.discourse.group/uploads/short-url/hq9hpHpnHm6xtW02nEubpZwj5ur.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.

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**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\
**Post date:** [April 22, 2025, 1:03pm UTC](https://prepomax.discourse.group/t/independent-geometries-affecting-each-other/2643/2 "2025-04-22T13:03:48Z")

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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?).