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Difference between contact pair and identity boundary pair

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Hi,
I am new to Comsol and I was building my model, a cylinder inserted into a closed end sleeve. Load is applied on the top surface of the inner cylinder (like a piston-cylinder configuration). They are two separate objects, so I used 'Form Assembly in Model 1'.

The issue I am confused about is when you define whether it is a contact pair or a identity boundary pair. There are two surfaces on the cylinder contact with the sleeve: bottom surface of cylinder with closed end surface of sleeve, peripheral surface of cylinder with inner surface of the sleeve.

If I am not mistaken, a corresponding boundary condition need to be defined on both contacting surfaces, in 'pair'. There are several options in 'pair': 'contact', 'boundary load', 'fixed constraint', 'free' etc. If I use 'boundary load', it is working, however, when I use 'contact', error appears (results not converge).

Please check the attachment for my model.

I will be glad if someone can help me with this.

Jing


0 Replies Last Post 2013年11月21日 GMT-5 04:42
COMSOL Moderator

Hello Jinghua Tang

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