## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### Bonded, but there is a seperation

• Elena Maier
Subscriber

Hello,

so I have a specific problem:
my model contains a plate and on top of this plate is a smaller plate (cover plate) welded. See picture below:

The mode is fixed at the right end and it is pulled on the left end, so the model is under a tension.
The weld triangles and the big plat are a shared topology and so there are one body.
The contact faces/areas between the plate and the cover plate (upper plate) are in contact through friction, so I used frictional with the coefficient 0,2.

The weld triangles and the cover plate are welded together, so I used BONDED to attach them, but when I look at the displacements, they seperate. Although the definition is that there is no spereation. See the pictures below:

I also tried to connect them with "no seperation", but that also didn´t work because then there is a seperation in the other direction, see the picture below:

I would really appreciate, if someone knows a solution for that problem. Bacause I can´t use a complete shared geometry for the model, because there is no connection between the plate and the cover plate besides the friction.

Elena

• Akshay Maniyar
Ansys Employee

Hi Elena,

Can you try to refine the mesh on the plate and weld? Also, try using MPC formulation with bonded contact.

Thanks,

Akshay maniyar

• Elena Maier
Subscriber

Hello Akshay,

I already tried it with a refinement befor (just didn´t take a picture that time).
But now I tried the solution with the MPC formulation and that worked:

Thank you so much for your help!
Now the faces should be really bonded right, and ANSYS interpolates in between them? So that it gives the information from the weld to the coverplate exactly, and it doesnt matter that the mesh isn´t continuously?

Thank you so much for your help!!!
This solved a lot of my problems.

Have a good day,

Elena Maier

• Akshay Maniyar
Ansys Employee

Hi Elena,

It is great that your issue is solved. For Bonded and No Separation Types of contact between two faces, a Multi-Point Constraint (MPC) formulation is available. MPC internally adds constraint equations to "tie" the displacements between contacting surfaces. This approach is not penalty-based or Lagrange multiplier-based. It is a direct, efficient way of relating surfaces of contact regions which are bonded. Large-deformation effects are supported with MPC-based Bonded contact.

Thanks,

Akshay maniyar