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How to Set Contact Surface

Contact Surface Classification

 

Set [Contactor surface] on one face and [Contactee surface] on the other.

Their boundary conditions need to be paired in the the [Boundary Pair] dialog box.

 

Contactor surface can be a face, an edge or a vertex for 3D. (An edge and a vertex for 2D)

Contactee surface needs to be a face for 3D. (An edge for 2D)

 

Example 3 of [Examples of Contact Analysis] is a 2D model.

 

Example 2 of [Examples of Contact Analysis] is a 3D model.

 

 

Tips for Setting Contactor and Contactee

Femtet treats the contactor and the contactee so as to generate the constraint, that will balance the nodes on the contactor face and faces or edges on the contactee face.

It is, therefore, important to set them properly.

The contactor and the contactee behave differently as shown below.

 

The contactor, characteristically, reacts to the deformation more flexibly than the contactee.

 

Therefore, it is useful to keep the following in mind so as to have the stable analysis;

[Set the body, that shows larger deformation by the contact, as a contactor, and set the body, that shows smaller deformation, as a contactee.]

 

Examples of setting are shown below.

1. If the stiffness (hardness and Young's modulus) of the contacting bodies is equal

 

 

2. If the stiffness (hardness and Young's modulus) of the contacting bodies is greatly different

It is recommended to set the contactor to the softer material, and contactee to the harder material.

 

Below is an example of sheet metal press.

 

An aluminum plate (Al) is pressed by a forming machine of stainless steel (SUS).

A left figure below is a recommended setting, where the aluminum plate is set as the contactor. A right figure below shows the reverse setting of contactor and contactee which is not recommendable.

 

 

The contacting area in the left figure shows the contactor (Al) bending along the contactee (SUS) leaving no gap in between.

The bent part indicated by yellow frame in the left figure shows more natural deformation than the right figure.

In this project, the calculation converges for both settings. Please be aware, however, that it may not converge depending on the model form or conditions,

3. Others

 

• The face with constraint to be the contactee.

• The contactor not to overhang from the contactee surface.
  The overhang to be within the overhang tolerance to ensure the convergence.

 

 

In some cases, you might as well exchange the contactor and the contactee.

 

 

The penetration could be minimized if not avoided.