How to Define Contact in 2-D Analysis

For linear static stress analysis of two-dimensional (2-D) assembly models that are created using FEMPRO's Superdraw sketching, modeling and meshing capabilities, you can conveniently and quickly define contact between parts. To do so, use the following general method:

1. Sketch the 2-D parts (the parts must share at least one identical-length, coincident edge).
2. Select the sketches in the tree view and right click to access a pop-up menu of options. Choose the "Generate 2-D Mesh..." command (see Figure 1). The "2-D Mesh Generation" dialog will appear.

Figure 1: In the tree view, select the sketches that share a coincident edge and then right click to access the "Generate 2-D Mesh..." command.

3. In the model display, right click on the coincident edge. In the pop-up menu, choose "Contact" and then specify the type of contact from three options (see Figure 2):
• Bonded - The nodes on the two edges will be matched and will be in perfect contact throughout the analysis. When a node on one edge deflects, the node on the adjoining edge will deflect the same amount in the same direction. This is the default option.
• Free/No Contact - The nodes on the two edges will not be matched and will be free to move relative to each other.
• Surface Contact - The nodes on the two edges will be matched and will be free to move away from each other. If the nodes move toward each other, a stiffness will be applied to resist this movement.

Figure 2: With the "2-D Mesh Generation" dialog active, you can right click on the coincident edge and specify the type of contact: bonded, free/no contact or surface contact.

4. Generate the mesh. After meshing, the contact surfaces will be listed in the tree view.
5. In the tree view, right click on the contact surface and choose "Friction..." (see Figure 3).

Figure 3: Right click on the contact surface in the tree view and choose "Friction...".

6. In the "Friction Settings" dialog, you can specify the coefficient of friction for the coincident edges (see Figure 4).

Figure 4: Choose whether or not to include friction in the analysis and specify the static friction coefficient.

7. Set up for linear static stress analysis (define material properties, loadings and constraints) and run the analysis.
8. In the Superview IV Results environment of FEMPRO, you can inquire on the total contact force for each contact pair in the model. Right click on the heading for the contact pair in the tree view and choose the "Contact Force..." command (see Figure 5).

Figure 5: In FEMPRO's Superview IV Results environment, you can inquire on the total contact force.

9. A "Contact Force" dialog will appear with the total contact force for that pair (see Figure 6).

Figure 6: The calculated total contact force will be displayed.

Thus, the ability to quickly and easily define 2-D contact helps you to perform linear static stress analysis of 2-D assembly models that were created with FEMPRO's Superdraw sketching, modeling and meshing tools.

For more information about 2-D contact, see the ALGOR User's Guide.