Several structures have connections like bolts, rivets, and screws. It is important to simulate this connection, to calculate the amount of stress they receive. Α FEA model might consist of dozens of bolts, and an automatic way to model is by using Universal Bolt Connection. In Simcenter 3D and NX the command that you are going to need is the following:

Figure 1: Universal Bolt Connection. (Path: Home- Universal Connection- Bolt).

Let’s assume that half of the geometry we want to model is a heat exchanger.

Figure 2: Real case geometry with bolt connections.

This structure contains lots of bolts and it would be time spending if someone wants to model all of them one by one.

The first step is to delete the bolts from the CAD because you are going to model them as 1D elements. So, the modified CAD file is shown below:

Figure 3: Simplified geometry.

In the next step, you must draw lines in the same places where there were all the bolts and for your own best, you should paint these lines with one color like the next figure.

Figure 4: Line’s position.

After that, in fem file, you may create a Selection Recipe with all curves. The Selection Recipe can select all the lines that have the same color, so the process is automated. Figure 5 shows the way to make an Attribute Recipe.

Figure 5: One option to create a Selection Recipe.

Afterward, is time to press the button in Figure 1. The window that opens has four steps:

• General: Name and description,
• Targets: Select the flanges connecting with the bolt’s head and nut,
• Location: Select the lines (Selection Recipe),
• Physical: Geometrical characterization.

Finally, create the Universal Bolt Connection by pressing the command Automatic Element to specify the combination of 1D elements that you want to model the bolt.

Figure 6: Combination of 1D elements.

Simcenter 3D provides the opportunity to model bolts easily, making your simulation more accurate. In four steps you can model a large number of bolts.

Figure 7: The Result.

In summary, we can say that the procedure is the following:

• Create lines,
• Create Selection Recipe,
• Assign the geometrical characteristics,
• Select the combination of 1D elements.

Wasn’t that easy?

We at FEAC hope that this blog post has been interesting and that you will be able to create a nice FE Analysis after reading this. If you have any questions, you are always welcome to contact us at support@feacomp.com