Applying bolt preload is critical in node analysis. However, it can be cumbersome to do so in ANSYS Classic. The good news is that applying preload in Workbench and HyperMesh is much simpler. In this article, we will show you step by step how to apply bolt preload using HyperMesh and import it to ANSYS for calculation.
Our case study involves connecting two steel plates using two bolts with a preload of 100 KN and a friction coefficient of 0.2 between the bolts and the plates. The steel plates are made of Q235. First, we need to establish the contact element based on the contact relationship in HyperMesh.
To apply the bolt preload, we need to select the bolt group, click “Tools” in the menu bar, and then “Pretension Bolt”. This will open the panel where we input the following parameters:
Specify the type of element that the preload is attached to. It can be either 1D or 3D. If you use beam elements to simulate the bolts, choose 1D. In this case, we use solid elements, so we choose 3D.
Specify the node number of the preload element. The system will automatically capture the current maximum node number and add 1 to it. You can also customize it if you want, but the default option usually works.
Specify the name of the preload section. You can use a customized name.
Next, we need to specify the type of preload, which can be either force loading or displacement loading. Here, we choose force and input a preload of 100kN.
The last two parameters are to specify the preload load step and the start lock load step.
Once the parameters are set, click “Create” to enter the specific creation process.
After clicking “Create,” we need to select the element group to create the preload element. In this case, since we have already created a bolt group, we can select it directly. Click “Proceed” in the lower right corner to proceed to the next step.
In the preload element selection interface, we can determine the position of the preload element by selecting the combination of selected and unselected elements. For example, the white element here is already selected, and the red one below is not. The preload element is created at the intersection of the white and red elements. If your bolt is approximately symmetrical, you can select half of the elements.
Next, we need to specify the direction of the preload by selecting the specific node orientation. For example, if the preload is in the axial direction of the bolt, we can select two nodes vertically. Click “Processed” in the lower right corner to create the preload element automatically.
Once the preload element is created, it will generate a corresponding group to store the preload element in the original model tree under “Components”. Additionally, the original node at the intersection now becomes two identical nodes at the same location. The corresponding sensor and property will also be generated. By clicking on the sensor, we can see that the called element is Prets179. Moreover, we can find a new Sload command under the “Cards” section for the solution information. After checking everything, we can export it to a CDB file and import it into ANSYS for calculation.
The following figure shows the ANSYS calculation result of the preload: