Ansys Model Analysis Share Topology Issue

Beams share nodes issue fixed!

Recently I saw a Paper “Structural Optimization of 3D-Printed Synthetic Spider Webs for High Strength”, this paper makes me want to dive deeper into the field of spider web and explore the wonder of this nature creation.

The very first step is to plot the geometry on SolidWorks, in the paper the author produce a spider web.

“Structural optimization of 3D-printed synthetic
spider webs for high strength”
Spider web plotted in SolidWorks

After importing this geometry file into SpaceClaim in ANSYS, and set all the boundary conditions, such as Fixed Support and the Force exerted at the center of the web, the error message “Solver pivot warnings or errors have been encountered during the solution”.

“Solver pivot warnings or errors have been encountered during the solution” in ANSYS

After reading the detail message, I found out that this error relates to the degree of freedom of the node in the elements. The most intuitive way I could think of to resolve this at the moment is to use “share topology” in SpaceClaim and change it to either “Share” or “Merge”. However, even after the modification in SpaceClaim, I still couldn’t solve the issue after clicking Solve in ANSYS Mechanical.

But there will always be a silver lining, after Google Google and Google….

I finally found out a way to diagnose this-to run model analysis and show the disconnected lines/beams/nodes in the model!

First step is to go to Display tab in ANSYS Mechanical and click Preferences, and check the Node Number and hit OK. By doing this, the Annotation Preferences would show the node number on the model. If there are two number interfere with each other, then that means there is the problem!

Node Number in Annotation Preferences

How to solve it? Well, we need to add “Mesh Edit” under the Model. And add Mode Merge Group to merge all the interference nodes. There are 3 types of Tolerance Type: Slider, Value, Use Sheet Thickness.

In this problem, I use the tolerance Value to be 1 mm (noted: this value should not be larger than Element size in Mesh). And change Face/Edge No to “Yes” and click Solve. And we would see the information pops up with the number of nodes merged!

Reference:

  1. Structural Optimization of 3D-Printed Synthetic Spider Webs for High Strength
  2. 7.2.6 Troubleshoot Solver Pivot Error (https://www.youtube.com/watch?v=QF-NLcLZLFw)
  3. ANSYS Discussion Forum (https://forum.ansys.com/discussion/30294/solver-pivot-warnings-or-errors-have-been-encountered-during-the-solution#latest)
  4. ANSYS Mechanical: Node Merge (https://www.youtube.com/watch?v=m7UVzKSXjWM)

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