Friday, November 27, 2015

FEA : Steps for Collapsing and Removing Triangular Elements | Meshing in Ansys, Hypermesh, Solidworks

When we use Element Collapse to remove triangular elements from your model, we should be very careful in selecting the elements to collapse.
In many cases, we won't want to collapse all elements that don't meet the specified quality criteria like, included angle threshold.
For example, depending on your geometry, when you use Element Collapse, the resulting mesh may not have nodes at the vertex of two edges.

For illustration, just assume a simple model of a block with a shallow groove cut through the top. and an FE models created and defined a mesh of linear triangle elements on all surfaces.

Now, assume We used the Tri-Inc Angles option on the Element Quality Checks form to check the model for triangular elements with included angles smaller than 15°.

Now the software will

  • show a group of the elements that failed the check.
  • show the same group of elements displayed within the context of the model's surfaces.

As case 1, we can make Element Collapse to remove all the elements that failed the initial Tri Inc Angles check. By collapsing those elements, we significantly change the relationship between the mesh and the geometry in the region of the groove. Specifically, the software no longer generates a node at the vertex between the two edges

In case 2, we can make element Collapse to remove only the eight elements in the middle of the groove. Notice the difference in the resulting mesh at that vertex. However, also notice that there is now no longer a node at a different vertex.