Splitting shell elements

Use Split Shell to subdivide 2D elements. When you subdivide a shell element, the new elements have the same attributes as the original element, such as physical and material properties. Split Shell is useful, for example, if you need to divide elements to manually refine a mesh in a specific area.

Dividing quadrilateral and triangular elements

Use the options in the Type list to control the type of elements the software creates when it divides the selected elements. For example, you can use Split Shell to divide:

• A quadrilateral element into two (A), three (B) , or four (C) quadrilateral elements.

• A quadrilateral element into two (A) or three triangular elements (B).

• A triangular element into two (A) or four (B) triangular elements.

You can also use the Split by Line option to divide selected 2D elements along a line that you specify.

Splitting elements interactively

Use the Interactive Location option in the Based on list to have the software preview the possible split patterns as you move your mouse over the selected element. The following graphic shows an example of the four possible split patterns that the software previews for the Quad to 4 Quads option.

Splitting quadrilateral elements into a matrix of smaller elements

Use the Quad to M by N Quads option in the Split Shell dialog box to subdivide selected 2D quadrilateral elements both vertically and horizontally into a matrix of smaller elements. You can use the Split Into option to control how many smaller elements are created in this process. This option is useful when you need to refine a quadrilateral mesh, or a region within that mesh, with smaller quadrilateral elements.

After you use the Quad to M by N Quads option to subdivide an element, you must modify the surrounding elements to:

• Transition between the size of the new elements and the size of the elements in the surrounding mesh. For example, you can use the Split Shell command to subdivide the surrounding elements to transition between the new, smaller elements and the size of the elements in the overall mesh.

• Ensure that the smaller elements are connected to the elements in the surrounding mesh. For example, you can use Move Node to move selected nodes on the new elements to make them coincident with nodes on the surrounding elements. You can then merge duplicate nodes to connect the new elements to the elements in the surrounding mesh.

The following graphic is an example of this process.

	The Quad to M by N Quads option was used to divide the center quadrilateral element into six smaller elements.
	The Quad to 3 Quads option was used to subdivide the four elements that share edges with the center element. Two of those elements are shown in red, for clarity.
	The Quad to 3 Quads option was used to split more of the adjacent elements. The Move Node command was used to reposition nodes on new elements and make them coincident with nodes on surrounding elements.
	The Duplicate Nodes command was used to delete coincident nodes.

Splitting quadrilateral elements based on their warp value

For the Quad to 2 Triangles and Quad to 3 Triangles options, you can use the Element Quality option in the Based on list to divide selected quadrilateral elements whose warp values exceed a specified threshold value. This allows you to eliminate highly warped elements from your model. How the software splits the warped elements depends on whether you want to divide the quadrilateral element into two or three triangular elements.

• With the Quad to 2 Triangles type, the software divides a warped element along the shorter of the element’s diagonal edges.

• With the Quad to 3 Triangles type, the software divides a warped element by inserting a new node in the middle of the element’s longest edge.

Splitting elements by a specified line

With the Split by Line option, the software uses the location of a line you specify as the basis for where and how to split the element. However, the software may not split the element exactly along that line. The software uses the line you specify to determine:

• Which element to split.

• How to split the element (for example, whether the software needs to split a quadrilateral element into small quadrilateral elements or split a quadrilateral element into triangular elements).

• Which edge of the element needs to be divided to facilitate the split.

If the software needs to create a new node to divide an element’s edge, it creates that node in the middle of the element’s edge.

Splitting elements by the length of their shortest diagonal

With the Shortest Diagonal option, the software calculates the length of both of the quadrilateral element's diagonals and then splits the element along the length of its shortest diagonal.

Where do I find it?

Application	Pre/Post
Prerequisite	A FEM file as the displayed part and work part
Command Finder	Split Shell

How do I

Split shell elements

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Splitting shell elements, Simcenter 3D 2021.1 Series

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