Checking and orienting the normals of 3D element faces

Use the 3D Element Face Normals command to:

• Examine the normals of selected or all 3D element faces in the model.

• Reverse the orientation of inward-oriented elements to achieve consistent element connectivity.

Importance of consistent normals for 3D elements

Each element face has a normal that establishes whether the element is oriented inward or outward. The outward normal direction of an element is defined by the right-hand rule.

Consistent elements normals help ensure that the FEM is setup correctly. For example, consistent normals are important for properly defining contact between two surfaces.

This check is also important to avoid mixing elements in a model that could lead to a misinterpretation of results.

Checking and reorienting element normals

The software displays green (default) to represent the faces of elements with outward-facing normals and red (default) to represent the faces of elements with inward-facing normals.

Faces shown in green to indicate outward-facing normals and in red to indicate inward-facing normals

After you check the 3D element face normals, you can use the Re-orient Left-Handed Elements command in the 3D Element Face Normals dialog box to reorient the direction of the normals. The software reorients the normals for all 3D elements on the selected face or within the selected mesh. When you reorient element normals, you reverse the connectivity of that element. For example, if the software created an element's nodes in the order of 1, 12, 13, 2, 122, 133, 134, 123, the order changes to 1, 2, 13, 12, 122, 123, 134, 133.

You can use the Create Group of Left-Handed Elements command in the 3D Element Face Normals dialog box to create a group of the 3D elements that have inward-facing normals. The software creates a Left-Handed 3D Elements group in the Simulation Navigator under the Groups folder.

Where do I find it?

Application	Pre/Post
Prerequisite	A FEM file or Simulation file as the work part and displayed part
Command Finder	3D Element Face Normals
Simulation Navigator	Right-click the 3D Collectors collector container→Check All→3D Element Face NormalsorRight-click the 3D mesh collector→Check→3D Element Face Normals

Learn more

Checking your finite element model

Checking for free and non-manifold element edges

Aligning the first edges of 2D elements

Checking and orienting the directions of 1D elements

Checking and orienting the normals of 2D elements

Checking aerodynamic panel meshes

Checking for duplicate elements and nodes

Detecting interference and clearance issues between faces

Checking CAE model consistency

Checking the association of nodes to geometry

Checking the completeness of your model prior to a solve

Computing mechanical loads

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Checking and orienting the normals of 3D element faces, Simcenter 3D 2021.1 Series

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