Creating a midsurface by pairing faces

Use the Midsurface by Face Pairs command to define a midsurface on a body by selecting the faces to pair. The software uses the paired faces to:

• Determine the appropriate size and shape of the midsurface.

• Calculate the thickness values to apply to the midsurface.

The process for creating a midsurface by face pairs

The Midsurface by Face Pairs command:

• Lets you define pairs of faces for a selected solid body.

• Creates a separate mid-sheet for each face pair.Note: The Midsurface by Face Pairs command does not stitch the individual mid-sheets.

• Extends each individual mid-sheet with respect to the other mid-sheets.

• Trims each individual mid-sheet with respect to the related face pair and the solid body.

Creating the face pairs and generating the mid-sheets on those face pairs is an iterative process. The Midsurface by Face Pairs dialog box contains a number of tools that you can use to define and modify the face pairs as well as control the mid-sheet creation and trimming. See Create a midsurface by face pairs and Understanding midsurface creation and trimming methods for more information.

Selecting a solid body for midsurface creation

In the Midsurface by Face Pairs dialog box, you must select a solid body on which to define the face pairs. You cannot use the Midsurface by Face Pairs command to create face pairs between individual sheet bodies or between faces on a sheet body.

Although the Midsurface by Face Pairs dialog box allows you to select multiple solid bodies, you cannot use this option to establish a connection between the solid bodies.

• The software creates one midsurface feature for each solid body.

• The software does not extend or connect mid-sheets between solid bodies.

Note:

You can only use the Midsurface by Face Pairs command on a solid body that has been either promoted or WAVE linked. For more information, see Associative copy techniques for CAE workflows.

Creating a midsurface on an imported solid body

You can use Midsurface by Face Pairs to create a midsurface on a solid body that you imported from another CAD software package. Before you use Midsurface by Face Pairs on an imported solid body, you can choose Home tab→Synchronous Modeling group→Optimize Face to convert B-spline surfaces to simple analytical surfaces. Typically, analytical surfaces have tighter tolerances and cleaner geometry than imported B-spline surfaces.

For more information, see Optimize Face.

Computing the thickness of a midsurface created by face pairs

How the software computes the thickness of a midsurface created by face pairs depends upon whether the pair contains single faces or multiple faces.

• For face pairs that are comprised of multiple faces on each side, the software casts a ray along the normal from each node in the mesh on the midsurface to the faces in the face pairs. The software sums the calculated lengths of the rays to determine the appropriate thickness at that node.If the software casts a ray from a node and the ray does not intersect with a face in the face pair, the software searches for the next closest point on the side 1 faces in the pair. The software uses that point to find the closest distance to the side 2 faces and uses this value as the thickness value at the node.

• For face pairs that are comprised of a single face on each side, the software performs a quick check of the thickness by computing the thickness values at sample points. If the distance between these points is < 5% deviation, the software assumes that the thickness is constant. The software then assigns a single, constant thickness value to each node on the midsurface.If the distance between these points is > 5% deviation, the software assumes that the thickness is non-uniform. The software then uses the same ray-casting technique it uses for multi-face pairs to calculate the thickness value at each node.

To determine the thickness of a midsurface you created with the Midsurface by Face Pairs command,

After you create and mesh a midsurface, you should validate that the assigned thickness values are correct. For more information, see Creating displays to validate element thickness.

How do I

Create a midsurface by face pairs

Modify the face pairs in an existing midsurface

Define a midsurface with the Offset method

Define a midsurface with the User Defined method

Insert a replacement mid-sheet into a face pair

Learn more

Creating midsurfaces before meshing

Selecting appropriate parts for midsurfacing

Understanding face pair creation

Working with the Face Pair list

Understanding midsurface creation and trimming methods

Controlling midsurface display

Creating a midsurface with the Offset method

Creating user-defined midsurfaces

Quick links

Command reference

Pre/Post video examples

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Creating a midsurface by pairing faces, Simcenter 3D 2021.1 Series

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