Cubit
15.9 *User
Documentation*

The collapse command allows the user to collapse small angles using virtual geometry. The command syntax is:

Collapse Angle at Vertex <id range> [angle <degrees>] [Curve <id1> [Arc_length <length>]] [Curve <id2> [Arc_length <length> | Same_size | Perpendicular | Tangent]] [Composite_vertex <angle>] [Preview]

The collapse angle command is used to eliminate small angles at vertices, where curves meet at a tangential point. The command will split each curve at a specified distance (δ1 and δ2 ) as shown in Figure 1, and create two new vertices along those curves. The remaining small angle will be composited into its neighboring surface using virtual geometry. One of two methods may be used for specifying options for the **collapse angle** command: **(1) Simple**, and **(2) Complete** as described below:

**(1) Simple**

Curves are not specified for this option. Instead, Cubit will automatically identify the smallest angle at the vertex and collapse it using the **tangent** option described below (see Figure 4). An optional **angle** option may also be specified that controls the arc length (δ1) along curve C1 where the curve will be split. If not specified a value of 30 degrees will be used. For the **simple** option of this command, a range of vertices may be used. The **complete** version of the command requires exactly one vertex and two curves.

**(2) Complete**

The complete options of the command allow you to specify which curves and where to split each curve. You must input a distance for the first curve ( δ1), but the second location can be determined based on the length and direction of the first curve.

The **arclength** option will split each curve at a specified distance δ1 and δ2, (See Figure 1) measured from the vertex. You must input at least one **arclength** for each of the options listed below.

The **same_size** option will split curve 2 so that the two resulting curves, δ1 and δ2, are the same length as shown in Figure 2.

The **perpendicular** option will split curve 2 so it is perpendicular to the split location on curve 1, as shown in Figure 3.

The **tangent** option will split curve 2 where a line tangent to curve 1 at the split location intersects curve 2, as shown in Figure 4.

The **composite_vertex** option automatically composites resulting surfaces if there are only two curves left at the vertex, and the angle is less than a specified tolerance.

The **preview** option will preview composited surface before applying changes.