Sheet Body Overview | Statement List
BSURF creates a body whose underlying surface type is a B-surface.
Create these bodies in three different ways: through a series of points, through a series of curves, and by converting an existing sheet.
BSURF can create both solid bodies and sheet bodies. Solid bodies are created when you use the optional minor word CLOSED and the resulting body is closed in both U and V directions, or closed in one direction and the other direction has planar ends.
A patch is a portion of a sheet. Using more patches to create a sheet gives you more localized control over the curvature of the sheet. B-surface can consist of either a single patch or multiple patches.
There are many different types of B-surfaces. The ones used in NX are non-uniform rational B-surfaces, sometimes referred to as NURB surfaces.
A B-surface has a degree in its U direction and a degree in its V direction. Degree is a mathematical concept; it actually refers to the degree of the polynomial or rational functions that are used to describe the surface.
A higher degree surface is stiffer in the sense that you have to move its control vertices a long way to produce any appreciable change in the shape of the surface. Lower degree surfaces are more pliable, and tend to follow their control vertices much more closely.
In NX, the degree of a B-surface (in either direction) must be between 1 and 24. However, we recommend that you use cubics (a degree of 3) when creating B-surfaces. Creating lower degree surfaces results in faster performance during subsequent operations such as machining and display. Using higher degree surfaces reduces the chance of transferring data to other systems which may not support them. Also, the creation of a high degree surface through many points may lead to unpredictable results.