6 U-splines

U-splines are a novel spline technology developed by Coreform which seeks to alleviate, if not eliminate, many longstanding limitations in prevailing spline representations, providing a smooth spline meshing technology for industrial-scale FEA applications.

In particular, U-splines can be seen as a generalization of the key innovations underlying both analysis-suitable T-splines (ASTS) and Bézier extraction. Bézier extraction is a method for providing a local Bernstein representation of a non-local smooth spline function, and is used widely in isogeometric analysis (IGA).

With this release, U-splines are now implemented in Coreform Cubit™, making it the world’s first general-purpose isogemetric analysis mesh-preprocessor.

    6.1 U-splines

      6.1.1 Current Limitations

    6.2 Basic CAD to U-spline workflow

      6.2.1 Building U-spline surfaces

      6.2.2 Building U-spline volumes  Map  SubMap  Sweep

 Source surfaces must be contiguous in many-to-one swept meshes

 Entities cannot be creased using build crease group  Sphere  Polyhedron  TetPrimitive

      6.2.3 Commands set uspline build uspline fit uspline quality uspline draw uspline draw uspline projection_error remove uspline

    6.3 Automatic creasing of U-splines

      6.3.1 Creasing of extraordinary vertices

      6.3.2 Continuity grading near creased vertices

      6.3.3 Maintaining distance between perpendicular continuity transitions

      6.3.4 Global creasing options

      6.3.5 Automatic minimal creasing example on a Cubit mesh

      6.3.6 Automatic full creasing on a Cubit mesh

      6.3.7 Automatic full creasing with user-specified creased edges

      6.3.8 Automatic minimial creasing with user-specified creased edges

      6.3.9 U-spline creasing commands build uspline crease group

    6.4 Display U-spline projection error in Cubit

    6.5 Save and load U-splines with Cubit file

      6.5.1 Saving considerations

      6.5.2 History and snapshots

    6.6 Exporting U-splines

      6.6.1 Export formats

      6.6.2 Special options for BEXT U-spline export Exporting block-partitioned BEXT U-splines Exporting U-splines with LS-DYNA node sets Exporting block-partitioned U-splines with node sets Specifying node offsets to prevent node ID collision