To use NIP geometry in a CATPart:
Before diving into the "how," let's define the acronym. NIP stands for NURBS Intersection Point. NURBS (Non-Uniform Rational B-Splines) are the mathematical foundation of CATIA surfaces. An Intersection Point is where a curve or surface boundary interacts with the internal knot vectors of a NURBS patch.
NIP Activity refers to the dynamic visualization and analysis of how these internal control points align or misalign across adjacent surfaces. When you activate NIP display, CATIA shows you the internal "tessellation" or the "skeleton" of the surface—specifically, the isoparametric curves at the knot locations.
Many users stop at just turning the NIP view on. To get the best diagnostic insight, you must interpret and manipulate the view correctly. nip activity catia best
Once your NIP surface is created, the next activity is Harmonize.
Modern aircraft utilize carbon fiber composites, which have complex curing behaviors. The residual stresses in composites are notoriously difficult to predict. CATIA’s NUP capabilities are tailored to handle the orthotropic nature of composites, making it the "best" choice for modern lightweight structures.
For the most robust NIP activity, stop hardcoding numbers. Use CATIA Parameters to build strings dynamically. To use NIP geometry in a CATPart: Before
Create a set of parameters in the Root Product:
Then, create a Formula for the Part Number:
Part Number = ProjectCode + "-" + ZoneCode + "-" + Sequence
Why this is the best method: If the project code changes (e.g., from a prototype to a production code), you only change the Root Parameter, and every single part in the assembly updates its NIP code automatically. Then, create a Formula for the Part Number:
If you are using the FreeStyle Shaper workbench, you have access to the ultimate "nip" tool: Stitch and Trim Free.
The Trim Free command allows you to draw a curve directly onto the intersection of two surfaces to define the nip manually. This offers the highest degree of control. For the absolute best result:
One of the most common frustrations in CATIA is slow drawing regeneration. Before generating views in a Drafting workbench, set all non-essential reference parts to NIP. The drawing will still show them (since they are visible), but CATIA will not generate exact 2D projections for them. Result: 50-70% faster view generation. Remember to reactivate them for final detailing.