When two surfaces are assembled (e.g., a door panel meeting a fender), the eye (and mathematics) looks for continuity:
However, you can have G2 continuity globally but still have local "waviness" or "pulsing" reflections. This happens when the internal knot vectors (the NIPs) of the two surfaces do not align. The best CATIA users rely on NIP activity to catch this "micro-waviness" that standard curvature analysis misses. nip activity catia best
CATIA’s Cache System works excellently with NIP. Set non-critical parts to NIP during initial loading. This loads their visual representation (CGR - Visualization mode) without loading their full geometric data. Best practice: For standard nuts, bolts, and small brackets in a master assembly, set them to NIP by default. Activate them only when detailed design work is required. When two surfaces are assembled (e
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. However, you can have G2 continuity globally but
Aviation authorities require proof that an aircraft structure can withstand limit loads. NUP activity provides the documented simulation data necessary to prove that the structure is sound even after the initial manufacturing distortions have occurred.
| Mistake | Consequence | Fix | | :--- | :--- | :--- | | Too many NIPs | Wavy, "golf ball" surface | Use Decrease NIP Density | | Ignoring Tangency | Sharp shadows across the surface | Use Connect Checker before NIP activity | | Moving NIPs individually | Local dimples | Use Global Deformation or Smoothing |
For organizations utilizing the 3DEXPERIENCE platform or standalone CATIA analysis tools, NUP activity offers distinct competitive advantages: