CATIA

CATIA is the high-end CAD platform of aerospace and automotive. Learn its workbenches, part and assembly design, generative shape design (surfacing), continuity (G0–G3), Class-A surfaces, knowledgeware (parameters, formulas, rules) and the 3DEXPERIENCE environment.

Aircraft, cars and ships are dominated by complex, flowing surfaces and gigantic assemblies. CATIA was built for exactly that: Boeing and Airbus airframes, most car bodies-in-white and many engines are designed in it.

Its strength is hybrid solid-and-surface modelling, powerful surfacing and knowledge-based engineering for large, rule-driven programmes.

An analogy

If solid modelling is carving from a block, surface modelling is tailoring fabric: you shape thin skins precisely, stitch them together, then thicken or close them into solids.

Workbenches

Part Design (solids), Sketcher, Assembly Design, Generative Shape Design (wireframe and surfaces), Drafting, Sheet Metal, Composites Design, Kinematics, Knowledgeware, and analysis modules. In 3DEXPERIENCE they become apps on a shared database.

Hybrid and surface modelling

Create wireframe (points, lines, splines), build surfaces (extrude, sweep, fill, multi-section), trim/join them, and close or thicken into solids. Geometric sets organise construction geometry. This is how car panels, aircraft skins and moulded plastics are modelled.

Continuity and quality

G1 (tangent) blends hide sharp edges; G2 (curvature) continuity avoids visible reflection breaks on painted surfaces. Class-A surfacing (ICEM/CATIA Imagine & Shape) targets G2–G3 with smooth curvature combs and zebra/highlight analysis.

Knowledge-based engineering and scale

Parameters, formulas, rules, checks, templates (PowerCopies, UDFs) and scripts (VBA, EKL, CAA) automate repetitive design — e.g. thousands of aircraft brackets or ribs. Large assemblies use cache mode, skeleton/master-geometry approaches and PLM (ENOVIA) for configuration management.

Formulas

• Curvature: κ = 1 / R
• Knowledgeware formula: Thickness = Length / 20
• Pappus (revolved volume): V = A · 2π r_centroid

Worked example: Volume of a revolved ring

Given: Rectangle 20 × 40 mm; Centroid 50 mm from axis

Find: Volume of the revolved solid.

• V = A · 2π r = 800 × 2π × 50
• = 251 327 mm³ ≈ 251 cm³

Answer: ≈ 251 cm³ (CATIA's Measure Inertia confirms)

Worked example: Rule-driven material

Given: Rule: Load > 5000 N → titanium

Find: Material for Load = 6200 N and Length = 120 mm.

• Thickness = 120/20 = 6 mm
• Load > 5000 → Ti-6Al-4V

Answer: 6 mm, titanium

Knowledgeware rule (EKL-style)

/* Parameters: Length (mm), Load (N), Thickness (mm), Material (string) */
Thickness = Length / 20

if Load > 5000N
{
   Material = "Ti-6Al-4V"
   Message("High load: switching to titanium")
}
else
{
   Material = "Al 7075-T6"
}

/* Check: warn if the part is too thin */
Check_MinThk : Thickness >= 2mm

Formulas, rules and checks embed engineering knowledge so models adapt and flag violations automatically.

Common mistakes

• Wrong: Building everything as solids when shape is surface-driven. — Right: Model complex skins as surfaces, then close/thicken.
• Wrong: Ignoring curvature quality on visible surfaces. — Right: Check G2 with curvature combs, zebra and highlight lines.

Applications

• Aerospace: Airframes, wiring harnesses, composites layup design (Airbus, Boeing, Dassault).
• Automotive: Body-in-white, Class-A exterior surfaces, powertrain.
• Shipbuilding & industrial: Hull surfaces, large assemblies with PLM.

Key takeaways

• Hybrid solids + surfaces for complex shapes.
• Know G0–G3 continuity; Class-A needs G2+.
• Knowledgeware embeds rules and checks.
• Built for massive aerospace/auto programmes with PLM.

Going further

• CAA: Component Application Architecture (C++) for deep customisation.
• Composites design: Ply layup, draping simulation and flat patterns for carbon-fibre structures.
• 3DEXPERIENCE: Cloud/PLM platform unifying CAD, simulation, manufacturing and data management.