Wednesday, January 12, 2011

How do you create a composite part in CATIA Composites Design workbench?

First of all, before we begin getting into creating parts I want to review some information and notes about composites.

What is a composite? Composites = Matrix (resin) + Reinforcing Material (Fiber)

Types of resin include: Polyester, Vinylester, and Epoxy.

Type of fibers include glass, carbon, Kevlar, and aluminum.

Why use composites? Benefits include: reduced weight, high strength and stiffness properties, high thermal and corrosion resistance, and a good fatigue life. What are the manufacturing technology benefits from using composites? Tailor ability, flexibility, and part number reduction.

How are composites manufactured? There are several different methods:

  • Fabric Hands Lay-up – monolithic type or sandwich structures
  • Tape Laying – large composite structures
  • RTM – complex shapes
  • Fiber Placement – large composite structures
  • Filament winding – mandrel shapes
What are some of the cons and challenges of using composites? Number one factor is cost; the raw material can be expensive. There's also a large upfront investment required for manufacturing facilities and equipment. Composites are hard to model due to their unpredictable behavior. Manufacturing cycle time can be longer than machined or sheet metal parts. There are also health hazards and reusability issues.

Composite Terminology

  • IML=inner mold line. Corresponds to top surface of a composites part
  • NCF=non crimp fabrics
  • ETBS=Edges to be Staggered
  • EOP=Edge of Part
  • MEOP=Manufacturing Edge of Part
  • EEOP=Engineering Edge of Part
  • Rosette=axis system
  • TL=thickness law
  • SS=Stacking Sequences
There are two primary methods of creating a composite part in CATIA Composites Design workbench: grid and zone

For the grid method the part is divided up into a grid. Each section of the grid has a name (C1, C2, etc.). Each section of the grid is then given a defined thickness law. The thickness law says how thick the material will be in that zone. This is done by indicating the number of plies in each direction. Example:

Thickness Law 1's material will be Carbon 0.4. # plies in the zero degree direction = 8, number of plies rotated 45 degree = 8, number of plies rotated -45 degree=8, number of plies rotated 90 degrees=9.

Looks like this in Excel which is then imported into CATIA.

Carbon 0.4

Thickness laws can be applied manually or imported through an Excel table.

Be sure to become a follow of this blog and stay tuned for more about composites!

1 comment:

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