Composite materials are composed of two or more constituents, a reinforcement like fibers and a matrix like epoxy. Composites offer advantages like high strength and stiffness with low weight. They can be designed and manufactured to eliminate joints. Common applications include aerospace, sports, automotive, and construction. Composite manufacturing involves assembling fibers, impregnating resin, shaping the product, and curing the resin. Different manufacturing methods include sheet molding compound, filament winding, prepregs, layups, autoclaves, resin transfer molding, and pultrusion. Each has advantages and limitations depending on the application.

1. Composite Materials
Manufacturing
정분방

3. Introduction
 Definition: a material composed of 2 or more
constituents
 Reinforcement (e.g., Fibers)
 matrix (e.g.,epoxy)
 Advantages
 High strength and stiffness
 Low weight ratio
 Material can be designed in addition to the structure
 Can manufacture structures and eliminate joints

4. Applications
 Aerospace industry
 Sporting goods
 Automotive
 Construction

5. Costs of composite manufacture
 Material costs -- higher for composites
 Constituent materials (e.g., fibers and resin)
 Processing costs -- embedding fibers in matrix
 Design costs -- lower for composites
 Can reduce the number of parts in a complex assembly by
designing the material in combination with the structure

6. Material Forms and manufacturing
 Objectives of material production
 assemble fibers
 impregnate resin
 shape product
 cure resin

7. Sheet Molding Compound (SMC)
 Chopped glass fiber added to polyester resin
mixture

8. Manufacturing - Filament Winding
 Highly automated
 low manufacturing costs if
high throughput
 e.g., Glass fiber pipe,
sailboard masts
 the only manufacturing
technique suitable for
making certain specialized
structures, such as
pressure vessels.

9. Prepregs
 Prepreg and prepreg layup
 “prepreg” - partially cured mixture of fiber and
resin
 Unidirectional prepreg tape with paper backing
 wound on spools
 Cut and stacked
 Curing conditions
 Typical temperature and pressure in autoclave is 120-
200C, 100 psi

10. Manufacturing - Layups
compression
molding
vacuum bagging

11. Autoclave
Limitations
labor intensive, high
labor cost
Advantages
good for building prototype
parts and small quantity runs

12. Resin transfer molding (RTM)
 Dry-fiber preform placed in a closed mold, resin
injected into mold, then cured
 High cost, tooling design is complex

13. Manufacturing - Pultrusion
 Fiber and matrix are pulled through a die, like extrusion
of metals -- assembles fibers, impregnates the resin,
shapes the product, and cures the resin in one step.
 Example:Fishing rods
Advantages:
simple low-cost, continuous, and automatic process.
Limitations:
the axial direction, fiber angles 0°, not suit for tapered
and complex shapes

14. Pultrusion

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