Composite Composite MaterialsMaterialsManufacturingManufacturing
정분방
IntroductionIntroduction 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
Applications
Aerospace industry Sporting goods Automotive Construction
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
Material Forms and Material Forms and mmanufacturinganufacturing
Objectives of material production assemble fibers impregnate resin shape product cure resin
Sheet Molding Compound (SMC)Sheet Molding Compound (SMC)
Chopped glass fiber added to polyester resin mixture
Manufacturing - Filament WindingManufacturing - 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.
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
Manufacturing - LayupsManufacturing - Layups
compressionmolding
vacuum bagging
AutoclaveAutoclave
Limitationslabor intensive, high labor cost
Advantagesgood for building prototype parts and small quantity runs
Resin transfer molding (RTM)Resin transfer molding (RTM)
Dry-fiber preform placed in a closed mold, resin injected into mold, then cured
High cost, tooling design is complex
Manufacturing - Manufacturing - PultrusionPultrusion 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
PultrusionPultrusion
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