Composite Materials Manufacturing Composite Materials Manufacturing 정분방.
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Transcript of Composite Materials Manufacturing Composite Materials Manufacturing 정분방.
IntroductionDefinition: a material composed of 2 or more constituentsReinforcement (e.g., Fibers)matrix (e.g.,epoxy)
AdvantagesHigh strength and stiffnessLow weight ratioMaterial can be designed in addition to the structureCan manufacture structures and eliminate joints
Aerospace industrySporting goodsAutomotiveConstruction
Costs of composite manufacture
Material costs -- higher for compositesConstituent materials (e.g., fibers and resin)Processing costs -- embedding fibers in matrix
Design costs -- lower for compositesCan reduce the number of parts in a complex assembly by designing the material in combination with the structure
Material Forms and manufacturingObjectives of material productionassemble fibersimpregnate resinshape productcure resin
Sheet Molding Compound (SMC)Chopped glass fiber added to polyester resin mixture
Manufacturing - Filament WindingHighly automatedlow manufacturing costs if high throughpute.g., Glass fiber pipe, sailboard maststhe only manufacturing technique suitable for making certain specialized structures, such as pressure vessels.
PrepregsPrepreg and prepreg layupprepreg - partially cured mixture of fiber and resinUnidirectional prepreg tape with paper backingwound on spoolsCut and stackedCuring conditionsTypical temperature and pressure in autoclave is 120-200C, 100 psi
Manufacturing - Layupscompressionmoldingvacuum bagging
Autoclave Limitationslabor intensive, high labor cost
Advantagesgood for building prototype parts and small quantity runs
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 - PultrusionFiber 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